- vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 39183] GRB 250720B: Fermi GBM Final Localization Correction
by GCN Circulars 20 Jul '25

20 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41127 SUBJECT: GRB 250720B: Fermi GBM Final Localization Correction DATE: 25/07/20 22:45:55 GMT FROM: sumanbala2210(a)gmail.com The Fermi GBM team reports the detection of a likely SHORT GRB "At 18:57:10.30 UT on 20 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250720B (trigger 774730635/250720790). This trigger was initially classified as Distant Particles by the flight software, but is in fact a GRB. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 92.04, Dec = -80.65 (J2000 degrees, equivalent to J2000 6h 8m, -80d 39'), with a statistical uncertainty of 5.52 degrees. The angle from the Fermi LAT boresight is 152 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250720790/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250720790/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250720790/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/41127. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39182] GRB 250720A: Fermi GBM Final Localization
by GCN Circulars 20 Jul '25

20 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41126 SUBJECT: GRB 250720A: Fermi GBM Final Localization DATE: 25/07/20 22:44:51 GMT FROM: sumanbala2210(a)gmail.com The Fermi GBM team reports the detection of a likely LONG GRB "At 08:13:44.04 UT on 20 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250720A (trigger 774692029/250720343). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 69.25, Dec = 23.87 (J2000 degrees, equivalent to J2000 4h 36m, +23d 52'), with a statistical uncertainty of 9.02 degrees. The angle from the Fermi LAT boresight is 94 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250720343/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250720343/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250720343/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/41126. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39181] Fermi trigger No 774730635: Global MASTER-Net observations report
by GCN Circulars 20 Jul '25

20 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41125 SUBJECT: Fermi trigger No 774730635: Global MASTER-Net observations report DATE: 25/07/20 22:16:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB250720.79 (trigger No 774730635,06h 08m 09.60s , -80d 39m 00.0s, R=5.52) errorbox 8747 sec after notice time and 8781 sec after trigger time at 2025-07-20 21:23:31 UT, with upper limit up to 19.7 mag. The observations began at zenith distance = 67 deg. The sun altitude is -68.5 deg. The galactic latitude b = -29 deg., longitude l = 293 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2942376 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 8811 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 02m 59.30s , -80d 27m 46.8s) | C | 60 | 18.8 | 8871 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 02m 59.34s , -80d 27m 46.6s) | C | 180 | 19.6 | Coadd 8811 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 13m 30.89s , -80d 42m 49.8s) | C | 60 | 18.8 | 8871 | 2025-07-20 21:23:31 | MASTER-SAAO | (06h 13m 30.90s , -80d 42m 49.8s) | C | 180 | 19.7 | Coadd 8891 | 2025-07-20 21:24:50 | MASTER-SAAO | (06h 02m 59.31s , -80d 27m 43.2s) | C | 60 | 19.0 | 8891 | 2025-07-20 21:24:50 | MASTER-SAAO | (06h 13m 30.67s , -80d 42m 46.5s) | C | 60 | 19.0 | 8970 | 2025-07-20 21:26:09 | MASTER-SAAO | (06h 02m 59.58s , -80d 27m 41.8s) | C | 60 | 19.0 | 8970 | 2025-07-20 21:26:09 | MASTER-SAAO | (06h 13m 30.80s , -80d 42m 44.5s) | C | 60 | 19.0 | 9048 | 2025-07-20 21:27:28 | MASTER-SAAO | (06h 02m 59.74s , -80d 27m 41.8s) | C | 60 | 18.9 | 9048 | 2025-07-20 21:27:28 | MASTER-SAAO | (06h 13m 30.95s , -80d 42m 43.7s) | C | 60 | 19.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41125. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39180] LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate
by GCN Circulars 20 Jul '25

20 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41124 SUBJECT: LIGO/Virgo/KAGRA S250720j: Retraction of GW compact binary merger candidate DATE: 25/07/20 03:09:16 GMT FROM: Sourav Das at IUCAA <sourav.das(a)iucaa.in> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: The trigger S250720j is no longer considered to be a candidate of interest. The significance arose from a coincidence with a Fermi GRB trigger. Further analysis by Fermi showed that the event was not a GRB [1]. [1] R. Hamburg, et al., GCN Circ. 41123 (https://gcn.nasa.gov/circulars/41123) View this GCN Circular online at https://gcn.nasa.gov/circulars/41124. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39179] Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB
by GCN Circulars 20 Jul '25

20 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41123 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 774670514/250720094 is not a GRB DATE: 25/07/20 02:42:21 GMT FROM: rhamburg(a)usra.edu R. Hamburg (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 774670514/250720094 at 02:15:09.73 UT on 20 July 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/41123. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39178] EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit
by GCN Circulars 19 Jul '25

19 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41122 SUBJECT: EP250702a/GRB250702B,D,E: SVOM/VT optical upper limit DATE: 25/07/19 15:21:36 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM mission team. SVOM/VT conducted two ToO follow-up observations of EP250702a (Cheng et al., GCNs 40906, 40917), which was likely associated with the long burst GRB250702B,D,E (Fermi GBM Team, GCNs 40883, 40886, 40890; DeLaunay et al., GCN 40903; Frederiks et al., GCN 40914; Wang et al., GCN 40923). The first observation was made on July 3, 2025 in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channel simultaneously, between 10:54:08 and 15:10:00 (UTC), 32.0 to 36.3 hours after the EP/WXT trigger (Cheng et al., GCN 40906). The second one was made on July 5, 2025, between 08:56:18 and 15:41:13, 3.25 days to 3.53 days after the EP/WXT trigger (Cheng et al., GCN 40906). The counterpart detected by VLT (Martin-Carrillo et al., GCN 40924; Levan et al., GCN 40961), MOSFIRE (Sharma et al., GCN 41044), HST (Levan et al., GCN 41096), MeerKAT (Bright et al., GCN 40985), VLA (Sfaradi et al., GCN 41053) and ALMA (Alexander et al., GCN 41059) was not detected in our images for both observations. The 3 sigma upper limit magnitudes were estimated: Mid-time | Exposure time | Band | upper limit (AB) 34.2 hours | 80*100 sec | VT_R | 23.6 34.2 hours | 81*100 sec | VT_B | 23.8 3.53 days | 81*100 sec | VT_R | 23.6 3.53 days | 81*100 sec | VT_B | 23.8 The Mid-time above is the relative time from the trigger time of EP/WXT (Cheng et al., GCN 40906). The result is consistent with the optical upper limit from GOTO (Kumar et al., GCN 40908), MASTER (Lipunov et al., GCN 40912), Colibri (Becerra et al., GCN 40918), CAHA (Pérez-García et al., GCN 40929), WFST (Hua et al., GCN 40943), FTW (Busmann et al., GCN 40949), UVOT (Siegel et al., GCN 40952), SYSU (Li et al., GCN 40986) and GRANDMA(Akl et al., GCN 41016). The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. View this GCN Circular online at https://gcn.nasa.gov/circulars/41122. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39177] GRB 250717B: COLIBRÍ optical upper limit
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41121 SUBJECT: GRB 250717B: COLIBRÍ optical upper limit DATE: 25/07/18 21:30:53 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Enrique Moreno Méndez (UNAM), Francis Fortin (IRAP), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the Fermi/GBM GRB 250717B (Fermi GBM Team et al., GCN Circ. 41107) at the Swift/BAT-GUANO localization (Ronchini et al., GCN Circ. 41110) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-07-18 09:16 to 11:31 UTC (from 19.5 to 21.8 hours after the trigger) and obtained 101 minutes of exposure in the i filter. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source at the Swift/BAT-GUANO error region (Ronchini et al., GCN Circ. 41110), including the XRT candidate position (Dichiara et al., GCN Circ. 41119) down to the following 5-sigma limit: i > 21.8 We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41121. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39176] LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41120 SUBJECT: LIGO/Virgo/KAGRA S250711q: Upper limits from Swift/BAT-GUANO DATE: 25/07/18 19:06:21 GMT FROM: Maia Williams at PSU <mjw6837(a)psu.edu> Maia Williams (PSU), Samuele Ronchini (PSU), Gayathri Raman, James DeLaunay (PSU), Tyler Parsotan (NASA GSFC), Jamie A. Kennea (PSU), Aaron Tohuvavohu (Caltech) report: Swift/BAT was observing 73.58% of the GW localization probability ([bayestar.multiorder.fits](https://gracedb.ligo.org/api/superevents/S250711q…) at merger time. A fraction 58.56% of the GW localization posterior is contained inside the BAT coded FoV. The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; [Tohuvavohu et al. 2020, ApJ, 900, 1](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. Using the NITRATES analysis ([DeLaunay + Tohuvavohu 2022, ApJ, 941, 169](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits. We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins. In units of 10^-7 erg/s/cm^2: |time_bin (s) |soft |normal|hard |GRB170817 |-|-|-|-|-| |0.256 |3.27 |2.72 |2.52 |2.89 |1.024 |1.67 |1.39 |1.29 |1.48 |4.096 |0.90 |0.75 |0.70 |0.80 |16.384 |0.57 |0.47 |0.44 |0.50 The upper limits as function of sky position are plotted here, alongside the GW localization: https://zenodo.org/records/16106142 The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/41120. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39175] GRB 250717B: Swift-XRT observations
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41119 SUBJECT: GRB 250717B: Swift-XRT observations DATE: 25/07/18 16:03:37 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 250717B, collecting 2.8 ks of Photon Counting (PC) mode data between T0+27.9 ks and T0+34.0 ks. One uncatalogued X-ray source has been detected within the estimated BAT-GUANO error region (3 arcmin), it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below: Source 1: RA (J2000.0): 44.1037 = 02:56:24.88 Dec (J2000.0): +26.3758 = +26:22:32.8 Error: 8.9 arcsec (radius, 90% conf.) Count-rate: (1.90 [+1.27, -0.91])e-3 ct s^-1 Distance: 47 arcsec from BAT-GUANO position. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021846. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41119. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39174] GRB 250717B: Swift-XRT observations
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41119 SUBJECT: GRB 250717B: Swift-XRT observations DATE: 25/07/18 16:03:37 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), D.N. Burrows (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 250717B, collecting 2.8 ks of Photon Counting (PC) mode data between T0+27.9 ks and T0+34.0 ks. One uncatalogued X-ray source has been detected within the estimated BAT-GUANO error region (3 arcmin), it is below the RASS limit and shows no definitive signs of fading. Therefore, at the present time we cannot confirm this as the afterglow. Details of this source are given below: Source 1: RA (J2000.0): 44.1037 = 02:56:24.88 Dec (J2000.0): +26.3758 = +26:22:32.8 Error: 8.9 arcsec (radius, 90% conf.) Count-rate: (1.90 [+1.27, -0.91])e-3 ct s^-1 Distance: 47 arcsec from BAT-GUANO position. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/ToO_GRBs/00021846. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41119. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39173] GRB 250718B: Fermi GBM Final Localization Correction
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41118 SUBJECT: GRB 250718B: Fermi GBM Final Localization Correction DATE: 25/07/18 09:55:46 GMT FROM: Marianna Dafčíková at Masaryk University <500025(a)mail.muni.cz> The Fermi GBM team reports the detection of a likely SHORT GRB "At 07:05:40.09 UT on 18 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250718B (trigger 774515145/250718296) which was initially named GRB 250718A (GCN 41117). The updated on-ground calculated location, using the Fermi GBM trigger data, is RA = 213.5, Dec = 1.7 (J2000 degrees, equivalent to J2000 14h 14m, 01d 40'), with a statistical uncertainty of 11.2 degrees. The angle from the Fermi LAT boresight is 87 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250718296/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250718296/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250718296/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/41118. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39172] GRB 250718A: Fermi GBM Final Real-time Localization
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41117 SUBJECT: GRB 250718A: Fermi GBM Final Real-time Localization DATE: 25/07/18 07:16:14 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely SHORT GRB At 07:05:40 UT on 18 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250718A (trigger 774515145.094648 / 250718296). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 233.0, Dec = -26.0 (J2000 degrees, equivalent to J2000 15h 31m, -26d 00'), with a statistical uncertainty of 20.3 degrees. The angle from the Fermi LAT boresight is 119.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250718296/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250718296/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250718296/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41117. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39171] Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41116 SUBJECT: Swift Trigger 1334535 / GRB 250718A: COLIBRÍ optical upper limits DATE: 25/07/18 05:24:16 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Enrique Moreno Méndez (UNAM), Francis Fortin (IRAP), Camila Angulo (UNAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Kin Ocelotl López (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of Swift Trigger 1334535 (Siegel et al, GCN Circ. 41115), possibly GRB 250718A, using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-07-18 03:52 to 04:30 UTC (from 3:38 to 4:16 hours after the trigger at 00:14 UTC) and obtained 32 minutes of exposure in the i filter. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. In the stacked image, after subtracting the a template image from Legacy Survey DR10 (Dey et al. 2019), we do not detect any new source in the BAT uncertainty region (Siegel et al, GCN Circ. 41115) down to the following 5-sigma limit: i > 22.7 Our results are compatible with the earlier upper limit reported by Lipunov et al. (GCN Circ. 41114). We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41116. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39170] Swift Trigger 1334535: a possible GRB 250718A
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41115 SUBJECT: Swift Trigger 1334535: a possible GRB 250718A DATE: 25/07/18 00:47:35 GMT FROM: Mike Siegel at PSU/Swift MOC <siegel(a)swift.psu.edu> M. H. Siegel (PSU), R. Gupta (NASA GSFC), S. Lanava (PSU), D. M. Palmer (LANL), B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 00:14:02 UT, the Swift Burst Alert Telescope (BAT) triggered and located possible GRB 250718A (trigger=1334535). The BAT on-board calculated location is RA, Dec 241.998, -11.993 which is RA(J2000) = 16h 07m 59s Dec(J2000) = -11d 59' 35" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a sharp rise with a duration of just a few milliseconds. The peak count rate was ~1070 counts/sec (15-350 keV), at ~0 sec after the trigger. Due to an observing constraint, Swift will not slew to the burst until 01:07 UT. Due to the marginal significance of the BAT image (6.85 sigma), and the lack of prompt XRT and UVOT data, this trigger may be due to a noise fluctuation. Further data are required to determine the nature of this trigger. Burst Advocate for this burst is M. H. Siegel (siegel AT swift.psu.edu). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/41115. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39169] Swift GRB250718.01: Global MASTER-Net observations report
by GCN Circulars 18 Jul '25

18 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41114 SUBJECT: Swift GRB250718.01: Global MASTER-Net observations report DATE: 25/07/18 00:18:39 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB250718.01 (trigger No 1334535,16h 07m 59.47s , -11d 59m 35.9s, R=0.05) errorbox 16 sec after notice time and 35 sec after trigger time at 2025-07-18 00:14:38 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 22 deg. The sun altitude is -30.2 deg. The galactic latitude b = 28 deg., longitude l = 1 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2939309 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 41 | MASTER-OAFA | C | 10 | 19.0 | 57 | MASTER-OAFA | C | 10 | 19.0 | 73 | MASTER-OAFA | C | 10 | 19.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41114. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39168] GRB 250717B: Swift ToO observations
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41113 SUBJECT: GRB 250717B: Swift ToO observations DATE: 25/07/17 21:29:37 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Fermi/GBM-detected event GRB 250717B. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021846 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/GBM event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41113. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39167] EP270713a: Kitab and AbAO Optical Observations
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41112 SUBJECT: EP270713a: Kitab and AbAO Optical Observations DATE: 25/07/17 20:04:29 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), A. Pozanenko (IKI), A. Schmalz (KIAM), R. Ya. Inasaridze (AbAO) and A. Volnova (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 250713A detected by SVOM/ECLAIRs (Maggi et. al, GCN 41078) using the RC-36 telescope of the ISON-Kitab Observatory and the AS-32 telescope of the Abastumani Observatory (AbAO). The observations at Kitab began on 2025-07-13 at 19:29 UT, i.e. ~0.13 days after the trigger, while AS-32 started observations 2025-07-13 at 19:59 UT, i.e. ~0.14 days since trigger. We obtained a series of 120x60 sec images in the clear light with RC-36 and a series of 71x60 sec images in the R-band with AS-32. We have inspected the co-added images from both telescopes for any new optical sources spatially consistent with the X-ray candidates found by EP-FXT (Liang et. al, GCN 41085) and Swift/XRT (Evans et. al, GCN 41086). No new optical sources were found in our observations. However, our searches revealed one known, but brightened optical source J222746.80+384743.9 from the SDSS-DR12 catalog found within the localization of EPF_J222746.7+384738 (90% error radius is 10 arcsec). The magnitudes of J222746.80+384743.9 in SDSS-DR12 are g = 21.54 +/- 0.06 and r = 20.58 +/- 0.04, and i = 20.13 +/- 0.04, which can be transformed by Lupton 2005 transformation into R = 20.31 +/- 0.11. The preliminary photometry of SDSS J222746.80+384743.9 is provided below: Date UT start t-T0 Exp. Filter OT Err. UL Telescope (mid, days) (n*s) (3sigma) 2025-07-13 19:29:20 0.13431 101*60 R n/d n/d 18.5 Kitab 2025-07-13 19:59:02 0.14313 67*60 R 19.28 0.14 19.7 AS-32 The photometry was calibrated using nearby stars from the SDSS-DR12 catalog (R-mags obtained with Lupton 2005 transformations) and not corrected for the Galactic extinction. We can tentatively assume that SDSS J222746.80+384743.9 is a stellar flare if indeed the gamma-ray and X-ray emission came from SDSS J222746.80+384743.9. The optical source reported by NOT (Saccardi et. al, GCN 41091) was not detected by our telescopes. Ref. stars SDSS-DR12 RA Dec R(Lupton 2005 transformation) 336.9314 38.7641 14.28 336.9030 38.7712 16.08 336.9267 38.7809 15.76 336.9080 38.7704 16.35 View this GCN Circular online at https://gcn.nasa.gov/circulars/41112. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39166] GRB 250717B: Fermi GBM Observation
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41111 SUBJECT: GRB 250717B: Fermi GBM Observation DATE: 25/07/17 18:59:30 GMT FROM: Jacob Smith at Fermi-GBM Team <jrs0118(a)uah.edu> Jacob Smith (UAH) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 13:44:22.95 UT on 17 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250717B (trigger 774452667/250717572). which was also detected by Swift/BAT-GUANO (Samuele Ronchini et al. 2025, GCN 41110). The Fermi GBM on-ground location is consistent with the Swift/BAT-GUANO position. The angle from the Fermi LAT boresight is 74 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 6.4 s (50-300 keV). The time-averaged spectrum from T0+0.002 to T0+7.360 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.9 +/- 0.1 and the cutoff energy, parameterized as Epeak, is 75 +/- 5 keV. A Band function fits equally well with Epeak = 72 +/- 6 keV, alpha = -0.9 +/- 0.2 and beta = -3.2 +/- 0.9. The event fluence (10-1000 keV) in this time interval is (1.36 +/- 0.05)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+0.13 s in the 10-1000 keV band is 6.1 +/- 0.3 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/41111. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39165] GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41110 SUBJECT: GRB 250717B: Swift/BAT-GUANO arcminute localization of a burst DATE: 25/07/17 16:46:46 GMT FROM: Samuele Ronchini at PSU <sjs8171(a)psu.edu> Samuele Ronchini (PSU), James DeLaunay (PSU), Aaron Tohuvavohu (Caltech), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (PSU) report: Swift/BAT did not localize GRB 250717B onboard (T0: 2025-07-17T13:44:22 UTC, Fermi GCN 41107). The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. The position is found with the newly developed pipeline BAT-GLIMPSE: Gamma-ray Localization using Imaging and Mosaic techniques for Pointing and Slew Epochs (Ronchini et. al, in prep). The pipeline makes use of the tools from BatAnalysis ([Parsotan et al. 2025](https://iopscience.iop.org/article/10.3847/1538-4357/ade240)). The source is found with an SNR = 26.3. The BAT position is: RA, Dec = 44.1179, 26.3789 deg which is RA(J2000) = 02h 56m 28.30s Dec(J2000) = 26d 22’ 44.0″ with an estimated uncertainty of 3 arcmin radius. More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=774452698 XRT and UVOT follow-up has been requested. Results of follow-up observations will be reported in future circulars. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/41110. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39164] Konus-Wind detection of GRB 250716A
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41109 SUBJECT: Konus-Wind detection of GRB 250716A DATE: 25/07/17 15:32:45 GMT FROM: Dmitry Svinkin at Ioffe Institute <svinkin(a)mail.ioffe.ru> D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, A. Tsvetkova, M. Ulanov, and T. Cline on behalf of the Konus-Wind team, report: The bright, long-duration GRB 250716A (Fermi-GBM detection: Fermi GBM team, GCN 41099; Mukherjee and Meegan, GCN 41102) triggered Konus-Wind at T0=5348.122 s UT (01:29:08.122). The burst light curve shows a multipeaked structure which starts at ~T0-91 s and has a total duration of ~235 s. The emission is seen up to ~20 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250716_T05348/ As observed by Konus-Wind, the burst had a fluence of 2.39(-0.09,+0.09)x10^-4 erg/cm2, and a 64-ms peak flux, measured from T0+2.544 s, of 4.26(-0.33,+0.33)x10^-5 erg/cm2/s (both in the 20 keV - 10 MeV energy range). The time-averaged spectrum of the burst (measured from T0 to T0+88.064 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -1.25(-0.04,+0.04), the high energy photon index beta = -1.78(-0.04,+0.03), the peak energy Ep = 554(-84,+93) keV (chi2 = 124/97 dof). The spectrum near the maximum count rate (measured from T0+0.256 to T0+4.096 s) is best fit in the 20 keV - 10 MeV range by the GRB (Band) model with the following parameters: the low-energy photon index alpha = -0.78(-0.06,+0.07), the high energy photon index beta = -1.59(-0.03,+0.03), the peak energy Ep = 726(-113,+139) keV (chi2 = 106/86 dof). All the quoted errors are at the 68% confidence level. All the quoted values are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/41109. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39163] GRB 250716A: Swift-XRT afterglow detection
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41108 SUBJECT: GRB 250716A: Swift-XRT afterglow detection DATE: 25/07/17 15:12:43 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.A. Williams (PSU), S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/GBM-detected burst GRB 250716A. We searched for X-ray sources in 2.6 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 2.6 ks, obtained between T0+79.5 ks and T0+91.7 ks. An uncatalogued X-ray source is detected within the GOTO error region and is above the RASS 3-sigma upper limit at this position, and is therefore likely the GRB afterglow. Using 2790 s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 66.77171, -46.56649 which is equivalent to: RA (J2000): 04h 27m 05.21s Dec(J2000): -46d 33' 59.4" with an uncertainty of 2.7 arcsec (radius, 90% confidence). This position is 1.9 arcsec from the GOTO position. The light curve can be modelled with a power-law decay with a decay index of alpha=2.755 (+0.015, -0.755). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 2.22 (+0.30, -0.27). The best-fitting absorption column is 6.9 (+6.4, -5.2) x 10^20 cm^-2, in excess of the Galactic value of 1.2 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.0 x 10^-11 (3.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 6.9 (+6.4, -5.2) x 10^20 cm^-2 Galactic foreground: 1.2 x 10^20 cm^-2 Excess significance: 1.8 sigma Photon index: 2.22 (+0.30, -0.27) The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/ToO_GRBs/00021845/Source1.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021845. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41108. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39162] GRB 250717B: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41107 SUBJECT: GRB 250717B: Fermi GBM Final Real-time Localization DATE: 25/07/17 13:54:55 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 13:44:22 UT on 17 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250717B (trigger 774452667.945704 / 250717572). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 44.4, Dec = 20.9 (J2000 degrees, equivalent to J2000 02h 57m, 20d 53'), with a statistical uncertainty of 3.8 degrees. The angle from the Fermi LAT boresight is 70.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717572/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717572/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717572/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41107. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39161] GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41106 SUBJECT: GRB 250716A: Lesedi Detection of Fading Optical Transient GOTO25eyp DATE: 25/07/17 11:01:22 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK <amitkundu515(a)gmail.com> Amit Kumar (RHUL), Nikita Rawat (SAAO), David Buckley (SAAO), Justyn R. Maund (RHUL), Danny Steeghs (Warwick) and Raya Dastidar (UNAB) report: We observed the optical transient GOTO25eyp (AT 2025rhc; Rayson et al., GCN 41103), a candidate counterpart to GRB 250716A (Fermi GBM Team, GCNs 41099, 41102), using the 1-m Lesedi telescope at the South African Astronomical Observatory (SAAO), Sutherland, South Africa. Observations were conducted on 2025 July 17 between 03:08:39 and 04:09:30 UT (~25.66 to ~26.67 hours post-trigger) in g’, r’, i’, and z’ bands (3×360s in g and z, 3×300s in r and i bands). GOTO25eyp was clearly detected in all individual exposures across the four filters. Preliminary aperture photometry yields the following magnitudes in g’ and r’ bands: DATE-OBS T-T0 (hrs) Filter Exp (s) Magnitude (AB) ------------------------------------------------------------------------------------- 2025-07-17T03:08:39 25.66 g’ 360s 18.95 ± 0.09 2025-07-17T03:26:56 25.96 r’ 300s 18.67 ± 0.07 These observations indicate a decline of ~0.6 mag over ~8.4 hours since the initial detection reported by GOTO. This fading behaviour suggests a transient origin for GOTO25eyp and is broadly consistent with the temporal evolution expected from a GRB afterglow. We note that we are considering the GOTO L-band (400–700 nm), which approximates the mean wavelength coverage of the g and r filters. Photometric calibration was performed using reference stars from the SDSS catalogue. Follow-up observations are ongoing, and further analysis is in progress. Data were obtained using the 1-m Lesedi robotic telescope at the SAAO, equipped with the Mookodi low-resolution spectrograph and imager operating in fully robotic imaging mode. We thank the SAAO Instrumentation and Operations (IO) team for their continued support. View this GCN Circular online at https://gcn.nasa.gov/circulars/41106. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39160] GRB 250717A: Fermi GBM Final Real-time Localization
by GCN Circulars 17 Jul '25

17 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41105 SUBJECT: GRB 250717A: Fermi GBM Final Real-time Localization DATE: 25/07/17 03:58:51 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 03:48:11 UT on 17 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250717A (trigger 774416896.059134 / 250717158). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 22.9, Dec = 3.5 (J2000 degrees, equivalent to J2000 01h 31m, 3d 30'), with a statistical uncertainty of 2.9 degrees. The angle from the Fermi LAT boresight is 60.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717158/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717158/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250717158/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41105. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39159] GRB 250716A: Swift ToO observations
by GCN Circulars 16 Jul '25

16 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41104 SUBJECT: GRB 250716A: Swift ToO observations DATE: 25/07/16 23:30:19 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. A. Evans (U. Leicester) reports on behalf of the Swift team: Swift has initiated a ToO observation of the Fermi/GBM-detected event GRB 250716A. Automated analysis of the XRT data will be presented online at https://www.swift.ac.uk/ToO_GRBs/00021845 Any uncatalogued X-ray sources detected in this analysis will be reported on this website and via GCN COUNTERPART notices. These are not necessarily related to the Fermi/GBM event. Any X-ray source considered to be a probable afterglow candidate will be reported via a GCN Circular after manual consideration. Details of the XRT automated analysis methods are detailed in Evans et al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41104. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39158] GRB 250716A: GOTO tentative optical counterpart candidate
by GCN Circulars 16 Jul '25

16 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41103 SUBJECT: GRB 250716A: GOTO tentative optical counterpart candidate DATE: 25/07/16 20:30:19 GMT FROM: Ben Rayson at University of Leicester <br155(a)leicester.ac.uk> B. Rayson, D. O’Neill, B. P. Gompertz, A. Kumar, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to GRB 250716A (Fermi GBM Team, GCNs 41099, 41102). Targeted observations were performed beginning at 2025-07-16 17:07:29 UT, (+15.64h post trigger) and continued through to 2025-07-16 19:03:17 UT (+17.57h post trigger). 85 images were taken, across 10 unique pointings, covering 203 sq degrees, within the 90% localisation contour. ~90.0% of the total 2D localisation probability was covered, with an average 5-sigma depth of 19.9 mag. Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks. A new optical source GOTO25eyp (AT 2025rhc) is identified within the GBM 90% localisation region, lying on the 16% probability contour. The source was initially detected with magnitude L = 18.20 ± 0.04 AB mag at +16.33h post trigger, before fading to L = 18.26 ± 0.04 AB mag at +17.46h post trigger. In total the source was detected in three consecutive epochs. The measured magnitudes are consistent with a decay rate of ~t^(-0.83±0.09). However, we caution that the measured decay is based on a relatively short temporal baseline and is therefore sensitive to scatter in the photometric measurements. The source is coincident with a faint (g=25.15 AB mag) extended source in the legacy survey with a mean photo z=0.98 ± 0.21. We find no evidence of the source prior to the GRB trigger time in previous GOTO observations or the ATLAS forced photometry server (Shingles et al. 2021). Due to the absence of pre-trigger detections, possible power-law decay, and the presence of a candidate host galaxy, we propose GOTO25eyp / AT 2025rhc as a candidate optical counterpart for GRB 250716A. Follow-up observations are encouraged. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/41103. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39157] GRB 250716A: Fermi GBM Observation
by GCN Circulars 16 Jul '25

16 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41102 SUBJECT: GRB 250716A: Fermi GBM Observation DATE: 25/07/16 15:35:42 GMT FROM: oindabimukherjee(a)gmail.com O. Mukherjee (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 01:29:06.25 UT on 16 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250716A (trigger 774322151/250716062). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 65.72, Dec = -48.56 (J2000 degrees, equivalent to J2000 4h 22m, -48d 33'), with a statistical uncertainty of 1.00 degrees. (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a mixture of two Gaussians, one with a radius of 1.8 degrees (52% contribution) and one with a radius of 4.1 degrees (47% contribution) [A. Goldstein et al. 2020, ApJ, 895, 1]). The angle from the Fermi LAT boresight is 126 degrees. The GBM light curve consists of two pulses with a duration (T90) of about 66 s (50-300 keV). The time-averaged spectrum from T0-3.1 to T0+79.9 s is best fit by a Band function with Epeak = 1153 +/- 133 keV, alpha = -1.29 +/- 0.01, and beta = -1.89 +/- 0.03. The event fluence (10-1000 keV) in this time interval is (9.9 +/- 0.1)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+5.5 s in the 10-1000 keV band is 37.9 +/- 0.7 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/41102. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39156] GRB 250714A: SVOM/GRM observation
by GCN Circulars 16 Jul '25

16 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41101 SUBJECT: GRB 250714A: SVOM/GRM observation DATE: 25/07/16 15:02:55 GMT FROM: tanwj(a)ihep.ac.cn SVOM/GRM team: Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Jean-Luc Atteia, Olivier Godet (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright burst GRB 250714A (SVOM trigger reference: sb25071402) at 2025-07-14T07:15:27.00 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#41088). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a main peak following behind a relatively weak emission, with a T90 of 21.6+/-10.2 s in the 15-500 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250714A.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 94.7, DEC= -21.2, GCN#41088), is located at about 101 degree from the SVOM optical axis, which is well outside the ECLAIRs field of view. But the burst emission has been detected by ECLAIRs through reflection onto the Earth atmosphere, and some of the low-energy emission of GRM is also detected through atmosphere reflection. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Wen-Jun Tan (IHEP) (tanwj(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/41101. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39155] Fermi GRB 250716A: Global MASTER-Net observations report
by GCN Circulars 16 Jul '25

16 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41100 SUBJECT: Fermi GRB 250716A: Global MASTER-Net observations report DATE: 25/07/16 02:15:32 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250716A ( Fermi GBM team, GCN 41099) errorbox 93 sec after notice time and 128 sec after trigger time at 2025-07-16 01:31:14 UT, with upper limit up to 20.3 mag. The observations began at zenith distance = 65 deg. The sun altitude is -51.6 deg. The galactic latitude b = -44 deg., longitude l = 255 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2937727 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 144 | 2025-07-16 01:31:14 | MASTER-SAAO | (04h 21m 01.64s , -48d 49m 17.3s) | C | 30 | 18.7 | 144 | 2025-07-16 01:31:15 | MASTER-SAAO | (04h 23m 46.59s , -49d 04m 32.8s) | C | 30 | 18.9 | 445 | 2025-07-16 01:36:01 | MASTER-SAAO | (04h 10m 39.54s , -50d 08m 38.2s) | C | 60 | 19.1 | 445 | 2025-07-16 01:36:01 | MASTER-SAAO | (04h 13m 29.24s , -50d 23m 52.1s) | C | 60 | 19.3 | 644 | 2025-07-16 01:39:20 | MASTER-SAAO | (04h 19m 15.27s , -48d 35m 54.2s) | C | 60 | 19.1 | 704 | 2025-07-16 01:39:20 | MASTER-SAAO | (04h 19m 15.27s , -48d 35m 54.2s) | C | 180 | 20.1 | Coadd 644 | 2025-07-16 01:39:20 | MASTER-SAAO | (04h 21m 59.51s , -48d 51m 08.0s) | C | 60 | 19.5 | 704 | 2025-07-16 01:39:20 | MASTER-SAAO | (04h 21m 59.50s , -48d 51m 08.0s) | C | 180 | 20.3 | Coadd 723 | 2025-07-16 01:40:39 | MASTER-SAAO | (04h 19m 15.21s , -48d 35m 54.7s) | C | 60 | 19.2 | 723 | 2025-07-16 01:40:39 | MASTER-SAAO | (04h 21m 59.40s , -48d 51m 08.0s) | C | 60 | 19.3 | 802 | 2025-07-16 01:41:58 | MASTER-SAAO | (04h 19m 15.12s , -48d 35m 55.6s) | C | 60 | 19.2 | 802 | 2025-07-16 01:41:58 | MASTER-SAAO | (04h 21m 59.30s , -48d 51m 08.5s) | C | 60 | 19.4 | 881 | 2025-07-16 01:43:17 | MASTER-SAAO | (04h 19m 14.99s , -48d 35m 56.7s) | C | 60 | 19.2 | 881 | 2025-07-16 01:43:17 | MASTER-SAAO | (04h 21m 59.18s , -48d 51m 09.2s) | C | 60 | 19.5 | 1549 | 2025-07-16 01:54:25 | MASTER-SAAO | (04h 23m 14.98s , -50d 08m 51.1s) | C | 60 | 19.2 | 1549 | 2025-07-16 01:54:25 | MASTER-SAAO | (04h 26m 05.15s , -50d 24m 04.2s) | C | 60 | 19.3 | 1642 | 2025-07-16 01:55:58 | MASTER-SAAO | (04h 10m 40.25s , -50d 08m 03.6s) | C | 60 | 19.2 | 1642 | 2025-07-16 01:55:58 | MASTER-SAAO | (04h 13m 30.51s , -50d 23m 15.5s) | C | 60 | 19.2 | 1737 | 2025-07-16 01:57:32 | MASTER-SAAO | (04h 24m 02.44s , -48d 13m 28.0s) | C | 60 | 19.2 | 1737 | 2025-07-16 01:57:33 | MASTER-SAAO | (04h 26m 45.90s , -48d 28m 40.4s) | C | 60 | 19.3 | 1830 | 2025-07-16 01:59:05 | MASTER-SAAO | (04h 35m 57.93s , -48d 13m 47.8s) | C | 60 | 19.2 | 1830 | 2025-07-16 01:59:06 | MASTER-SAAO | (04h 38m 41.15s , -48d 29m 00.3s) | C | 60 | 19.3 | 2023 | 2025-07-16 02:02:18 | MASTER-SAAO | (04h 13m 05.25s , -48d 15m 56.4s) | C | 60 | 19.2 | 2023 | 2025-07-16 02:02:19 | MASTER-SAAO | (04h 15m 48.99s , -48d 31m 08.2s) | C | 60 | 19.5 | 2117 | 2025-07-16 02:03:53 | MASTER-SAAO | (04h 14m 31.65s , -46d 20m 24.2s) | C | 60 | 19.1 | 2117 | 2025-07-16 02:03:53 | MASTER-SAAO | (04h 17m 09.42s , -46d 35m 36.2s) | C | 60 | 19.3 | 2210 | 2025-07-16 02:05:26 | MASTER-SAAO | (04h 26m 08.46s , -46d 21m 08.9s) | C | 60 | 19.1 | 2210 | 2025-07-16 02:05:26 | MASTER-SAAO | (04h 28m 46.06s , -46d 36m 20.9s) | C | 60 | 19.4 | 2504 | 2025-07-16 02:10:19 | MASTER-SAAO | (04h 23m 06.32s , -50d 07m 32.2s) | C | 60 | 19.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41100. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39154] GRB 250716A: Fermi GBM Final Real-time Localization
by GCN Circulars 16 Jul '25

16 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41099 SUBJECT: GRB 250716A: Fermi GBM Final Real-time Localization DATE: 25/07/16 01:39:42 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 01:29:06 UT on 16 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250716A (trigger 774322151.245036 / 250716062). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 65.7, Dec = -48.6 (J2000 degrees, equivalent to J2000 04h 22m, -48d 36'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 126.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250716062/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250716062/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250716062/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41099. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39153] Fermi GRB 250715A: Global MASTER-Net observations report
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41098 SUBJECT: Fermi GRB 250715A: Global MASTER-Net observations report DATE: 25/07/15 17:31:36 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250715A ( Fermi GBM team, GCN 41097) errorbox 6778 sec after notice time and 6809 sec after trigger time at 2025-07-15 16:47:48 UT, with upper limit up to 19.0 mag. Observations started at twilight. The observations began at zenith distance = 73 deg. The sun altitude is -11.8 deg. The galactic latitude b = 72 deg., longitude l = 88 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2936965 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 6840 | 2025-07-15 16:47:48 | MASTER-SAAO | (13h 39m 24.98s , +41d 17m 09.8s) | C | 60 | 17.4 | 6840 | 2025-07-15 16:47:48 | MASTER-SAAO | (13h 41m 45.27s , +41d 01m 47.1s) | C | 60 | 17.4 | 6933 | 2025-07-15 16:49:21 | MASTER-SAAO | (13h 49m 58.86s , +41d 14m 56.3s) | C | 60 | 17.5 | 6933 | 2025-07-15 16:49:21 | MASTER-SAAO | (13h 52m 19.04s , +40d 59m 32.5s) | C | 60 | 17.5 | 7121 | 2025-07-15 16:52:30 | MASTER-SAAO | (13h 36m 16.48s , +39d 23m 35.6s) | C | 60 | 18.2 | 7121 | 2025-07-15 16:52:30 | MASTER-SAAO | (13h 38m 33.02s , +39d 08m 13.3s) | C | 60 | 18.0 | 7665 | 2025-07-15 17:01:34 | MASTER-SAAO | (13h 46m 43.77s , +39d 21m 51.3s) | C | 60 | 18.6 | 7665 | 2025-07-15 17:01:34 | MASTER-SAAO | (13h 49m 00.33s , +39d 06m 23.4s) | C | 60 | 18.6 | 7759 | 2025-07-15 17:03:07 | MASTER-SAAO | (13h 39m 31.43s , +41d 17m 22.0s) | C | 60 | 18.7 | 7759 | 2025-07-15 17:03:07 | MASTER-SAAO | (13h 41m 51.72s , +41d 01m 53.4s) | C | 60 | 18.6 | 7852 | 2025-07-15 17:04:41 | MASTER-SAAO | (13h 50m 06.50s , +41d 15m 29.6s) | C | 60 | 18.7 | 7852 | 2025-07-15 17:04:41 | MASTER-SAAO | (13h 52m 26.74s , +41d 00m 00.9s) | C | 60 | 18.7 | 8040 | 2025-07-15 17:07:48 | MASTER-SAAO | (13h 36m 21.22s , +39d 23m 06.4s) | C | 60 | 19.0 | 8040 | 2025-07-15 17:07:49 | MASTER-SAAO | (13h 38m 37.98s , +39d 07m 39.5s) | C | 60 | 18.9 | 8230 | 2025-07-15 17:10:58 | MASTER-SAAO | (13h 43m 46.68s , +43d 09m 56.5s) | C | 60 | 18.8 | 8230 | 2025-07-15 17:10:58 | MASTER-SAAO | (13h 46m 11.14s , +42d 54m 27.8s) | C | 60 | 18.5 | 8325 | 2025-07-15 17:12:33 | MASTER-SAAO | (13h 54m 46.94s , +43d 09m 33.9s) | C | 60 | 18.9 | 8325 | 2025-07-15 17:12:33 | MASTER-SAAO | (13h 57m 11.37s , +42d 54m 04.2s) | C | 60 | 18.8 | 8418 | 2025-07-15 17:14:06 | MASTER-SAAO | (13h 46m 44.39s , +39d 23m 28.0s) | C | 60 | 19.0 | 8418 | 2025-07-15 17:14:06 | MASTER-SAAO | (13h 49m 01.18s , +39d 07m 60.0s) | C | 60 | 19.0 | 8511 | 2025-07-15 17:15:40 | MASTER-SAAO | (13h 39m 34.83s , +41d 16m 33.4s) | C | 60 | 18.9 | 8511 | 2025-07-15 17:15:40 | MASTER-SAAO | (13h 41m 55.31s , +41d 01m 04.1s) | C | 60 | 18.8 | 8605 | 2025-07-15 17:17:13 | MASTER-SAAO | (13h 50m 14.55s , +41d 17m 42.6s) | C | 60 | 18.9 | 8605 | 2025-07-15 17:17:13 | MASTER-SAAO | (13h 52m 35.07s , +41d 02m 12.8s) | C | 60 | 19.0 | 8698 | 2025-07-15 17:18:46 | MASTER-SAAO | (13h 38m 42.15s , +39d 07m 59.9s) | C | 60 | 19.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41098. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39152] GRB 250713A: SVOM detection of a long burst
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41078 SUBJECT: GRB 250713A: SVOM detection of a long burst DATE: 25/07/13 17:46:03 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> P. Maggi (ObAS), M. Brunet, L.Bouchet (IRAP), D. Gotz (CEA) report on behalf of the SVOM mission team: At 2025-07-13T17:06:26 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250713A (SVOM burst-id sb25071320). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 7 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 14.04 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2025-07-13T17:06:02. The localization of the best alert is R.A., Dec. 336.9666, 38.7686 degrees (J2000) with a 90% confidence level (C.L.) radius of 5.84 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-07-13T17:08:48 UTC, 142 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 336.9045, 38.7670 degrees: R.A. (J2000) = 22h27m37.09s Dec. (J2000) = 38d46m01.31s with a 90% C.L. radius of 55 arcseconds (including systematic error of 25 arcsec added in quadrature). This location is 2.90 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Pierre Maggi: pierre.maggi(a)astro.unistra.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/41078. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39151] GRB 250715A: Fermi GBM Final Real-time Localization
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41097 SUBJECT: GRB 250715A: Fermi GBM Final Real-time Localization DATE: 25/07/15 15:04:48 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 14:54:18 UT on 15 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250715A (trigger 774284063.63281 / 250715621). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 205.4, Dec = 41.2 (J2000 degrees, equivalent to J2000 13h 41m, 41d 12'), with a statistical uncertainty of 4.3 degrees. The angle from the Fermi LAT boresight is 92.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250715621/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250715621/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250715621/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41097. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39150] EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41096 SUBJECT: EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations DATE: 25/07/15 12:48:10 GMT FROM: Andrew Levan at Radboud University <a.levan(a)astro.ru.nl> EP250702a / GRB 250702BD,D,E: Hubble Space Telescope Observations A. J. Levan (Radboud and Warwick), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Saccardi (CEA/Irfu), P. O’Brien (Univ. of Leicester), R. A. J. Eyles-Ferris (Univ. of Leicester), A. de Ugarte Postigo (LAM), G. Corcoran (UCD), S. D. Vergani (LUX-Paris Obs.), N. R. Tanvir (U. Leicester), B. P. Gompertz (U. Birmingham) report for the Stargate collaboration: We observed the location of EP250702a / GRB 250702B,D,E (Cheng et al., GCNs 40906, 40917; Fermi GBM Team, GCNs 40883, 40886, 40890; DeLaunay et al., GCN 40903; Frederiks et al., GCN 40914) with the Hubble Space Telescope on 15 July 2025. A total of 2196 s of observations were obtained using WFC3 and the F160W (broad-band H) filter. At the location of the infrared counterpart (Martin-Carrillo et al., GCN 40924; Levan et al., GCN 40961) we clearly resolve a galaxy, whose nucleus is offset 0.7” from the transient location. The galaxy has an edge-on morphology, and either a disturbed disc or prominent dust lane. The transient lies on the stellar field of this galaxy, and the low probability of chance alignment (0.05%: Levan et al., GCN 40961) strongly implies that EP250702a / GRB 250702BDE is indeed an extragalactic transient. A weak excess of emission over the smooth disc is present at the transient location, but it appears likely the flux is now dominated by galaxy light. If extragalactic in origin the very long duration of the outburst is extremely unusual. Only relativistic TDEs have been seen to have such long-lived emission in gamma-rays. However, the non-nuclear nature of the transient is not in keeping with the expected location of a supermassive black hole, although is consistent with the expectations for white-dwarf - intermediate mass black hole disruptions. We thank Bill Januszewski, Joel Green, Claus Leitherer and Jennifer Lotz for their rapid work in approving and scheduling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41096. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39149] GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41095 SUBJECT: GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations DATE: 25/07/15 09:19:06 GMT FROM: Mathieu de Naurois at Laboratoire Leprince Ringuet, CNRS, Deputy Director of the H.E.S.S. Collaboration <denauroi(a)in2p3.fr> The H.E.S.S. array of imaging atmospheric Cherenkov telescopes conducted follow-up observations of the transient EP250702a, at the localization provided by the EP-WXT (Cheng et al., GCN 40906). H.E.S.S. observed this source position for a total of 6 hours over 4 consecutive nights, starting on 2025-07-04, under fairly good observing conditions. A preliminary off-site analysis shows no evidence for a significant signal in either the full dataset or the four nights individually, consistent with the non-detection reported by the LST-1 and MAGIC telescopes (Paneque et al., GCN 41067). Our upper limits are expected to be compatible with the H.E.S.S. sensitivity curves (e.g., Fig. 6 of https://doi.org/10.22323/1.236.0847), scaled to the observation duration. The observations took place during the following times: 2025-07-04, 00:06 - 03:01 UTC 2025-07-05, 00:48 - 02:19 UTC 2025-07-06, 01:41 - 03:08 UTC 2025-07-07, 02:36 - 03:00 UTC H.E.S.S. is an array of five imaging atmospheric Cherenkov telescopes that detects very-high-energy gamma rays (>100 GeV) and is located in the Khomas Highland in Namibia. It was constructed and is operated by researchers from Armenia, Australia, Austria, France, Germany, Ireland, Japan, the Netherlands, Poland, South Africa, Sweden, UK, and the host country, Namibia. For more details see https://hess.in2p3.fr/. View this GCN Circular online at https://gcn.nasa.gov/circulars/41095. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39148] GRB 250713A: Mephisto optical upper limits
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41094 SUBJECT: GRB 250713A: Mephisto optical upper limits DATE: 25/07/15 05:31:26 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Helong Guo, Yuan Fang, Yuze Zhao, Runnan Jiang, Guowang Du, Xingzhu Zou, Xinlei Chen, Yu Pan, Xufeng Zhu, Tao Wang, Jinghua Zhang, Brajesh Kumar, Edorardo Lagioia, Dezi Liu, Chenxu Liu, Shiyan Zhong, Weikang Lin, Jianhui Lian, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team: Simultaneous multi-band photometric observations of the SVOM GRB 250713A (Maggi et al., GCN 41078) were performed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations started from 17:11:19 2025-07-13 UT (~5 minutes after the trigger), and several frames were obtained in uvgr bands. In our stacked images, no new optical source was detected within the SVOM/MXT error region and in particular at the EP/FXT Source 2 position (Liang et al., GCN 41085). The 3-sigma upper limits are below: Start_Time(UT) Band Exp (sec) LimMag(AB) 2025-07-13T17:11:19 u 45*6 >20.53 2025-07-13T17:32:27 v 45*6 >20.65 2025-07-13T17:11:19 g 45*6 >21.17 2025-07-13T17:32:27 r 45*6 >21.32 Our results are consistent with Fu et al. (GCN 41079), Wu et al. (GCN 41089), Braun et al. (GCN 41090), Saccardi et al. (GCN 41091) and Li et al. (GCN 41092). ---------------------------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21. ---------------------------------------------------------------------------- View this GCN Circular online at https://gcn.nasa.gov/circulars/41094. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39147] Fermi GRB 250714A: Global MASTER-Net observations report
by GCN Circulars 15 Jul '25

15 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41093 SUBJECT: Fermi GRB 250714A: Global MASTER-Net observations report DATE: 25/07/15 05:31:23 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250714A ( Fermi GBM team, GCN 41088) errorbox 76645 sec after notice time and 76677 sec after trigger time at 2025-07-15 04:33:10 UT, with upper limit up to 18.2 mag. Observations started at twilight. The observations began at zenith distance = 63 deg. The sun altitude is -13.5 deg. The galactic latitude b = -16 deg., longitude l = 229 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2935479 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 76707 | 2025-07-15 04:33:10 | MASTER-SAAO | (06h 08m 06.67s , -21d 35m 24.6s) | C | 60 | 17.9 | 76707 | 2025-07-15 04:33:10 | MASTER-SAAO | (06h 10m 03.90s , -21d 50m 47.4s) | C | 60 | 18.1 | 76801 | 2025-07-15 04:34:43 | MASTER-SAAO | (06h 16m 39.44s , -21d 36m 00.7s) | C | 60 | 17.7 | 76801 | 2025-07-15 04:34:43 | MASTER-SAAO | (06h 18m 36.55s , -21d 51m 23.8s) | C | 60 | 18.0 | 76894 | 2025-07-15 04:36:17 | MASTER-SAAO | (06h 13m 14.34s , -23d 28m 23.7s) | C | 60 | 18.1 | 76894 | 2025-07-15 04:36:17 | MASTER-SAAO | (06h 15m 13.24s , -23d 43m 46.0s) | C | 60 | 18.2 | 76988 | 2025-07-15 04:37:50 | MASTER-SAAO | (06h 21m 58.36s , -23d 29m 38.0s) | C | 60 | 17.8 | 76988 | 2025-07-15 04:37:50 | MASTER-SAAO | (06h 23m 57.16s , -23d 45m 00.4s) | C | 60 | 18.0 | 77361 | 2025-07-15 04:44:03 | MASTER-SAAO | (06h 10m 03.46s , -21d 50m 52.0s) | C | 60 | 16.9 | 77361 | 2025-07-15 04:44:03 | MASTER-SAAO | (06h 08m 05.85s , -21d 35m 28.9s) | C | 60 | 16.5 | 77454 | 2025-07-15 04:45:37 | MASTER-SAAO | (06h 18m 34.24s , -21d 51m 29.2s) | C | 60 | 16.8 | 77548 | 2025-07-15 04:47:10 | MASTER-SAAO | (06h 15m 15.43s , -23d 45m 20.1s) | C | 60 | 16.9 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41093. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39146] GRB 250713A: SVOM/VT optical upper limit
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41092 SUBJECT: GRB 250713A: SVOM/VT optical upper limit DATE: 25/07/14 11:38:39 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), P. Maggi (ObAS), M. Brunet(IRAP), report on behalf of the SVOM mission team. SVOM performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Maggi et al., GCN 41078). SVOM/VT began observing the field at 2025-07-13T17:09:14 UTC, 168 seconds after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued candidate was detected in our single or stacked images within the errorbox of the SVOM/MXT position (Maggi et al., GCN 41078) or FXT (Liang et al., 41085) or XRT (Evens et al., GCN 41086) . The 3-sigma upper limits are: [T-T0, mid-time] | exposure time (s) | band | upper limit (AB) ----------- --------|-------------------|------|----------------- 20.7 min | 44*50 | VT_B | 23.5 20.7 min | 44*50 | VT_R | 23.2 Our results are consistent with Fu et al. (GCN 41079), Wu et al. (GCN 41089), and Braun et al. (GCN 41090) and Saccardi et al. (GCN 41091). NIR follow-ups are encouraged to investigate the nature of the burst. The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. The Burst Advocate (BA) on shift for this alert is Pierre Maggi: pierre.maggi(a)astro.unistra.fr View this GCN Circular online at https://gcn.nasa.gov/circulars/41092. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39145] GRB 250713A: NOT optical upper limits
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41091 SUBJECT: GRB 250713A: NOT optical upper limits DATE: 25/07/14 10:43:55 GMT FROM: Andrea Saccardi at CEA/Irfu <andrea.saccardi(a)cea.fr> A. Saccardi (CEA/Irfu), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. de Ugarte Postigo (LAM), G. Corcoran (UCD), J. T. Palmerio (CEA/Irfu), L. Izzo (INAF/OACN and DARK/NBI), B. P. Gompertz (Birmingham), N. Pyykkinen (Univ. of Turku and NOT), K. Valeckas (NBI and NOT), report on behalf of a larger collaboration: We observed the field of GRB 250713A detected by SVOM/ECLAIRs (Maggi et al., GCN 41078), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT) centered at the X-ray source detected by SVOM/MXT. We obtained 5x200 s exposures in each of the SDSS i and z bands, starting at 23:46:40 UT on 2025-07-13 (6.67 hr after the SVOM/ECLAIRs trigger). No new optical source is detected at a position consistent with the SVOM/MXT error region and in particular with the EP/FXT Source 2 (Liang et al., GCN 41085) in the stacked images of either band, down to the 5-sigma limiting AB magnitudes of i > 22.9 and z > 22.5, calibrated against nearby stars from the Pan-STARRS catalog and not corrected for Galactic extinction. Our results are consistent with Fu et al. (GCN 41079), Wu et al. (GCN 41089), and Braun et al. (GCN 41090). We note the presence of an object just north of EP/FXT Source 2, at coordinates (J2000): RA = 22:27:34.17 Dec = +38:46:23.8 This is just 11" away from the centre of the 10"-radius EP/FXT error circle. This point-like object is detected in both our images and in the archival Pan-STARRS images of the field. It is fainter in the NOT images, by ~0.3 and 0.2 mag in the i and z bands, respectively, indicating long-term variability. It is also listed in the Gaia catalog (doi:10.1051/0004-6361/202243940) as having a ~68% probability of being a QSO. It is thus possible that this object is responsible for the EP/FXT X-ray source, which would be then unrelated to GRB 250713A. We encourage further EP/FXT observations to test for variability of this X-ray source. Further NOT images are planned at a later date to test for short-term variability of objects in the field. View this GCN Circular online at https://gcn.nasa.gov/circulars/41091. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39144] GRB 250713A: OHP/T193 upper limit
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41090 SUBJECT: GRB 250713A: OHP/T193 upper limit DATE: 25/07/14 09:21:22 GMT FROM: Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa(a)lam.fr> O. Braun (LAM/OHP/Pytheas/AMU), C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), report on behalf of a larger collaboration: We observed the field of the GRB 250713A (Maggi et al., GCN 41078; Fu et al., GCN 41079) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 14 exposures (for a total of 60 min) in the r-band starting at 22:26:02 UT on 2025-07-13 (5.3 hours after the trigger). In the stacked images, we do not detect any new source at the MXT position (Maggi et al., GCN 41078). The preliminary upper limit is r > 22.3 mag (AB) at 3 sigma. No other credible source compatible with a GRB is detected in MISTRAL's field of view up to r > 21.7 mag (AB) at 5 sigma. The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025). We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen for the MISTRAL observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41090. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39143] GRB 250713A: OHP/T193 upper limit
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41090 SUBJECT: GRB 250713A: OHP/T193 upper limit DATE: 25/07/14 09:21:22 GMT FROM: Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa(a)lam.fr> O. Braun (LAM/OHP/Pytheas/AMU), C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), report on behalf of a larger collaboration: We observed the field of the GRB 250713A (Maggi et al., GCN 41078; Fu et al., GCN 41079) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 14 exposures (for a total of 60 min) in the r-band starting at 22:26:02 UT on 2025-07-13 (5.3 hours after the trigger). In the stacked images, we do not detect any new source at the MXT position (Maggi et al., GCN 41078). The preliminary upper limit is r > 22.3 mag (AB) at 3 sigma. No other credible source compatible with a GRB is detected in MISTRAL's field of view up to r > 21.7 mag (AB) at 5 sigma. The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025). We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen for the MISTRAL observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41090. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39142] GRB 250713A: SVOM/C-GFT upper limit
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41089 SUBJECT: GRB 250713A: SVOM/C-GFT upper limit DATE: 25/07/14 07:50:58 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei, Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), P. Maggi (ObAS) report on behalf of the SVOM/C-GFT team: We observed the field of GRB250713A (sb25071320) detected by SVOM/ECLAIRs (GCN 41078) with LATIOS on SVOM/C-GFT. Observations started at 2025-07-13T17:07:44 UTC, ~78 seconds after the trigger. A series of g, r, and i band images were obtained under brighter Moon. No credible candidate was detected within the error box provided by SVOM/MXT(GCN 41078), EP/FXT (GCN 41085), and Swift/XRT(GCN 41086) in our images after preliminary processing, the three sigma upper limits are: | Date-Obs (mid-time) | Mid_t - T0 (s) | Exposure Time (s) | Band | Upper Limit (AB) | |---------------------|----------------|-------------------|------|------------------| | 2025-07-13T17:09:13 | 167 | 6×10 | i | 18.12 | | 2025-07-13T17:20:51 | 864 | 6×30 | g | 18.84 | | 2025-07-13T17:24:26 | 1080 | 6×30 | r | 18.38 | This result is consistent with GCN 41079. The photometry was calibrated with UCAC4 catalogue. We thank the observation assistants Chunlei Guo and Guangsheng Zhang at Jilin observatory for their excellent support. The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching. View this GCN Circular online at https://gcn.nasa.gov/circulars/41089. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39141] GRB 250714A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41088 SUBJECT: GRB 250714A: Fermi GBM Final Real-time Localization DATE: 25/07/14 07:25:43 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 07:15:13 UT on 14 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250714A (trigger 774170118.010932 / 250714302). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 94.7, Dec = -21.2 (J2000 degrees, equivalent to J2000 06h 18m, -21d 11'), with a statistical uncertainty of 2.7 degrees. The angle from the Fermi LAT boresight is 57.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250714302/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250714302/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250714302/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41088. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39140] GRB 250706B/C: 7DT Follow-up Observations
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41087 SUBJECT: GRB 250706B/C: 7DT Follow-up Observations DATE: 25/07/14 06:58:11 GMT FROM: Mankeun Jeong <jmk5040(a)gmail.com> Mankeun Jeong (SNU/SNUARC), Myungshin Im (SNU/SNUARC), Hyeonho Choi (SNU/SNUARC), and Seo-Won Chang (SNU/SNUARC) report on behalf of the 7-Dimensional Telescope collaboration We observed the field of GRB 250706B/C (Palmerio et al., GCN 40989; Zhu et al., GCN 40991; Frederiks et al., GCN 41013; Longo et al., GCN 41019) using the 7-Dimensional Telescope (7DT). Observations were conducted on 2025 July 8 in multiple broadband and medium-band filters. We performed forced photometry at the position of the UVOT optical counterpart (GCN 41015; RA = 02:44:53.43, Dec = −50:03:40.2, J2000), using a coadded image from all filters for source detection. Photometric calibration was performed using Gaia XP synthetic photometry (Gaia Collaboration et al. 2022). We report a marginal detection only in the i-band, with a magnitude of i = 19.68±0.38 AB mag at T-T0 ≈ 1.84 days. The following table lists our photometric measurements (AB magnitudes). For non-detections, we provide 5σ upper limits: Filter Mag (AB) Exp(s) UT Date-Obs T−T₀ (days) ----------------------------------------------------------------------- g >19.90 300 2025-07-08 07:21:36 1.842 r >19.88 300 2025-07-08 07:26:58 1.846 i 19.68 ± 0.38 1200 2025-07-08 07:38:17 1.841 m400 >18.19 300 2025-07-08 07:27:01 1.846 m450 >18.85 300 2025-07-08 07:21:33 1.842 m475 >18.94 300 2025-07-08 07:26:58 1.846 m550 >18.65 300 2025-07-08 07:21:40 1.842 m575 >18.69 300 2025-07-08 07:27:08 1.846 m600 >18.71 300 2025-07-08 07:21:41 1.842 m625 >18.56 300 2025-07-08 07:27:15 1.846 m650 >18.81 300 2025-07-08 07:21:34 1.842 m675 >18.78 300 2025-07-08 07:26:57 1.846 m700 >18.62 300 2025-07-08 07:21:29 1.841 m725 >18.46 300 2025-07-08 07:26:50 1.846 m750 >18.31 300 2025-07-08 07:21:36 1.842 m775 >17.94 300 2025-07-08 07:26:59 1.846 m800 >17.70 300 2025-07-08 07:21:43 1.842 m825 >17.63 300 2025-07-08 07:27:13 1.846 m850 >17.06 300 2025-07-08 07:21:31 1.842 m875 >16.84 300 2025-07-08 07:21:37 1.842 View this GCN Circular online at https://gcn.nasa.gov/circulars/41087. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39139] GRB 250713A: Swift-XRT observations
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41086 SUBJECT: GRB 250713A: Swift-XRT observations DATE: 25/07/14 05:58:35 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N. Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA), P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro (INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato (INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source GRB 250713A, collecting 2.0 ks of Photon Counting (PC) mode data between T0+429 s and T0+6.4 ks after the trigger. We have detected 1 source. This has been automatically classified as an uncatalogued X-ray source. Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J222820.3+385214): ================================== RA (J2000.0): 337.0847 = 22h 28m 20.33s Dec (J2000.0): +38.8706 = +38d 52' 14.2" Error: 7.0 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 8.2 arcmin from the SVOM/ECLAIRs position. Mean rate: (7.7 [+2.8, -2.3])e-3 ct s^-1 Mean flux: (2.94 [+1.07, -0.88])e-13 erg cm^-2 s^-1 Peak rate: (7.7 [+2.8, -2.3])e-3 ct s^-1 Peak flux: (2.94 [+1.07, -0.88])e-13 erg cm^-2 s^-1 ECF: 3.84e-11 erg cm^-2 ct^-1, assuming NH=1.27e+21 cm^-2, gamma=1.63; determined from a spectral fit. XMM UL: 2.2e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 19.2-sigma above this 3-sigma upper limit. There is no evidence for fading. This source is not spatially consistent with any of those detected by EP-FXT (Circ. 41085). All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with catalogues and upper limits from other missions, we assumed a power-law spectrum with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated. The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/SVOM. This circular is an officicial product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41086. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39138] GRB 250713A: EP-FXT counterpart detection
by GCN Circulars 14 Jul '25

14 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41085 SUBJECT: GRB 250713A: EP-FXT counterpart detection DATE: 25/07/14 03:06:19 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. F. Liang (PMO, CAS), M. H. Zhang (NAO, CAS), C. Y. Dai (NJU), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 250713A (SVOM/sb25071320) at 2025-07-13T18:52:11 (UTC), about 2 hours after the SVOM/ECLAIRs trigger, with an exposure time of 4919s. Five uncatalogued sources are detected within the ECLAIRs error circle, among which Source 2 is spatially consistent with the candidate counterpart detected by SVOM/MXT (Maggi et al. GCN #41078). Preliminary analysis on these source are automatically conducted, and the details are listed as follows. Source 1: EPF_J222746.7+384738 RA (J2000): 336.9445 Dec (J2000): 38.7939 Flux: 2.68 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev) Flux_err: 4.65 x 10^-14 erg/s/cm^2 (1 sigma) Source 2: EPF_J222734.0+384613 RA (J2000): 336.8919 Dec (J2000): 38.7702 Flux: 1.05 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev) Flux_err: 4.09 x 10^-14 erg/s/cm^2 (1 sigma) Note: This source is spatially consistent with the candidate counterpart detected by SVOM/MXT. Source 3: EPF_J222734.3+384800 RA (J2000): 336.8931 Dec (J2000): 38.8000 Flux: 1.39 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev) Flux_err: 3.05 x 10^-14 erg/s/cm^2 (1 sigma) Source 4: EPF_J222729.6+384709 RA (J2000): 336.8733 Dec (J2000): 38.7859 Flux: 9.13 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev) Flux_err: 2.37 x 10^-13 erg/s/cm^2 (1 sigma) Source 5: EPF_J222815.4+384825 RA (J2000): 337.0641 Dec (J2000): 38.8070 Flux: 8.94 x 10^-14 erg/s/cm^2 (observed, 0.5-10 kev) Flux_err: 3.54 x 10^-14 erg/s/cm^2 (1 sigma) The Source 1, 2, and 3 were detected by both FXT-A and FXT-B, while Source 4 and 5 were detected only by FXT-B. The positional uncertainty of the sources are about 10 arcsec in radius (90% C.L. statistical and systematic). Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/41085. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39137] EP250711a: COLIBRÍ continuous optical observations
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41084 SUBJECT: EP250711a: COLIBRÍ continuous optical observations DATE: 25/07/13 21:34:30 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Nikos Mandarakas (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We continued the follow-up campaign of EP250711a (Wang et al., GCN Circ. 41070) using the DDRAGO wide-field imager on the COLIBRÍ telescope. Observations were conducted on 2025-07-13 from 04:57 to 10:32 UTC (35.8 to 41.4 hours after the trigger), obtaining 61 minutes of exposure in each of the g, r and i filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We measure preliminary magnitudes of: g = 23.02 +/- 0.24 r = 22.78 +/- 0.22 i = 21.64 +/- 0.11 Compared with the value reported in Becerra et al. (GCN Circ. 41073), we estimate a temporal decay index of ~0.9. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41084. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39136] GRB 250706A: Swift-BAT refined analysis
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41083 SUBJECT: GRB 250706A: Swift-BAT refined analysis DATE: 25/07/13 21:01:31 GMT FROM: Takanori Sakamoto at AGU <tsakamoto(a)phys.aoyama.ac.jp> D. M. Palmer (LANL), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), M. J. Moss (GSFC), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+962 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250706A (trigger #1330958) (Moss, et al., GCN Circ. 40988). The BAT ground-calculated position is RA, Dec = 284.011, 32.327 deg which is RA(J2000) = 18h 56m 02.7s Dec(J2000) = +32d 19' 36.8" with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment). The partial coding was 26%. The mask-weighted light curve shows a single-peak structure that starts at ~T-1 s, peaks at ~T+2 s, and ends at ~T+40 s. T90 (15-350 keV) is 31.9 +- 7.2 sec (estimated error including systematics). The time-averaged spectrum from T0 to T+40 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.34 +- 0.17. The fluence in the 15-150 keV band is 1.6 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+1.93 sec in the 15-150 keV band is 1.3 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1330958 View this GCN Circular online at https://gcn.nasa.gov/circulars/41083. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39135] GRB 250702F: Swift-BAT refined analysis
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41082 SUBJECT: GRB 250702F: Swift-BAT refined analysis DATE: 25/07/13 21:00:20 GMT FROM: Takanori Sakamoto at AGU <tsakamoto(a)phys.aoyama.ac.jp> M. J. Moss (GSFC), S. D. Barthelmy (GSFC), R. Gupta (GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII) H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250702F (trigger #1329888) (Klingler, et al., GCN Circ. 40894). The BAT ground-calculated position is RA, Dec = 212.942, 16.739 deg which is RA(J2000) = 14h 11m 46.1s Dec(J2000) = +16d 44' 20.6" with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment). The partial coding was 81%. The mask-weighted light curve shows a complex structure that starts at ~T-3 s, peaks at ~T+38 s, and ends at ~T+80 s. T90 (15-350 keV) is 63.7 +- 12.5 sec (estimated error including systematics). The time-averaged spectrum from T-29.13 to T+76.44 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.49 +- 0.06. The fluence in the 15-150 keV band is 4.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T+37.35 sec in the 15-150 keV band is 5.1 +- 0.3 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1329888 View this GCN Circular online at https://gcn.nasa.gov/circulars/41082. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39134] GRB 250628A: Swift-BAT refined analysis
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41081 SUBJECT: GRB 250628A: Swift-BAT refined analysis DATE: 25/07/13 20:59:21 GMT FROM: Takanori Sakamoto at AGU <tsakamoto(a)phys.aoyama.ac.jp> C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), M. Ferro (INAF-OAB), R. Gupta (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), M. J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula (GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team): Using the data set from T-240 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250628A (trigger #1328546) (Ferro, et al., GCN Circ. 40853). The BAT ground-calculated position is RA, Dec = 38.539, -38.082 deg which is RA(J2000) = 02h 34m 09.3s Dec(J2000) = -38d 04' 54.3" with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment). The partial coding was 51%. The mask-weighted light curve shows a double-peak structure that starts at ~T-9 s, peaks at ~T+1 s, and ends at ~T+70 s. T90 (15-350 keV) is 64 +- 11 sec (estimated error including systematics). The time-averaged spectrum from T-9.42 to T+68.56 sec is best fit by a simple power-law model. The power law index of the time-averaged spectrum is 1.99 +- 0.12. The fluence in the 15-150 keV band is 1.9 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from T-0.10 sec in the 15-150 keV band is 1.2 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90% confidence level. The results of the batgrbproduct analysis are available at https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1328546 View this GCN Circular online at https://gcn.nasa.gov/circulars/41081. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39133] LIGO/Virgo/KAGRA S250712cd: Updated Sky localization
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41080 SUBJECT: LIGO/Virgo/KAGRA S250712cd: Updated Sky localization DATE: 25/07/13 19:39:42 GMT FROM: Sylvia Biscoveanu at Northwestern CIERA <sylvia.biscoveanu(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250712cd (GCN Circular 41075). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250712cd For the Bilby.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 180 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(19h24m, +55d04m, 10.93d, 5.26d, 101.96d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2439 +/- 870 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41080. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39132] GRB 250713A: JinShan optical upper limits
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41079 SUBJECT: GRB 250713A: JinShan optical upper limits DATE: 25/07/13 19:06:10 GMT FROM: syfu(a)nao.cas.cn S.Y. Fu(HUST), S.Q. Jiang, J. An, X. Liu, Z.P. Zhu, L.B. He, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB250713A (sb25071320) detected by SVOM/ECLAIRs (Maggi et al., GCN 41078), using the 50cm & 100cm telescopes of the JinShan project, located at Altay, Xinjiang, China. Observations began at 17:08:08 UT on 2025-07-13, i.e., 102 seconds after the trigger, and a series of frames were obtained in the Sloan r, i and z-band. No new optical source is detected within the SVOM/MXT error circle, down to 5-sigma upper limits of r ~ 21.0, i ~ 17.7 and z ~ 20.8, calibrated with nearby Pan-STARRS stars and not corrected for Galactic extinction. We acknowledge the excellent support from T.Q. Chen for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41079. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39131] GRB 250713A: SVOM detection of a short burst
by GCN Circulars 13 Jul '25

13 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41078 SUBJECT: GRB 250713A: SVOM detection of a short burst DATE: 25/07/13 17:46:03 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> P. Maggi (ObAS), M. Brunet, L.Bouchet (IRAP), D. Gotz (CEA) report on behalf of the SVOM mission team: At 2025-07-13T17:06:26 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250713A (SVOM burst-id sb25071320). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 7 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 14.04 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2025-07-13T17:06:02. The localization of the best alert is R.A., Dec. 336.9666, 38.7686 degrees (J2000) with a 90% confidence level (C.L.) radius of 5.84 arcmin (including systematic error of 2 arcmin added in quadrature). The lightcurve shows a short spike which could be followed by an extended emission. SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-07-13T17:08:48 UTC, 142 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 336.9045, 38.7670 degrees: R.A. (J2000) = 22h27m37.09s Dec. (J2000) = 38d46m01.31s with a 90% C.L. radius of 55 arcseconds (including systematic error of 25 arcsec added in quadrature). This location is 2.90 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the data will be published in a future circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Pierre Maggi: pierre.maggi(a)astro.unistra.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/41078. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39130] EP250711a: Global MASTER-Net observations report
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41077 SUBJECT: EP250711a: Global MASTER-Net observations report DATE: 25/07/12 22:18:20 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP250711a ( EP Team et al., GCN 41070) errorbox 51485 sec after notice time and 1 days 18055 sec after trigger time at 2025-07-12 22:11:51 UT, with upper limit up to 16.4 mag. The observations began at zenith distance = 40 deg. The sun altitude is -23.9 deg. The galactic latitude b = -7 deg., longitude l = 42 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2933283 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 104485 | 2025-07-12 22:11:51 | MASTER-Kislovodsk | (19h 27m 47.40s , +04d 52m 25.4s) | C | 60 | 16.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41077. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39129] GRB 250711A: DDOTI Optical Upper Limit
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41076 SUBJECT: GRB 250711A: DDOTI Optical Upper Limit DATE: 25/07/12 15:29:33 GMT FROM: sahil.atri(a)students.uniroma2.eu Sahil Atri (U Roma), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM), Margarita Pereyra (UNAM) and Eleonora Troja (U Roma) report: We observed the field of GRB 250711A detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 41064) and SVOM/GRM (SVOM/GRM Team GCN Circ. 41072) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on Sierra San Pedro Mártir (http://ddoti.astroscu.unam.mx) on the night of 2025-07-12 UTC. DDOTI observed the BALROG error region (Pries et al., GCN Circ. 41065) from 04:12 UTC to 11:28 UTC (from T+ 13.5 h to T+ 20.8 h after the trigger) and obtained a total exposure of 1.7 hours, alternating with other scientific programs. Comparing our observations to the USNO-B1 and Pan-STARRS PS1 DR2 catalogues, we detect no uncatalogued fading sources within the observed field down to a 10-sigma limiting AB magnitude of: w > 20.1 This value is not corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41076. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39128] LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41075 SUBJECT: LIGO/Virgo/KAGRA S250712cd: Identification of a GW compact binary merger candidate DATE: 25/07/12 15:04:55 GMT FROM: Cassius Melo at Universidade Federal de Alfenas - UNIFAL-MG <cassiusanderson.melo(a)ligo.org> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250712cd during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-07-12 14:25:32.329 UTC (GPS time: 1436365550.329). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], and MBTA [4] analysis pipelines. S250712cd is an event of interest because its false alarm rate, as estimated by the online analysis, is 2.7e-11 Hz, or about one in 1e3 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S250712cd The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), BNS (<1%), or NSBH (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 28 seconds after the candidate event time. * bayestar.multiorder.fits,2, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,2. For the bayestar.multiorder.fits,2 sky map, the 90% credible region is well fit by an ellipse with an area of 395 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(19h30m, +55d32m, 15.21d, 8.35d, 104.26d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 2177 +/- 664 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [2] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [4] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [5] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [6] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/41075. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39127] EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41074 SUBJECT: EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate DATE: 25/07/12 13:03:56 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Jean-Luc Atteia (IRAP), Kin Ocelotl López (UNAM), Stéphane Basa (UAR Pytheas), Alan M. Watson (UNAM), William H. Lee (UNAM), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We continued the follow-up campaign of EP250711a (Wang et al., GCN Circ. 41070) using the DDRAGO wide-field imager on the COLIBRÍ telescope. Observations were conducted on 2025-07-12 from 03:40 to 05:46 UTC (10.5 to 12.6 hours after the trigger), obtaining 96 minutes of exposure in the i band. Additional observations were carried out from 2025-07-12 09:46 to 11:21 UTC (16.6 to 18.2 hours after the trigger), with a total of 64 minutes of exposure in the r band. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. Due to the significantly larger number of images in the stacks than in López et al. (GCN Circ. 41069), it is now possible to confirm the candidate reported by Fu et al. (GCN Circ. 41071). We measure preliminary magnitudes of: r = 22.02 +/- 0.17 i = 21.13 +/- 0.11 We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41074. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39126] EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41073 SUBJECT: EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate DATE: 25/07/12 13:02:51 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Jean-Luc Atteia (IRAP), Kin Ocelotl López (UNAM), Stéphane Basa (UAR Pytheas), Alan M. Watson (UNAM), William H. Lee (UNAM), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We continued the follow-up campaign of EP250711a (Wang et al., GCN Circ. 41070) using the DDRAGO wide-field imager on the COLIBRÍ telescope. Observations were conducted on 2025-07-12 from 03:40 to 05:46 UTC (10.5 to 12.6 hours after the trigger), obtaining 96 minutes of exposure in the i band. Additional observations were carried out from 2025-07-12 09:46 to 11:21 UTC (16.6 to 18.2 hours after the trigger), with a total of 64 minutes of exposure in the r band. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. Due to the significantly larger number of images in the stacks than in López et al. (GCN Circ. 41069), it is now possible to confirm the candidate reported by Fu et al. (GCN Circ. 41071). We measure preliminary magnitudes of: r = 22.02 +/- 0.17 i = 21.13 +/- 0.11 We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41073. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39125] EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41073 SUBJECT: EP250711a: COLIBRÍ refined photometry and optical confirmation of the candidate DATE: 25/07/12 13:02:51 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Jean-Luc Atteia (IRAP), Kin Ocelotl López (UNAM), Stéphane Basa (UAR Pytheas), Alan M. Watson (UNAM), William H. Lee (UNAM), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We continued the follow-up campaign of EP250711a (Wang et al., GCN Circ. 41070) using the DDRAGO wide-field imager on the COLIBRÍ telescope. Observations were conducted on 2025-07-12 from 03:40 to 05:46 UTC (10.5 to 12.6 hours after the trigger), obtaining 96 minutes of exposure in the i band. Additional observations were carried out from 2025-07-12 09:46 to 11:21 UTC (16.6 to 18.2 hours after the trigger), with a total of 64 minutes of exposure in the r band. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. Due to the significantly larger number of images in the stacks than in López et al. (GCN Circ. 41069), it is now possible to confirm the candidate reported by Fu et al. (GCN Circ. 41071). We measure preliminary magnitudes of: r = 22.02 +/- 0.17 i = 21.13 +/- 0.11 We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41073. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39124] GRB 250711A: SVOM/GRM observation
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41072 SUBJECT: GRB 250711A: SVOM/GRM observation DATE: 25/07/12 09:36:26 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Olivier Godet, Sébastien Guillot (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright burst GRB 250711A (SVOM trigger reference: sb25071104) at 2025-07-11T14:40:14.00 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#41064). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of double pulses with a T90 of 38.5 +/-4.0 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250711A.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 261.2, DEC= 44.9, GCN#41064), is located at about 48 degrees from the SVOM optical axis, which is just outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-10 to T0+70 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.20 +0.09/-0.10 and the cutoff energy, parameterized as Epeak, is 146 +23/-17 keV. The event fluence (10-1000 keV) in this time interval is (1.69 +0.12/-0.10)E-05 erg/cm^2. The localization of GRB 250620C in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/grb250711A_amati.png The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS. The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/41072. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39123] EP250711a: NOT optical counterpart candidate
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41071 SUBJECT: EP250711a: NOT optical counterpart candidate DATE: 25/07/12 08:45:33 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> S.Y. Fu (HUST), S.Q. Jiang, J. An, Z.P. Zhu, X. Liu, L.B. He, D. Xu (NAOC), J.P.U. Fynbo (DAWN/NBI), V. Vuolteenaho (NOT) report on behalf of a large collaboration: We observed the field of EP250711a detected by EP/WXT (Wang et al., GCN 41070), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 5 x 200 s exposures in the SDSS z-band, starting at 03:02:59 UT on 2025-07-12, i.e., 9.87 hrs after the EP trigger. An uncatalogued optical transient (OT) is detected within the EP/FXT error circle (Wang et al., GCN 41070) at coordinates R.A.(J2000) = 19:28:37.94 Dec.(J2000) = +4:42:06.80 with an uncertainty of ~ 0.5 arcsec. The source has z ~ 20.2 mag, calibrated with nearby PanSTARRS stars and not corrected for Galactic extinction. We think the source is likely the optical counterpart of EP250711a. We also note that there is a source north-west to the OT, being offset only by ~ 0.9 arcsec in the PanSTARRS, which has z ~ 21.5 mag and may be physically connected to EP250711a. View this GCN Circular online at https://gcn.nasa.gov/circulars/41071. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39122] EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41070 SUBJECT: EP250711a: EP-WXT detection and FXT follow-up observation of a fast X-ray transient DATE: 25/07/12 07:53:13 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. Wang (PMO, CAS), D.Y. Li, W.X. Wang, W. Yuan (NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient by EP-WXT, designated EP250711a (trigger ID: 08500000365). The source was detected on ground from the telemetry data, causing a significant delay from the occuring time of the event. The onboard alert system was not triggered due to the low Galactic lattitude of the source, and no automated follow-up was performed with EP-FXT due to the observation was an non-interruptible one.The WXT position of the source is R.A. = 292.153 deg, DEC = 4.707 deg (J2000) with an uncertainty of 2.2 arcmin in radius (90% C.L. statistical and systematic). The observation begun at 2025-07-11T17:10:56 (UTC), and as suggested from the EP-WXT light curve, the transient was already present at the start time of the observation. The light curve exihbits a double-peak profile, and lasted for about 1300 seconds. The average 0.5-4 keV spectrum can be fitted with an absorbed powerlaw model, with the absorption fixed at the Galactic value of 3.78 x 10^22 cm^-2, and a photon index of 2.5 (+/-0.5). The derived average unabsorbed 0.5-4 keV flux is 2.1 (+/-0.4) x 10^-10 erg/s/cm2. The peak flux is about 8 x 10^(-10) erg/s/cm2. The uncertainties are at the 90% confidence level for the above parameters. We performed a follow-up target of opportunity observation with EP-FXT, starting at 2025-07-12T04:02:18Z, about 11 hours after the WXT detection. Within the WXT error circle, an uncataloggued X-ray source was detected at R.A. = 292.1614 , Dec.= 4.7035 with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further analysis will be updated after receiving the telemetry data. An i band upper limit of 21.3 magnitude was given by a COLIBRÍ observation performed about 10.5 hours after the EP-WXT trigger (GCN 41069). Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/41070. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39121] EP candidate (ID=08500000365): COLIBRÍ optical Upper limit
by GCN Circulars 12 Jul '25

12 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41069 SUBJECT: EP candidate (ID=08500000365): COLIBRÍ optical Upper limit DATE: 25/07/12 05:52:18 GMT FROM: Kin Océlotl Cuauhtli López Mendoza at Instituto de Astronoma, UNAM <koclopez(a)astro.unam.mx> Kin Ocelotl López (UNAM), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the EP alert (ID=08500000365 and trigger time T= 2025-07-11 17:10:56.00) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-07-12 03:40 to 03:59 UTC (from 10.5 to 10.8 hours after the trigger and starting 1.3 hours after the arrival of the notice) and obtained 16 minutes of exposure in the i filter. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction (which is considerably high due to the proximity to the Galactic plane). In our stacked image, and after performing image subtraction using Pan-STARRS as a reference, we do not detect any new source at the WXT position, down to the following 5-sigma limit: i > 21.3 Nevertheless, we noticed the presence inside the WXT error box of the eclipsing binary (Gaia DR3 4292676364775382144) and an RR Lyrae star (Gaia DR3 4292676394808888448), suggesting that the alert is likely associated with one of these objects. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico. View this GCN Circular online at https://gcn.nasa.gov/circulars/41069. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39120] Fermi GRB 250711A: Global MASTER-Net observations report
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41068 SUBJECT: Fermi GRB 250711A: Global MASTER-Net observations report DATE: 25/07/11 20:30:49 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250711A ( Fermi GBM team, GCN 41064) errorbox 16346 sec after notice time and 16354 sec after trigger time at 2025-07-11 19:12:47 UT, with upper limit up to 14.3 mag. The observations began at zenith distance = 3 deg. The sun altitude is -19.0 deg. The galactic latitude b = 33 deg., longitude l = 71 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2932393 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 16384 | 2025-07-11 19:12:47 | MASTER-Kislovodsk | (17h 35m 16.38s , +45d 13m 31.4s) | C | 60 | 14.3 | 16560 | 2025-07-11 19:15:42 | MASTER-Kislovodsk | (17h 23m 53.68s , +45d 14m 28.9s) | C | 60 | 14.1 | 16814 | 2025-07-11 19:19:57 | MASTER-Kislovodsk | (17h 27m 35.59s , +47d 07m 43.8s) | C | 60 | 14.1 | 16990 | 2025-07-11 19:22:53 | MASTER-Kislovodsk | (17h 35m 19.19s , +45d 13m 39.0s) | C | 60 | 14.3 | 17157 | 2025-07-11 19:25:39 | MASTER-Kislovodsk | (17h 25m 01.99s , +45d 04m 21.7s) | C | 60 | 14.1 | 17316 | 2025-07-11 19:28:19 | MASTER-Kislovodsk | (17h 12m 47.71s , +43d 09m 45.1s) | C | 60 | 13.8 | 17396 | 2025-07-11 19:29:38 | MASTER-Kislovodsk | (17h 23m 53.71s , +43d 09m 27.0s) | C | 60 | 14.0 | 17475 | 2025-07-11 19:30:58 | MASTER-Kislovodsk | (17h 16m 58.46s , +46d 58m 51.1s) | C | 60 | 14.0 | 17555 | 2025-07-11 19:32:17 | MASTER-Kislovodsk | (17h 28m 41.84s , +46d 57m 30.3s) | C | 60 | 14.3 | 17725 | 2025-07-11 19:35:07 | MASTER-Kislovodsk | (17h 14m 53.39s , +45d 04m 13.4s) | C | 60 | 14.2 | 17804 | 2025-07-11 19:36:27 | MASTER-Kislovodsk | (17h 24m 56.77s , +45d 02m 55.6s) | C | 60 | 13.9 | 17883 | 2025-07-11 19:37:46 | MASTER-Kislovodsk | (17h 33m 42.38s , +43d 11m 07.6s) | C | 60 | 14.1 | 18042 | 2025-07-11 19:40:25 | MASTER-Kislovodsk | (17h 12m 51.25s , +43d 11m 29.3s) | C | 60 | 13.5 | 18122 | 2025-07-11 19:41:44 | MASTER-Kislovodsk | (17h 23m 46.84s , +43d 10m 09.4s) | C | 60 | 14.1 | 18201 | 2025-07-11 19:43:04 | MASTER-Kislovodsk | (17h 16m 53.40s , +46d 58m 56.6s) | C | 60 | 14.1 | 18281 | 2025-07-11 19:44:23 | MASTER-Kislovodsk | (17h 28m 41.67s , +46d 58m 00.4s) | C | 60 | 14.1 | 19103 | 2025-07-11 19:58:05 | MASTER-Kislovodsk | (17h 14m 39.74s , +45d 06m 31.7s) | C | 60 | 14.2 | 19183 | 2025-07-11 19:59:25 | MASTER-Kislovodsk | (17h 24m 52.80s , +45d 05m 05.2s) | C | 60 | 14.2 | 19262 | 2025-07-11 20:00:45 | MASTER-Kislovodsk | (17h 33m 37.59s , +43d 12m 30.2s) | C | 60 | 14.3 | 19421 | 2025-07-11 20:03:23 | MASTER-Kislovodsk | (17h 12m 39.43s , +43d 12m 29.1s) | C | 60 | 14.1 | 19500 | 2025-07-11 20:04:43 | MASTER-Kislovodsk | (17h 23m 43.29s , +43d 11m 35.5s) | C | 60 | 14.1 | 19580 | 2025-07-11 20:06:03 | MASTER-Kislovodsk | (17h 16m 41.83s , +46d 58m 18.5s) | C | 60 | 14.1 | 19660 | 2025-07-11 20:07:22 | MASTER-Kislovodsk | (17h 28m 32.18s , +46d 58m 57.2s) | C | 60 | 14.0 | 19739 | 2025-07-11 20:08:42 | MASTER-Kislovodsk | (17h 36m 11.71s , +45d 06m 17.3s) | C | 60 | 14.1 | 20058 | 2025-07-11 20:14:00 | MASTER-Kislovodsk | (17h 33m 29.49s , +43d 12m 34.0s) | C | 60 | 14.1 | 20217 | 2025-07-11 20:16:39 | MASTER-Kislovodsk | (17h 12m 38.24s , +43d 10m 13.3s) | C | 60 | 13.8 | 20296 | 2025-07-11 20:17:59 | MASTER-Kislovodsk | (17h 23m 42.07s , +43d 10m 47.1s) | C | 60 | 14.2 | 20376 | 2025-07-11 20:19:18 | MASTER-Kislovodsk | (17h 16m 42.38s , +47d 00m 04.9s) | C | 60 | 13.8 | 20455 | 2025-07-11 20:20:38 | MASTER-Kislovodsk | (17h 28m 26.32s , +46d 58m 17.9s) | C | 60 | 14.1 | 20535 | 2025-07-11 20:21:57 | MASTER-Kislovodsk | (17h 36m 11.04s , +45d 06m 15.9s) | C | 60 | 14.1 | 20694 | 2025-07-11 20:24:36 | MASTER-Kislovodsk | (17h 14m 31.90s , +45d 06m 29.8s) | C | 60 | 13.8 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41068. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39119] EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41067 SUBJECT: EP250702a: gamma-ray upper limits from joint observations by the LST-1 and MAGIC telescopes DATE: 25/07/11 17:01:56 GMT FROM: David Paneque at Max Planck Institute for Physics <dpaneque(a)mppmu.mpg.de> D. Paneque (MPP Munich), M. Teshima (MPP Munich), Arnau Aguasca-Cabot (UB, ICCUB, and IEEC-UB), Alessio Berti (MPP Munich), Sweta Menon (UNIROMA2 & INAF), Edna Ruiz-Velasco (LAPP Annecy), Monica Seglar-Arroyo (IFAE Barcelona) and Andrea Simongini (UNIROMA2 & INAF), on behalf of the CTAO-LST and MAGIC Collaborations report: We observed the field of EP250702a / GRBs 250702B,D,E (GCN 40883, 40886, 40890, 40891, 40906). A total of 2.94 hours of observations were conducted with the MAGIC telescopes, beginning at 2025-07-04 01:25:53 UTC. The final 1.79 hours of this period were carried out jointly with LST-1. A preliminary offline analysis of the LST-1 and MAGIC dataset shows no excess of gamma rays above 200 GeV in the field of EP250702a (GCN 40906). These results have been obtained using the LST analysis software, lst-chain (LST Collaboration, 2023 ApJ 956 80, v0.10.7), and the MAGIC analysis software MARS (Zanin et al. 2013, v 3.2.1). Observations were affected by reduced atmospheric transparency. A more in-depth analysis of this data set is ongoing. Subsequent observations are planned after the moonbreak, subject to the nature of upcoming detections. LST-1 is a prototype of the Large-Sized Telescope (LST) for the Cherenkov Telescope Array Observatory, and is located on the Canary island of La Palma, Spain. The telescope design is optimized for observation of gamma rays in the range from 20 GeV to 3 TeV. MAGIC is a system of two 17m-diameter Imaging Atmospheric Cherenkov Telescopes located on the Canary island of La Palma, Spain, and designed to perform gamma-ray astronomy in the energy range from 50 GeV to greater than 50 TeV. View this GCN Circular online at https://gcn.nasa.gov/circulars/41067. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39118] GRB 250704A: GRANDMA observations
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41066 SUBJECT: GRB 250704A: GRANDMA observations DATE: 25/07/11 16:12:40 GMT FROM: Sarah Antier at OCA <sarah.antier(a)oca.eu> A. Manasanun, K. Noysena (NARIT), R. Hellot (KNC), S. Antier (OCA/IJCLAB), D. Akl (AUS), N. Kochiashivili (AbAO), T. Du Laz (Caltech), A. Klotz (IRAP), C. Limonta (OCA), M. Masek (FZU), M. Lamoureux (UCLouvain) on behalf of GRANDMA: We observed the field of SVOM GRB 250704A (Cao et al., GCN Circ. 40934) with TAROT, TRT and Kilonova catcher. All our measurements are made public and can be downloaded from: https://skyportal-icare.ijclab.in2p3.fr/public/sources/GCN-250704_034220/ve… All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2025). Images obtained with the Sloan filters were calibrated using the PanSTARRS DR1 catalog. Images obtained with the Johnson-Cousin filters were calibrated using the Gaia DR3 Synphot catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). Our observations are consistent with previously reported measurements (see the Skyportal page), such as Schneider et al., GCN Circ. 40953; Cao et al., GCN Circ 40964; and Siegel et al., GCN 40981. GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/). Skyportal/ICARE is supported by ACME. View this GCN Circular online at https://gcn.nasa.gov/circulars/41066. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39117] GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611)
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41065 SUBJECT: GRB 250711A: BALROG localization (Fermi Trigger 773937617 / GRB 250711611) DATE: 25/07/11 15:08:21 GMT FROM: Jochen Greiner at MPE <jcgrog(a)mpe.mpg.de> T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report: The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger 773937617 at 14:40:12 on 11 July 2025 were automatically fitted for spectrum and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427; Berlato et al. 2019, ApJ 873, 60). The best-fit position is: RA(2000.0) = 267.8 deg Decl.(2000.0) = 35.9 deg The 1 sigma statistical error radius is 2.1 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB250711611/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB250711611/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB250711611/json View this GCN Circular online at https://gcn.nasa.gov/circulars/41065. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39116] GRB 250711A: Fermi GBM Final Real-time Localization
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41064 SUBJECT: GRB 250711A: Fermi GBM Final Real-time Localization DATE: 25/07/11 14:50:44 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 14:40:12 UT on 11 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250711A (trigger 773937617.940244 / 250711611). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 261.2, Dec = 44.9 (J2000 degrees, equivalent to J2000 17h 24m, 44d 53'), with a statistical uncertainty of 1.2 degrees. The angle from the Fermi LAT boresight is 28.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250711611/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250711611/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250711611/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41064. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39115] GRB 250704A: SVOM/ECLAIRs refined analysis
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41063 SUBJECT: GRB 250704A: SVOM/ECLAIRs refined analysis DATE: 25/07/11 12:20:56 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Authors: N. Dagoneau (CEA), U. Jacob (LUPM), J.X Cao (GXU), Y.H Cheng (SWIFAR, YNU), J.-L. Atteia, M. Brunet, O. Godet (IRAP), F. Cangemi, A. Coleiro (APC) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 250704A (SVOM burst-id sb25070404). The burst that triggered ECLAIRs onboard (GCN 40934) consists of a single pulse with a duration of T90 = 9.0 +0.6/-0.5 s in the 4-120 keV energy band. The time-averaged spectrum of the burst from T0 - 1.50 s to T0 + 7.48 s (T0 = 2025-07-04T03:42:22) in the energy range 8-120 keV is best fit by a power-law model with a photon index of -1.3 +/- 0.2. With this model, the total 4-120 keV fluence, assuming the T90 measured, is 1.23 +/- 0.21 x 10^-6 erg/cm^2. All the quoted errors are at the 68% confidence level. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic Universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. The SVOM/ECLAIRs point of contact for this burst is: Nicolas Dagoneau (nicolas.dagoneau at cea.fr) View this GCN Circular online at https://gcn.nasa.gov/circulars/41063. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39114] LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate
by GCN Circulars 11 Jul '25

11 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41062 SUBJECT: LIGO/Virgo/KAGRA S250711q: Identification of a GW compact binary merger candidate DATE: 25/07/11 04:36:24 GMT FROM: Jyotirmaya Mohanta at University of Tsukuba <s2430161(a)u.tsukuba.ac.jp> The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We identified the compact binary merger candidate S250711q during real-time processing of data from LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) at 2025-07-11 03:27:25.108 UTC (GPS time: 1436239663.108). The candidate was found by the cWB [1], cWB BBH [2], GstLAL [3], and MBTA [4] analysis pipelines. S250711q is an event of interest because its false alarm rate, as estimated by the online analysis, is 1.6e-09 Hz, or about one in 20 years. The event's properties can be found at this URL: https://gracedb.ligo.org/superevents/S250711q The classification of the GW signal, in order of descending probability, is BBH (>99%), Terrestrial (<1%), NSBH (<1%), or BNS (<1%). Assuming the candidate is astrophysical in origin, the probability that at least one of the compact objects is consistent with a neutron star mass (HasNS) is <1%. [5] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [5] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The source chirp mass falls with highest probability in the bin (22.0, 44.0) solar masses, assuming the candidate is astrophysical in origin. Two sky maps are available at this time and can be retrieved from the GraceDB event page: * bayestar.multiorder.fits,0, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 31 seconds after the candidate event time. * bayestar.multiorder.fits,1, an initial localization generated by BAYESTAR [6], distributed via GCN and SCiMMA notices about 5 minutes after the candidate event time. The preferred sky map at this time is bayestar.multiorder.fits,1. For the bayestar.multiorder.fits,1 sky map, the 90% credible region is 2964 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 9738 +/- 2925 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Klimenko et al. PRD 93, 042004 (2016) doi:10.1103/PhysRevD.93.042004 [2] T. Mishra et al. PRD 105, 083018 (2022) doi:10.1103/PhysRevD.105.083018 [3] Tsukada et al. PRD 108, 043004 (2023) doi:10.1103/PhysRevD.108.043004 and Ewing et al. PRD 109, 042008 (2024) doi:10.1103/PhysRevD.109.042008 [4] Alléné et al. CQG 42, 105009 (2025) doi:10.1088/1361-6382/add234 [5] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe [6] Singer & Price PRD 93, 024013 (2016) doi:10.1103/PhysRevD.93.024013 View this GCN Circular online at https://gcn.nasa.gov/circulars/41062. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39113] GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41061 SUBJECT: GRB 250702B,D,E/EP250702A: JCMT sub-mm observations at 350 GHz DATE: 25/07/10 21:08:34 GMT FROM: alexandra.tetarenko(a)uleth.ca A.J. Tetarenko (ULethbridge), J. Bright (Oxford), G. Bower (EAO/JCMT), S. Graves (EAO/JCMT): The James Clerk Maxwell Telescope (JCMT) observed the position of GRB 250702B,D,E/EP250702A (GCNs [40906](https://gcn.nasa.gov/circulars/40906?view=group&limit=100), [40883](https://gcn.nasa.gov/circulars/40883?view=group&limit=100), [40885](https://gcn.nasa.gov/circulars/40885?view=group&limit=100), [40886](https://gcn.nasa.gov/circulars/40886?view=group&limit=100), [40890](https://gcn.nasa.gov/circulars/40890?view=group&limit=100), [40891](https://gcn.nasa.gov/circulars/40891?view=group&limit=100), ATels [17259](https://www.astronomerstelegram.org/?read=17259), [17261](https://www.astronomerstelegram.org/?read=17261)) on 2025 July 08 between ~08:50 - 12:30 UTC for 3 scans totalling 0.55 hrs on-source and 2025 July 09 between ~08:15 - 09:20 UTC for 2 scans totalling 1.05 hrs on-source. The observations were made at a central frequency of 850 um (350 GHz) with the SCUBA-2 instrument. We do not detect a target source at the previously reported VLA radio position (RA: 18:58:45.565, Dec: -07:52:26.42; GCN [41053](https://gcn.nasa.gov/circulars/41053?view=group&limit=100)), yielding a 3-sigma upper limit of 6.3 mJy from stacking all of the data. Extrapolating the previous radio detections with MeerKAT/VLA at 1.28/10 GHz of ~0.1/0.5 mJy (which imply a spectral index of ~1.3; GCN [41053](https://gcn.nasa.gov/circulars/41053?view=group&limit=100)), we would expect a clear detection at 350 GHz of ~50 mJy, suggesting a break in the spectrum between the cm and mm/sub-mm regions for this source. However, the recent ALMA detection at 97.5 GHz of ~2 mJy (GCN [41059](https://gcn.nasa.gov/circulars/41059)), taken nearly simultaneously with our JCMT observations, implies a flatter spectral index of ~0.6. Therefore, a more accurate estimate of the expected 350 GHz flux density at the time of our JCMT observations would be ~4 mJy, consistent with our 3-sigma upper limit. Given these constraints, the source appears to likely have an inverted optically thick spectrum extending into the sub-mm bands. *We thank the JCMT staff for rapidly scheduling these observations. The JCMT is operated by the EAO on behalf of ASIAA and NARIT. Additional funds for the construction of SCUBA-2 were provided by the Canada Foundation for Innovation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.* View this GCN Circular online at https://gcn.nasa.gov/circulars/41061. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39112] GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41060 SUBJECT: GRB 250704B / EP250704a: 1.3 GHz MeerKAT Detection DATE: 25/07/10 20:58:22 GMT FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu> G. Schroeder (Cornell), L. Rhodes (TSI/McGill), W. Fong (Northwestern), T. Laskar (Utah), E. Berger (Harvard) report: We observed the location of the short-duration GRB 250704B/EP 250704A (Wang et al., GCN 40940; Li et al., GCNs 40941, 40956, Frederiks et al., GCN 40972; Wang et al., GCN 40978; Shimizu et al., GCN 41025) with the MeerKAT radio telescope under program MKT-24032 (PI Schroeder) at a central frequency of 1.3 GHz for a total of 2 hours with a mid time of 2025 July 10 at 00:07 UT (5.7 days post burst). In preliminary analysis, we detect the radio afterglow (Schroeder et al., GCN 41038; Ricci et al., GCN 41046), and measure a flux density of ~70 microJy. Further observations are planned. We thank the staff at the South African Radio Astronomy Observatory for scheduling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41060. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39111] GRB 250702B,D,E / EP250702a: ALMA detection
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41059 SUBJECT: GRB 250702B,D,E / EP250702a: ALMA detection DATE: 25/07/10 18:59:43 GMT FROM: Kate D. Alexander at University of Arizona <katedenhamalexander(a)gmail.com> Kate D. Alexander (U of Arizona), James Miller-Jones (Curtin U), Adelle Goodwin, (Curtin U), Noah Franz (U of Arizona), Raffaella Margutti (UC Berkeley) Ryan Chornock (UC Berkeley), Dheeraj Pasham (Eureka Scientific/George Washington), Edo Berger (Harvard), Yvette Cendes (U of Oregon), and Collin Christy (U of Arizona) report on behalf of a larger collaboration: We observed the location of the unusual transient GRB 250702B,D,E / EP250702a (GCNs 40906, 40883, 40885, 40886, 40890, 40891) with the Atacama Large Millimeter/submillimeter Array (ALMA) at multiple frequencies (program 2023.1.01731.T, PI: Miller-Jones). On 2025 July 9 02:09:03 UT, 6.97 days after the first detection with the Einstein Probe (GCN 40906) and 6.51 days after the first Fermi trigger (GCN 40883), we clearly detected the source at a mean frequency of 97.5 GHz with a preliminary flux density of ~2 mJy. Further ALMA observations are planned. We thank the ALMA staff for quickly scheduling these observations and for providing the quick-look reduction. View this GCN Circular online at https://gcn.nasa.gov/circulars/41059. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39110] LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41058 SUBJECT: LIGO/Virgo/KAGRA S250629bs: Upper limits from Swift/BAT-GUANO DATE: 25/07/10 14:47:59 GMT FROM: Maia Williams at PSU <mjw6837(a)psu.edu> Maia Williams (PSU), Samuele Ronchini (PSU), Gayathri Raman (PSU), James DeLaunay (PSU), Tyler Parsotan (NASA GSFC), Jamie A. Kennea (PSU), Aaron Tohuvavohu (Caltech) report: Swift/BAT was observing 86.28% of the GW localization probability ([Bilby.multiorder.fits](https://gracedb.ligo.org/api/superevents/S250629bs/f…) at merger time. A fraction 64.89% of the GW localization posterior is contained inside the BAT coded FoV. The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; [Tohuvavohu et al. 2020, ApJ, 900, 1](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. Using the NITRATES analysis ([DeLaunay + Tohuvavohu 2022, ApJ, 941, 169](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits. We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins. In units of 10^-7 erg/s/cm^2: |time_bin (s) |soft |normal|hard |GRB170817 |-|-|-|-|-| |0.256 |3.65 |3.14 |2.87 |3.39 |1.024 |1.87 |1.61 |1.47 |1.74 |4.096 |1.02 |0.88 |0.80 |0.95 |16.384 |0.65 |0.56 |0.51 |0.60 The upper limits as function of sky position are plotted here, alongside the GW localization: https://zenodo.org/records/15843754 The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/41058. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39109] LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41057 SUBJECT: LIGO/Virgo/KAGRA S250629ae: Upper limits from Swift/BAT-GUANO DATE: 25/07/10 14:43:39 GMT FROM: Maia Williams at PSU <mjw6837(a)psu.edu> Maia Williams (PSU), Samuele Ronchini (PSU), Gayathri Raman (PSU), James DeLaunay (PSU), Tyler Parsotan (NASA GSFC), Jamie A. Kennea (PSU), Aaron Tohuvavohu (Caltech) report: Swift/BAT was observing 50.9% of the GW localization probability ([Bilby.multiorder.fits](https://gracedb.ligo.org/api/superevents/S250629ae/f…) at merger time. A fraction 42.48% of the GW localization posterior is contained inside the BAT coded FoV. The LVK notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; [Tohuvavohu et al. 2020, ApJ, 900, 1](https://iopscience.iop.org/article/10.3847/1538-4357/aba94f)). Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. Using the NITRATES analysis ([DeLaunay + Tohuvavohu 2022, ApJ, 941, 169](https://iopscience.iop.org/article/10.3847/1538-4357/ac9d38)), we searched for emission on 8 timescales from 0.128s to 16.384s in the interval [-20,+20] seconds around the merger time. We find no evidence for a signal, and derive the following upper limits. We quote the 5-sigma flux upper limits in the 15-350 keV band, weighted over the GW localization, for four spectral templates (soft, normal, and hard GRB-like templates described in [arXiv:1612.02395], and spectral shape from GRB170817A [arXiv:1710.05446]) and for four time bins. In units of 10^-7 erg/s/cm^2: |time_bin (s) |soft |normal|hard |GRB170817 |-|-|-|-|-| |0.256 |2.96 |2.54 |2.33 |2.73 |1.024 |1.51 |1.29 |1.19 |1.39 |4.096 |0.81 |0.69 |0.63 |0.74 |16.384 |0.49 |0.42 |0.39 |0.45 The upper limits as function of sky position are plotted here, alongside the GW localization: https://zenodo.org/records/15843728 The solid and dashed lines indicate the 90% and 50% GW contour levels, respectively. The corresponding fits file is also included. GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/ View this GCN Circular online at https://gcn.nasa.gov/circulars/41057. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39108] IceCube-250708A: No Candidates from WINTER
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41056 SUBJECT: IceCube-250708A: No Candidates from WINTER DATE: 25/07/10 01:14:38 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Robert Stein (UMD), Danielle Frostig (CfA), Viraj Karambelkar (Caltech), Mansi Kasliwal (Caltech), Nathan Lourie (MIT), Geoffrey Mo (MIT), and Robert Simcoe (MIT) report: On behalf of Wide-Field Infra-Red Transient Explorer (WINTER) collaboration: We observed the localization region of the neutrino event IceCube-250708A (Zegarelli et. al, GCN 41039) with the 1.2 sq. degree near-IR WINTER camera on the Palomar 1-m telescope (Lourie et al. 2021, Frostig et al. 2024). We conducted observations in J-band beginning at 2025-07-09 02:42 UTC, approximately 12.6 hours after event time. Our observations covered a total of 0.8 sq. deg. of sky for which reference images were available, corresponding to 89.9% of the total probability. Our observations reached a median depth of 18.7 mag AB. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565). We use data from the UKIRT Hemisphere survey (Dye et al. 2018) as references for image subtraction. We search for WINTER sources with multiple detections, and for WINTER sources with cross-matches in the alert stream of the Zwicky Transient Facility (Bellm et al. 2019). After removing likely stellar sources and likely subtraction artefacts, we find no candidate counterparts. Observations of this field will continue as part of the WINTER neutrino follow-up program. WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/41056. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39107] IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility
by GCN Circulars 10 Jul '25

10 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41055 SUBJECT: IceCube-250708A: No Candidate Transients from the Zwicky Transient Facility DATE: 25/07/10 01:13:48 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Jannis Necker (DESY), Akshay Eranhalodi (DESY), Robert Stein (JSI) and Anna Franckowiak (Ruhr University Bochum) report: On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-250708A (Zegarelli et. al, GCN 41039) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-07-09 04:37 UTC, approximately 14.5 hours after event time. We covered 82.2% (0.7 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019) . We are left with the following high-significance transient candidate by our pipeline, lying within the 90.0% localization of the skymap. +--------------------------------------------------------------------------------+ | ZTF Name | IAU Name | RA (deg) | DEC (deg) | Filter | Mag | MagErr | +--------------------------------------------------------------------------------+ | ZTF25abanmjp | ------- | 222.4281885 | +26.5431350 | r | 20.63 | 0.13 | +--------------------------------------------------------------------------------+ ZTF25abanmjp was first detected on 2025-06-10. It is nuclear, with a WISE-detected host (W1-W2=0.58). With these colours, this galaxy is a likely AGN. These detections are brighter than archival PS1 photometry of this galaxy (g=22.1, r=21.5), indicating an elevated flux level. However, forced potometry at this position reveals many previous detections at this position in ZTF data over the past six months, with no obvious flaring activity at the time of the neutrino. We conclude that ZTF25abanmjp likely arises from AGN variability. Given the lack of obvious flaring at the time of the neutrino, we have no reason to think that ZTF25abanmjp is associated with IC250708A based on our observations. Observations of this field will continue as part of our standard ToO cadence for high-energy neutrinos (Stein et al. 2023). Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan, and OKC, University of Stockholm, Sweden. Operations are conducted by Caltech's Optical Observatory (COO), Caltech/IPAC, and the University of Washington at Seattle, USA. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ). View this GCN Circular online at https://gcn.nasa.gov/circulars/41055. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39106] GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41054 SUBJECT: GRB 250702B,D,E/EP250702A: MeerKAT radio observations at 1.28GHz DATE: 25/07/09 22:26:57 GMT FROM: lauren.rhodes(a)mcgill.ca Pikky Atri (Astron), Lauren Rhodes (TSI/McGill), Rob Fender (Oxford), Andrew Hughes (Oxford),and Sara Motta (INAF-OAB) report on behalf of the XKAT Collaboration. The MeerKAT radio telescope observed the position of GRB 250702B,D,E/EP250702A (GCNs 40906, 40883, 40885, 40886, 40890, 40891) as part of the XKAT program on 06-07-2025 starting at 18:53:41 UT for 15 minutes. The observation was made at a central frequency of 1.28GHz with a bandwidth of 856MHz. We detect a point source with a flux density of ~100uJy at the coordinates R.A.: 18:58:45.5, Dec: -07:52:28.2 with a positional uncertainty of ~1" (please note the slight offset in declination). The proximity of EP250702a on the sky to the neutron star X-ray Swift J1858.6-0814 allowed us to check archival observations from MeerKAT of the new transient’s position. Using our most recent observation of the Swift J1858.6-0814 from 02-03-2020 (Rhodes et al 2020), we place a 3-sigma upper limit of 114uJy/beam at the position of the EP250702a. Further observations are planned. We thank the SARAO staff for rapidly scheduling these observations. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. X-KAT is a large MeerKAT open-time programme to observe X-ray binaries in the radio band, performing weekly monitoring of bright, active systems, with capacity for higher cadence observations, and in coordination with large X-ray and optical monitoring programmes. For further information on this programme contact Rob Fender. View this GCN Circular online at https://gcn.nasa.gov/circulars/41054. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39105] GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41053 SUBJECT: GRB 250702B,D,E / EP250702a: 10 GHz detection with the VLA DATE: 25/07/09 18:15:39 GMT FROM: Itai Sfaradi at University of California, Berkeley <itai.sfaradi(a)mail.huji.ac.il> Authors: I. Sfaradi (UC Berkeley), Y. Yao (UC Berkeley), H. Sears (Rutgers), E. Wiston (UC Berkeley), R. Margutti (UC Berkeley), R. Chornock (UC Berkeley), K.D. Alexander (U of Arizona), T. Laskar (Utah), E. Hammerstein (UC Berkeley), W. Lu (UC Berkeley) We report here a radio detection of GRB 250702B,D,E / EP250702a (GCNs 40906, 40883, 40885, 40886, 40890, 40891) with the Karl G. Jansky Very Large Array (VLA program 25A-109; PI: Yao). We conducted our observation from 2025-07-08 05:29:18 (UTC) to 2025-07-08 06:29:03 (UTC), 6.13 days after the first detection with the Einstein Probe (GCN 40906) and 5.7 days after the first Fermi trigger (GCN 40883). Calibration and imaging were performed in CASA using the VLA calibration pipeline, with 3C286 as a bandpass and flux density calibrator, and J1832-1035 as the complex gain calibrator. Our observation in X-band, with a 3.9 GHz bandwidth centered around 10 GHz, results in a detection of a point source with a flux density of 0.49 +/- 0.05 mJy (including 10% systematic flux calibration uncertainties) at R.A.: 18:58:45.565 +/- 0.015s, Dec.: -07:52:26.42 +/- 0.35’’ (J2000), consistent within 1 sigma uncertainty with the NIR counterpart (GCN 40924) and the EP X-ray counterpart (GCN 40906). The in-band spectral slope of F_nu ~ nu^1.3 implies optically thick emission. Radio detection with the MeerKAT telescope of a 0.1 mJy point source at 3 GHz was previously reported in GCN 40985. We plan to continue monitoring this source and encourage further multi-wavelength observations. We thank the VLA and the NRAO staff for scheduling and performing this observation. View this GCN Circular online at https://gcn.nasa.gov/circulars/41053. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39104] IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41052 SUBJECT: IceCube-250708A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/07/09 18:02:33 GMT FROM: Alicia Mand at IceCube/UW-Madison <aemand(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250708A (https://gcn.nasa.gov/circulars/41039) in a time range of 1000 seconds centered on the alert event time (2025-07-08 13:56:59.540 UTC to 2025-07-08 14:13:39.540 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-250708A. We report a p-value of 1.00 in this time window. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250708A is 1.4e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 7e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-07-07 14:05:19.540 UTC to 2025-07-09 14:05:19.540 UTC). In this case, we report a p-value of 0.02, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250708A is 1.7e-01 GeV cm^-2 in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/41052. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39103] GRB 250709A: Fermi GBM Final Localization
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41051 SUBJECT: GRB 250709A: Fermi GBM Final Localization DATE: 25/07/09 17:32:31 GMT FROM: oindabimukherjee(a)gmail.com The Fermi GBM team reports the detection of a likely LONG GRB "At 15:39:54.99 UT on 09 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250709A (trigger 773768399/250709653). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 303.29, Dec = 34.66 (J2000 degrees, equivalent to J2000 20h 13m, +34d 39'), with a statistical uncertainty of 4.56 degrees. The angle from the Fermi LAT boresight is 24 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250709653/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250709653/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250709653/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/41051. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39102] IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a)
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41050 SUBJECT: IPN triangulation of GRB 250704B (short/hard, consistent with EP 250704a) DATE: 25/07/09 15:26:13 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, E. Burns on behalf of the IPN, Y. Zhang, C. Wang, S. Xiong, J. Wei, and B. Cordier on behalf of the SVOM-GRM team, C. Wang, S. Xiong, S. Zheng and Y. Zhang, on behalf of the Insight-HXMT team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The bright, short-duration GRB 250704B (SVOM/GRM observation: Wang et al., GCN 40940; Konus-Wind detection: Frederiks et al., GCN 40972; Insight-HXMT detection: Wang et al., GCN 40978; CALET/CGBM detection: Shimizu et al., GCN 41025) was detected by SVOM(GRB), Konus-Wind, Insight (HXMT), CALET (CGBM), and Mars-Odyssey (HEND) at about 29791 s UT (08:16:31). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 300.880 (20h 03m 31s) +12.053 (+12d 03' 11") Corners: 300.926 (20h 03m 42s) +12.075 (+12d 04' 30") 300.872 (20h 03m 29s) +12.109 (+12d 06' 33") 300.834 (20h 03m 20s) +12.031 (+12d 01' 52") 300.888 (20h 03m 33s) +11.997 (+11d 59' 49") --------------------------------------------- The error box area is 19 sq. arcmin, and its maximum dimension is 7 arcmin (the minimum one is 4 arcmin). The Sun distance was 141 deg. This localization may be improved. The position of EP250704a (Li et al., GCNs 40941, 40956) is consistent with the IPN localization, supporting the association of the GRB and EP 250704a. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250704_T29791/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. View this GCN Circular online at https://gcn.nasa.gov/circulars/41050. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39101] GRB 250706B/C: Insight-HXMT detection
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41049 SUBJECT: GRB 250706B/C: Insight-HXMT detection DATE: 25/07/09 09:05:53 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> Chen-Wei Wang, Shao-Lin Xiong, Cheng-Kui Li, Chao Zheng, Wen-Jun Tan, Jia-Cong Liu, Hao-Xuan Guo, Xiao-Bo Li and Wang-Chen Xue report on behalf of the Insight-HXMT team: At 2025-07-06T16:45:26.900 (T0), Insight-HXMT/HE was triggered on-ground by the long bright burst GRB 250706B/C, which is also detected by Konus-Wind (D. Frederiks, GCN #41013, GCN #41027) , SVOM (Jesse Palmerio et al., GCN #40989, GCN #41026) and Fermi/LAT (F. Longo, GCN #41019). The Insight-HXMT/HE light curve mainly consists of numerous pulses with a T90 of 36.6 +/- 0.1s. The 1s peak rate, measured from T0+36.150 s, is 18784 cnts/sec. The total counts from this burst is 293497 counts. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb250706C.png All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org. View this GCN Circular online at https://gcn.nasa.gov/circulars/41049. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39100] EP/WXT 01709181970: GOTO observations confirm stellar variability
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41048 SUBJECT: EP/WXT 01709181970: GOTO observations confirm stellar variability DATE: 25/07/09 08:35:58 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK <amitkundu515(a)gmail.com> A. Kumar, D. O'Neill, G. Ramsay, B. P. Gompertz, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, B. Godson, D. Steeghs, D. K. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report on behalf of the GOTO collaboration: We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to EP/WXT trigger ID 01709181970 (Peng et al. GCN 41045). Targeted observations were obtained using the GOTO North on 2025-07-08 22:31:40 UT (8.301 minutes post-trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using deeper template observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogues. Human vetting was carried out in real time on any candidates that passed the above checks. No new transients within the EP/WXT localisation are found, except for a variable star Gaia DR3 4587345820285675136, which is also reported by Perez-Garcia et al. GCN 41047. This source exhibited significant variability in GOTO archival L-band images, brightening from magnitude 20.2 to 18.8 (AB) between 2025-04-07 and 2025-06-15. In our post-trigger observation on 2025-07-08 at 22:31:40 UT (8.30 minutes post-trigger), the source appeared much brighter and was saturated even in our single frames, indicating it was brighter than ~12 mag. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/41048. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39099] EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41047 SUBJECT: EP-WXT trigger 01709181970. confirmation of a stellar flare by BOOTES-6 DATE: 25/07/09 05:14:17 GMT FROM: Alberto Castro-Tirado at Inst.de Astro. de Andalucia <ajct(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, E. Fernandez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, G. Garcia-Segura and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), M. Gritsevich (Univ. of Helsinki) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report: Following the detection of trigger 01709181970 by EP-WXT (Peng et al. GCNC 41045), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) responded to the alert on July 08, 22:29 UT (i.e. 6 min after detection and 2 min after notification). Within the reported EP-FXT error circle we find the star Gaia DR3 4587345820285675136 decreasing in brightness from 11.3 to 12.2 mag in clear filter and using Gaia DR3 Gmag magnitude as reference, during a ~1 hour time interval, confirming as due to a stellar flare. We thank the staff at Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/41047. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39098] EP250704a/GRB 250704B: 10 GHz VLA detection
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41046 SUBJECT: EP250704a/GRB 250704B: 10 GHz VLA detection DATE: 25/07/09 04:57:07 GMT FROM: Roberto Ricci at INAF-IRA <ricci(a)ira.inaf.it> Roberto Ricci, Rosa L. Becerra, Eleonora Troja (Rome U.) report on behalf of the ERC BHianca team: We observed the field of GRB 250704B/EP250704a (Wang et al. GCN 40940; Li et al. GCN 40491) with the Jansky Very Large Array (VLA) at the center frequency of 10 GHz (with a bandwidth of 4 GHz) in C-array configuration on 2025 July 8th at mid observing time 07:53 UT (3.98 days after burst). A radio source was detected within the error circle of optical transient position (Schneider et al. GCN 40942) with a flux density of 92 +/- 7 microJy. This is consistent with the radio detection reported by Schroeder et al. GCN 41038. Further observations are planned. We thank the VLA staff for executing the observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41046. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39097] The EP-WXT trigger 01709181970 is likely a flaring star
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41045 SUBJECT: The EP-WXT trigger 01709181970 is likely a flaring star DATE: 25/07/09 03:30:49 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H.L. Peng (NNU), C. Zhou, P. Y. Han (HUST) , Q. C. Liu (THU), B. B. Zhang (NAO, CAS), G. Y. Zhao (SYSU), Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709181970 at the time of 2025-07-08T22:23:23, is likely a stellar flare associated with Gaia DR3 4587345820285675136. The estimated flux of the flare is around 2.4 x 10^-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 4.5 x 10^31 erg/s. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/41045. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39096] GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow
by GCN Circulars 09 Jul '25

09 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41044 SUBJECT: GRB250702 B,D,E / EP250702a: MOSFIRE imaging of the afterglow DATE: 25/07/09 03:22:13 GMT FROM: Tomas Ahumada Mena at Caltech <tahumada(a)caltech.edu> Kaustav K. Das, Kritti Sharma, Viraj Karambelkar, Mansi Kasliwal, Tomas Ahumada (Caltech), Xander J. Hall (CMU) on behalf of the ZTF collaboration: We used MOSFIRE on Keck I to image the afterglow candidate reported by Martin-Carrillo et al. (GCN 40924), likely associated with EP250702a (Cheng et al., GCNs 40906, 40917) and GRB 250702B, D, and E, detected by Fermi/GBM (Fermi GBM Team, GCNs 40883, 40886, 40890), Swift/BAT (via GUANO; DeLaunay et al., GCN 40903), and Konus/Wind (Frederiks et al., GCN 40914). Observations began at 2025-07-05T10:14:00 UTC and consisted of imaging in the J, H, and Ks bands. We detect the afterglow candidate in the Ks band with m_K = 21.7±0.1 (AB). The source is not detected in the H and J bands, with limiting magnitudes of m_H > 22.4 (AB) and m_J > 22.8 (AB), respectively. These results are consistent with a temporal decay index of ~1.7 (Martin-Carrillo et al., GCN 40924; Levan et al., GCN 40961). We thank the Keck Observatory staff for their support in facilitating these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41044. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39095] LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41043 SUBJECT: LIGO/Virgo/KAGRA S250704ab: NED Galaxies in the 4-Update Localization Volume DATE: 25/07/08 23:42:55 GMT FROM: David Cook at Caltech/IPAC-NED <dcook(a)ipac.caltech.edu> David O. Cook (Caltech/IPAC), Rick Ebert (Caltech/IPAC), George Helou (Caltech/IPAC), Joseph M. Mazzarella (Caltech/IPAC), Marion Schmitz (Caltech/IPAC), and Leo Singer (NASA/GSFC) On behalf of the NASA/IPAC Extragalactic Database (NED) Team. We spatially cross-matched the LVK S250704ab-4-Update sky localization with the NED Local Volume Sample (NED-LVS; Cook et al. 2023), which is a subset of NED with a redshift or redshift-independent distance less than 1000 Mpc. We find 611 galaxies within the 90% containment volume, and we list here the top 20 galaxies sorted by the joint probability of the 3D localization and the WISE W1 luminosity (an observable proxy for stellar mass). For the full or top 20 list of galaxies in the 90% volume go either to the NED Gravitational Wave Followup service at https://ned.ipac.caltech.edu/uri/NED::GWF/ or click on the following links: Full List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S250704ab/4 Top 20 List Download: https://ned.ipac.caltech.edu/uri/NED::GWFglist/fits/S250704ab/4/20 The NED-GWF service provides downloadable galaxy lists and visualizations for candidate host galaxies. For each GW alert, these products are automatically generated and made available within minutes to expedite efficient electromagnetic follow-up observations. The NED top 20 list is sorted by the joint probability of the 3D localization and the WISE W1 luminosity, but users can sort on additional pre-computed prioritization metrics (star formation rate, P_3D * P_SFR; and specific star formation rate, P_3D * P_sSFR; etc.) which are available via downloading the entire galaxy list inside the event's probability volume. | objname| ra| dec|objtype| DistMpc|DistMpc_unc| m_NUV|m_NUV_unc| m_Ks| m_Ks_unc| m_W1| m_W1_unc| P_3D|P_3D_LumW1| |-------------------------|--------------|--------------|-------|-----------|-----------|-------|---------|------------|------------|------------|------------|--------|----------| |WISEA J053516.57+442623.7| 83.81906| 44.43992| G| 509.25| null| null| null| 13.033| 0.125| 10.237| 0.006|1.71e-06| 1.82e-08| |WISEA J054250.35+455634.2| 85.70983| 45.94286| G| 483.57| null| null| null| 12.898| 0.119| 10.988| 0.007|3.12e-06| 1.51e-08| |WISEA J053923.04+451743.3| 84.84603| 45.29538| G| 605.62| null| null| null| 12.453| 0.119| 11.620| 0.009|3.61e-06| 1.51e-08| |WISEA J053539.37+465222.0| 83.91405| 46.87278| G| 461.85| null| null| null| 13.055| 0.145| 11.308| 0.009|4.47e-06| 1.46e-08| |WISEA J054541.19+423211.5| 86.42163| 42.53653| G| 510.30| null| null| null| 13.697| 0.200| 10.637| 0.006|1.80e-06| 1.33e-08| |WISEA J054353.77+433318.3| 85.97407| 43.55511| G| 578.18| null| null| null| 13.998| 0.142| 11.554| 0.010|2.53e-06| 1.03e-08| |WISEA J053847.35+462114.1| 84.69732| 46.35394| G| 470.87| null| null| null| 12.551| 0.100| 12.067| 0.011|5.61e-06| 9.44e-09| |WISEA J053634.97+455156.1| 84.14573| 45.86561| G| 530.56| null| null| null| 13.218| 0.133| 12.261| 0.014|4.81e-06| 8.65e-09| |WISEA J053258.59+491405.3| 83.24413| 49.23481| G| 523.55| null| null| null| 13.311| 0.109| 9.424| 0.006|3.47e-07| 8.31e-09| |WISEA J053723.16+460044.4| 84.34651| 46.01236| G| 407.49| null| null| null| 13.495| 0.191| 11.529| 0.007|3.82e-06| 7.98e-09| |WISEA J054001.86+462259.3| 85.00789| 46.38354| G| 428.04| null| null| null| 12.805| 0.107| 11.667| 0.008|3.94e-06| 7.89e-09| |WISEA J054201.60+460028.5| 85.50669| 46.00793| G| 563.41| null| null| null| 12.939| 0.138| 11.887| 0.008|2.69e-06| 7.68e-09| |WISEA J053208.93+475055.0| 83.03725| 47.84862| G| 557.44| null| null| null| 13.767| 0.225| 11.121| 0.007|1.33e-06| 7.56e-09| |WISEA J053425.20+462348.5| 83.60502| 46.39682| G| 552.92| null| null| null| 13.309| 0.150| 12.061| 0.011|2.86e-06| 6.71e-09| |WISEA J054301.87+435708.0| 85.75780| 43.95222| G| 559.29| null| null| null| 13.811| 0.207| 12.385| 0.016|3.59e-06| 6.34e-09| |WISEA J053625.76+453611.0| 84.10735| 45.60307| G| 500.51| null| null| null| 13.030| 0.166| 12.439| 0.024|4.61e-06| 6.27e-09| |WISEA J054328.21+450858.0| 85.86756| 45.14945| G| 449.66| null| null| null| 13.406| 0.172| 11.996| 0.011|3.70e-06| 6.12e-09| |WISEA J053715.47+424503.7| 84.31447| 42.75103| G| 404.22| null| null| null| 12.767| 0.107| 9.881| 0.006|6.42e-07| 6.01e-09| |WISEA J053606.08+462143.1| 84.02537| 46.36199| G| 573.70| null| null| null| 13.989| 0.253| 12.477| 0.020|3.44e-06| 5.93e-09| |WISEA J054047.69+451204.5| 85.19873| 45.20127| G| 455.94| null| null| null| 13.402| 0.074| 12.608| 0.024|6.10e-06| 5.84e-09| Table 1: Top 20 galaxies in NED-LVS that fall in the 90% probability volume for S250704ab sorted by the joint probability of 3D position and WISE W1 luminosity (P_3D * P_LumW1). Galaxy is the NED preferred name. RA and Dec are the Equatorial coordinates in degrees (J2000). Objtype is the object type of the galaxy candidate. Distance is the distance to the galaxy in Mpc. m_NUV and mErr_NUV are the apparent magnitude and error from GALEX. m_Ks and mErr_Ks are the apparent magnitude and error from 2MASS. m_W1 and mErr_W1 are the apparent magnitude and error from AllWISE. P_3D is the probability that the galaxy is in the volume given the distance of GW event. P_3D_LumW1 is the joint probability within the volume weighted by the WISE1 luminosity of the galaxy (P_3D * P_LumW1). View this GCN Circular online at https://gcn.nasa.gov/circulars/41043. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39094] IceCube-250706A: No Candidates from WINTER
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41042 SUBJECT: IceCube-250706A: No Candidates from WINTER DATE: 25/07/08 20:35:14 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Robert Stein (UMD), Danielle Frostig (CfA), Viraj Karambelkar (Caltech), Mansi Kasliwal (Caltech), Nathan Lourie (MIT), Geoffrey Mo (MIT), and Robert Simcoe (MIT) report: On behalf of Wide-Field Infra-Red Transient Explorer (WINTER) collaboration: We observed the localization region of the neutrino event IceCube-250706A (Zegarelli et. al, GCN 40994) with the 1.2 sq. degree near-IR WINTER camera on the Palomar 1-m telescope (Lourie et al. 2021, Frostig et al. 2024). We conducted observations in J-band beginning at 2025-07-07 02:42 UTC, approximately 13.5 hours after event time. Our observations covered a total of 0.7 sq. deg. of sky for which reference images were available, corresponding to 77.3% of the total probability. Our observations reached a median depth of 18.8 AB mag. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565). We use data from the UKIRT Hemisphere survey (Dye et al. 2018) as references for image subtraction. We search for WINTER sources with multiple detections, and for WINTER sources with cross-matches in the alert stream of the Zwicky Transient Facility (Bellm et al. 2019). After removing likely stellar sources and likely subtraction artefacts, we find no candidate counterparts. This is consistent with similar non-detections reported in the optical by Globus et al. (GCN 41003), Becerra et al. (GCN 41004) and Stein et al. (GCN 41040). Observations of this field will continue as part of the WINTER neutrino follow-up program. WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/41042. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39093] IPN triangulation of GRB 250706C (consistent with the GRB 250706B)
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41041 SUBJECT: IPN triangulation of GRB 250706C (consistent with the GRB 250706B) DATE: 25/07/08 19:30:06 GMT FROM: Anna Ridnaia at Ioffe Institute <ridnaia(a)mail.ioffe.ru> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, A. Ridnaia, D. Frederiks, A. Lysenko, D. Svinkin, and T. Cline on behalf of the Konus-Wind team, E. Burns on behalf of the IPN, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The very bright, long-duration GRB 250706C (Konus-Wind detection: Frederiks et al., GCNs 41013, 41027; Fermi-LAT detection: Longo et al., GCN 41019) was detected by Konus-Wind and Mars-Odyssey (HEND) at about 60322 s UT (16:45:22), ~1200 s before GRB 250706B (SVOM detection: Palmerio et al, GCNs 40989, 41026) We have triangulated it to a Konus-HEND annulus centered at RA(2000)=342.841 deg (22h 51m 22s) Dec(2000)=-8.288 deg (-8d 17' 19"), whose radius is 63.671 +/- 0.024 deg (3 sigma). This localization may be improved. The SVOM/ECLAIRs source localization reported for GRB 250706B (GCN 40989) is consistent with the Konus-HEND annulus, the Konus-Wind ecliptic latitude response and the Fermi-LAT position (GCN 41019), indicating that GRB 250706B and GRB 250706C are distinct emission episodes of the same GRB. A triangulation map and HEALPix FITS file are posted at http://www.ioffe.ru/LEA/GRBs/GRB250706_T60322/IPN/ The HEALPix triangulation map is the multi-order HEALPix in units of probability density. View this GCN Circular online at https://gcn.nasa.gov/circulars/41041. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39092] IceCube-250706A: No Candidates from the Zwicky Transient Facility
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41040 SUBJECT: IceCube-250706A: No Candidates from the Zwicky Transient Facility DATE: 25/07/08 19:04:15 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Robert Stein (JSI), Jannis Necker (DESY), Anna Franckowiak (Ruhr University Bochum) and Akshay Eranhalodi (DESY) report: On behalf of the Zwicky Transient Facility (ZTF) and Global Relay of Observatories Watching Transients Happen (GROWTH) collaborations: As part of the ZTF neutrino follow up program (Stein et al. 2023), we observed the localization region of the neutrino event IceCube-250706A (Zegarelli et. al, GCN 40994) with the Palomar 48-inch telescope, equipped with the 47 square degree ZTF camera (Bellm et al. 2019, Graham et al. 2019). We started observations in the g- and r-band beginning at 2025-07-07 05:03 UTC, approximately 15.8 hours after event time. We covered 67.1% (0.6 sq deg) of the reported localization region. This estimate accounts for chip gaps. Each exposure was 300s with a typical depth of 21.0 mag. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC to search for potential counterparts (Masci et al. 2019). AMPEL (Nordin et al. 2019, Stein et al. 2021) was used to search the alerts database for candidates. We reject stellar sources (Tachibana and Miller 2018) and moving objects, and apply machine learning algorithms (Mahabal et al. 2019). No candidate counterparts were detected. This is consistent with similar non-detections reported by Globus et al. (GCN 41003) and Becerra et al. (GCN 41004). Observations of this field will continue as part of our standard ToO cadence for high-energy neutrinos (Stein et al. 2023). Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Award #2407588 and a partnership including Caltech, USA; Caltech/IPAC, USA; University of Maryland, USA; University of California, Berkeley, USA; University of Wisconsin at Milwaukee, USA; Cornell University, USA; Drexel University, USA; University of North Carolina at Chapel Hill, USA; Institute of Science and Technology, Austria; National Central University, Taiwan, and OKC, University of Stockholm, Sweden. Operations are conducted by Caltech's Optical Observatory (COO), Caltech/IPAC, and the University of Washington at Seattle, USA. GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949. Alert distribution service provided by DIRAC@UW (Patterson et al. 2019). Alert database searches are done by AMPEL (Nordin et al. 2019). Alert filtering is performed with the nuztf (Stein et al. 2021, https://github.com/desy-multimessenger/nuztf ). View this GCN Circular online at https://gcn.nasa.gov/circulars/41040. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39091] IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41039 SUBJECT: IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/07/08 18:56:33 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 25-07-08 at 14:05:19.54 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.6259 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141112_11292662.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 25-07-08 Time: 14:05:19.54 UT RA: 222.71 (+0.52/-0.54 deg 90% PSF containment) J2000 Dec: 26.49 (+0.47/-0.47 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/41039. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39090] IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41039 SUBJECT: IceCube-250708A - IceCube observation of a high-energy neutrino candidate track-like event DATE: 25/07/08 18:56:33 GMT FROM: A. Zegarelli at Ruhr University Bochum <azegarelli(a)icecube.wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 25-07-08 at 14:05:19.54 UT IceCube detected a track-like event with a moderate probability of being of astrophysical origin. The event was selected by the ICECUBE_Astrotrack_BRONZE alert stream. The average astrophysical neutrino purity for Bronze alerts is 30%. This alert has an estimated false alarm rate of 1.6259 events per year due to atmospheric backgrounds. The IceCube detector was in a normal operating state at the time of detection. After the initial automated alert (https://gcn.gsfc.nasa.gov/notices_amon_g_b/141112_11292662.amon), more sophisticated reconstruction algorithms have been applied offline, with the direction refined to: Date: 25-07-08 Time: 14:05:19.54 UT RA: 222.71 (+0.52/-0.54 deg 90% PSF containment) J2000 Dec: 26.49 (+0.47/-0.47 deg 90% PSF containment) J2000 We encourage follow-up by ground and space-based instruments to help identify a possible astrophysical source for the candidate neutrino. No known gamma-ray sources listed in the Fermi 4FGL-DR4 or 3FHL catalogs are located within the 90% uncertainty region of the event. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu View this GCN Circular online at https://gcn.nasa.gov/circulars/41039. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39089] GRB 250704B / EP250704a: VLA radio detection
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41038 SUBJECT: GRB 250704B / EP250704a: VLA radio detection DATE: 25/07/08 17:46:51 GMT FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu> G. Schroeder (Cornell), J. Rastinejad, W. Fong (Northwestern), T. Laskar (Utah) report: We observed the location of the short-duration GRB 250704B/EP 250704A (Wang et al., GCN 40940; Li et al., GCNs 40941, 40956, Frederiks et al., GCN 40972; Wang et al., GCN 40978; Shimizu et al., GCN 41025) with the Karl G. Jansky Very Large Array (VLA) in C configuration under program 25A-063 (PI Schroeder) at a mid time of 2025 July 8 at 09:57 UT (4.1 days post-burst) for 1.25 hours at a mean frequency of 6 GHz. In preliminary analysis, we detect a 20-sigma radio source with a flux density of ~150 microJy at the position: RA(J2000) = 20:03:29.511 Dec(J2000) = +12:01:23.31 with an uncertainty of ~0.2" in each coordinate. This position is consistent with the X-ray position (Li et al., GCNs 40941, 40956; Evans et al. GCN 40951, Salvaggio et al. GCN 40987) and optical position (Schneider et al., GCN 40942). At z=0.661 (An et al. GCN 40966), this corresponds to a rest-frame luminosity of ~ 2e30erg/s/Hz, on the bright end of typical short-duration Gamma-ray burst radio afterglow luminosities at a similar rest-frame time (e.g., Laskar et al. 2022). Further observations are planned to assess the variability of the radio source and its connection to GRB 250704B and EP250704A. We thank the VLA staff for quickly approving and executing these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41038. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39088] Fermi GRB 250708A: Global MASTER-Net observations report
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41037 SUBJECT: Fermi GRB 250708A: Global MASTER-Net observations report DATE: 25/07/08 17:30:48 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 250708A ( Fermi GBM team, GCN 41028) errorbox 8298 sec after notice time and 8329 sec after trigger time at 2025-07-08 17:10:51 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 63 deg. The sun altitude is -17.2 deg. The galactic latitude b = 30 deg., longitude l = 33 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2929280 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 8359 | 2025-07-08 17:10:51 | MASTER-SAAO | (16h 44m 30.84s , +12d 39m 32.4s) | C | 60 | 17.2 | 8359 | 2025-07-08 17:10:51 | MASTER-SAAO | (16h 46m 19.84s , +12d 23m 56.8s) | C | 60 | 17.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41037. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39087] IceCube Alert 250708.59: Global MASTER-Net observations report
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41036 SUBJECT: IceCube Alert 250708.59: Global MASTER-Net observations report DATE: 25/07/08 17:26:22 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A.Sosnovskij (CrAO), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), D.Buckley (SAAO), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-SAAO robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in South Africa (South African Astronomical Observatory) was pointed to the IceCube Alert 250708.59 (trigger No 11292662,14h 52m 41.28s , +26d 45m 18.0s, R=0.51) errorbox 10955 sec after notice time and 11017 sec after trigger time at 2025-07-08 17:08:56 UT, with upper limit up to 18.8 mag. Observations started at twilight. The observations began at zenith distance = 61 deg. The sun altitude is -16.8 deg. The galactic latitude b = 63 deg., longitude l = 39 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2929205 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 11047 | 2025-07-08 17:08:56 | MASTER-SAAO | (14h 49m 32.05s , +26d 51m 11.1s) | C | 60 | 18.1 | 11047 | 2025-07-08 17:08:56 | MASTER-SAAO | (14h 51m 28.75s , +26d 35m 32.5s) | C | 60 | 18.0 | 11275 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 51m 31.65s , +26d 35m 43.8s) | C | 60 | 17.9 | 11335 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 51m 31.65s , +26d 35m 43.8s) | C | 180 | 18.7 | Coadd 11275 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 49m 32.60s , +26d 51m 19.6s) | C | 60 | 18.0 | 11335 | 2025-07-08 17:12:44 | MASTER-SAAO | (14h 49m 32.59s , +26d 51m 19.6s) | C | 180 | 18.8 | Coadd 11369 | 2025-07-08 17:14:18 | MASTER-SAAO | (14h 51m 34.49s , +26d 37m 22.8s) | C | 60 | 18.0 | 11369 | 2025-07-08 17:14:18 | MASTER-SAAO | (14h 49m 35.36s , +26d 52m 58.0s) | C | 60 | 18.1 | 11462 | 2025-07-08 17:15:51 | MASTER-SAAO | (14h 51m 29.28s , +26d 36m 44.1s) | C | 60 | 18.0 | 11462 | 2025-07-08 17:15:51 | MASTER-SAAO | (14h 49m 30.14s , +26d 52m 18.7s) | C | 60 | 18.0 | 11584 | 2025-07-08 17:17:23 | MASTER-SAAO | (14h 49m 30.78s , +26d 53m 23.3s) | C | 120 | 18.4 | 11584 | 2025-07-08 17:17:23 | MASTER-SAAO | (14h 51m 29.90s , +26d 37m 48.8s) | C | 120 | 18.3 | 11737 | 2025-07-08 17:19:56 | MASTER-SAAO | (14h 49m 37.53s , +26d 52m 27.5s) | C | 120 | 18.4 | 11737 | 2025-07-08 17:19:56 | MASTER-SAAO | (14h 51m 36.64s , +26d 36m 53.2s) | C | 120 | 18.3 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/41036. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39086] IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41035 SUBJECT: IceCube-250706A: Upper limits from a search for additional neutrino events in IceCube DATE: 25/07/08 17:20:16 GMT FROM: Jessie Thwaites at IceCube/U Wisc-Madison <thwaites(a)wisc.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: IceCube has performed a search [1] for additional track-like muon neutrino events arriving from the direction of IceCube-250706A (https://gcn.nasa.gov/circulars/40994) in a time range of 1000 seconds centered on the alert event time (2025-07-06 13:06:20.040 UTC to 2025-07-06 13:23:00.040 UTC) during which IceCube was collecting good quality data. Excluding the event that prompted the alert, zero track-like events are found within the 90% containment region of IceCube-250706A. We report a p-value of 1.00 in this time window. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250706A is 1.5e-01 GeV cm^-2 in a 1000 second time window. 90% of events IceCube would detect from a source at this declination with an E^-2.5 spectrum have energies in the approximate energy range between 2e+02 GeV and 6e+04 GeV. A subsequent search was performed including 2 days of data centered on the alert event time (2025-07-05 13:14:40.040 UTC to 2025-07-07 13:14:40.040 UTC). In this case, we report a p-value of 1.00, consistent with no significant excess of track events. The IceCube sensitivity to neutrino point sources with an E^-2.5 spectrum (E^2 dN/dE at 1 TeV) within the locations spanned by the 90% spatial containment region of IceCube-250706A is 1.8e-01 GeV cm^-2 in a 2 day time window. The IceCube Neutrino Observatory is a cubic-kilometer neutrino detector operating at the geographic South Pole, Antarctica. The IceCube realtime alert point of contact can be reached at roc(a)icecube.wisc.edu. [1] IceCube Collaboration, R. Abbasi et al., ApJ 910 4 (2021) View this GCN Circular online at https://gcn.nasa.gov/circulars/41035. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39085] LIGO/Virgo/KAGRA S250705cb: Updated Sky localization
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41034 SUBJECT: LIGO/Virgo/KAGRA S250705cb: Updated Sky localization DATE: 25/07/08 16:03:00 GMT FROM: lucy.thomas(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250705cb (GCN Circular 40980). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250705cb For the Bilby.multiorder.fits,0 sky map, the 90% credible region is 333 deg2. Marginalized over the whole sky, the a posteriori luminosity distance estimate is 1143 +/- 299 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 View this GCN Circular online at https://gcn.nasa.gov/circulars/41034. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 39084] LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification
by GCN Circulars 08 Jul '25

08 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41033 SUBJECT: LIGO/Virgo/KAGRA S250704ab: Updated Sky localization and EM Bright Classification DATE: 25/07/08 15:59:56 GMT FROM: lucy.thomas(a)ligo.org The LIGO Scientific Collaboration, the Virgo Collaboration, and the KAGRA Collaboration report: We have conducted further analysis of the LIGO Hanford Observatory (H1), LIGO Livingston Observatory (L1), and Virgo Observatory (V1) data around the time of the compact binary merger (CBC) candidate S250704ab (GCN Circular 40935). Parameter estimation has been performed using Bilby [1] and a new sky map, Bilby.multiorder.fits,0, distributed via GCN and SCiMMA notices, is available for retrieval from the GraceDB event page: https://gracedb.ligo.org/superevents/S250704ab Based on posterior support from parameter estimation [1], under the assumption that the candidate S250704ab is astrophysical in origin, the probability that the lighter compact object is consistent with a neutron star mass (HasNS) is <1%. [2] Using the masses and spins inferred from the signal, the probability of matter outside the final compact object (HasRemnant) is <1%. [2] Both HasNS and HasRemnant consider the support of several neutron star equations of state for maximum neutron star mass. The probability that either of the binary components lies between 3 and 5 solar masses (HasMassGap) is <1%. The probability that the lighter compact object is below 1 solar mass (HasSSM) is <1%. The source chirp mass falls with highest probability in the bin (5.5, 11.0) solar masses after parameter estimation [1], assuming the candidate is astrophysical in origin. For the Bilby.multiorder.fits,0 sky map, the 90% credible region is well fit by an ellipse with an area of 57 deg2 described by the following DS9 region (right ascension, declination, semi-major axis, semi-minor axis, position angle of the semi-minor axis): icrs; ellipse(05h40m, +44d43m, 7.74d, 2.35d, 77.56d) Marginalized over the whole sky, the a posteriori luminosity distance estimate is 531 +/- 101 Mpc (a posteriori mean +/- standard deviation). For further information about analysis methodology and the contents of this alert, refer to the LIGO/Virgo/KAGRA Public Alerts User Guide https://emfollow.docs.ligo.org/. [1] Ashton et al. ApJS 241, 27 (2019) doi:10.3847/1538-4365/ab06fc and Morisaki et al. PRD 108, 123040 (2023) doi:10.1103/PhysRevD.108.123040 [2] Chatterjee et al. ApJ 896, 54 (2020) doi:10.3847/1538-4357/ab8dbe View this GCN Circular online at https://gcn.nasa.gov/circulars/41033. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0