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[vsnet-grb-info 38518] GRB 250516A: COLIBRÍ optical upper limit
by GCN Circulars 18 May '25

18 May '25

TITLE: GCN CIRCULAR NUMBER: 40486 SUBJECT: GRB 250516A: COLIBRÍ optical upper limit DATE: 25/05/18 16:00:54 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Francis Fortin (IRAP), Kin Ocelotl López (UNAM), Rosa L. Becerra (U Roma), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Sarah Antier (OCA), 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), 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 GRB 250516A (Fermi GBM team GCN Circ. 40466; Beardmore et al., GCN Circ. 40467; Frederiks et al., GCN Circ. 40485) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-05-18 09:59 to 11:20 UTC (from 43.4 to 44.8 hours after the trigger) and obtained 64 minutes of exposure in the r 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, we do not detect any new source at the XRT source position (Evans et al., GCN Circ. 40468) down to the following 3-sigma limit: r > 22.08 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/40486. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38517] Konus-Wind detection of GRB 250516A
by GCN Circulars 18 May '25

18 May '25

TITLE: GCN CIRCULAR NUMBER: 40485 SUBJECT: Konus-Wind detection of GRB 250516A DATE: 25/05/18 13:53:49 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaya, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report The long GRB 250516A (Fermi GBM detection: Fermi GBM team, GCN 40466; Mukherjee & Meegan, GCN 40473; Swift detection: Beardmore et al., GCN 40467) was detected by Konus-Wind (KW) in the waiting mode. A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band reveals a ~11 sigma count-rate increase in the interval from T0-2.757 s to T0+23.739 s where T0 = 14:35:29 UT. The KW light curve of this burst is available at http://www.ioffe.ru/LEA/GRBs/GRB250516A/ Modeling the time-integrated spectrum of the burst by a power law with exponential cutoff (CPL) model dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) yields alpha = -1.21 (-0.10, + 0.10) and Ep = 164(-9,+10) keV. Modelling the spectrum near the peak count rate (T0+3.131 s to T0+9.019 s) by a CPL function yields alpha = -1.35 (-0.10, + 0.11) and Ep = 403(-53,+82) keV. In the 20 keV -10 MeV band, standard for the KW analysis, the burst fluence is (4.41 ± 1.33)x10^-6 erg/cm^2 and the 2.944 s peak energy flux, measured from T0+6.075 s, is (5.85 ± 0.42)x10^-7 erg/cm^2/s. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/40485. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38516] GRB 250516B: NuSTAR Detection of the Prompt Emission
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40484 SUBJECT: GRB 250516B: NuSTAR Detection of the Prompt Emission DATE: 25/05/17 19:08:14 GMT FROM: Brian Grefenstette at Caltech/NuSTAR <bwgref(a)srl.caltech.edu> B. Grefenstette (Caltech) reports on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group: The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 250516B in both the NuSTAR CsI anti-coincidence shields and in the CdZnTe detectors. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper. The NuSTAR SINGS algorithm triggered at 2025-05-16 06:31:39 with a resolution ~5-seconds. This is consistent with the GECAM-B reported time of 2025-05-16T06:31:34.7 (Wang et al., GCN circ. 40469). The GRB is a broad burst with multiples peaks. The brightest has a peak count rates in the anti-coincidence shields near 4,000 cps over a baseline of ~1,000 cps. The burst is also clearly seen in the CdZnTe detectors. Discovery report and a preliminary lightcurves for this GRB can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2025/250516B/ Information on NuSTAR SINGS can be found here: https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/ NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA’s Science Mission Directorate in Washington. View this GCN Circular online at https://gcn.nasa.gov/circulars/40484. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38515] EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40483 SUBJECT: EP-WXT trigger (ID: 01709176312): a new X-ray outburst of HMXB RX J0111.2-7317 DATE: 25/05/17 15:40:03 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. C. Liu (THU), X.-Y. Zhou (PRIC), Y.-H. I. Yin (NJU) and C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: We report on the detection of a new X-ray outburst of the High Mass X-ray Binary (HMXB) RX J0111.2-7317 by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The burst triggered EP-WXT (ID: 01709176312) at 2025-05-16T19:26:03 (UTC). The emission lasted for around 100 min. The WXT position of the source, inferred from the onground analysis, is R.A. = 17.759 deg, DEC = -73.279 deg (J2000) with an uncertainty of 2.5 arcmin in radius (90% C.L. statistical and systematic). The averaged WXT spectrum in 0.5-4 keV can be fitted by an absorbed power law model a Galactic hydrogen column density of 4.9 x 10^21 cm^-2 and a photon index of 3.10 (+/-0.43). The average unabsorbed 0.5-4 keV flux is 1.3 (-2.0, +2.0) x 10^-10 erg/cm^2/s. Following the WXT trigger, a follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. The FXT observation started at 2025-05-16T19:26:35 (UTC), around 30 seconds after the trigger. The analysis of the data, with an exposure of 2 ks, reveals a detection of an X-ray source at RA = 17.7851 deg, Dec = -73.2799 deg (J2000) with an uncertainty of 10 arcsec in radius (90% C.L. statistical and systematic). This position is consistent with the known HMXB RX J0111.2-7317, confirming the WXT detection as the outburst of this X-ray source. The averaged FXT spectrum in 0.5-10 keV can be roughly fitted by an absorbed power law model a Galactic hydrogen column density of 4.9 x 10^21 cm^-2 and a photon index of 1.86 (+/-0.01). The average unabsorbed 0.5-10 keV flux is 1.48 (-0.02, +0.02) x 10^-10 erg/cm^2/s, which is consistent with the flux detected by the WXT. The X-ray outburst was previously detected by WXT at 2025-05-13T14:15:40 (UTC). The observed flux is around 3.26 x 10^-11 erg/cm^2/s, consistent with the following WXT and FXT observations. More follow-up observations are encouraged. 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/40483. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38514] Fermi GRB 250516A: Global MASTER-Net observations report
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40482 SUBJECT: Fermi GRB 250516A: Global MASTER-Net observations report DATE: 25/05/17 13:16:04 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) started inspect of the Fermi GRB 250516A ( Fermi GBM team, GCN 40466) errorbox 53236 sec after notice time and 53273 sec after trigger time at 2025-05-17 05:23:23 UT, with upper limit up to 19.8 mag. The observations began at zenith distance = 81 deg. The sun altitude is -73.4 deg. The galactic latitude b = -43 deg., longitude l = 63 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2872281 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 53354 | 2025-05-17 05:23:23 | MASTER-OAFA | (22h 08m 57.57s , -09d 53m 16.4s) | C | 160 | 16.3 | 54587 | 2025-05-17 05:43:56 | MASTER-OAFA | (22h 08m 53.80s , -09d 49m 35.9s) | C | 160 | 16.6 | 54724 | 2025-05-17 05:47:13 | MASTER-OAFA | (22h 08m 48.08s , -09d 50m 58.9s) | C | 40 | 16.7 | 55010 | 2025-05-17 05:50:59 | MASTER-OAFA | (22h 09m 00.15s , -09d 50m 43.3s) | C | 160 | 16.9 | 55020 | 2025-05-17 05:50:59 | MASTER-OAFA | (22h 19m 10.53s , -09d 28m 33.4s) | C | 180 | 15.5 | 55206 | 2025-05-17 05:54:15 | MASTER-OAFA | (22h 08m 57.96s , -09d 49m 01.8s) | C | 160 | 17.0 | 55216 | 2025-05-17 05:54:15 | MASTER-OAFA | (22h 19m 08.28s , -09d 26m 54.9s) | C | 180 | 16.0 | 55401 | 2025-05-17 05:57:30 | MASTER-OAFA | (22h 08m 58.20s , -09d 49m 52.9s) | C | 160 | 17.0 | 55411 | 2025-05-17 05:57:30 | MASTER-OAFA | (22h 19m 08.56s , -09d 27m 47.0s) | C | 180 | 16.7 | 55597 | 2025-05-17 06:00:46 | MASTER-OAFA | (22h 09m 01.12s , -09d 48m 33.7s) | C | 160 | 17.1 | 55607 | 2025-05-17 06:00:46 | MASTER-OAFA | (22h 19m 11.35s , -09d 26m 29.4s) | C | 180 | 16.9 | 56557 | 2025-05-17 06:16:46 | MASTER-OAFA | (22h 08m 55.08s , -09d 48m 15.8s) | C | 160 | 17.1 | 56568 | 2025-05-17 06:16:46 | MASTER-OAFA | (22h 19m 06.24s , -09d 26m 09.9s) | C | 180 | 17.9 | 56752 | 2025-05-17 06:20:01 | MASTER-OAFA | (22h 08m 57.37s , -09d 46m 58.3s) | C | 160 | 17.3 | 56763 | 2025-05-17 06:20:02 | MASTER-OAFA | (22h 19m 08.29s , -09d 24m 56.6s) | C | 180 | 18.0 | 56946 | 2025-05-17 06:23:15 | MASTER-OAFA | (22h 09m 01.40s , -09d 47m 45.6s) | C | 160 | 17.4 | 56956 | 2025-05-17 06:23:15 | MASTER-OAFA | (22h 19m 12.42s , -09d 25m 45.4s) | C | 180 | 18.3 | 57850 | 2025-05-17 06:39:19 | MASTER-OAFA | (22h 08m 51.04s , -09d 48m 32.1s) | C | 40 | 17.1 | 57860 | 2025-05-17 06:39:19 | MASTER-OAFA | (22h 18m 01.41s , -09d 25m 06.5s) | C | 60 | 18.3 | 58215 | 2025-05-17 06:44:23 | MASTER-OAFA | (22h 09m 03.18s , -09d 45m 55.1s) | C | 160 | 17.5 | 58225 | 2025-05-17 06:44:24 | MASTER-OAFA | (22h 19m 14.38s , -09d 23m 59.1s) | C | 180 | 18.8 | 59041 | 2025-05-17 06:59:10 | MASTER-OAFA | (22h 08m 45.76s , -09d 46m 30.8s) | C | 40 | 17.1 | 59051 | 2025-05-17 06:59:10 | MASTER-OAFA | (22h 17m 56.74s , -09d 23m 08.5s) | C | 60 | 18.5 | 59424 | 2025-05-17 07:04:33 | MASTER-OAFA | (22h 08m 56.48s , -09d 46m 31.6s) | C | 160 | 17.5 | 59434 | 2025-05-17 07:04:33 | MASTER-OAFA | (22h 19m 08.49s , -09d 24m 38.0s) | C | 180 | 18.9 | 60168 | 2025-05-17 07:17:57 | MASTER-OAFA | (22h 08m 45.17s , -09d 46m 41.0s) | C | 40 | 17.1 | 60179 | 2025-05-17 07:17:57 | MASTER-OAFA | (22h 17m 56.70s , -09d 23m 17.5s) | C | 60 | 18.7 | 60363 | 2025-05-17 07:21:11 | MASTER-OAFA | (22h 08m 48.12s , -09d 44m 50.5s) | C | 40 | 17.3 | 60373 | 2025-05-17 07:21:12 | MASTER-OAFA | (22h 17m 59.64s , -09d 21m 30.3s) | C | 60 | 18.9 | 60616 | 2025-05-17 07:24:25 | MASTER-OAFA | (22h 09m 03.10s , -09d 43m 57.6s) | C | 160 | 17.8 | 60626 | 2025-05-17 07:24:25 | MASTER-OAFA | (22h 19m 14.88s , -09d 21m 57.0s) | C | 180 | 19.1 | 62075 | 2025-05-17 07:48:44 | MASTER-OAFA | (22h 08m 55.13s , -09d 42m 54.6s) | C | 160 | 17.7 | 62086 | 2025-05-17 07:48:44 | MASTER-OAFA | (22h 19m 08.48s , -09d 20m 53.2s) | C | 180 | 19.3 | 62214 | 2025-05-17 07:52:02 | MASTER-OAFA | (22h 08m 49.30s , -09d 44m 23.1s) | C | 40 | 17.4 | 62224 | 2025-05-17 07:52:03 | MASTER-OAFA | (22h 18m 01.84s , -09d 20m 58.6s) | C | 60 | 19.2 | 63302 | 2025-05-17 08:09:10 | MASTER-OAFA | (22h 08m 57.42s , -09d 43m 55.7s) | C | 160 | 18.0 | 63312 | 2025-05-17 08:09:11 | MASTER-OAFA | (22h 19m 11.59s , -09d 21m 56.1s) | C | 180 | 19.6 | 65610 | 2025-05-17 08:47:39 | MASTER-OAFA | (22h 08m 55.02s , -09d 41m 06.6s) | C | 160 | 18.1 | 65620 | 2025-05-17 08:47:39 | MASTER-OAFA | (22h 19m 09.74s , -09d 19m 09.9s) | C | 180 | 19.6 | 66945 | 2025-05-17 09:09:53 | MASTER-OAFA | (22h 08m 56.20s , -09d 42m 17.9s) | C | 160 | 18.2 | 66955 | 2025-05-17 09:09:54 | MASTER-OAFA | (22h 19m 12.01s , -09d 20m 14.9s) | C | 180 | 19.8 | 68016 | 2025-05-17 09:28:45 | MASTER-OAFA | (21h 54m 48.23s , -07d 54m 13.2s) | C | 40 | 17.7 | 68155 | 2025-05-17 09:30:04 | MASTER-OAFA | (22h 27m 36.59s , -08d 43m 27.0s) | C | 160 | 18.4 | 68165 | 2025-05-17 09:30:04 | MASTER-OAFA | (22h 17m 17.92s , -09d 03m 28.4s) | C | 180 | 19.7 | 68957 | 2025-05-17 09:44:25 | MASTER-OAFA | (21h 54m 46.25s , -07d 53m 07.2s) | C | 40 | 17.7 | 69276 | 2025-05-17 09:49:45 | MASTER-OAFA | (22h 27m 06.28s , +01d 35m 10.8s) | C | 40 | 17.4 | 69286 | 2025-05-17 09:49:45 | MASTER-OAFA | (22h 17m 55.04s , +01d 12m 56.3s) | C | 60 | 18.7 | 69415 | 2025-05-17 09:51:03 | MASTER-OAFA | (22h 27m 35.48s , -08d 42m 28.0s) | C | 160 | 18.6 | 69425 | 2025-05-17 09:51:04 | MASTER-OAFA | (22h 17m 16.20s , -09d 02m 35.8s) | C | 180 | 19.7 | 69553 | 2025-05-17 09:54:21 | MASTER-OAFA | (22h 26m 50.43s , -00d 18m 25.4s) | C | 40 | 17.5 | 69563 | 2025-05-17 09:54:22 | MASTER-OAFA | (22h 17m 38.98s , -00d 40m 37.2s) | C | 60 | 19.2 | 69631 | 2025-05-17 09:55:39 | MASTER-OAFA | (22h 11m 55.19s , +01d 37m 25.6s) | C | 40 | 17.4 | 69641 | 2025-05-17 09:55:40 | MASTER-OAFA | (22h 02m 43.70s , +01d 15m 10.5s) | C | 60 | 19.4 | 69706 | 2025-05-17 09:56:55 | MASTER-OAFA | (22h 28m 42.02s , +03d 30m 10.0s) | C | 40 | 17.0 | 69716 | 2025-05-17 09:56:55 | MASTER-OAFA | (22h 19m 30.05s , +03d 07m 48.2s) | C | 60 | 18.1 | 69785 | 2025-05-17 09:58:14 | MASTER-OAFA | (22h 42m 12.03s , +01d 36m 43.5s) | C | 40 | 17.9 | 69795 | 2025-05-17 09:58:14 | MASTER-OAFA | (22h 33m 00.73s , +01d 14m 23.6s) | C | 60 | 19.3 | 69865 | 2025-05-17 09:59:33 | MASTER-OAFA | (22h 43m 22.31s , -02d 12m 22.6s) | C | 40 | 17.8 | 69875 | 2025-05-17 09:59:34 | MASTER-OAFA | (22h 34m 10.40s , -02d 34m 34.0s) | C | 60 | 19.3 | 69944 | 2025-05-17 10:00:52 | MASTER-OAFA | (22h 27m 01.19s , +01d 35m 18.5s) | C | 40 | 17.4 | 69954 | 2025-05-17 10:00:53 | MASTER-OAFA | (22h 17m 49.81s , +01d 12m 59.9s) | C | 60 | 18.8 | 70024 | 2025-05-17 10:02:12 | MASTER-OAFA | (22h 30m 55.45s , -04d 06m 35.7s) | C | 40 | 17.7 | 70034 | 2025-05-17 10:02:13 | MASTER-OAFA | (22h 21m 42.26s , -04d 28m 41.7s) | C | 60 | 19.2 | 70103 | 2025-05-17 10:03:31 | MASTER-OAFA | (22h 12m 53.62s , -02d 10m 32.8s) | C | 40 | 17.7 | 70113 | 2025-05-17 10:03:32 | MASTER-OAFA | (22h 03m 41.57s , -02d 32m 40.4s) | C | 60 | 19.3 | 70179 | 2025-05-17 10:04:48 | MASTER-OAFA | (22h 26m 50.63s , -00d 18m 22.6s) | C | 40 | 17.4 | 70189 | 2025-05-17 10:04:48 | MASTER-OAFA | (22h 17m 39.16s , -00d 40m 35.4s) | C | 60 | 19.0 | 70258 | 2025-05-17 10:06:07 | MASTER-OAFA | (22h 11m 54.89s , +01d 37m 38.1s) | C | 40 | 17.4 | 70268 | 2025-05-17 10:06:07 | MASTER-OAFA | (22h 02m 43.38s , +01d 15m 22.1s) | C | 60 | 19.3 | 70335 | 2025-05-17 10:07:24 | MASTER-OAFA | (22h 28m 43.22s , +03d 30m 23.6s) | C | 40 | 17.0 | 70346 | 2025-05-17 10:07:24 | MASTER-OAFA | (22h 19m 31.24s , +03d 08m 01.5s) | C | 60 | 18.1 | 70413 | 2025-05-17 10:08:42 | MASTER-OAFA | (22h 42m 12.23s , +01d 36m 55.4s) | C | 40 | 17.9 | 70423 | 2025-05-17 10:08:42 | MASTER-OAFA | (22h 33m 00.93s , +01d 14m 35.7s) | C | 60 | 19.3 | 70490 | 2025-05-17 10:09:59 | MASTER-OAFA | (22h 43m 21.90s , -02d 12m 10.0s) | C | 40 | 17.6 | 70500 | 2025-05-17 10:09:59 | MASTER-OAFA | (22h 34m 09.98s , -02d 34m 21.8s) | C | 60 | 19.1 | 70629 | 2025-05-17 10:11:18 | MASTER-OAFA | (22h 27m 33.04s , -08d 43m 51.9s) | C | 160 | 18.5 | 70639 | 2025-05-17 10:11:18 | MASTER-OAFA | (22h 17m 13.64s , -09d 04m 01.9s) | C | 180 | 19.6 | 70767 | 2025-05-17 10:14:36 | MASTER-OAFA | (22h 27m 07.09s , +01d 35m 50.2s) | C | 40 | 17.4 | 70777 | 2025-05-17 10:14:36 | MASTER-OAFA | (22h 17m 55.62s , +01d 13m 33.1s) | C | 60 | 18.7 | 70845 | 2025-05-17 10:15:54 | MASTER-OAFA | (22h 30m 52.15s , -04d 04m 48.9s) | C | 40 | 17.5 | 70856 | 2025-05-17 10:15:54 | MASTER-OAFA | (22h 21m 38.89s , -04d 26m 54.1s) | C | 60 | 19.0 | 70923 | 2025-05-17 10:17:12 | MASTER-OAFA | (22h 12m 53.74s , -02d 11m 39.7s) | C | 40 | 17.6 | 70933 | 2025-05-17 10:17:12 | MASTER-OAFA | (22h 03m 41.60s , -02d 33m 46.9s) | C | 60 | 19.3 | 70999 | 2025-05-17 10:18:28 | MASTER-OAFA | (22h 26m 52.97s , -00d 16m 47.4s) | C | 40 | 17.5 | 71009 | 2025-05-17 10:18:28 | MASTER-OAFA | (22h 17m 41.41s , -00d 38m 59.6s) | C | 60 | 19.0 | 71076 | 2025-05-17 10:19:44 | MASTER-OAFA | (22h 11m 47.30s , +01d 37m 17.4s) | C | 40 | 17.4 | 71086 | 2025-05-17 10:19:45 | MASTER-OAFA | (22h 02m 35.75s , +01d 15m 02.1s) | C | 60 | 19.0 | 71153 | 2025-05-17 10:21:02 | MASTER-OAFA | (22h 28m 42.63s , +03d 31m 39.9s) | C | 40 | 16.9 | 71164 | 2025-05-17 10:21:02 | MASTER-OAFA | (22h 19m 30.49s , +03d 09m 19.0s) | C | 60 | 17.9 | 71231 | 2025-05-17 10:22:20 | MASTER-OAFA | (22h 42m 19.67s , +01d 36m 09.6s) | C | 40 | 17.5 | 71241 | 2025-05-17 10:22:20 | MASTER-OAFA | (22h 33m 08.20s , +01d 13m 51.0s) | C | 60 | 18.7 | 71309 | 2025-05-17 10:23:38 | MASTER-OAFA | (22h 43m 15.76s , -02d 12m 56.3s) | C | 40 | 17.4 | 71319 | 2025-05-17 10:23:38 | MASTER-OAFA | (22h 34m 03.65s , -02d 35m 05.9s) | C | 60 | 18.8 | 71386 | 2025-05-17 10:24:55 | MASTER-OAFA | (22h 27m 07.17s , +01d 36m 13.3s) | C | 40 | 16.8 | 71396 | 2025-05-17 10:24:55 | MASTER-OAFA | (22h 17m 55.54s , +01d 13m 57.3s) | C | 60 | 18.3 | 71464 | 2025-05-17 10:26:13 | MASTER-OAFA | (22h 30m 52.43s , -04d 04m 36.5s) | C | 40 | 17.1 | 71475 | 2025-05-17 10:26:13 | MASTER-OAFA | (22h 21m 38.98s , -04d 26m 39.6s) | C | 60 | 18.5 | 71542 | 2025-05-17 10:27:31 | MASTER-OAFA | (22h 12m 53.84s , -02d 11m 34.0s) | C | 40 | 17.1 | 71552 | 2025-05-17 10:27:31 | MASTER-OAFA | (22h 03m 41.51s , -02d 33m 39.0s) | C | 60 | 18.5 | 71620 | 2025-05-17 10:28:49 | MASTER-OAFA | (22h 26m 53.05s , -00d 16m 22.4s) | C | 40 | 16.7 | 71631 | 2025-05-17 10:28:49 | MASTER-OAFA | (22h 17m 41.27s , -00d 38m 32.2s) | C | 60 | 18.3 | 71697 | 2025-05-17 10:30:06 | MASTER-OAFA | (22h 11m 49.08s , +01d 37m 28.1s) | C | 40 | 16.6 | 71708 | 2025-05-17 10:30:06 | MASTER-OAFA | (22h 02m 37.28s , +01d 15m 16.2s) | C | 60 | 18.3 | 71836 | 2025-05-17 10:31:25 | MASTER-OAFA | (22h 27m 34.11s , -08d 41m 29.1s) | C | 160 | 17.4 | 71974 | 2025-05-17 10:34:43 | MASTER-OAFA | (22h 28m 49.55s , +03d 30m 54.7s) | C | 40 | 15.9 | 72050 | 2025-05-17 10:35:59 | MASTER-OAFA | (22h 42m 11.99s , +01d 35m 23.8s) | C | 40 | 16.2 | 72127 | 2025-05-17 10:37:16 | MASTER-OAFA | (22h 43m 23.70s , -02d 12m 28.1s) | C | 40 | 16.0 | 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/40482. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38513] GRB 250515A: Swift-XRT observations
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40481 SUBJECT: GRB 250515A: Swift-XRT observations DATE: 25/05/17 08:43:22 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) 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 250515A, centred on the location of GOTO25cqo (GCN 40464) collecting 4.5 ks of Photon Counting (PC) mode data between T0+88.8 ks and T0+117.8 ks. No X-ray sources have been detected within the estimated 3-sigma GOTO error region (4.9 arcsec). The 3-sigma upper limit in the field ranges from ~0.002 to ~0.003 ct s^-1, corresponding to a 0.3-10 keV observed flux of 9.2e-14 to 1.4e-13 erg cm^-2 s^-1 (assuming a typical GRB spectrum). GOTO25cqo has since been classified as a type Ia supernova. 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/00021829. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40481. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38512] GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40480 SUBJECT: GRB 250515A: NOT classification of GOTO25cqo as a type-Ia SN DATE: 25/05/17 08:32:02 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> A. Martin-Carrillo (UCD), Z. P. Zhu (NAOC), L. Izzo (INAF/OACN and DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud), B. P. Gompertz (U. Birmingham), G. Corcoran (UCD), R. Rautio (Univ. Oulu), report on behalf of a larger collaboration. We observed the position of GOTO25cqo (Gompertz et al., GCN 40464), a candidate optical counterpart to GRB 250515A (Fermi GBM team, GCN 40462), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained exposures in the SDSS r band (3x300 s) starting at 23:44:29 UT on 2025-05-16 (27 hours after the Fermi trigger). The candidate is detected in single exposures with an AB magnitude of r = 20.18 +/- 0.02, calibrated against nearby Pan-STARRS stars. We further obtained 4x600 s of spectroscopic observations. The flux-calibrated spectrum shows features not consistent with typical GRB afterglows. Using SNID (Blondin & Tonry 2007, doi:10.1086/520494), the spectrum matches well several normal rising type-Ia supernovae at z = 0.18 +/- 0.01. This excludes the association of GOTO25cqo with GRB 250515A, as already suggested by Xin et al. (GCN 40474) and Lopez et al. (GCN 40478). The slit was oriented so to cover the bright galaxy 5.3” NW of GOTO25cqo. We detect several emission lines which we identify Halpha, Hbeta, [O III] and [O II] at a common redshift of z = 0.169. With a 15 kpc projected separation, this galaxy is thus a plausible host of GOTO25cqo. We acknowledge excellent support from the NOT staff, in particular Joonas Viuho and Amanda Djupvik. View this GCN Circular online at https://gcn.nasa.gov/circulars/40480. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38511] Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40479 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 769160489/250517320 is not a GRB DATE: 25/05/17 08:24:02 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 769160489/250517320 at 07:41:24.32 UT on 17 May 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/40479. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38510] GRB 250515A:COLIBRÍ optical observations of the GOTO candidate
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40478 SUBJECT: GRB 250515A:COLIBRÍ optical observations of the GOTO candidate DATE: 25/05/17 06:16:42 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Kin Ocelotl López (UNAM), Alan M. Watson (UNAM), Rosa L. Becerra (U Roma), Benjamin Schneider (LAM), 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), Noémie Globus (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Antonio de Ugarte Postigo (LAM): We imaged the field of the GOTO candidate afterglow (Gompertz et al., GCN Circ. 40464) of the Fermi GRB 250515A (Fermi GBM team., GCN Circ. 40462) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-05-17 03:23 to 05:27 UTC (median epoch 1.30 days after the trigger) and obtained 32 minutes of exposure in the i filter and 3 minutes in each of the g and r filters. The data were reduced and coadded with the COLIBRÍ pipeline and analyzed 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 detected the optical candidate at preliminary magnitudes of: g = 20.31 +/- 0.03 r = 20.24 +/- 0.04 i = 20.45 +/- 0.03 This source was also detected by SVOM/VT (Xin et al., GCN Circ. 40474) and Mephisto (Zhang et al., GCN Circ. 40476). Our magnitudes are similar in g, fainter in r, and brighter in i than those reported at 0.71 days by Zhang et al. (GCN Circ. 40746), and these changes are not obviously compatible with the temporal evolution of a GRB afterglow after about 1 day. 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/40478. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38509] Swift GRB 250516A: Global MASTER-Net observations report
by GCN Circulars 17 May '25

17 May '25

TITLE: GCN CIRCULAR NUMBER: 40477 SUBJECT: Swift GRB 250516A: Global MASTER-Net observations report DATE: 25/05/17 05:58:24 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 GRB 250516A ( A. P. Beardmore et al., GCN 40467) errorbox 54907 sec after notice time and 54930 sec after trigger time at 2025-05-17 05:50:59 UT, with upper limit up to 15.5 mag. The observations began at zenith distance = 77 deg. The sun altitude is -68.5 deg. The galactic latitude b = -50 deg., longitude l = 53 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2872228 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 55020 | MASTER-OAFA | C | 180 | 15.5 | 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/40477. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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