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

[vsnet-grb-info 38777] GRB 250615A: Prompt enhanced Swift-XRT position
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40737 SUBJECT: GRB 250615A: Prompt enhanced Swift-XRT position DATE: 25/06/15 23:00:07 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-XRT team: Using 1.0 ks of promptly downlinked XRT event data for GRB 250615A, we find an enhanced XRT position of the afterglow: RA, Dec: 290.38555, 4.68527 which is equivalent to: RA (J2000) = 19 21 32.53 Dec (J2000) = +04 41 07.0 with an uncertainty of 2.0 arcseconds (radius, 90% confidence). Analysis of the promptly available data is online at http://www.swift.ac.uk/sper/1324646. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40737. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38776] GRB 250615A: Swift detection of a burst
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40736 SUBJECT: GRB 250615A: Swift detection of a burst DATE: 25/06/15 22:44:24 GMT FROM: Simone Dichiara at Pennsylvania State University <sbd5667(a)psu.edu> S. Dichiara (PSU), J. J. DeLaunay (PSU), R. Gupta (NASA GSFC) and T. Sakamoto (AGU) report on behalf of the Neil Gehrels Swift Observatory Team: At 22:25:19.59 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250615A (trigger=1324646). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 290.344, +4.672 which is RA(J2000) = 19h 21m 23s Dec(J2000) = +04d 40â 21" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 55 sec. The peak count rate was ~5000 counts/sec (15-350 keV), at ~1 sec after the trigger. The XRT began observing the field at 22:26:46.4 UT, 86.9 seconds after the BAT trigger. Using promptly downlinked data we find a bright, fading, uncatalogued X-ray source located at RA, Dec 290.38466, 4.68467 which is equivalent to: RA(J2000) = 19h 21m 32.32s Dec(J2000) = +04d 41' 04.8" with an uncertainty of 3.6 arcseconds (radius, 90% containment). This location is 152 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data does not constrain the column density. The initial flux in the 2.5 s image was 9.89e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 152 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. Results from the 2.7'x2.7' sub-image are not available at this time. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the large, but uncertain, extinction expected. Burst Advocate for this burst is S. Dichiara (sbd5667 AT 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/40736. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38775] Swift GRB250615.93: Global MASTER-Net observations report
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40735 SUBJECT: Swift GRB250615.93: Global MASTER-Net observations report DATE: 25/06/15 22:32:26 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 Swift GRB250615.93 (trigger No 1324646,19h 21m 22.56s , +04d 40m 19.2s, R=0.05) errorbox 25 sec after notice time and 42 sec after trigger time at 2025-06-15 22:26:02 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 46 deg. The sun altitude is -80.9 deg. The galactic latitude b = -5 deg., longitude l = 41 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2903527 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 48 | MASTER-SAAO | C | 10 | 16.9 | 48 | MASTER-SAAO | C | 10 | 17.1 | 77 | MASTER-SAAO | C | 10 | 17.0 | 77 | MASTER-SAAO | C | 10 | 17.1 | 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/40735. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38774] Fermi trigger No 771718064: Global MASTER-Net observations report
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40734 SUBJECT: Fermi trigger No 771718064: Global MASTER-Net observations report DATE: 25/06/15 22:15:32 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 GRB250615.92 (trigger No 771718064,08h 56m 28.80s , -44d 43m 48.0s, R=9.43) errorbox 119 sec after notice time and 154 sec after trigger time at 2025-06-15 22:10:13 UT, with upper limit up to 17.3 mag. The observations began at zenith distance = 83 deg. The sun altitude is -79.2 deg. The galactic latitude b = 1 deg., longitude l = 266 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2903453 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 170 | 2025-06-15 22:10:13 | MASTER-SAAO | (09h 14m 46.22s , -47d 11m 07.1s) | C | 30 | 17.0 | 170 | 2025-06-15 22:10:13 | MASTER-SAAO | (09h 12m 12.28s , -46d 55m 37.8s) | C | 30 | 15.0 | 224 | 2025-06-15 22:11:03 | MASTER-SAAO | (09h 14m 46.07s , -47d 11m 01.9s) | C | 40 | 17.3 | 224 | 2025-06-15 22:11:03 | MASTER-SAAO | (09h 12m 12.19s , -46d 55m 31.5s) | C | 40 | 15.1 | 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/40734. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38773] Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40733 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771704505/250615765 is not a GRB DATE: 25/06/15 19:29:24 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 771704505/250615765 at 18:21:40.49 UT on 15 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to solar flare." View this GCN Circular online at https://gcn.nasa.gov/circulars/40733. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38772] GRID detection of GRB 250612C
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40732 SUBJECT: GRID detection of GRB 250612C DATE: 25/06/15 16:40:18 GMT FROM: GRID Student Team at Tsinghua University <grid(a)tsinghua.edu.cn> Zirui Yang, Longhao Li and Chenyu Wang report on behalf of the GRID Collaboration: GRID-11B reports the detection of the GRB 250612C, which was also detected by Fermi/GBM (GCN Circular 40704) and SVOM/GRM (GCN Circular 40708). The event was triggered with GRID on 2024-06-12 at 14:53:16 UTC. The measured burst duration (T90) is approximately 2.6 ± 0.9 seconds. The GRID light curve of this event can be found at https://mirrors.tuna.tsinghua.edu.cn/GRID/data/GRID-GCN/GRB250612C/GRID_GRB…. GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4. View this GCN Circular online at https://gcn.nasa.gov/circulars/40732. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38771] sb25061207: Mephisto optical upper limits
by GCN Circulars 15 Jun '25

15 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40731 SUBJECT: sb25061207: Mephisto optical upper limits DATE: 25/06/15 03:55:24 GMT FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn> Ziwei Li, Guowang Du, Haipeng Lei, Jianhui Lian, Haoyang He, Xingzhu Zou, Yu Pan, Xinlei Chen, Xufeng Zhu, Helong Guo, Tao Wang, Yuan Fang, Jinghua Zhang, Dezi Liu, Chenxu Liu, Shiyan Zhong, Edoardo Lagioia, Brajesh Kumar, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team: We conducted simultaneous multi-band photometric observations of sb25061207 detected by SVOM/ECLAIRs (Zhang et al., GCN 40697) with the Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University, located at the Lijiang Observatory. Simultaneous u, g and v, r band observations of the field were initiated at 15:52:39 UTC on 2025-06-12 (~5.42 hours after the trigger) and three exposures of 300 seconds were acquired. In the stack images, no credible source was detected at the position of SVOM/VT (Li et al., GCN 40707), Swift/XRT (Evans et al., GCN 40711) and EP-FXT (Song et al., GCN 40718). The preliminary 3-sigma upper limits are listed below which are consistent with SVOM/COLIBRÍ (FM-GFT) (Becerra et. al., GCN 40723). | UT Start |T-T0 (hr)|Band| EXP(s) |Lim-mag (AB) |2025-06-12T15:52:39| 5.42 | u | 300.0*3 | >21.24 |2025-06-12T16:10:13| 5.71 | v | 300.0*3 | >21.31 |2025-06-12T15:52:38| 5.42 | g | 300.0*3 | >21.60 |2025-06-12T16:10:12| 5.71 | r | 300.0*3 | >21.83 ---------------------------------------------------------- Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6-m 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/40731. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38770] IceCube alert 141029_8144692 retraction
by GCN Circulars 14 Jun '25

14 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40730 SUBJECT: IceCube alert 141029_8144692 retraction DATE: 25/06/14 15:31:50 GMT FROM: Erik Blaufuss at University of Maryland, College Park <blaufuss(a)umd.edu> The IceCube Collaboration (http://icecube.wisc.edu/) reports: On 14 June 2025 at 09:14:04 UT IceCube issued an alert (https://gcn.gsfc.nasa.gov/notices_amon_icecube_cascade/141029_8144692.amon) reporting the detection of a neutrino cascade candidate event with a high chance of being of astrophysical origin. Upon further examination by the IceCube collaboration, the event was found to be from a non-standard configuration that was intended to be excluded from alert selection At the time of this alert, the detector was operating normally but taking data in a non-standard test configuration. Normally, these periods of operation are excluded from generating alerts, but an alert message was significantly delayed in transit from the detector site at the South Pole and arrived after resuming normal operations We apologize for any confusion this error may have caused. 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/40730. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38769] Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB
by GCN Circulars 14 Jun '25

14 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40729 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771596290/250614513 is not a GRB DATE: 25/06/14 13:13:42 GMT FROM: Cuán de Barra at UCD <cuan.debarra(a)ucdconnect.ie> C.de Barra (University College Dublin) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771596290/250614513 at 12:18:05.02 UT on 14 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particle activity." View this GCN Circular online at https://gcn.nasa.gov/circulars/40729. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38768] GRB 250614A: Fermi GBM Final Real-time Localization
by GCN Circulars 14 Jun '25

14 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40728 SUBJECT: GRB 250614A: Fermi GBM Final Real-time Localization DATE: 25/06/14 12:28:37 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 12:18:05 UT on 14 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250614A (trigger 771596290.023932 / 250614513). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 343.1, Dec = 54.6 (J2000 degrees, equivalent to J2000 22h 52m, 54d 36'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 1.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250614513/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250614513/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250614513/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40728. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38767] EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate
by GCN Circulars 14 Jun '25

14 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40727 SUBJECT: EP250612a / GRB 250612B: NOT optical observations of the afterglow candidate DATE: 25/06/14 08:29:34 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> A. de Ugarte Postigo (LAM), A. Martin-Carrillo (UCD), G. Corcoran (UCD), D. B. Malesani (DAWN/NBI and Radboud), D. Xu (NAOC), L. Cotter (UCD), B. P. Gompertz (U. Birmingham), A. A. Djupvik (NOT), L. Fuglsang (NOT), report on behalf of a larger collaboration. We observed the field of EP250612a / GRB 250612B detected by EP (Hua et al., GCN 40700) and Fermi (Fermi GBM team, GCN 40702), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 12x100 s exposures in the SDSS r-band, starting at 23:19 UT on 2025-05-13 (1.952 days after the EP trigger). At J2000 coordinates RA:15:18:36.667, DEC: -26:46:03.624 (error 0.5”), consistent with those by Li et al. (GCN 40716), the optical counterpart is detected in our stacked image with a preliminary magnitude: r = 23.59 +/- 0.22 (AB). The photometric calibration was performed using nearby stars from the Pan-STARRS catalog and the magnitudes are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40727. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38766] Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB
by GCN Circulars 14 Jun '25

14 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40726 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771547945/250613953 is not a GRB DATE: 25/06/14 00:57:35 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771547945/250613953 at 22:52:20.54 UT on 13 June 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/40726. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38765] Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40725 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771541927/250613883 is not a GRB DATE: 25/06/13 23:39:36 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771541927/250613883 at 21:12:02.66 UT on 13 June 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/40725. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38764] sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40724 SUBJECT: sb25061218: SVOM/COLIBRÍ (FM-GFT) optical upper limits DATE: 25/06/13 20:05:07 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Rosa L. Becerra (U Roma), Enrique Moreno Méndez (UNAM), Sarah Antier (OCA), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), and Jerome Rodriguez (CEA): We imaged the field of the SVOM X-ray transient sb25061218 (Rodriguez et al., GCN 40712) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-06-13 06:18 to 10:34 UTC (from 9.7 to 14.0 hours after the trigger) and obtained 112 minutes of exposure in the i filter. 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 Pan-STARRS DR1 catalog, is on the AB scale, and is not corrected for Galactic extinction. In the stacked image, we do not detect any new source within the ECLAIRs source region reported by Rodriguez et al. (GCN 40712) to a formal 10-sigma limit of: i > 23.0, although we note that this is roughly the 50% completion limit of the Pan-STARRS DR1 catalog used to identify new sources. We also performed image subtraction against Pan-STARRS DR2 at the position of the two XRT sources 1 and 2 reported by Evans et al. (GCN Circ. 40721) and see no evidence for optical counterparts to the same limit. 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/40724. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38763] sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40723 SUBJECT: sb25061207: SVOM/COLIBRÍ (FM-GFT) optical upper limit DATE: 25/06/13 19:16:15 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> 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), 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), Antonio de Ugarte Postigo (LAM), L. Zhang (IHEP), and Y. D. Hu (GXU): We imaged the field of the SVOM/ECLAIR sb25061207 (Zhang et al., GCN Circ. 40697) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-06-13 03:49 to 05:52 UTC (from 17.36 to 19.41 hours after the trigger) and obtained 63 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 EP/FXT position (Song et al., GCN Circ. 40718) or the optical candidate by SVOM/VT (Li et al. GCN Circ. 40717) down to the following 3-sigma limit: r > 22.9 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/40723. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38762] Fermi trigger No 771494087: Global MASTER-Net observations report
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40722 SUBJECT: Fermi trigger No 771494087: Global MASTER-Net observations report DATE: 25/06/13 18:16:25 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 GRB250613.33 (trigger No 771494087,17h 33m 19.92s , -38d 28m 01.2s, R=22.7) errorbox 32096 sec after notice time and 32128 sec after trigger time at 2025-06-13 16:50:10 UT, with upper limit up to 17.9 mag. Observations started at twilight. The observations began at zenith distance = 60 deg. The sun altitude is -14.4 deg. The galactic latitude b = -3 deg., longitude l = 351 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2901954 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 32158 | 2025-06-13 16:50:10 | MASTER-SAAO | (16h 41m 27.50s , -39d 04m 53.5s) | C | 60 | 17.8 | 32158 | 2025-06-13 16:50:10 | MASTER-SAAO | (16h 39m 08.66s , -38d 49m 46.2s) | C | 60 | 17.8 | 32346 | 2025-06-13 16:53:18 | MASTER-SAAO | (16h 41m 29.84s , -39d 04m 40.2s) | C | 60 | 17.9 | 32346 | 2025-06-13 16:53:18 | MASTER-SAAO | (16h 39m 10.94s , -38d 49m 34.3s) | C | 60 | 17.9 | 32992 | 2025-06-13 17:04:04 | MASTER-SAAO | (16h 41m 23.49s , -39d 06m 43.4s) | C | 60 | 17.8 | 32992 | 2025-06-13 17:04:04 | MASTER-SAAO | (16h 39m 05.20s , -38d 51m 34.7s) | C | 60 | 17.8 | 33181 | 2025-06-13 17:07:13 | MASTER-SAAO | (16h 41m 25.91s , -39d 05m 03.0s) | C | 60 | 17.9 | 33181 | 2025-06-13 17:07:13 | MASTER-SAAO | (16h 39m 07.41s , -38d 49m 54.4s) | C | 60 | 17.9 | 33369 | 2025-06-13 17:10:21 | MASTER-SAAO | (16h 41m 29.24s , -39d 04m 53.3s) | C | 60 | 17.8 | 33369 | 2025-06-13 17:10:21 | MASTER-SAAO | (16h 39m 10.68s , -38d 49m 45.2s) | C | 60 | 17.8 | 33558 | 2025-06-13 17:13:30 | MASTER-SAAO | (16h 41m 22.46s , -39d 04m 40.0s) | C | 60 | 17.8 | 33558 | 2025-06-13 17:13:30 | MASTER-SAAO | (16h 39m 03.78s , -38d 49m 32.6s) | C | 60 | 17.8 | 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/40722. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38761] sb25061218: Swift-XRT observations
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40721 SUBJECT: sb25061218: Swift-XRT observations DATE: 25/06/13 15:59:11 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 sb25061218, collecting 1.7 ks of Photon Counting (PC) mode data between T0+5.9 ks and T0+7.7 ks after the trigger. We have detected 2 sources. These have been automatically classified as follows: * 0 likely counterparts * 0 candidate counterparts * 2 uncatalogued X-ray sources * 0 known X-ray sources Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J131445.9+544759): ================================== RA (J2000.0): 198.6914 = 13h 14m 45.94s Dec (J2000.0): +54.7999 = +54d 47' 59.6" Error: 11.2 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 10.7 arcmin from the SVOM/ECLAIRs position. Mean rate: (9.8 [+3.7, -3.0])e-3 ct s^-1 Mean flux: (4.8 [+1.8, -1.4])e-13 erg cm^-2 s^-1 Peak rate: (9.8 [+3.7, -3.0])e-3 ct s^-1 Peak flux: (4.8 [+1.8, -1.4])e-13 erg cm^-2 s^-1 ECF: 4.85e-11 erg cm^-2 ct^-1, assuming NH=2.15e+20 cm^-2, gamma=1.50; determined from a spectral fit. XMM UL: 2.1e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 10.0-sigma above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `[VV2006] J131446.6+544804' is 6.6" away. Source 2 (SWIFT J131433.3+544329): ================================== RA (J2000.0): 198.6390 = 13h 14m 33.36s Dec (J2000.0): +54.7249 = +54d 43' 29.6" Error: 9.7 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 6.2 arcmin from the SVOM/ECLAIRs position. Mean rate: (5.9 [+2.8, -2.1])e-3 ct s^-1 Mean flux: (1.01 [+0.47, -0.37])e-13 erg cm^-2 s^-1 Peak rate: (5.9 [+2.8, -2.1])e-3 ct s^-1 Peak flux: (1.01 [+0.47, -0.37])e-13 erg cm^-2 s^-1 ECF: 1.71e-11 erg cm^-2 ct^-1, assuming NH=1.76e+22 cm^-2, gamma=7.90; determined from a spectral fit. XMM UL: 2.4e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 54.2-sigma above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `SDSS J131433.74+544331.8' is 3.9" away. There is 1 2MASS object within the source's 3-sigma error radius. 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 official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40721. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38760] EP250612a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40720 SUBJECT: EP250612a: refined analysis of the EP-WXT and EP-FXT observations DATE: 25/06/13 14:07:36 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.L.Hua (PMO, CAS), J. W. Hu, T. Zhao, Y. J. Song ,W. Yuan(NAO, CAS) report on behalf of the Einstein Probe team: The fast X-ray transient EP250612a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Hua et al., GCN 40700), and followed up by several optical and X-ray telescopes (Hua et al., GCN 40709, Li et al., GCN 40716). Refined analysis of the WXT data shows that the event started at T0=2025-06-12T12:27:38 (UTC) and lasted for about 35s before the interruption by the autonomous follow-up observation. The peak flux (0.5-4 keV) is estimated to be 3.9 x 10^-8 erg/s/cm^2. The averaged 0.5-4 keV spectrum can be fitted with an absorbed power-law with a Galactic hydrogen column density of 4.3 x 10^21 cm^-2(-2.1, +2.4) and a photon index of 1.01 (-0.1, +0.1). The derived average unabsorbed 0.5-4 keV flux is 3.67 (-0.74, +1.10) x 10^-9 erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously at 2025-06-12 12:30:08, about 3 minutes after T0, with an exposure time of 5858 seconds. Within the WXT error circle, on-ground analysis of the FXT data found an uncatalogued source at R.A. = 229.6534, DEC = -26.7673 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic), which is spatially consistent with the candidate X-ray counterpart detected by Fermi(Fermi GBM team., GCN 40702). The averaged 0.5-10 keV FXT spectrum can be fitted with an absorbed power-law with a Galactic hydrogen column density of 1.49 x 10^21 cm^-2 and a photon index of 2.2 (-0.045, +0.045). The derived unabsorbed 0.5-10 keV flux is 1.37 (-0.03, +0.04) x 10^-11 erg/s/cm^2. The uncertainties are at the 90% confidence level for all the above parameters. EP-FXT will continue monitoring the source in the forthcoming days. Multi-band follow-up observations are encouraged. The contact TA of EP250612a is Y.L.Hua, please contact him via the email ylhua(a)pmo.ac.cn if needed. 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/40720. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38759] GRB 250610B: J band upper limit by SYSU 80cm infrared telescope
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40719 SUBJECT: GRB 250610B: J band upper limit by SYSU 80cm infrared telescope DATE: 25/06/13 13:43:34 GMT FROM: zengxt27(a)mail2.sysu.edu.cn Xiang-Tao Zeng, Duo-Le Cao, Chun Chen, Zhong-Nan Dong, Jia-Qi Lin, Wei-Sen Huang, Jin-Ji Li, Xia Li, Pu Lin, Hao-Nan Yang, Yan Yu, Hao-Ran Zhang, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team: We observed the field of GRB 250610B (Saccardi et. al., GCN 40671; Evans et. al., GCN 40679; Liang et. al., GCN 40681) using the Sun Yat-sen University 80cm infrared telescope with 51 x 20 s exposures in J band. The calculated position is RA. = 200.1744 deg, DEC = 31.1751 deg J2000, from SVOM observation. Our observations began at 2025-6-10 16:55:00 UTC, 22 minutes after the SVOM trigger. We do not detect any counterpart at the position of the optical afterglow (Wang et al., GCN 40672, Gompertz et al., GCN 40674, Schneider et al., GCN 40676, Gompertz et al., GCN 40677, Li et al., GCN 40678, Brivio, et al., GCN 40687, Schneider, et al., GCN 40689, Adami, et al., GCN 40698), down to a 5-sigma depth of J~ 17 Vega magnitudes. The SYSU 80cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University. View this GCN Circular online at https://gcn.nasa.gov/circulars/40719. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38758] sb25061207: EP-FXT follow-up observation and afterglow candidate
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40718 SUBJECT: sb25061207: EP-FXT follow-up observation and afterglow candidate DATE: 25/06/13 07:28:28 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. J. Song (NAO, CAS), Y.L. Hua (PMO, CAS), T. Zhao, J. W. Hu , W. Yuan (NAO, CAS), A. Foisseau, C. Lachaud (APC), M. Brunet (IRAP), N. Dagoneau (CEA) report on behalf of the Einstein Probe and SVOM team We performed a follow-up observation of sb25061207 (detected by SVOM/ECLAIRs, Zhang et al, GCN #40697; followed by SVOM/VT, Li et al. GCN #40707 and Swift/XRT, Evans et al. GCN #40711), with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2025-06-12 18:37:49, about 8 hours after the detection, and the exposure time is about 6.0 ks. Only 1 uncatalogued source was detected by both FXT-A and FXT-B in the 90% localization error circle provided by SVOM/VT (with a radius of 0.5 arcsec centered at R.A., DEC = 198.09415, +0.07508 deg), as listed below (the FXT flux is taken from FXT-B module). Source name | RA | DEC | Estimated Flux | SNR | Dist from SVOM/VT | | deg | deg | (erg/s/cm^2) | | offset (in arcsec) | ----------------------------------------------------------------------------- EP_J131222.6+000433 | 198.0939 | 0.0753 | 5.4(+/-1.7) x 10^-14 | 5.6 | 1.1 (with an uncertainty of 10 arcsec) | ----------------------------------------------------------------------------- Note: * EP_J131222.6+000433 was also detected by Swift/XRT (GCN #40711) in a ~2.6 ks observation conducted at T0+8.8 ks after the trigger, with a flux of ~6.0e-13 erg/s/cm^2. The source thus exhibits a decreasing trend in the X-ray flux within two epochs. The above observation was made with the EP-FXT instrument. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/40718. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38757] sb25061207: EP-FXT follow-up observation and afterglow candidate
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40718 SUBJECT: sb25061207: EP-FXT follow-up observation and afterglow candidate DATE: 25/06/13 07:28:28 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. J. Song (NAO, CAS), Y.L. Hua (PMO, CAS), T. Zhao, J. W. Hu , W. Yuan (NAO, CAS), A. Foisseau, C. Lachaud (APC), M. Brunet (IRAP), N. Dagoneau (CEA) report on behalf of the Einstein Probe and SVOM team We performed a follow-up observation of sb25061207 (detected by SVOM/ECLAIRs, Zhang et al, GCN #40697; followed by SVOM/VT, Li et al. GCN #40707 and Swift/XRT, Evans et al. GCN #40711), with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2025-06-12 18:37:49, about 8 hours after the detection, and the exposure time is about 6.0 ks. Only 1 uncatalogued source was detected by both FXT-A and FXT-B in the 90% localization error circle provided by SVOM/VT (with a radius of 0.5 arcsec centered at R.A., DEC = 198.09415, +0.07508 deg), as listed below (the FXT flux is taken from FXT-B module). Source name | RA | DEC | Estimated Flux | SNR | Dist from SVOM/VT | | deg | deg | (erg/s/cm^2) | | offset (in arcsec) | ----------------------------------------------------------------------------- EP_J131222.6+000433 | 198.0939 | 0.0753 | 5.4(+/-1.7) x 10^-14 | 5.6 | 1.1 (with an uncertainty of 10 arcsec) | ----------------------------------------------------------------------------- Note: * EP_J131222.6+000433 was also detected by Swift/XRT (GCN #40711) in a ~2.6 ks observation conducted at T0+8.8 ks after the trigger, with a flux of ~6.0e-13 erg/s/cm^2. The source thus exhibits a decreasing trend in the X-ray flux within two epochs. The above observation was made with the EP-FXT instrument. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/40718. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38756] GRB 250612B: Fermi GBM Observation
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40717 SUBJECT: GRB 250612B: Fermi GBM Observation DATE: 25/06/13 06:34:50 GMT FROM: Rushikesh Sonawane at IISER, TVM <rushikesh23(a)iisertvm.ac.in> R. Sonawane (IISER, TVM) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 12:27:56.19 UT on 12 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250612B (trigger 771424081/250612519). which was also detected by EP-WXT (Hua et al. 2025, GCN 40700). The Fermi GBM on-ground location is consistent with the EP-WXT position. The angle from the Fermi LAT boresight is 68 degrees. The GBM light curve consists of single emission episode with a duration (T90) of about 10.8 s (50-300 keV). The time-averaged spectrum from T0-4.4 to T0+18.2 s is best fit by a Band function with Epeak = 47.80 +/- 1.53 keV, alpha = -0.92 +/- 0.09, and beta = -3.47 +/- 0.39. A Comp model fits the spectrum equally well, with a power-law index = –0.98 +/- 0.07 and cutoff energy parameterized as Epeak = 49.14 +/- 1.26 keV. The event fluence (10-1000 keV) in this time interval is (5.2 +/- 0.2)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0+2.9 s in the 10-1000 keV band is 12.1 +/- 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/40717. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38755] EP250612a: SVOM/VT optical candidate
by GCN Circulars 13 Jun '25

13 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40716 SUBJECT: EP250612a: SVOM/VT optical candidate DATE: 25/06/13 02:45:04 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, Y. N. Ma, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), Y. L. Hua (PMO, CAS), T. Zhao, Y. J. Song, J. W. Hu , W. Yuan (NAO, CAS) report on behalf of the SVOM and EP Teams: SVOM/VT observed the field of EP250612a (Hua et al., GCN 40700) in ToO mode in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. The observation started at 2025-06-12T21:08:02 UT, about 8.67 hours after the trigger time. One uncatalogued source, compared to Legacy Survey, was detected within FXT error circle (Hua et al., GCN 40700), RA = 229.65265, DEC = -26.76771, corresponding to: R. A. (J2000) = 15:18:36.6 DEC. (J2000) = -26:46:03.8 Error = 0.5 arcseconds The brightness of the candidate is derived as below : mid-time band mag(AB) exposure 9.45 hour VT_B 22.3+/-0.1 20*70 sec 9.46 hour VT_R 21.8+/-0.1 19*70 sec Our photometry was derived in AB magnitude and not corrected for Galactic extinction. 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/40716. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38754] Fermi trigger No 771424081: Global MASTER-Net observations report
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40715 SUBJECT: Fermi trigger No 771424081: Global MASTER-Net observations report DATE: 25/06/12 23:30:27 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 GRB250612.52 (trigger No 771424081,15h 27m 31.20s , -29d 52m 48.0s, R=2.4) errorbox 35391 sec after notice time and 35422 sec after trigger time at 2025-06-12 22:18:18 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 24 deg. The sun altitude is -80.1 deg. The galactic latitude b = 21 deg., longitude l = 339 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2901131 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 35453 | 2025-06-12 22:18:18 | MASTER-SAAO | (15h 17m 45.90s , -26d 51m 07.4s) | C | 60 | 18.5 | 35453 | 2025-06-12 22:18:18 | MASTER-SAAO | (15h 15m 46.32s , -26d 35m 46.7s) | C | 60 | 18.8 | 35644 | 2025-06-12 22:21:29 | MASTER-SAAO | (15h 17m 42.75s , -26d 50m 04.0s) | C | 60 | 18.6 | 35644 | 2025-06-12 22:21:29 | MASTER-SAAO | (15h 15m 43.63s , -26d 34m 41.7s) | C | 60 | 18.9 | 35836 | 2025-06-12 22:24:42 | MASTER-SAAO | (15h 17m 49.62s , -26d 49m 56.6s) | C | 60 | 18.6 | 35836 | 2025-06-12 22:24:42 | MASTER-SAAO | (15h 15m 50.50s , -26d 34m 33.7s) | C | 60 | 18.8 | 36028 | 2025-06-12 22:27:53 | MASTER-SAAO | (15h 17m 48.24s , -26d 50m 30.1s) | C | 60 | 18.6 | 36028 | 2025-06-12 22:27:53 | MASTER-SAAO | (15h 15m 49.05s , -26d 35m 06.7s) | C | 60 | 18.8 | 36220 | 2025-06-12 22:31:06 | MASTER-SAAO | (15h 17m 45.74s , -26d 50m 25.6s) | C | 60 | 18.5 | 36220 | 2025-06-12 22:31:06 | MASTER-SAAO | (15h 15m 46.54s , -26d 35m 01.8s) | C | 60 | 18.8 | 36412 | 2025-06-12 22:34:18 | MASTER-SAAO | (15h 17m 43.26s , -26d 49m 35.9s) | C | 60 | 18.6 | 36412 | 2025-06-12 22:34:18 | MASTER-SAAO | (15h 15m 44.01s , -26d 34m 11.9s) | C | 60 | 18.9 | 36819 | 2025-06-12 22:41:05 | MASTER-SAAO | (15h 17m 27.58s , -29d 16m 42.2s) | C | 60 | 18.8 | 36819 | 2025-06-12 22:41:05 | MASTER-SAAO | (15h 15m 25.41s , -29d 01m 18.1s) | C | 60 | 19.0 | 36913 | 2025-06-12 22:42:39 | MASTER-SAAO | (15h 26m 33.96s , -29d 15m 28.8s) | C | 60 | 18.7 | 36913 | 2025-06-12 22:42:39 | MASTER-SAAO | (15h 24m 31.63s , -29d 00m 04.3s) | C | 60 | 18.9 | 37006 | 2025-06-12 22:44:12 | MASTER-SAAO | (15h 17m 32.04s , -31d 08m 59.1s) | C | 60 | 18.6 | 37006 | 2025-06-12 22:44:12 | MASTER-SAAO | (15h 15m 27.34s , -30d 53m 34.4s) | C | 60 | 18.8 | 37101 | 2025-06-12 22:45:46 | MASTER-SAAO | (15h 24m 40.84s , -30d 54m 55.8s) | C | 60 | 18.9 | 37101 | 2025-06-12 22:45:46 | MASTER-SAAO | (15h 26m 45.73s , -31d 10m 20.7s) | C | 60 | 18.6 | 37400 | 2025-06-12 22:50:46 | MASTER-SAAO | (15h 32m 46.05s , -29d 00m 20.4s) | C | 60 | 18.9 | 37400 | 2025-06-12 22:50:46 | MASTER-SAAO | (15h 34m 48.67s , -29d 15m 47.0s) | C | 60 | 18.7 | 37496 | 2025-06-12 22:52:21 | MASTER-SAAO | (15h 41m 54.86s , -29d 02m 31.9s) | C | 60 | 18.9 | 37496 | 2025-06-12 22:52:21 | MASTER-SAAO | (15h 43m 57.74s , -29d 17m 58.3s) | C | 60 | 18.6 | 37589 | 2025-06-12 22:53:55 | MASTER-SAAO | (15h 15m 24.67s , -28d 59m 08.1s) | C | 60 | 18.8 | 37589 | 2025-06-12 22:53:55 | MASTER-SAAO | (15h 17m 27.19s , -29d 14m 33.9s) | C | 60 | 18.8 | 37683 | 2025-06-12 22:55:28 | MASTER-SAAO | (15h 24m 28.23s , -29d 00m 36.4s) | C | 60 | 18.8 | 37683 | 2025-06-12 22:55:28 | MASTER-SAAO | (15h 26m 30.96s , -29d 16m 02.0s) | C | 60 | 18.6 | 37989 | 2025-06-12 23:00:35 | MASTER-SAAO | (15h 15m 27.98s , -30d 53m 53.2s) | C | 60 | 18.8 | 37989 | 2025-06-12 23:00:35 | MASTER-SAAO | (15h 17m 33.30s , -31d 09m 17.4s) | C | 60 | 18.6 | 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/40715. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38753] EP250612a: Global MASTER-Net observations report
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40714 SUBJECT: EP250612a: Global MASTER-Net observations report DATE: 25/06/12 22:36:21 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 EP250612a ( EP Team et al., GCN 40700) errorbox 33238 sec after notice time and 35413 sec after trigger time at 2025-06-12 22:18:18 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 24 deg. The sun altitude is -80.1 deg. The galactic latitude b = 25 deg., longitude l = 340 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2901165 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 35444 | 2025-06-12 22:18:18 | MASTER-SAAO | (15h 17m 45.90s , -26d 51m 07.4s) | C | 60 | 18.5 | 35444 | 2025-06-12 22:18:18 | MASTER-SAAO | (15h 15m 46.32s , -26d 35m 46.7s) | C | 60 | 18.8 | 35635 | 2025-06-12 22:21:29 | MASTER-SAAO | (15h 17m 42.75s , -26d 50m 04.0s) | C | 60 | 18.6 | 35635 | 2025-06-12 22:21:29 | MASTER-SAAO | (15h 15m 43.63s , -26d 34m 41.7s) | C | 60 | 18.9 | 35828 | 2025-06-12 22:24:42 | MASTER-SAAO | (15h 17m 49.62s , -26d 49m 56.6s) | C | 60 | 18.6 | 35828 | 2025-06-12 22:24:42 | MASTER-SAAO | (15h 15m 50.50s , -26d 34m 33.7s) | C | 60 | 18.8 | 36019 | 2025-06-12 22:27:53 | MASTER-SAAO | (15h 17m 48.24s , -26d 50m 30.1s) | C | 60 | 18.6 | 36019 | 2025-06-12 22:27:53 | MASTER-SAAO | (15h 15m 49.05s , -26d 35m 06.7s) | C | 60 | 18.8 | 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/40714. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38752] GRB 250612C: Fermi GBM Observation
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40713 SUBJECT: GRB 250612C: Fermi GBM Observation DATE: 25/06/12 21:54:11 GMT FROM: eliza.neights(a)gmail.com E. Neights (GWU, NASA GSFC) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 14:53:16.58 UT on 12 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250612C (trigger 771432801/250612620). which was also detected by SVOM/GRM (Wang et al. 2025, GCN 40708). The Fermi-GBM position was reported in GCN 40708 (Fermi GBM Team 2025). The angle from the Fermi LAT boresight is 96 degrees. The GBM light curve consists of multiple emission episodes with a duration (T90) of about 1.62 s (50-300 keV). The time-averaged spectrum from T0-0.128 to T0+2.688 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -0.97 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 2110 +/- 70 keV. A Band function fits the spectrum equally well with Epeak = 2110 +/- 70 keV, alpha = -0.97 +/- 0.01, and beta = -4 +/- 1. The event fluence (10-1000 keV) in this time interval is (2.80 +/- 0.02)E-05 erg/cm^2. The 64-ms peak photon flux measured starting from T0+0.77 s in the 10-1000 keV band is 154 +/- 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/40713. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38751] sb25061218: SVOM detection of a X-ray transient
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40712 SUBJECT: sb25061218: SVOM detection of a X-ray transient DATE: 25/06/12 21:40:47 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> J. Rodriguez, T. Sadibekova, B. Cordier, N. Dagoneau (CEA), U. Jacob (LUPM) on behalf of the SVOM mission team. At 2025-06-12T20:36:00 UTC (T0), SVOM/ECLAIRs triggered and located the X-ray transient sb25061218 (SVOM burst-id sb25061218). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 1 alert. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.01 in the [8-120] keV energy band over a time window of 81.92 seconds starting at 2025-06-12T20:34:38. The localization of the best alert is R.A., Dec. 198.5028, 54.6582 degrees: R.A. (J2000) = 13h14m00.67s Dec. (J2000) = 54d39m29.47s with a 90% confidence level (C.L.) radius of 11.16 arcmin (including systematic error of 2 arcmin added in quadrature). This burst was also detected by SVOM/GRM with a significance of 5.80. Due to the detection significance being below the slew threshold, no immediate slew was performed on this burst. 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. GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Jerome Rodriguez: jerome.rodriguez(a)cea.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/40712. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38750] sb25061207: Swift-XRT observations
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40711 SUBJECT: sb25061207: Swift-XRT observations DATE: 25/06/12 21:12:28 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 sb25061207, collecting 2.6 ks of Photon Counting (PC) mode data between T0+8.8 ks and T0+20 ks after the trigger. We have detected 4 sources. These have been automatically classified as follows: * 0 likely counterparts * 0 candidate counterparts * 4 uncatalogued X-ray sources * 0 known X-ray sources Uncatalogued X-ray sources -------------------------- Source 1 (SWIFT J131222.8+000431): ================================== RA (J2000.0): 198.0954 = 13h 12m 22.90s Dec (J2000.0): +0.0753 = +00d 04' 31.1" Error: 6.4 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 7.2 arcmin from the SVOM/ECLAIRs position; 4.6 arcsec from SVOM/VT counterpart (GCN 40707). Mean rate: 0.0133 [+0.0031, -0.0028] ct s^-1 Mean flux: (6.0 [+1.4, -1.3])e-13 erg cm^-2 s^-1 Peak rate: 0.0147 +/- 0.0037 ct s^-1 Peak flux: (6.6 +/- 1.7)e-13 erg cm^-2 s^-1 ECF: 4.50e-11 erg cm^-2 ct^-1, assuming NH=2.24e+20 cm^-2, gamma=1.42; determined from a spectral fit. XMM UL: 2.7e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 12.4-sigma above this 3-sigma upper limit. The source may be fading, at the 0.6-sigma level. Source 2 (SWIFT J131136.2+000123): ================================== RA (J2000.0): 197.9010 = 13h 11m 36.24s Dec (J2000.0): +0.0233 = +00d 01' 23.9" Error: 5.9 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 5.2 arcmin from the SVOM/ECLAIRs position. Mean rate: (7.2 +/- 2.1)e-3 ct s^-1 Mean flux: (7.4 +/- 2.1)e-13 erg cm^-2 s^-1 Peak rate: (7.2 +/- 2.1)e-3 ct s^-1 Peak flux: (7.4 +/- 2.1)e-13 erg cm^-2 s^-1 ECF: 1.03e-10 erg cm^-2 ct^-1, assuming NH=2.41e+21 cm^-2, gamma=0.47; determined from a spectral fit. XMM UL: 4.4e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 17.2-sigma above this 3-sigma upper limit. There is no evidence for fading. A SIMBAD object `MGC 42939' is 5.7" away. Source 3 (SWIFT J131139.2-000814): ================================== RA (J2000.0): 197.9134 = 13h 11m 39.22s Dec (J2000.0): -0.1375 = -00d 08' 15.0" Error: 7.3 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 10.5 arcmin from the SVOM/ECLAIRs position. Mean rate: (6.3 [+2.4, -1.9])e-3 ct s^-1 Mean flux: (1.36 [+0.52, -0.42])e-18 erg cm^-2 s^-1 Peak rate: (6.3 [+2.4, -1.9])e-3 ct s^-1 Peak flux: (1.36 [+0.52, -0.42])e-18 erg cm^-2 s^-1 ECF: 2.14e-16 erg cm^-2 ct^-1, assuming NH=4.37e+21 cm^-2, gamma=96.83; determined from a spectral fit. XMM UL: 2.7e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 5817530.8-sigma above this 3-sigma upper limit. There is no evidence for fading. Source 4 (SWIFT J131140.3-000120): ================================== RA (J2000.0): 197.9181 = 13h 11m 40.34s Dec (J2000.0): -0.0225 = -00d 01' 21.0" Error: 6.1 (arcsec, radius, 90% confidence). Detect flag: REASONABLE Distance: 4.9 arcmin from the SVOM/ECLAIRs position. Mean rate: (2.6 [+1.5, -1.2])e-3 ct s^-1 Mean flux: (1.61 [+0.96, -0.73])e-13 erg cm^-2 s^-1 Peak rate: (2.6 [+1.5, -1.2])e-3 ct s^-1 Peak flux: (1.61 [+0.96, -0.73])e-13 erg cm^-2 s^-1 ECF: 6.23e-11 erg cm^-2 ct^-1, assuming NH=3.65e+22 cm^-2, gamma=2.45; determined from a spectral fit. XMM UL: 4.8e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 55.2-sigma above this 3-sigma upper limit. There is no evidence for fading. 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 official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40711. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38749] EP250612a/GRB 250612B: JinShan optical upper limit
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40710 SUBJECT: EP250612a/GRB 250612B: JinShan optical upper limit DATE: 25/06/12 17:24:35 GMT FROM: liuxing(a)nao.cas.cn X. Liu, Z.P. Zhu, J. An, S.Q. Jiang, D. Xu (NAOC), S.Y. Fu(HUST), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of EP250612a detected by EP/WXT (Hua et al., GCN 40700), which is very likely GRB 250612B by Fermi/GBM (Preis & Greiner, GCN 40701; Fermi GBM tea, GCN 40702), using the 100cm-C telescope (100C) of the JinShan project, located at Altay, Xinjiang, China. Observations started at 15:45:13 UT on 2025-06-12, i.e., 3.29 hr after the EP trigger, and 18 x 200 s frames were obtained in the Sloan i-band. No new optical source is detected within the EP/FXT error circle (Hua et al., GCN 40700), down to a 3-sigma upper limit of i ~ 20.2 mag (AB), calibrated with nearby PanSTARRS 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/40710. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38748] EP 250612a: AST3-3 Yaoan Optical Observation
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40709 SUBJECT: EP 250612a: AST3-3 Yaoan Optical Observation DATE: 25/06/12 16:49:28 GMT FROM: ylhua(a)pmo.ac.cn Yan-Long Hua, Tian-Rui Sun, Lei Hu, Jin-Jun Geng, Xue-Feng Wu (PMO, CAS), report on behalf the AST3 Team: Following the detection of EP 250612a detected by Einstein Probe (Hua et al., GCN 40700), and its potential gamma-ray counterpart by Fermi (Fermi GBM team, GCN 40702), we use Antarctic Survey Telescope 3-3 at Yaoan Astronomy Observation (China, Yunnan) to follow up for the afterglow. We observed the target position with 30 x 180s exposure in g-band starting from 2025-06-12T13:12:59.95 about 0.75 hours after the burst. No new optical source was detected within the error box (Hua et al., GCN 40700) down to 20.27 mag in the coadd image (total 30x180s, g-band). View this GCN Circular online at https://gcn.nasa.gov/circulars/40709. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38747] GRB 250612C: SVOM/GRM observation an intermedium duration burst
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40708 SUBJECT: GRB 250612C: SVOM/GRM observation an intermedium duration burst DATE: 25/06/12 16:01:33 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: Ulysse Jacob (LUPM), Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright burst GRB 250612C (SVOM trigger reference: sb25061214) at 2025-06-12T14:53:16.700 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#40704). The real-time alert data and light curves of SVOM/GRM were downlinked to the ground through the VHF system with low latency. With the VHF data, the GRM light curve shows that this burst consists of a single spike with a T90 of 2.4 +/-0.8 s in the 15-5000 keV band. This burst is clearly detected in GRM VHF data beyond 550 keV, indicating a hard spectrum. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250612C.png At the time of the burst, ECLAIRs was not taking data. Refined analysis will be reported later. 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/40708. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38746] sb25061207: SVOM/VT optical counterpart
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40707 SUBJECT: sb25061207: SVOM/VT optical counterpart DATE: 25/06/12 15:40:31 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), L. Zhang (IHEP), Y.-D. Hu (GXU), X.-L. Chen (YNU) report on behalf of the SVOM mission team SVOM performed an automatic slew on the burst (sb25061207) triggered by SVOM/ECLAIRs (Zhang et al., GCN 40697). SVOM/VT began observing the field at 2025-06-12T10:30:44 UTC, 202 seconds after Tb, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. A candidate is found using VT X-band data, compared to Legacy survey, within the error box of SVOM/Eclairs (Zhang et al., GCN 40697) at R.A., Dec 198.09415, +0.07508 degrees: RA (J2000) = 13:12:22.597 Dec (J2000) = +00:04:30.28 with an uncertainty of 0.5 arcsec. The source is detected in both VT_R and VT_B bands. With the data available, the light curve shows that this source was fading at first time, and then rebrightening to the peak of VT_R ~ 18.0 mag at around 1000 seconds after the trigger time, and then decayed. mid-time | exposure time | band | mag (AB) ------------ |----------------- |------------------- 1.79 hour | 50 sec | VT_B | 21.6+/-0.2 1.79 hour | 50 sec | VT_R | 20.8+/-0.1 Given the VT colour of the candidate, it might be a low redshift transient. We also noticed that there is a faint blue source at the Legacy survey image at the location of the candidate, which might be the host. More followups are encouraged. 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 Y.-D. Hu : hyd(a)gxu.edu.cn. View this GCN Circular online at https://gcn.nasa.gov/circulars/40707. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38745] GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620)
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40706 SUBJECT: GRB 250612C: BALROG localization (Fermi Trigger 771432801 / GRB 250612620) DATE: 25/06/12 15:19:24 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 771432801 at 14:53:16 on 12 June 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) = 118.9 deg Decl.(2000.0) = 18.8 deg The 1 sigma statistical error radius is 1.1 deg. We estimate an additional systematic error of 1 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB250612620/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB250612620/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB250612620/json View this GCN Circular online at https://gcn.nasa.gov/circulars/40706. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38744] GRB 250610B: Swift-XRT refined Analysis
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40705 SUBJECT: GRB 250610B: Swift-XRT refined Analysis DATE: 25/06/12 15:11:21 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P. D'Avanzo (INAF-OAB), J.A. Kennea (PSU), D.N. Burrows (PSU), M.A. Williams (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 5.0 ks of XRT data for GRB 250610B, from 2.9 ks to 105.7 ks after the SVOM/ECLAIRs trigger. The data are entirely in Photon Counting (PC) mode. Using 2013 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 = 200.17991, +31.10477 which is equivalent to: RA (J2000): 13h 20m 43.18s Dec(J2000): +31d 06' 17.2" with an uncertainty of 2.8 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=0.68 (+0.12, -0.10). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.86 (+0.33, -0.25). The best-fitting absorption column is 3.1 (+7.7, -2.0) x 10^20 cm^-2, consistent with the Galactic value of 1.1 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 3.5 x 10^-11 (3.7 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 3.1 (+7.7, -2.0) x 10^20 cm^-2 Galactic foreground: 1.1 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 1.86 (+0.33, -0.25) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00019863. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40705. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38743] GRB 250612C: Fermi GBM Final Real-time Localization
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40704 SUBJECT: GRB 250612C: Fermi GBM Final Real-time Localization DATE: 25/06/12 15:02:11 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 14:53:16 UT on 12 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250612C (trigger 771432801.582428 / 250612620). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 113.2, Dec = 16.2 (J2000 degrees, equivalent to J2000 07h 32m, 16d 11'), with a statistical uncertainty of 1.4 degrees. The angle from the Fermi LAT boresight is 96.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250612620/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250612620/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250612620/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40704. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38742] EP250610a: Upper limit from Fermi-GBM Observations
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40703 SUBJECT: EP250610a: Upper limit from Fermi-GBM Observations DATE: 25/06/12 14:32:39 GMT FROM: mariaedvige.ravasio(a)ru.nl M. E. Ravasio (Radboud Univ.), E. Burns (LSU), and P.G. Jonker (Radboud Univ.) report on behalf of the Fermi-GBM Team: Fermi-GBM had full spatial coverage of the transient EP250610a detected by EP-WXT (Zhang et al., GCN 40660, Lian et al. GCN 40669). There was no Fermi-GBM onboard trigger around the EP starting time T0=2025-06-10T04:23:24 UTC. The GBM targeted search [1], the most sensitive, coherent search for GRB-like signals, was run in the time interval [T0-50;T0+500] s, seeking signals between 64 ms and 32.768 s in duration. No signal consistent with the EP transient, both temporally and spatially, is identified, as confirmed also by visual inspection of the data. Assuming a “soft” spectral template (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7), and a duration of 8.192 s, we derive a flux upper limit of 2.8e-08 erg/cm2/s in the energy band 10-1000 keV. [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/40703. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38741] GRB 250612B (250612519/771424081): Fermi GBM Final Localization
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40702 SUBJECT: GRB 250612B (250612519/771424081): Fermi GBM Final Localization DATE: 25/06/12 14:23:44 GMT FROM: eliza.neights(a)gmail.com The Fermi GBM team reports the detection of a likely LONG GRB "At 12:27:56.19 UT on 12 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250612B (trigger 771424081/250612519). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 231.28, Dec = -29.05 (J2000 degrees, equivalent to J2000 15h 25m, -29d 03'), with a statistical uncertainty of 2.0 degrees. The angle from the Fermi LAT boresight is 71.04 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250612519/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250612519/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250612519/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/40702. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38740] GRB 250612A: BALROG localization (Fermi Trigger 771424081 / GRB 250612519)
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40701 SUBJECT: GRB 250612A: BALROG localization (Fermi Trigger 771424081 / GRB 250612519) DATE: 25/06/12 13:17:08 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 771424081 at 12:27:56 on 12 June 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) = 226.1 deg Decl.(2000.0) = -28.9 deg The 1 sigma statistical error radius is 2.4 deg. We estimate an additional systematic error of 1 deg. This is consistent in time and position with the Einstein Probe detection of the X-ray transient EP 250612a (GCN 40700). Further details are available at: https://grb.mpe.mpg.de/grb/GRB250612519/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB250612519/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB250612519/json View this GCN Circular online at https://gcn.nasa.gov/circulars/40701. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38739] EP250612a: Einstein Probe detection of an X-ray transient
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40700 SUBJECT: EP250612a: Einstein Probe detection of an X-ray transient DATE: 25/06/12 13:03:13 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. L. Hua (PMO, CAS), T. Zhao, Y. J. Song, J. W. Hu , W. Yuan (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250612a. The transient triggered EP-WXT (ID: 01709178580) at 2025-06-12T12:28:05 (UTC). The WXT position of the source is R.A. = 229.654 deg, DEC = -26.757 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 229.6503 deg, DEC = -26.7661 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. The contact TA of EP250612a is Y. L. Hua, please contact him via email ylhua(a)pmo.ac.cn if needed. 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/40700. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38738] GRB 250610B: Liverpool Telescope continued monitoring
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40699 SUBJECT: GRB 250610B: Liverpool Telescope continued monitoring DATE: 25/06/12 12:54:32 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz (U. Birmingham), Dimple (U. Birmingham) and A. Bochenek (LJMU) report on behalf of a larger collaboration: We continued follow-up observations of GRB 250610B (Saccardi et al., GCN 40671) for a second night with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations began at 21:56:59 UT on 2025-06-11, ~29.4 hr after the SVOM/ECLAIRs trigger, and consisted of 8x180 s exposures in the SDSS r and i filters. We detect the optical counterpart (Schneider et al., GCN 40676; Gompertz et al., GCN 40677; Li et al., GCN 40678; Bochenek & Perley, GCN 40684; Qiu et al., GCN 40685; Schneider et al., GCN 40689; Breeveld & Williams, GCN 40691) with AB magnitudes of r = 22.38 ± 0.13 (mid-time t0+1.23 days) and i = 22.13 ± 0.08 (mid-time t0+1.25 days). Magnitudes are calibrated against nearby Pan-STARRS stars and are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40699. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38737] GRB 250610B: MISTRAL/T193 and T120 OHP further observations
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40698 SUBJECT: GRB 250610B: MISTRAL/T193 and T120 OHP further observations DATE: 25/06/12 11:57:50 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), A. de Ugarte Postigo (LAM), Y. Degot-Longui (Pytheas/OHP), J. Balcaen (Pytheas/OHP), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), report on behalf of a larger collaboration: We re-observed the field of the GRB 250610B (Saccardi et al., GCN 40671; Wang et al., GCN 40672; Gompertz et al., GCN 40674; Schneider et al., GCN 40676; Gompertz et al., GCN 40677; Li et al., GCN 40678; Evans et al., GCN 40679; Liang et al., GCN 40681; Wang et al., GCN 40682; Wang et al., GCN 40683; Bochenek et al., GCN 40684; Qiu et al., GCN 40685; Brivio et al., GCN 40687; Schneider et al., GCN 40689; Breeveld et al., GCN 40691; Hamburg et al., GCN 40692; Godet al., GCN 40695) using the T120cm and T193cm (MISTRAL instrument) telescopes at Observatoire de Haute-Provence (France). We obtained 60 minutes with MISTRAL and 75 minutes with the T120 CCD camera simultaneously in the r-band, from 2025-06-11 at 20:41 to 22:17 UTC (from 28.13 to 29.73 hr after the trigger). In the stacked and combined image from both instruments, the optical counterpart is detected at a preliminary magnitude of: r = 22.59 +/- 0.21 mag (AB) The photometric calibration was performed using nearby stars from the PanStarrs catalog and the magnitude is not corrected for Galactic extinction. We acknowledge the excellent support from Observatoire de Haute-Provence and in particular the students and professors from the summer camp OHP 2025 and the SOPHIE observer T. Llopis View this GCN Circular online at https://gcn.nasa.gov/circulars/40698. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38736] sb25061207: SVOM detection of a X-ray transient
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40697 SUBJECT: sb25061207: SVOM detection of a X-ray transient DATE: 25/06/12 11:30:52 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> L. Zhang (IHEP), Y.-D. Hu (GXU), X.-L. Chen (YNU), N. Dagoneau (CEA), U. Jacob (LUPM), C. Van Hove (IJCLab) on behalf of the SVOM mission team. At 2025-06-12T10:27:22 UTC (T0), SVOM/ECLAIRs triggered and located the X-ray transient sb25061207 (SVOM burst-id sb25061207). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was only detected by the Image Trigger (IMT), which produced a sequence of 3 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.34 in the [5-20] keV energy band over a time window of 40.96 seconds starting at 2025-06-12T10:27:02. The localization of the best alert is R.A., Dec. 197.9873, 0.0214 degrees: R.A. (J2000) = 13h11m56.95s Dec. (J2000) = +00d01m17.04s with a 90% confidence level (C.L.) radius of 10.68 arcmin (including systematic error of 2 arcmin added in quadrature). The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/sb25061207.png SVOM slewed to the burst. MXT began observing the field at 2025-06-12T10:31:00 UTC, ~ 4 min after T0. Using onboard processed data, no source was detected in 750 seconds. The MXT team is waiting for the full dataset to detect and localise the possible MXT counterpart. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Y.-D. Hu : hyd(a)gxu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/40697. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38735] EP250610a: continuous follow-up observations with EP-FXT
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40696 SUBJECT: EP250610a: continuous follow-up observations with EP-FXT DATE: 25/06/12 08:52:14 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> H. Q. Cheng (NAO, CAS), Y. J. Zhang (THU) , T. Y. Lian, C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: Following the detection of the fast X-ray transient EP250610a (Zhang et al., GCN 40660, Lian et al. GCN 40669) and its multi-wavelength follow-up observations (Schneider et al., GCN 40661, Evans et al., GCN 40662, Brivio et al., GCN 40665, Yao et al., GCN 40666, Lipunov et al., GCN 40673, Eyles-Ferris et al., GCN 40686, Brivio et al., GCN 40688, Siegel et al., GCN 40690), we performed two target-of-opportunity (ToO) observations with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe mission. The X-ray counterpart detected in the autonomous follow-up observation (Lian et al. GCN 40669) as well as the Swift follow-up observation (Evans et al., GCN 40662) was detected in both epochs. The first ToO observation began at 2025-06-10 15:36:01 (UTC), about 11 hours after the EP-WXT detection. The exposure time is 2975 seconds. Preliminary analysis shows that the 0.5-10 keV FXT spectrum can be fitted with an absorbed power-law model with NH fixed at the Galactic value of 9.5e19 cm^-2 and a photon index of 1.97(-0.77, +0.86). The unabsorbed 0.5-10 keV flux is 1.13 (-0.53, +1.24) e-13 erg/s/cm^2 (90% C.L.), about one order of magnitude lower than that measured in the autonomous follow-up observation (Lian et al. GCN 40669). The second ToO observation began at 2025-06-11 15:35:15 (UTC), about 35 hours after the EP-WXT detection. The exposure time is 5950 seconds. Preliminary analysis shows that the 0.5-10 keV spectrum of this epoch can be fitted with an absorbed power-law model with NH fixed at the Galactic value of 9.5e19 cm^-2 and a photon index of 1.39(-0.94, +0.83), yielding an unabsorbed 0.5-10 keV flux of 6.91(-4.42, +14.50)e-14 erg/s/cm^2 (90% C.L.). The uncertainties are given at 90 percent confidence level for all the above parameters. EP-FXT will continue monitoring the source in the forthcoming days. Multi-band follow-up observations are encouraged. The contact TAs of EP250610a are Tianying Lian and Huaqing Cheng, please contact them via the email tylian(a)nao.cas.cn and hqcheng(a)nao.cas.cn if needed. 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/40696. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38734] GRB 250610B - SVOM/ECLAIRs refined analysis
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40695 SUBJECT: GRB 250610B - SVOM/ECLAIRs refined analysis DATE: 25/06/12 07:39:53 GMT FROM: ogodet(a)irap.omp.eu Authors: O. Godet (IRAP), A. Coleiro (APC), M.-G. Bernardini (INAF-OAB, LUPM), A. Saccardi (CEA), J. Rodriguez (CEA) Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 250610B (SVOM burst-id sb25061018). The burst that triggered ECLAIRs onboard (GCN #40671) consists of a single large peak with a duration of T90 = 108.25 -13.14 / +34.95 s in the 4-120 keV energy band. The time-averaged spectrum from T0-10s to T0+80s (T0 = 2025-06-10T16:32:58 UTC) in the energy range 5-120 keV is best fitted by a cutoff powerlaw model with a photon index of 0.9 +/- 0.1 and a cutoff energy of 49 +14/-10 keV. This translates to a Epeak-value of 53 +16/-12 keV. These spectral parameters are consistent with those obtained by SVOM/GRM (GCN #40683). With this model, the total 4-120 keV fluence is (2.9 +0.1/-0.4)e-6 erg/cm^2. All the quoted errors are given at the 68% confidence level. Given that the ECLAIRs calibration is still on-going, the above results shall be seen as preliminary. 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: O. Godet (IRAP) (ogodet at irap.omp.eu) View this GCN Circular online at https://gcn.nasa.gov/circulars/40695. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38733] GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40694 SUBJECT: GRB 250612A: Swift detection of a burst or new Galactic transient Swift J1643.6-3854 DATE: 25/06/12 01:27:51 GMT FROM: James DeLaunay at PSU <jjd330(a)psu.edu> M. H. Siegel (PSU), J. J. DeLaunay (PSU), R. Gupta (NASA GSFC) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 01:02:05.82 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250612A (trigger=1323295). The BAT on-board calculated location is RA, Dec 250.903, -38.902 which is RA(J2000) = 16h 43m 37s Dec(J2000) = -38d 54â 06" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 5 sec. The peak count rate was ~1000 counts/sec (15-350 keV), at ~1 sec after the trigger. Due to a Moon observing constraint, Swift cannot slew to the BAT position until 11:59 UT on 2025 June 12. There will thus be no XRT or UVOT data for this trigger before this time. Given the location of the BAT detection at a Galactic latitude of 4.6 deg and no confirmation of a fading afterglow due to observing constraints, we cannot rule out a Galactic origin. If this is a new Galactic transient we would name it Swift J1643.6-3854. 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/40694. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38732] Swift GRB250612.04: Global MASTER-Net observations report
by GCN Circulars 12 Jun '25

12 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40693 SUBJECT: Swift GRB250612.04: Global MASTER-Net observations report DATE: 25/06/12 01:14:39 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 GRB250612.04 (trigger No 1323295,16h 43m 36.72s , -38d 54m 07.2s, R=0.05) errorbox 42 sec after notice time and 83 sec after trigger time at 2025-06-12 01:03:28 UT, with upper limit up to 16.6 mag. The observations began at zenith distance = 36 deg. The sun altitude is -42.8 deg. The galactic latitude b = 4 deg., longitude l = 345 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2900722 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 93 | MASTER-OAFA | C | 20 | 16.6 | 120 | MASTER-OAFA | C | 20 | 16.6 | 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/40693. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38731] Fermi GBM Sub-Threshold Detection of GRB 250610B
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40692 SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 250610B DATE: 25/06/11 19:54:51 GMT FROM: rhamburg(a)usra.edu R. Hamburg (USRA) reports on behalf of the Fermi-GBM Team: The SVOM/ECLAIRs and SVOM/GRM instruments detected GRB 250610B on 2025-06-10T16:32:58 (GCN 40671). There was no Fermi-GBM onboard trigger around this event time. An automated, blind search for gamma-ray bursts below the onboard triggering threshold in Fermi-GBM identified no candidates. The GBM Targeted Search [1], the most sensitive, coherent search for GRB-like signals in GBM data, identified a transient starting approximately 31 seconds after the SVOM/ECLAIRs trigger time, most significantly on the 16.384 s timescale and with a false alarm rate of 9.7e-5 Hz. Using the standard search protocol, the Targeted Search localization was found to be spatially consistent with the SVOM/ECLAIRs location. Additionally, the GBM Targeted Search transient was found with the highest significance using a "soft" spectrum (Band function with Epeak = 70 keV, alpha = -1.9, beta = -3.7) for a GRB. This is roughly consistent with the soft spectrum found by Wang et al. 2025 (GCN 40682). [1] Goldstein et al. 2019 arXiv:1903.12597 View this GCN Circular online at https://gcn.nasa.gov/circulars/40692. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38730] GRB 250610B: Swift/UVOT Detection
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40691 SUBJECT: GRB 250610B: Swift/UVOT Detection DATE: 25/06/11 15:39:28 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and M.A. Williams (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250610B 2 ks after the SVOM trigger (Saccardi et al., GCN Circ. 40671). The optical source at the position of XRT source 1 (Evans et al., GCN Circ. 40679) seen by Schneider et al., (GCN Circ. 40676), Gompertz et al., (GCN Circ. 40677), Li et al., (GCN Circ. 40678), Bochenek et al., (GCN Circ. 40684) and Qiu et al. (GCN Circ. 40685) was also detected in the UVOT U-band filter and shows signs of fading. Preliminary detections and 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 2939 4660 1694 20.20 ± 0.15 u 8634 8923 285 20.50 ± 0.36 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.0104 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40691. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38729] EP250610A: Swift/UVOT Upper limits
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40690 SUBJECT: EP250610A: Swift/UVOT Upper limits DATE: 25/06/11 14:39:47 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of EP250610A 3 ks after the EP trigger (Zhang et al., GCN Circ. 40660). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 40662) is seen in the initial UVOT exposures. Preliminary detections using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u 3087 9399 2103 >21.44 u 35617 41300 1846 >21.33 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.01 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40690. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38728] GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40689 SUBJECT: GRB 250610B: SVOM/COLIBRÍ (FM-GFT) optical observations DATE: 25/06/11 13:50:37 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> Benjamin Schneider (LAM), Diego López-Cámara (UNAM), Rosa L. Becerra (U Roma), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Fredd Alvarez (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Antonio de Ugarte Postigo (LAM), A. Saccardi (CEA), and J. Rodriguez (CEA): We imaged the field of the SVOM GRB 250610B (Saccardi et al., GCN Circ. 40671) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-06-11 04:35 to 06:40 UTC (from 12.0 to 14.1 hours after the trigger) and obtained 32 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 detected the optical counterpart reported by Schneider et al., GCN Circ. 40676; Gompertz et al., GCN Circ. 40677; Li et al., GCN Circ. 40678; Bochenek et al., GCN Circ. 40684, and Qiu et al., GCN Circ. 40685 at preliminary magnitudes of: g = 21.83 +/- 0.14 r = 21.56 +/- 0.10 i = 21.49 +/- 0.09 Our detections are consistent with the shallow decay reported by the SVOM/VT team (Qiu et al., GCN Circ. 40685) and imply a temporal decay index of ~0.6. Further observations are planned. 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/40689. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38727] EP250610a: TNG NIR upper limit
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40688 SUBJECT: EP250610a: TNG NIR upper limit DATE: 25/06/11 11:56:27 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, P. D'Avanzo, M. Ferro, S. Campana (INAF-OAB), L. Izzo (INAF - OACn), D. B. Malesani (DAWN/NBI & Radboud Univ.), R. Salvaterra (INAF-IASF Milan), A. Melandri (INAF-OAR), V. Lorenzi (INAF-TNG) report on behalf of the CIBO collaboration: We observed the field of EP250610a detected by EP/WXT (Zhang et al., GCN 40660) with the Italian 3.6m TNG telescope, located in Canary Islands (Spain), equipped with the near-infrared camera NICS in imaging mode. A series of images were obtained with the J filter on 2025-06-11 at a mid-time of about 18.1 hours after the burst. No clear afterglow candidate is detected within the XRT position (source 1, Evans et al., GCN 40662) down to a 3-sigma limiting magnitude of J ~ 22 (Vega; calibrated against the 2MASS catalogue). View this GCN Circular online at https://gcn.nasa.gov/circulars/40688. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38726] GRB 250610B: REM optical/NIR observations
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40687 SUBJECT: GRB 250610B: REM optical/NIR observations DATE: 25/06/11 11:49:21 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of GRB 250610B detected by SVOM/ECLAIRs (Saccardi et al., GCN 40671) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, and H bands, started on 2025 June 10 at 22:45:52 UT (i.e. 6.2 hr after the burst), and lasted for about 1 hour. From preliminary inspection, we do not detect any possible counterpart at the position of the optical afterglow (Schneider et al., GCN 40676; Gompertz et al., GCN 40677; Li et al., GCN 40678; Bochenek et al., GCN 40684; Qiu et al., GCN 40685) down to the following 3sigma limits: r > 19.6 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 6.7 hr after the trigger; H > 15.6 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 6.2 hr after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/40687. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38725] EP250610a: Liverpool Telescope optical upper limits
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40686 SUBJECT: EP250610a: Liverpool Telescope optical upper limits DATE: 25/06/11 10:13:31 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris, P. T. O’Brien and R. L. C. Starling (U of Leicester) report: We observed the field of the X-ray transient EP250610a (Zhang et al., GCN 40660; Lian et al., GCN 40669) with the 2m Liverpool Telescope using the IO:O instrument. We obtained 6x150s exposures in each of the SDSS r’ and SDSS g’ filters starting at 2025-05-11 00:16:50 UT, approximately 19.9 hours after the X-ray detection. We performed image subtraction on the stacked images using reference images from Pan-STARRS and also compared the stacked and reference images manually. In agreement with Schneider et al. (GCN 40661), Brivio et al. (GCN 40665), Yao et al. (GCN 40666) and Lipunov et al. (GCN 40673), we identify no new sources within the positional uncertainty of the X-ray source identified by Evans et al. (GCN 40662) and Lian et al. (GCN 40669). At the position of the X-ray source, we derive 3-sigma upper limits of r’ > 22.1 and g’ > 22.1 with photometry calibrated to Pan-STARRS and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40686. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38724] GRB 250610B: SVOM/VT optical shallow decay
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40685 SUBJECT: GRB 250610B: SVOM/VT optical shallow decay DATE: 25/06/11 09:54:28 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> Y. L. Qiu, H. L. Li, L. P. Xin, C. Wu, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), A. Saccardi, J. Rodriguez, N. Dagoneau (CEA), C. Van Hove (IJCLab) report on behalf of the SVOM mission team. SVOM/VT made a second ToO observation for GRB250610B (Saccardi et al., GCN 40671; Wang et al., GCN 40682; Wang et al, GCN 40683). The observation was performed in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With more data, the brightness of the counterpart (Schneider et al., GCN 40676; Gompertz et al., GCN 40677; Li et al., GCN 40678; Bochenek et al., GCN 40684) was fading by about 0.6+/-0.1 mag in both band within 9 hours. The latest brightness is derived as follows: Mid-time after the burst | exposure time| band | mag (AB) | mag err -------------------------|--------------|------|----------|-------- 9.53 hour | 14*70 sec | VT_B | 21.3 ｜ 0.1 9.50 hour | 12*70 sec | VT_R | 21.1 ｜ 0.1 Our photometry was not corrected for Galactic extinction. We noticed that there is a faint blue source at the position of the counterpart in Legency Survey DR10 with g=23.0 mag and r=22.75 mag. Considering the possible host galaxy's brightness and blue color，the photometry at later phase might be contaminated by the host galaxy's light, particularly in the VT_B band. With the slow decaying behavior of X-ray emission (Evans et al., GCN 40679; Liang et al., GCN 40681) and optical at early phase, it is not an ordinary GRB event. More multiband follow-up and spectrum observations are encouraged. 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/40685. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38723] GRB 250610B: additional Liverpool Telescope optical observations
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40684 SUBJECT: GRB 250610B: additional Liverpool Telescope optical observations DATE: 25/06/11 08:39:42 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek and D. A. Perley (LJMU) report: We observed the field of GRB 250610B (Saccardi et al., GCN 40671) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 4x100s exposures in the SDSS r’ and i’ filters starting at 2025-06-10 23:34:02 UT, approximately 7.0 hours after the trigger. We report detections in stacked images in both filters at the position of the reported optical counterpart (Schneider et al., GCN 40676). The obtained magnitudes are r = 21.21 ± 0.11 and i = 21.14 ± 0.13, in line with previous optical observations (Schneider et al., GCN 40676; Gompertz et al., GCN 40677; Li et al., GCN 40678). The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. MJD (mid) T_mid-T_0 Filter Mag. (AB) 60836.98618 7.12 h r 21.21 ± 0.11 60836.99384 7.30 h i 21.14 ± 0.13 View this GCN Circular online at https://gcn.nasa.gov/circulars/40684. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38722] GRB 250610B: SVOM/GRM analysis
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40683 SUBJECT: GRB 250610B: SVOM/GRM analysis DATE: 25/06/11 06:39:58 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: A. Saccardi, J. Rodriguez, N. Dagoneau (CEA) Report on behalf of the SVOM team: SVOM/GRM detected the burst GRB 250610B at 2025-06-10T16:32:58 UTC (T0), which is also detected by SVOM/ECLAIRs (A. Saccardi et al., GCN #40671) and Fermi/GBM (Yun Wang et al., GCN #40682) With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of GRB 250610B. The GRM light curve shows that this burst consists of a single pulse with a T90 of 94 +/-14 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250610B.png With the localization of ECLAIRs (RA=200.1831, DEC=31.1028), the time-averaged spectrum from T0-10 to T0+80 s is best fitted by a Blackbody function. The temperature, parameterized as kT, is 13 +/- 1 keV. The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.2)E-06 erg/cm^2. The time-averaged spectrum can also be fitted by a power law function with an exponential high-energy cutoff adequately. The power law index is -1.2 +/- 0.5 and the cutoff energy, parameterized as Epeak, is 66 +15/-12 keV. The event fluence (10-1000 keV) in this time interval is (2.2 +/- 0.3)E-06 erg/cm^2. Thus GRB 250610B is consistent with Type II GRBs in the 'Amati' relation diagram, as shown at: https://www.bursthub.cn//admin/static/grb250610B_amati.png We note that the calibration of SVOM/GRM is undergoing thus these results are preliminary. Refined analysis will be reported later. 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/GRM 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/40683. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38721] GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40682 SUBJECT: GRB 250610B: Fermi/GBM sub-threshold detection of a possibly hard burst DATE: 25/06/11 03:32:59 GMT FROM: Hao Zhou at Purple Mountain Observatory, CAS <haozhou(a)pmo.ac.cn> Yun Wang, Hao Zhou, Zhi-Ping Jin, Yi-Zhong Fan (PMO,CAS): We report a possible sub-threshold detection of GRB 250610B by the Fermi Gamma-ray Burst Monitor (GBM). The burst was initially detected by SVOM/ECLAIRs (Saccardi et al., GCN 40671) at T0 = 2025-06-10 16:32:58 UTC. The reported position is R.A., Dec. 200.1831, 31.1028 degrees. Based on the poshist file, the GBM NaI detector with the smallest incident angle to the burst direction was nb. We used the GBM Time-Tagged Event (TTE) data to extract the spectrum over the interval from T0–10 s to T0+80 s. The background was estimated from two intervals: T0–200 s to T0–100 s and T0+300 s to T0+400 s. We fitted the spectrum with a cutoff power-law model (dN/dE ~ (E^-alpha)*exp(-E/Ec)), obtaining alpha ~ -0.6 and a peak energy Ep=(2-alpha)*Ec ~ 55 keV. The energy flux in the 1–10000 keV band is estimated to be ~ 5.72e-9 erg/cm^2/s. The spectrum can be fitted with a blackbody model, yielding a temperature of kT ~13 keV and providing a better goodness of fit than a cutoff power-law model. This is a test using RapidGBM (https://github.com/0neyun/RapidGBM), and the results presented here should be considered preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/40682. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38720] GRB 250610B: EP-FXT follow-up observation and afterglow counterpart
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40681 SUBJECT: GRB 250610B: EP-FXT follow-up observation and afterglow counterpart DATE: 25/06/11 02:44:20 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. F. Liang, Y. L. Hua (PMO, CAS), X. P. Xu, H. W. Pan(NAO, CAS), A. Saccardi, J. Rodriguez, N. Dagoneau (CEA), C. Van Hove (IJCLab) report on behalf of the Einstein Probe and SVOM team We performed a follow-up observation of GRB 250610B (detected through offline search of SVOM/ECLAIRs, Saccardi et al, GCN #40671; followed by Swift/XRT, Evans et al. GCN #40679), with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe (EP) mission. The observation began at 2025-06-10T17:04:27 (T-TGRB ~ 1.9ks), and the exposure time is about 5.8 ks. Only 1 uncatalogued source was detected both by FXTA and FXTB in the 90% localization error circle provided by SVOM/ECLAIRs (with a radius of 3.22 arcmin centered at RA, DEC = 200.1831 deg, +31.1028 deg), as listed below (the FXT flux is taken from FXTB module). ------------------------------------------------------------------------------------------------- Source name | RA | DEC | Estimated Flux | SNR | Dist from SVOM/ECLAIRs | | deg | deg | (erg/s/cm^2) | | offset (in arcmin) | EPF_J132043.1+310615 | 200.1795 | 31.1043 | 2.8(+/-0.2) x 10^-12 | 5.9 | 0.21 | ------------------------------------------------------------------------------------------------- Note: * EPF_J132043.1+310615 was also detected by Swift/XRT (GCN #40679) in a ~2.0 ks observation, with a mean flux of ~3.9(+/-0.3)e-12 erg/s/cm^2, the position of this source is also associated with the Optical counterpart detected by SVOM/VT (Li et al. GCN #40678). The above observation was made with the EP-FXT instrument. 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). EP is a mission of the Chinese Academy of Sciences in collaboration with ESA, MPE and CNES. View this GCN Circular online at https://gcn.nasa.gov/circulars/40681. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38719] Fermi Gamma-ray Burst Monitor trigger 771286888/250610932 is not a GRB
by GCN Circulars 11 Jun '25

11 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40680 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771286888/250610932 is not a GRB DATE: 25/06/11 00:48:18 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771286888/250610932 at 22:21:23.29 UT on 10 June 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/40680. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38718] GRB 250610B: Swift-XRT counterpart detection
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40679 SUBJECT: GRB 250610B: Swift-XRT counterpart detection DATE: 25/06/10 23:55:14 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 250610B, collecting 2.0 ks of Photon Counting (PC) mode data between T0+2.8 ks and T0+8.9 ks after the trigger. A likely counterpart has been found consistent with the optical detection (GCN Circ. 40676, 40677 and 40678). The details of this source are: Source 1 (SWIFT J132043.2+310614): ================================== RA (J2000.0): 200.1802 = 13h 20m 43.25s Dec (J2000.0): +31.1040 = +31d 06' 14.4" Error: 3.7 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 4.3 arcmin from the SVOM/ECLAIRs position. Mean rate: 0.1084 +/- 0.0084 ct s^-1 Mean flux: (3.91 +/- 0.30)e-12 erg cm^-2 s^-1 Peak rate: 0.134 +/- 0.022 ct s^-1 Peak flux: (4.85 +/- 0.81)e-12 erg cm^-2 s^-1 ECF: 3.61e-11 erg cm^-2 ct^-1, assuming NH=1.44e+20 cm^-2, gamma=1.78; determined from a spectral fit. XMM UL: 2.4e-12 erg cm^-2 s^-1, (0.3-10 keV) so the source is 3.0-sigma above this 3-sigma upper limit. There is no evidence for fading. 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/40679. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38717] GRB 250610B: SVOM/VT optical counterpart
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40678 SUBJECT: GRB 250610B: SVOM/VT optical counterpart DATE: 25/06/10 23:35:24 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), A. Saccardi, J. Rodriguez, N. Dagoneau (CEA), C. Van Hove (IJCLab) report on behalf of the SVOM mission team. SVOM performed a Target of Opportunity observation of GRB 250610B detected by SVOM/Eclairs (Saccardi et al., GCN 40671). SVOM/VT began observing the field at 2025-06-10 17:04:26 UTC, 0.52 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. An uncatalogued source, compared to legacy survey, is found using VT X-band data, within the error box of Swift/XRT1 at R.A., Dec 200.179739, 31.10496 degrees: RA (J2000) = 13:20:43.1 Dec (J2000) = +31:06:17.9 with an uncertainty of 0.5 arcsec. The source is detected in both VT_R and VT_B, and was fading by 0.3 mag in 2 orbits, the magnitudes are: Mid-time after the burst | exposure time (s) | band | mag (AB) | mag err --------------------|-------------------|------|----------|-------- 1.234 hour | 70 | VT_B | 20.7 ｜ 0.1 1.234 hour | 70 | VT_R | 20.3 ｜ 0.1 This position and the brightness is consistent with the reports (Schneider et al., GCN 40676, Gompertz et al., GCN 40677) 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 Andrea Saccardi(a)cea.fr. View this GCN Circular online at https://gcn.nasa.gov/circulars/40678. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38716] GRB 250610B: LT detection of the optical counterpart
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40677 SUBJECT: GRB 250610B: LT detection of the optical counterpart DATE: 25/06/10 23:30:06 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz (U. Birmingham), Dimple (U. Birmingham), A. Martin-Carrillo (UCD) and G. Corcoran (UCD) report on behalf of a larger collaboration: We initiated follow-up observations of GRB 250610B (Saccardi et al., GCN 40671) with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations began at 22:24:56 UT, ~5.85 hr after the SVOM/ECLAIRs trigger, and consisted of 7x120 s and 10x120 s exposures in the SDSS g and i filters, respectively. We detect the optical counterpart (Schneider et al., GCN 40676) with AB magnitudes of g = 21.38 ± 0.11 and i = 21.02 ± 0.06. Magnitudes are calibrated against nearby Pan-STARRS stars and are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40677. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38715] GRB 250610B: optical counterpart candidate
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40676 SUBJECT: GRB 250610B: optical counterpart candidate DATE: 25/06/10 23:26:37 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> B. Schneider (LAM), A. de Ugarte Postigo (LAM), C. Adami (LAM/Pytheas/AMU), J.P Troncin (Pytheas/OHP), A. Martin-Carrillo (UCD), 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 250610B (Saccardi et al., GCN 40671) using the T120cm telescope at Observatoire de Haute-Provence (France). We obtained 30 minutes of exposure in the r-band starting at 20:31:03.29 UT on 2025-06-10 (3.97 hr after the trigger). In the stacked image, we detected a new source at RA, DEC (J2000) 200.1796, +31.1047, not visible in the Legacy Survey and consistent with the XRT error: RA(J2000) = 13:20:43.11 DEC(J2000) = +31:06:16.8 with an uncertainty of 0.5 arcsec. The preliminary magnitude derived for that source is: r = 20.96 +/- 0.15 mag (AB) The photometric calibration was performed using nearby stars from the SDSS catalog and the magnitude is not corrected for Galactic extinction. We acknowledge the excellent support from Observatoire de Haute-Provence and in particular the students and professors from the summer camp OHP 2025. View this GCN Circular online at https://gcn.nasa.gov/circulars/40676. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38714] GRB 250610C: Fermi GBM Final Real-time Localization
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40675 SUBJECT: GRB 250610C: Fermi GBM Final Real-time Localization DATE: 25/06/10 23:21:44 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 23:11:04 UT on 10 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250610C (trigger 771289869.772446 / 250610966). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 26.8, Dec = 59.7 (J2000 degrees, equivalent to J2000 01h 47m, 59d 42'), with a statistical uncertainty of 2.5 degrees. The angle from the Fermi LAT boresight is 64.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610966/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610966/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610966/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40675. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38713] GRB 250610B: GOTO optical upper limit
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40674 SUBJECT: GRB 250610B: GOTO optical upper limit DATE: 25/06/10 21:43:38 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, D. O’Neill, D. Steeghs, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, A. Kumar, B. Godson, 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 the SVOM/ECLAIRS detected GRB 250610B (Saccardi et al., GCN 40671). Targeted observations were performed with GOTO-North centred at 2025-06-10 21:13:20 UT (+4.66h post trigger). Observations 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. We detect no new sources within the ECLAIRS localisation region down to a 3-sigma limiting magnitude of L > 19.92 AB mag. 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/40674. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38712] EP250610a: Global MASTER-Net observations report
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40673 SUBJECT: EP250610a: Global MASTER-Net observations report DATE: 25/06/10 19:36:20 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-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 EP250610a ( EP Team et al., GCN 40660) errorbox 972 sec after notice time and 9094 sec after trigger time at 2025-06-10 06:57:24 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 82 deg. The sun altitude is -57.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP250610a errorbox 44872 sec after notice time and 52993 sec after trigger time at 2025-06-10 19:09:03 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 15 deg. The sun altitude is -18.3 deg. The galactic latitude b = 42 deg., longitude l = 61 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2898181 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9229 | 2025-06-10 06:57:24 | MASTER-OAFA | (16h 33m 32.66s , +38d 48m 08.6s) | C | 270 | 17.6 | Coadd 53024 | 2025-06-10 19:09:03 | MASTER-Kislovodsk | (16h 31m 32.68s , +38d 50m 44.6s) | C | 60 | 17.0 | 53210 | 2025-06-10 19:12:09 | MASTER-Kislovodsk | (16h 31m 34.53s , +38d 48m 49.2s) | C | 60 | 17.4 | 53547 | 2025-06-10 19:17:46 | MASTER-Kislovodsk | (16h 31m 41.01s , +38d 50m 51.7s) | C | 60 | 17.1 | 53720 | 2025-06-10 19:20:40 | MASTER-Kislovodsk | (16h 31m 35.46s , +38d 50m 56.6s) | C | 60 | 16.0 | 53893 | 2025-06-10 19:23:32 | MASTER-Kislovodsk | (16h 31m 32.13s , +38d 48m 59.5s) | C | 60 | 17.0 | 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/40673. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38711] GRB 250610B : SVOM/GWAC-F60A and F50 observations
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40672 SUBJECT: GRB 250610B : SVOM/GWAC-F60A and F50 observations DATE: 25/06/10 18:53:15 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> J. Wang, W. L. Dong, L. P. Xin(NAOC), L. J. Chen(GXU), Y. G. Yang(HNU), X. H. Han, C. WU, Y. L. Qiu, H. L. Li, X .M. Lu, R. S. Zhang, Y. Xu, L. Huang, H. B. Cai, Y. J. Xiao, P. P. Zhang, L. Lan, W. J. Xie, Z. H. Yao, J. Y. Wei(NAOC), X. G. Wang, E. W. Liang(GXU) and W. Zheng (UCB) report on behalf of the SVOM follow-up team: We observed the field of SVOM GRB 250610B (Saccardi et al., GCN 40671) with the GWAC-F60A and GWAC-F50 at Xinglong Observatory, China. F60A started observing at 2025-06-10T17:14:17.39 UTC with a set of 34 images in R-band. F50 started observing at 2025-06-10T17:14:17.39 UTC and with a set of 9 images in R-band. After coadding the images, we do not find any uncatalog candidate within the SVOM/ECLAIRs error box. We estimate the upper limit of 16.0 mag for GWAC-F60A at mid time of 54.5 minutes after brust, and upper limit of 17.5 mag for GWAC-F50 at mid time of 54.0 minutes after brust. Two 60cm GWAC-F60(A/B) are operated by Guangxi University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 19*19 arcmin. The 50cm telescope (F50A) is operated by Huaibei Normal University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 27*27 arcmin. View this GCN Circular online at https://gcn.nasa.gov/circulars/40672. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38710] GRB 250610B: SVOM detection of a long burst
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40671 SUBJECT: GRB 250610B: SVOM detection of a long burst DATE: 25/06/10 17:27:30 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> A. Saccardi, J. Rodriguez, N. Dagoneau (CEA), C. Van Hove (IJCLab) report on behalf of the SVOM mission team. At 2025-06-10T16:32:58 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250610B (SVOM burst-id sb25061018). 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 40 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 30.55 in the [8-50] keV energy band over a time window of 81.92 seconds starting at 2025-06-10T16:33:19. The localization of the best alert is R.A., Dec. 200.1831, 31.1028 degrees: R.A. (J2000) = 13h20m43.94s Dec. (J2000) = 31d06m10.04s with a 90% confidence level (C.L.) radius of 3.22 arcmin (including systematic error of 2 arcmin added in quadrature). The ECLAIRs light curve may show a double narrow peak structure with a T90 duration of about 134.368 (-13.465 +23.518) s. The ECLAIRs peak count rate was ~496.6503 ± 191.3858 counts/sec in the band [20-50] keV, ~5.6 seconds after the trigger. This burst was also detected by SVOM/GRM with a significance of 14.30. The GRM light curve showed a single broad peak structure with a T90 duration of about 69.237 (-6.343 +6.558) s. The GRM peak count rate was ~470.4469 ± 82.6942 counts/sec in the band [4-5000] keV, ~34.4 seconds after the trigger. A SVOM ToO has been executed for follow-up and started to observe at 2025-06-10T16:59 UTC. 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. GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Andrea Saccardi: andrea.saccardi(a)cea.fr. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/40671. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38709] Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40670 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB DATE: 25/06/10 14:25:40 GMT FROM: eliza.neights(a)gmail.com E. Neights (GWU, NASA GSFC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771256110/250610575 at 13:48:25.58 UT on 10 June 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/40670. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38708] EP250610a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40669 SUBJECT: EP250610a: refined analysis of the EP-WXT and EP-FXT observations DATE: 25/06/10 14:16:44 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> T.Y. Lian, H. Q. Cheng (NAO, CAS), Y. J. Zhang (THU) and C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: The fast X-ray transient EP250610a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Zhang et al., GCN 40660), and followed up by several optical and X-ray telescopes (Schneider et al., GCN 40661, Brivio et al., GCN 40665, Evans et al., GCN 40662). Refined analysis of the WXT data shows that the event started at T0=2025-06-10T04:23:24 (UTC) and lasted for about 140s before the interruption by the autonomous follow-up observation. The peak flux (0.5-4 keV) is estimated to be 2.2 x 10^-9 erg/s/cm^2. The averaged 0.5-4 keV spectrum can be fitted with an absorbed power-law with a Galactic hydrogen column density of 9.5 x 10^19 cm^-2 and a photon index of 0.7 (-/+0.8). The derived average unabsorbed 0.5-4 keV flux is 5.2 (-2.3, +4.2) x 10^-10 erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously at 2025-06-10T04:26:32, about 3 minutes after T0, with an exposure time of 3946 seconds. Within the WXT error circle, on-ground analysis of the FXT data found an uncatalogued source at R.A. = 248.3567, DEC = 38.5362 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic), which is spatially consistent with the candidate X-ray counterpart detected by Swift/XRT (Source 1 in Evans et al., GCN 40662). The averaged 0.5-10 keV FXT spectrum can be fitted with an absorbed power-law with a Galactic hydrogen column density of 9.5 x 10^19 cm^-2 and a photon index of 2.34 (-0.12, +0.12). The derived unabsorbed 0.5-10 keV flux is 1.87 (-0.17, +0.19) x 10^-12 erg/s/cm^2. The uncertainties are at the 90% confidence level for all the above parameters. 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). The contact TAs of this source are Tianying Lian and Huaqing Cheng, please contact them via the email tylian(a)nao.cas.cn and hqcheng(a)nao.cas.cn if needed. View this GCN Circular online at https://gcn.nasa.gov/circulars/40669. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38707] GRB 250610A: Fermi GBM Final Real-time Localization
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40668 SUBJECT: GRB 250610A: Fermi GBM Final Real-time Localization DATE: 25/06/10 13:58:44 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 13:48:25 UT on 10 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250610A (trigger 771256110.581806 / 250610575). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 359.9, Dec = 65.1 (J2000 degrees, equivalent to J2000 23h 59m, 65d 05'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 0.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610575/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610575/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610575/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40668. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38706] GRB 250605A: Swift-BAT refined analysis
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40667 SUBJECT: GRB 250605A: Swift-BAT refined analysis DATE: 25/06/10 13:23:05 GMT FROM: Mike Moss at NASA GSFC <mikejmoss3(a)gmail.com> R. Gupta (GSFC), S. D. Barthelmy (GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC), 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-239 to T+963 sec from the recent telemetry downlink, we report further analysis of BAT GRB 250605A (trigger #1321323) (Gupta, et al., GCN Circ. 40633). The BAT ground-calculated position is RA, Dec = 166.963, -19.786 deg which is RA(J2000) = 11h 07m 51.1s Dec(J2000) = -19d 47' 10.5" with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment). The partial coding was 35%. The BAT light curve shows a complex light curve with multiple emission episodes: a period of very dim extended emission between ~T0-100 sec to T0-10 leading up to one strong pulse between T0-10 sec to T0+10 sec and followed by a dim broad pulse between T0+40 sec to ~T0+125 sec. T90 (15-350 keV) is 176.05 +- 5.15 sec (estimated error including systematics). The time-averaged spectrum from T-100.30 to T+126.69 sec is best fit by a power law with an exponential cutoff. This fit gives a photon index 1.50 +- 0.22, and Epeak of 76.7 +- 27.6 keV (chi squared 71.54 for 56 d.o.f.). For this model the total fluence in the 15-150 keV band is 1.2 +- 0.0 x 10^-05 erg/cm2 and the 1-sec peak flux measured from T-0.00 sec in the 15-150 keV band is 6.1 +- 0.4 ph/cm2/sec. A fit to a simple power law gives a photon index of 1.83 +- 0.05 (chi squared 79.05 for 57 d.o.f.). 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/1321323 View this GCN Circular online at https://gcn.nasa.gov/circulars/40667. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38705] EP250610a: SVOM/VT optical upper limit
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40666 SUBJECT: EP250610a: SVOM/VT optical upper limit DATE: 25/06/10 12:55:24 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> Z. H. Yao, L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA),Y. J. Zhang (THU), T. Y. Lian, H. Q. Cheng, C. C. Jin (NAO, CAS), Lin Lan (NAOC), Run-Chao Chen (NJU), Chen-Wei Wang, Wen-Jun Tan (IHEP) report on behalf of the SVOM and EP mission team: SVOM performed a Target of Opportunity observation of EP250610a detected by EP/WXT (Zhang et al., GCN 40660). SVOM/VT began observing the field at 2025-06-10 06:16:38 UTC, 1.85 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No credible candidate was detected in our single or stacked images within the errorbox of EP/FXT (Zhang et al., GCN 40660) or Swift/XRT (Evans et al., GCN 40662 ), the three sigma limits are: [date-obs|mid-time] | exposure time (s) | band | upper limit (AB) ----------- --------|-------------------|------|----------------- 2025-06-10T07:29:10 | 76×70 | VT_B | 23.93 2025-06-10T07:29:10 | 76×70 | VT_R | 23.45 The upper limit is consistent with reports (Schneider et al., GCN 40661, Brivio et al., GCN 40665). Deeper or redder follow-ups are encouraged to investigate the nature of the transient。 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. View this GCN Circular online at https://gcn.nasa.gov/circulars/40666. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38704] EP250610a: REM optical/NIR observations
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40665 SUBJECT: EP250610a: REM optical/NIR observations DATE: 25/06/10 12:20:35 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of EP 250610a detected by EP/WXT (Zhang et al., GCN 40660) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, and H bands, started on 2025 June 10 at 05:02:09 UT (i.e. 36 min after the burst), and lasted for about 1 hour. From preliminary inspection, we do not detect any possible counterpart at the position of the candidate detected by Swift/XRT (source 1, Evans et al., GCN 40662) down to the following 3sigma limits: r > 18.7 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 66 min after the trigger; H > 16.6 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 39 min after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/40665. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38703] GRB 250609A: Fermi GBM Observation
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40664 SUBJECT: GRB 250609A: Fermi GBM Observation DATE: 25/06/10 09:59:45 GMT FROM: Christian Malacaria at INAF-OAR <cmalacaria.astro(a)gmail.com> C. Malacaria (ISSI) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 08:47:18.61 UT on 09 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250609A (trigger 771151643/250609366). which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2025, GCN 40658). The Fermi GBM on-ground location was reported by the Fermi-GBM team in GCN 40652. The angle from the Fermi LAT boresight is 81 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 1 s (50-300 keV). The time-averaged spectrum from T0-5.5 to T0+1.7 s is best fit by a simple power law function with index -1.3 +/- 0.1. The event fluence (10-1000 keV) in this time interval is (4.5 +/- 0.9)E-07 erg/cm^2. The 64-ms peak photon flux measured starting from T0-0.13 s in the 10-1000 keV band is 4 +/- 1 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/40664. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38702] GRBAlpha reentry on June 9, 2025
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40663 SUBJECT: GRBAlpha reentry on June 9, 2025 DATE: 25/06/10 09:37:37 GMT FROM: Andras Pal at Konkoly Observatory <apal(a)szofi.net> A. Pal (Konkoly Observatory), N. Werner (Masaryk U.), L. Meszaros (Konkoly Observatory), J. Ripa (Masaryk U.), M. Ohno (Hiroshima U.), M. Dafcikova (Masaryk U.), H. Takahashi (Hiroshima U.), B. Csak (Konkoly Observatory), N. Husarikova, F. Munz , M. Topinka, M. Duriskova, M. Kolar, L. Szakszonova, J.-P. Breuer, F. Hroch (Masaryk U.), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus, M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner Research Center/Eotvos U.), Y. Uchida, H. Poon, H. Matake (Hiroshima U.), N. Uchida (ISAS/JAXA), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa, K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory), T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J. Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha collaboration. After more than 4 years of scientific operations, on June 9, 2025, GRBAlpha, an 1U CubeSat reentered the Earth's atmosphere. GRBAlpha was the first GRB detecting CubeSat of this size and the smallest astrophysical space observatory (Pál et al. 2023, A&A, 677, A40). With 127 GRBs and a similar number of solar flare detections it successfully demonstrated that monitoring of gamma-ray transients can be effectively performed by CubeSats. We thank for the support of the radio amateur community, especially the maintainers and the station owners of the SatNOGS network. We look forward to more successful nanosatellite missions! View this GCN Circular online at https://gcn.nasa.gov/circulars/40663. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38701] EP250610a: Swift-XRT counterpart detection
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40662 SUBJECT: EP250610a: Swift-XRT counterpart detection DATE: 25/06/10 08:55:22 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 Einstein Probe/WXT-detected source EP250610a, collecting 2.1 ks of Photon Counting (PC) mode data between T0+2.8 ks and T0+9.4 ks after the trigger. A candidate counterpart has been found. The details of this source are: Source 1 (SWIFT J163325.5+383159): ================================== RA (J2000.0): 248.3564 = 16h 33m 25.54s Dec (J2000.0): +38.5332 = +38d 31' 59.5" Error: 4.6 (arcsec, radius, 90% confidence). Detect flag: GOOD Distance: 2.2 arcmin from the Einstein Probe/WXT position. Mean rate: 0.0111 +/- 0.0027 ct s^-1 Mean flux: (4.4 +/- 1.1)e-13 erg cm^-2 s^-1 Peak rate: 0.0111 +/- 0.0027 ct s^-1 Peak flux: (4.4 +/- 1.1)e-13 erg cm^-2 s^-1 ECF: 3.96e-11 erg cm^-2 ct^-1, assuming NH=1.07e+20 cm^-2, gamma=1.73; determined from a spectral fit. LSXPS UL: 2.4e-03 ct/sec, (0.3-10 keV) so the source is 3.1-sigma above this 3-sigma upper limit. There is no evidence for fading. We have detected a total of 2 sources. These have been automatically classified as follows: * 0 likely counterparts * 1 candidate counterpart * 1 uncatalogued X-ray source * 0 known X-ray sources Uncatalogued X-ray sources -------------------------- Source 2 (SWIFT J163309.1+383226): ================================== RA (J2000.0): 248.2883 = 16h 33m 09.19s Dec (J2000.0): +38.5406 = +38d 32' 26.2" Error: 7.1 (arcsec, radius, 90% confidence). Detect flag: REASONABLE Distance: 78 arcsec from the Einstein Probe/WXT position. Mean rate: (2.4 [+1.6, -1.1])e-3 ct s^-1 Mean flux: (1.02 [+0.70, -0.49])e-13 erg cm^-2 s^-1 Peak rate: (2.4 [+1.6, -1.1])e-3 ct s^-1 Peak flux: (1.02 [+0.70, -0.49])e-13 erg cm^-2 s^-1 LSXPS UL: 3.1e-03 ct/sec, (0.3-10 keV) so the source is not above this 3-sigma upper limit. There is no evidence for fading. There is 1 2MASS object within the source's 3-sigma error radius. 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/EP. This circular is an officicial product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40662. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38700] EP250610a: COLIBRÍ optical upper limit
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40661 SUBJECT: EP250610a: COLIBRÍ optical upper limit DATE: 25/06/10 07:27:07 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> Benjamin Schneider (LAM), Ramandeep Gill (UNAM), Rosa L. Becerra (U Roma), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (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), Kin Ocelotl López (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 EP250610a (Zhang et al., GCN Circ. 40660) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-06-10T05:04:33 to 05:23:35 UTC (from 38.7 to 57.8 minutes after the trigger, 3 minutes after 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 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 FXT position (Zhang et al., GCN Circ. 40660) down to the following 3-sigma limit: i > 22.9 Further observations and analysis are ongoing. 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/40661. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38699] EP250610a: COLIBRÍ optical upper limit
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40661 SUBJECT: EP250610a: COLIBRÍ optical upper limit DATE: 25/06/10 07:27:07 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> Benjamin Schneider (LAM), Ramandeep Gill (UNAM), Rosa L. Becerra (U Roma), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (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), Kin Ocelotl López (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 EP250610a (Zhang et al., GCN Circ. 40660) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-06-10T05:04:33 to 05:23:35 UTC (from 38.7 to 57.8 minutes after the trigger, 3 minutes after 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 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 FXT position (Zhang et al., GCN Circ. 40660) down to the following 3-sigma limit: i > 22.9 Further observations and analysis are ongoing. 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/40661. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38698] EP250610a: Einstein Probe detection of an X-ray transient
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40660 SUBJECT: EP250610a: Einstein Probe detection of an X-ray transient DATE: 25/06/10 06:40:33 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. J. Zhang (THU), T. Y. Lian, H. Q. Cheng, C. C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250610a. The transient triggered EP-WXT (ID: 01709178308) at 2025-06-10T04:25:50 (UTC). The WXT position of the source is R.A. = 248.310 deg, DEC = 38.527 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 248.3573 deg, DEC = 38.5387 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). Further information will be updated when the telemetry data is received. 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/40660. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38697] Fermi trigger No 771072240: Global MASTER-Net observations report
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40659 SUBJECT: Fermi trigger No 771072240: Global MASTER-Net observations report DATE: 25/06/09 22:15:22 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-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 GRB250608.45 (trigger No 771072240,18h 58m 24.00s , -32d 43m 01.2s, R=6.1) errorbox 64054 sec after notice time and 64085 sec after trigger time at 2025-06-09 04:32:01 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 30 deg. The sun altitude is -81.9 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB250608.45 errorbox 1 days 36182 sec after notice time and 1 days 36214 sec after trigger time at 2025-06-09 20:47:29 UT, with upper limit up to 15.5 mag. The observations began at zenith distance = 77 deg. The sun altitude is -23.8 deg. The galactic latitude b = -16 deg., longitude l = 4 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2896146 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 64116 | 2025-06-09 04:32:01 | MASTER-OAFA | (19h 30m 55.33s , -36d 57m 14.1s) | C | 60 | 19.1 | 65166 | 2025-06-09 04:49:31 | MASTER-OAFA | (19h 30m 59.76s , -36d 56m 31.4s) | C | 60 | 19.5 | 65650 | 2025-06-09 04:57:34 | MASTER-OAFA | (19h 30m 58.75s , -36d 55m 39.0s) | C | 60 | 19.4 | 68036 | 2025-06-09 05:37:21 | MASTER-OAFA | (19h 31m 07.13s , -36d 41m 35.0s) | C | 60 | 19.4 | 68522 | 2025-06-09 05:45:27 | MASTER-OAFA | (19h 31m 06.30s , -36d 41m 13.9s) | C | 60 | 19.5 | 69009 | 2025-06-09 05:53:34 | MASTER-OAFA | (19h 31m 03.36s , -36d 42m 55.3s) | C | 60 | 19.5 | 69497 | 2025-06-09 06:01:42 | MASTER-OAFA | (19h 31m 04.35s , -36d 40m 37.0s) | C | 60 | 19.4 | 69826 | 2025-06-09 06:07:11 | MASTER-OAFA | (19h 31m 08.26s , -36d 40m 52.2s) | C | 60 | 19.4 | 70159 | 2025-06-09 06:12:44 | MASTER-OAFA | (19h 31m 06.33s , -36d 40m 14.9s) | C | 60 | 19.4 | 70469 | 2025-06-09 06:17:54 | MASTER-OAFA | (19h 31m 09.41s , -36d 41m 37.9s) | C | 60 | 19.4 | 70775 | 2025-06-09 06:23:00 | MASTER-OAFA | (19h 31m 12.45s , -36d 40m 50.8s) | C | 60 | 19.4 | 71084 | 2025-06-09 06:28:09 | MASTER-OAFA | (19h 31m 10.44s , -36d 41m 34.6s) | C | 60 | 19.5 | 71399 | 2025-06-09 06:33:24 | MASTER-OAFA | (19h 31m 14.25s , -36d 40m 30.1s) | C | 60 | 19.5 | 71707 | 2025-06-09 06:38:32 | MASTER-OAFA | (19h 31m 11.50s , -36d 41m 01.5s) | C | 60 | 19.5 | 72014 | 2025-06-09 06:43:39 | MASTER-OAFA | (19h 31m 15.65s , -36d 40m 10.5s) | C | 60 | 19.5 | 72321 | 2025-06-09 06:48:46 | MASTER-OAFA | (19h 31m 12.58s , -36d 40m 38.8s) | C | 60 | 19.5 | 72630 | 2025-06-09 06:53:55 | MASTER-OAFA | (19h 31m 17.14s , -36d 39m 51.6s) | C | 60 | 19.4 | 72936 | 2025-06-09 06:59:01 | MASTER-OAFA | (19h 31m 13.69s , -36d 40m 24.0s) | C | 60 | 19.5 | 73250 | 2025-06-09 07:04:15 | MASTER-OAFA | (19h 31m 17.14s , -36d 39m 33.8s) | C | 60 | 19.5 | 73560 | 2025-06-09 07:09:25 | MASTER-OAFA | (19h 31m 14.84s , -36d 40m 20.0s) | C | 60 | 19.5 | 73869 | 2025-06-09 07:14:33 | MASTER-OAFA | (19h 31m 19.03s , -36d 39m 17.2s) | C | 60 | 19.5 | 74177 | 2025-06-09 07:19:42 | MASTER-OAFA | (19h 31m 15.99s , -36d 39m 54.3s) | C | 60 | 19.5 | 74484 | 2025-06-09 07:24:49 | MASTER-OAFA | (19h 31m 20.12s , -36d 39m 02.1s) | C | 60 | 19.5 | 74789 | 2025-06-09 07:29:54 | MASTER-OAFA | (19h 31m 17.04s , -36d 39m 50.7s) | C | 60 | 19.5 | 75093 | 2025-06-09 07:34:58 | MASTER-OAFA | (19h 31m 20.15s , -36d 38m 47.4s) | C | 60 | 19.5 | 75403 | 2025-06-09 07:40:08 | MASTER-OAFA | (19h 31m 18.15s , -36d 39m 38.7s) | C | 60 | 19.5 | 75715 | 2025-06-09 07:45:19 | MASTER-OAFA | (19h 31m 21.22s , -36d 38m 34.1s) | C | 60 | 19.5 | 76022 | 2025-06-09 07:50:27 | MASTER-OAFA | (19h 31m 19.23s , -36d 39m 26.2s) | C | 60 | 19.5 | 122644 | 2025-06-09 20:47:29 | MASTER-Kislovodsk | (18h 44m 38.33s , -28d 52m 41.1s) | C | 60 | 14.9 | 123915 | 2025-06-09 21:08:40 | MASTER-Kislovodsk | (18h 53m 54.00s , -28d 54m 08.0s) | C | 60 | 15.5 | 124398 | 2025-06-09 21:16:43 | MASTER-Kislovodsk | (18h 44m 48.56s , -28d 52m 59.8s) | C | 60 | 15.3 | 125574 | 2025-06-09 21:36:19 | MASTER-Kislovodsk | (18h 54m 02.56s , -28d 52m 50.1s) | C | 60 | 15.5 | 125657 | 2025-06-09 21:37:42 | MASTER-Kislovodsk | (18h 44m 48.28s , -28d 53m 42.7s) | C | 60 | 15.1 | 125992 | 2025-06-09 21:43:17 | MASTER-Kislovodsk | (18h 48m 58.76s , -30d 47m 39.7s) | C | 60 | 15.2 | 126075 | 2025-06-09 21:44:40 | MASTER-Kislovodsk | (18h 58m 21.50s , -30d 46m 20.3s) | C | 60 | 15.3 | 127298 | 2025-06-09 22:05:03 | MASTER-Kislovodsk | (18h 44m 56.79s , -28d 53m 04.2s) | C | 60 | 15.2 | 127533 | 2025-06-09 22:08:58 | MASTER-Kislovodsk | (18h 54m 33.00s , -32d 42m 02.5s) | C | 60 | 15.4 | 127616 | 2025-06-09 22:10:20 | MASTER-Kislovodsk | (18h 49m 06.63s , -30d 47m 59.8s) | C | 60 | 15.4 | 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/40659. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38696] GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40658 SUBJECT: GRB 250609A: Swift/BAT-GUANO localization skymap of a likely short burst DATE: 25/06/09 20:11:32 GMT FROM: Jimmy DeLaunay at Penn State <delauj2(a)gmail.com> James DeLaunay (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (Caltech), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC), Maia Williams (PSU) report: Swift/BAT did not localize GRB 250609A onboard (T0: 2025-06-09T08:47:18.61 UTC, Fermi/GBM trig 771151643) 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 BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 11.0 in a 0.512 s analysis time bin, starting at T0 - 0.256 s. Using the NITRATES analysis, parameter estimation was performed to obtain the localization of this burst in the form of a HEALPIX Multi-Order Coverage (MOC) skymap. This localization accounts for both statistical and systematic errors. More details in the creation and calibration of these maps will soon be published (DeLaunay et al. 2025. in prep) The 90% credible area is 11,145 deg2 and the 50% credible area is 2,851 deg2. The integrated probability inside the coded field of view is 1%. The NITRATES skymap is consistent with the Fermi localization reported in the final position notice (GCN 40652). The combined Fermi/GBM+NITRATES 90% credible area is 1,746 deg2 and the 50% credible area is 417 deg2. A plot of the probability skymap can be viewed here: [skymap_plot](https://guano.swift.psu.edu/trigger_report?id=771151674/#:~:te… The probability skymap and joint skymap files can be downloaded from the links here [skymap_fits_file](https://guano.swift.psu.edu/files/771151674/0_n_PROBMAP) [joint_skymap_fits_file](https://guano.swift.psu.edu/files/771151674/0_n_JOI… Instructions on how to read and manipulate this map can be found here: https://guano.swift.psu.edu/documentation More details about this burst can be found on the trigger report page here: https://guano.swift.psu.edu/trigger_report?id=771151674 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/40658. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38695] GRB 250605A: Swift/UVOT Upper Limits
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40657 SUBJECT: GRB 250605A: Swift/UVOT Upper Limits DATE: 25/06/09 17:13:08 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and R. Gupta (NASA GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250605A 107 s after the BAT trigger (Gupta et al., GCN Circ. 40633). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 40642) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag white_FC 107 251 141 >20.9 white 5225 11166 933 >21.41 v 16403 17310 885 >20.07 b 5020 5220 196 >19.83 u 4815 22332 204 >19.32 uvw1 21418 22318 885 >20.16 uvm2 17315 18088 761 >20.44 uvw2 11173 11858 674 >20.47 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.039 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40657. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38694] The EP-WXT trigger 01709178283 is likely a flaring star
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40656 SUBJECT: The EP-WXT trigger 01709178283 is likely a flaring star DATE: 25/06/09 16:25:39 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. L. Wang (NAO, CAS; ICE, CSIC-IEEC), H. N. Yang (NAO, CAS), Y. F. Liang (PMO, CAS), Z. X. Ling (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709178283 at 2025-06-09 15:02:00 (UTC) is likely a stellar flare associated with RX J1204.6-7731. The estimated flux of the flare is around 5 x 10^-11 erg/s/cm^2 in 0.5-10 keV, corresponding to an X-ray luminosity of around 6 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/40656. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38693] GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40655 SUBJECT: GRB 250608A: SVOM/GRM detection of a possible magnetar X-ray burst DATE: 25/06/09 12:41:07 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 (IRAP), Jean-Luc Atteia (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright short burst GRB 250608A (SVOM trigger reference: sb25060810) at 2025-06-08T10:43:55.350 UTC (T0), which is also detected by Fermi/GBM (TrigNum 771072240). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a narrow spike with a T90 of 0.11 +/-0.01 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250608A.png The SVOM/GRM on-ground localization of this burst is (J2000): RA: 268.6 deg DEC: -23.0 deg Error: 2.2 deg (1sigma, statistical only) We caution that the calibration of SVOM/GRM is undergoing and this localization is subject to systematic errors. In addition, the position of this burst, as determined by GRM, is located at about 11 degrees from the SVOM optical axis. ECLAIRs was not collecting data at the time of this burst. With this localization, the time-averaged spectrum from T0-0.1 to T0+0.2 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.36 +/-0.17 and the cutoff energy, parameterized as Epeak, is 29 +/-3 keV. The event fluence (10-1000 keV) in this time interval is (5.78 +/-0.16)E-05 erg/cm^2. We note that the localization of this burst is relatively close to the Galactic disk, as well as the hardness and duration all suggest a magnetar X-ray burst. 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/40655. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38692] GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt)
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40654 SUBJECT: GRB 250529A: GOTO optical counterpart candidate (GOTO25dea/AT 2025ndt) DATE: 25/06/09 11:53:52 GMT FROM: Amit Kumar at Royal Holloway - UoL/ U of Warwick, UK <amitkundu515(a)gmail.com> A. Kumar, D. O’Neill, B. P. Gompertz, G. Ramsay, R. Starling, S. Belkin, 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 optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022; Dyer et al. 2024) in response to the Fermi/GBM detected GRB 250529A (GBM770183181; Fermi GBM Team, GCN 40567). Targeted observations were performed with GOTO-North beginning at 2025-05-29 03:59:57 UT (+0.23h post trigger) and continued through to 2025-05-29 04:49:24 UT (+1.05h 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. 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. Following the refinement of the GRB localisation (Kozyrev et al., GCN 40629), we reviewed our sources consistent with the new IPN annulus. We identify a new transient at RA, Dec = 18.071949, 58.347004 (equivalent to RA = 01:12:17.27 and Dec = +58:20:49.21), contained within the annulus. The source was initially detected with a magnitude of L = 18.76 ± 0.28 mag (+0.90h after the GBM trigger). The second epoch, taken at +1.05h post trigger, shows marginal evidence for fading, with a measured magnitude of L = 19.14 ± 0.12 mag. Observations taken on the following night (t0+25h) yield only a 3-sigma upper limit of L > 19.05 mag. We find no evidence of the source prior to the GRB trigger time in previous GOTO observations, the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021). While the candidate lies close to the Galactic plane (latitude -4.4 degrees) and has only weak evidence for fading, the significant reduction of the localisation area now makes it a much stronger (but still uncertain) afterglow candidate for GRB 250529A. Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and 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/40654. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38691] GRB 250527C: CrAO Optical Upper Limit
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40653 SUBJECT: GRB 250527C: CrAO Optical Upper Limit DATE: 25/06/09 10:19:33 GMT FROM: Nicolai Pankov at HSE, IKI RAS <colinsergesen(a)gmail.com> N. Pankov (HSE, IKI), S. Nazarov (CrAO), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN: We observed the field of GRB 250527C detected by Fermi/GBM (Trigger 770047117) and further localized by Swift/BAT-GUANO (Delaunay et. al, GCN 40563). The field has also been observed by Swift/XRT (Evans, GCN 40564), and Swift/UVOT (Klingler, GCN 40574). Our observations were carried out using the Sintez-Newton 0.36-meter telescope installed at the Crimean Astrophysical Observatory (CrAO). The series of images has taken in the R-filter. We do not detect candidate transients in comparison with USNO-B1.0, and PS1 catalogs in the stacked image of 22*120 sec. Particularly, we were searching for candidates inside localization circles of X-Ray sources provided in (Evans, GCN 40564). The preliminary upper limit is given below: Date UTstart T-T0 Exposure Filter OT Err UL (n*T) (3-sigma) 2025-05-28 23:46:57 1.42390 22*120 R n/d n/d 19.1 The photometry was calibrated using nearby USNO-B1.0 stars (R2 magnitudes) and has not been corrected for the Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40653. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38690] GRB 250609A: Fermi GBM Final Real-time Localization
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40652 SUBJECT: GRB 250609A: Fermi GBM Final Real-time Localization DATE: 25/06/09 08:57:49 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 08:47:18 UT on 9 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250609A (trigger 771151643.61016 / 250609366). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 150.6, Dec = -8.4 (J2000 degrees, equivalent to J2000 10h 02m, -8d 24'), with a statistical uncertainty of 36.2 degrees. The angle from the Fermi LAT boresight is 81.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250609366/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40652. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38689] GRB 250607A: SVOM/GRM observation of a long burst
by GCN Circulars 09 Jun '25

09 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40651 SUBJECT: GRB 250607A: SVOM/GRM observation of a long burst DATE: 25/06/09 03:13:00 GMT FROM: wenlongzhang2018(a)163.com SVOM/GRM team: Wen-Long Zhang, Wen-Jun Tan, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP) report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a long burst GRB 250607A (SVOM trigger reference: sb25060704) at 2025-06-07T14:00:56.000 UTC (T0), which is also detected by Fermi/GBM ( Fermi GBM team., GCN #40648). With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 12.60 +7.20/-5.40 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250607A.png In addition, the position of this burst, as determined by Fermi/GBM (RA = 243.84, Dec = -24.71 , GCN #40648), is located at about 53 degrees from the SVOM optical axis, and outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-5s to T0+5s is best fitted by a power law function. The power law index is -1.82+/-0.08. The event fluence (10-1000 keV) in this time interval is (1.37 +0.15/-0.15)E-06 erg/cm^2. 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-Long Zhang (IHEP)(zhangwl(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/40651. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38688] EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7
by GCN Circulars 08 Jun '25

08 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40650 SUBJECT: EP-WXT trigger 01709178244: confirmation of a stellar flare by BOOTES-5 & BOOTES-7 DATE: 25/06/08 09:27:31 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, A. J. Castro-Tirado, E. J. Fernandez-Garcia, M.D. Caballero-Garcia, S. Guziy, G. Garcia-Segura, R. Sanchez-Ramirez (IAA-CSIC), Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), L. Hernandez-Garcia (Univ. de Valparaiso), M. Gritsevich (Univ. of Helsinki), S. Jeong (ADD, Daejeon), D. Hiriart (IA-UNAM, Ensenada), W. H. Lee (UNAM, Mexico DF), D.-R. Xiong (Yunnan Observatories of CAS), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), on behalf of a larger collaboration, report: Following the detection of trigger 01709178244 by EP-WXT (Hu et al. GCN 40649), both the 0.6m robotic telescopes BOOTES-5/JGU robotic telescope at San Pedro Martir Observatory (Mexico) and BOOTES-7 at San Pedro de Atacama (Chile) responded to the alert on June 8, 5:00 UT (i.e. 1 min after notification and 6.5 min after the detection). Within the reported EP-FXT error circle we find the star Gaia DR3 6730332160799599744 decreasing 1.2 mag in brightness (g filter) and 0.8 mag (r filter) during a 120 min time interval, confirming the EP X-ray trigger due to a stellar flare. We thank the staff at San Pedro de Atacama Celestial Observations and San Pedro Martir Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/40650. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38687] The EP-WXT trigger 01709178244 is likely a flaring star
by GCN Circulars 08 Jun '25

08 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40649 SUBJECT: The EP-WXT trigger 01709178244 is likely a flaring star DATE: 25/06/08 05:41:59 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. F. Hu (PMO, CAS), Q. C. Liu (THU), B. B. Zhang (BNU), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709178244 at the time of 2025-06-08T04:53:30 (UTC), is likely a stellar flare associated with Gaia DR3 6730332160799599744. The estimated flux of the flare is around 1.6 x 10^-10 erg/s/cm^2 in 0.5-4 keV, corresponding to an X-ray luminosity of around 3.3 x 10^32 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/40649. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38686] GRB 250607A: Fermi GBM Final Localization
by GCN Circulars 07 Jun '25

07 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40648 SUBJECT: GRB 250607A: Fermi GBM Final Localization DATE: 25/06/07 15:22:38 GMT FROM: rhamburg(a)usra.edu The Fermi GBM team reports the detection of a likely LONG GRB. "At 14:00:55.64 UT on 07 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250607A (trigger 770997660/250607584). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 243.84, Dec = -24.71 (J2000 degrees, equivalent to J2000 16h 15m, -24d 42'), with a statistical uncertainty of 10.15 degrees. The angle from the Fermi LAT boresight is 90 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250607584/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250607584/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250607584/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/40648. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38685] EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7
by GCN Circulars 07 Jun '25

07 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40647 SUBJECT: EP-WXT trigger 01709178069: confirmation of a stellar flare by BOOTES-6 & BOOTES-7 DATE: 25/06/07 11:28:27 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, A. J. Castro-Tirado, E. J. Fernandez-Garcia, M.D. Caballero-Garcia, S. Guziy, G. Garcia-Segura, R. Sanchez-Ramirez (IAA-CSIC), Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), L. Hernandez-Garcia (Univ. de Valparaiso), M. Gritsevich (Univ. of Helsinki), D.-R. Xiong (Yunnan Observatories of CAS), B.-B. Zhang (Nanjing Univ.) and A. Maury (Space, San Pedro de Atacama), on behalf of a larger collaboration, report: Following the detection of trigger 01709178069 by EP-WXT (Hu et al. GCN 40646), both the 0.6m robotic telescopes BOOTES-6/DPRT 0.6m at Boyden Observatory in Maselspoort (South Africa) and BOOTES-7 at San Pedro de Atacama (Chile) responded to the alert on June 7, 23:45 UT (i.e. 2 min after notification and 7 min after the detection). Within the reported EP-FXT error circle we find the star UCAC4 204-077663 decreasing 0.25 mag in brightness (clear filter) during a 30 min time interval. Subsequent observations using the g filter and starting on June 8, 00:23 we find a decrease in 0.7 mag during a 2 hour time interval, confirming the EP X-ray trigger due to a stellar flare. We thank the staff at San Pedro de Atacama Celestial Observations and Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/40647. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38684] The EP-WXT trigger 01709178069 is likely a flaring star
by GCN Circulars 07 Jun '25

07 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40646 SUBJECT: The EP-WXT trigger 01709178069 is likely a flaring star DATE: 25/06/07 01:58:34 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> D. F. Hu, Y. Wang (PMO, CAS), H. Sun, W. D. Zhang (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709178069 at the time of 2025-06-06T23:38:19 (UTC), is likely a stellar flare associated with UCAC4 204-077663. The estimated flux of the flare is around 8 x 10^-11 erg/s/cm^2 in 0.5-4 keV, corresponding to an X-ray luminosity of around 1.1 x 10^32 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/40646. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38682] GRB 250605A: VT optical upper limit
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40645 SUBJECT: GRB 250605A: VT optical upper limit DATE: 25/06/06 15:40:20 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Z. H. Yao, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT conducted ToO follow-up observations of the GRB 250605A (Gupta et al., GCN 40633, Melandri et al., GCN 40644). The observation started on 2025-06-06T05:02:39 UT in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within the Swift/XRT error box (Evans et al., GCN 40642) and the possible optical candidate reported by Gompertz et al. (GCN 40634). The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 11.28 hour VT_B 59*70 sec >23.6 mag 11.28 hour VT_R 59*70 sec >23.6 mag 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/40645. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38683] GRB 250605A: VT optical upper limit
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40645 SUBJECT: GRB 250605A: VT optical upper limit DATE: 25/06/06 15:40:20 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> L. P. Xin, Y. L. Qiu, H. L. Li, C. Wu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Z. H. Yao, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA) report on behalf of the SVOM/VT team. SVOM/VT conducted ToO follow-up observations of the GRB 250605A (Gupta et al., GCN 40633, Melandri et al., GCN 40644). The observation started on 2025-06-06T05:02:39 UT in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. No uncatalogued sources are detected in single or stacked images within the Swift/XRT error box (Evans et al., GCN 40642) and the possible optical candidate reported by Gompertz et al. (GCN 40634). The 3 sigma limit magnitudes are derived as below: Mid time | Band | Exposure Time | 3 sigma limit magnitude 11.28 hour VT_B 59*70 sec >23.6 mag 11.28 hour VT_R 59*70 sec >23.6 mag 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/40645. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38681] GRB 250605A: Swift-XRT refined Analysis
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40644 SUBJECT: GRB 250605A: Swift-XRT refined Analysis DATE: 25/06/06 11:02:50 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), 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) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 7.0 ks of XRT data for GRB 250605A, from 90 s to 50.2 ks after the trigger. The data comprise 149 s in Windowed Timing (WT) mode (the first 6 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=4.36 (+0.19, -0.15). At T+164 s the decay flattens to an alpha of 3.19 (+0.29, -0.32) before breaking again at T+326 s to a final decay with index alpha=0.79 (+/-0.07). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 2.12 (+0.06, -0.05). The best-fitting absorption column is 2.59 (+0.20, -0.19) x 10^21 cm^-2, in excess of the Galactic value of 4.3 x 10^20 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.10 (+0.13, -0.12) and a best-fitting absorption column of 2.9 (+/-0.5) x 10^21 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (5.5 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.9 (+/-0.5) x 10^21 cm^-2 Galactic foreground: 4.3 x 10^20 cm^-2 Excess significance: 8.7 sigma Photon index: 2.10 (+0.13, -0.12) If the light curve continues to decay with a power-law decay index of 0.79, the count rate at T+24 hours will be 0.085 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 3.0 x 10^-12 (4.7 x 10^-12) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01321323. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40644. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38680] EP/WXT 01709177873: GOTO observations confirm stellar variability
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40643 SUBJECT: EP/WXT 01709177873: GOTO observations confirm stellar variability DATE: 25/06/06 10:10:51 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 optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the EP/WXT alert 01709177873. Targeted observations were performed beginning at 2025-06-05 21:27:07 UT (+2.59 hr post trigger) and continued through to 2025-06-05 23:43:10 UT (+4.86 hr post trigger). Each observation consisted of 4x90 s 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. 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. No new transients associated with the alert were identified, except for one source within the localisation region: RX J1553.0+4457, a low mass star + white binary at RA = 15:53:04.8, Dec = +44:57:44.6. This source exhibited significant variability, brightening by ~0.6 mag relative to the last pre-trigger image taken on 2025-05-30 at 00:18:22 UT (6.77 days pre-trigger), reaching 13.70 ± 0.01 mag in the first post-trigger image at 2025-06-05 21:27:07 UT (+2.59 hr). It then faded to 14.10  ±  0.01 mag by the final observation at 2025-06-05 23:43:10 UT (+4.86 hr post-trigger). All the reported magnitudes are in the GOTO L-band and the AB system. 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/40643. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38679] GRB 250605A: Enhanced Swift-XRT position
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40642 SUBJECT: GRB 250605A: Enhanced Swift-XRT position DATE: 25/06/06 08:44:00 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) report on behalf of the Swift-XRT team. Using 3740 s of XRT Photon Counting mode data and 7 UVOT images for GRB 250605A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 166.95715, -19.78841 which is equivalent to: RA (J2000): 11h 07m 49.72s Dec (J2000): -19d 47' 18.3" with an uncertainty of 2.0 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40642. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38678] Fermi GRB 250606A: Global MASTER-Net observations report
by GCN Circulars 06 Jun '25

06 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40641 SUBJECT: Fermi GRB 250606A: Global MASTER-Net observations report DATE: 25/06/06 06:31:54 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 250606A ( Fermi GBM team, GCN 40640) errorbox 91 sec after trigger time at 2025-06-06 04:30:12 UT, with upper limit up to 19.3 mag. Observations started at twilight. The observations began at zenith distance = 50 deg. The sun altitude is -13.2 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 250606A errorbox 133 sec after trigger time at 2025-06-06 04:30:55 UT, with upper limit up to 19.0 mag. The observations began at zenith distance = 69 deg. The sun altitude is -81.6 deg. The galactic latitude b = -38 deg., longitude l = 298 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2894070 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 101 | 2025-06-06 04:30:12 | MASTER-SAAO | (02h 08m 41.74s , -77d 25m 10.8s) | C | 20 | 18.5 | 136 | 2025-06-06 04:30:12 | MASTER-SAAO | (02h 08m 41.71s , -77d 25m 10.8s) | C | 90 | 19.3 | Coadd 101 | 2025-06-06 04:30:12 | MASTER-SAAO | (02h 17m 05.10s , -77d 40m 08.2s) | C | 20 | 18.4 | 136 | 2025-06-06 04:30:12 | MASTER-SAAO | (02h 17m 05.14s , -77d 40m 08.2s) | C | 90 | 19.2 | Coadd 145 | 2025-06-06 04:30:51 | MASTER-SAAO | (02h 08m 41.54s , -77d 25m 10.8s) | C | 30 | 18.7 | 145 | 2025-06-06 04:30:51 | MASTER-SAAO | (02h 17m 04.94s , -77d 40m 08.4s) | C | 30 | 18.6 | 149 | 2025-06-06 04:30:55 | MASTER-OAFA | (02h 17m 57.07s , -77d 44m 13.6s) | C | 30 | 16.1 | 185 | 2025-06-06 04:31:31 | MASTER-OAFA | (02h 17m 56.58s , -77d 44m 12.6s) | C | 30 | 15.8 | 199 | 2025-06-06 04:31:40 | MASTER-SAAO | (02h 08m 41.15s , -77d 25m 10.8s) | C | 40 | 18.9 | 199 | 2025-06-06 04:31:40 | MASTER-SAAO | (02h 17m 04.63s , -77d 40m 08.5s) | C | 40 | 18.8 | 226 | 2025-06-06 04:32:07 | MASTER-OAFA | (02h 17m 56.05s , -77d 44m 11.8s) | C | 40 | 16.1 | 263 | 2025-06-06 04:32:40 | MASTER-SAAO | (02h 08m 40.59s , -77d 25m 10.4s) | C | 50 | 18.9 | 263 | 2025-06-06 04:32:40 | MASTER-SAAO | (02h 17m 04.32s , -77d 40m 08.4s) | C | 50 | 18.8 | 277 | 2025-06-06 04:32:53 | MASTER-OAFA | (02h 17m 55.51s , -77d 44m 10.8s) | C | 50 | 17.0 | 337 | 2025-06-06 04:33:48 | MASTER-SAAO | (02h 08m 40.02s , -77d 25m 10.1s) | C | 60 | 18.9 | 337 | 2025-06-06 04:33:48 | MASTER-SAAO | (02h 17m 03.91s , -77d 40m 08.3s) | C | 60 | 18.8 | 376 | 2025-06-06 04:34:22 | MASTER-OAFA | (02h 17m 54.36s , -77d 44m 09.3s) | C | 70 | 16.6 | 457 | 2025-06-06 04:35:38 | MASTER-OAFA | (02h 17m 53.34s , -77d 44m 08.1s) | C | 80 | 16.0 | 552 | 2025-06-06 04:37:04 | MASTER-OAFA | (02h 17m 52.34s , -77d 44m 06.6s) | C | 100 | 17.2 | 633 | 2025-06-06 04:38:44 | MASTER-SAAO | (02h 01m 01.33s , -78d 21m 33.4s) | C | 60 | 18.4 | 693 | 2025-06-06 04:38:44 | MASTER-SAAO | (02h 01m 01.32s , -78d 21m 33.4s) | C | 180 | 18.9 | Coadd 633 | 2025-06-06 04:38:44 | MASTER-SAAO | (02h 10m 05.68s , -78d 36m 27.8s) | C | 60 | 18.2 | 693 | 2025-06-06 04:38:44 | MASTER-SAAO | (02h 10m 05.70s , -78d 36m 27.8s) | C | 180 | 18.9 | Coadd 702 | 2025-06-06 04:39:19 | MASTER-OAFA | (02h 10m 51.22s , -78d 38m 24.3s) | C | 130 | 17.1 | 712 | 2025-06-06 04:40:03 | MASTER-SAAO | (02h 01m 00.54s , -78d 21m 33.2s) | C | 60 | 18.2 | 712 | 2025-06-06 04:40:03 | MASTER-SAAO | (02h 10m 05.03s , -78d 36m 27.9s) | C | 60 | 18.1 | 791 | 2025-06-06 04:41:22 | MASTER-SAAO | (02h 00m 59.70s , -78d 21m 32.7s) | C | 60 | 18.1 | 791 | 2025-06-06 04:41:22 | MASTER-SAAO | (02h 10m 04.49s , -78d 36m 27.5s) | C | 60 | 17.9 | 849 | 2025-06-06 04:41:35 | MASTER-OAFA | (02h 10m 49.35s , -78d 38m 22.1s) | C | 150 | 17.0 | 870 | 2025-06-06 04:42:41 | MASTER-SAAO | (02h 00m 58.99s , -78d 21m 32.4s) | C | 60 | 17.8 | 870 | 2025-06-06 04:42:41 | MASTER-SAAO | (02h 10m 03.94s , -78d 36m 27.3s) | C | 60 | 17.8 | 1020 | 2025-06-06 04:44:12 | MASTER-OAFA | (02h 10m 47.45s , -78d 38m 19.3s) | C | 180 | 17.4 | 1206 | 2025-06-06 04:47:18 | MASTER-OAFA | (02h 10m 44.99s , -78d 38m 15.8s) | C | 180 | 14.2 | 3930 | 2025-06-06 05:32:42 | MASTER-OAFA | (02h 02m 27.41s , -77d 24m 58.8s) | C | 180 | 18.4 | 4117 | 2025-06-06 05:35:48 | MASTER-OAFA | (02h 02m 25.46s , -77d 24m 53.1s) | C | 180 | 18.4 | 4304 | 2025-06-06 05:38:55 | MASTER-OAFA | (02h 02m 23.74s , -77d 24m 48.4s) | C | 180 | 19.0 | 4490 | 2025-06-06 05:42:01 | MASTER-OAFA | (02h 02m 21.86s , -77d 24m 43.4s) | C | 180 | 18.9 | 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/40641. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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