June 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 42963] GRB 260604C: Jinshan optical observations
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44832 SUBJECT: GRB 260604C: Jinshan optical observations DATE: 26/06/05 02:52:57 GMT FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn> Z.P. Zhu, X. Liu, D. Xu, J. An,S.Q. Jiang, L.B. He (NAOC), S.Y. Fu, A.D. Zhu, L. Lei (HUST), J.Z. Liu (XAO) report: We observed the field of GRB260604C detected by Fermi-GBM (Fermi GBM team, GCN 44822) and SVOM (Gotz et al, GCN 44823), using the JinShan 100B telescope located at Altay, Xinjiang, China. Observation started at 2026-06-04T20:32:14 UT, i.e., about 13 min post-burst, and a series of r-band frames were obtained. The previously reported optical counterpart (Lipunov et al, GCN 44827; Konno et al, GCN 44828) is detected in our first single frame with a brightness of R = 16.1 +/- 0.1, calibrated with Pan-STARRS DR2 stars in the field and not corrected for Galactic extinction. We acknowledge the excellent support from T.Q. Chen, and J.F. Zhang for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/44832. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42962] GRB 260604C: Fermi GBM Observation
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44831 SUBJECT: GRB 260604C: Fermi GBM Observation DATE: 26/06/05 02:49:32 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 20:18:44.41 UT on 04 June 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260604C (trigger 802297129/260604846), which was also detected by SVOM ECLAIRs (Gotz et al. 2026, GCN 44823), MASTER (Lipunov et al. 2026, GCN 44827), and LAST (Konno et al. 2026, GCN 44828). The Fermi GBM on-ground location is consistent with the SVOM ECLAIRs position. The angle from the Fermi LAT boresight is 102 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 6.4 s (50-300 keV). The time-averaged spectrum from T0-2.2 to T0+12.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.03 +/- 0.01 and the cutoff energy, parameterized as Epeak, is 551 +/- 2 keV. The event fluence (10-1000 keV) in this time interval is (2.55 +/- 0.05)E-05 erg/cm^2. The 1-sec peak photon flux measured starting from T0+4.5 s in the 10-1000 keV band is 44.1 +/- 0.6 ph/s/cm^2. A Band function fits the spectrum equally well with Epeak= 394 +/- 3 keV, alpha = -0.95 +/- 0.01 and beta = -2 +/- 0.03. 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/44831. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42961] EP260602d: J-band upper limit with WINTER
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44830 SUBJECT: EP260602d: J-band upper limit with WINTER DATE: 26/06/05 01:19:18 GMT FROM: Geoffrey Mo at Caltech / Carnegie Observatories <gmo(a)mit.edu> Tanishk Mohan (IITB), Geoffrey Mo (Caltech/Carnegie), Tomas Ahumada (NOIRLab), Benjamin Schneider (LAM), Robert Stein (UMD), Viraj Karambelkar (Columbia), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of EP260602d (Cao et al., GCN 44796) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations began at 2026-06-03T08:06:13 UTC in the J band (10.88 hr after the EP trigger), consisting of 15*120 sec exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565) We do not detect any new source in the WXT localization (Aryan et al., GCN 44813; Cao et al., GCN 44796) after image subtraction performed relative to J-band images from the UKIRT Hemisphere survey (Dye et al., 2017). We obtain the following 5-sigma upper limit: J = 19.4 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/44830. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42960] EP260602b: J-band upper limit with WINTER
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44829 SUBJECT: EP260602b: J-band upper limit with WINTER DATE: 26/06/05 01:18:25 GMT FROM: Geoffrey Mo at Caltech / Carnegie Observatories <gmo(a)mit.edu> Tanishk Mohan (IITB), Geoffrey Mo (Caltech/Carnegie), Tomas Ahumada (NOIRLab), Benjamin Schneider (LAM), Robert Stein (UMD), Viraj Karambelkar (Columbia), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of EP260602b (Wu et al., GCN 44786; Wu et al., GCN 44802) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations began at 2026-06-03T04:53:16 UTC in the J band (~11 hr after the EP trigger), consisting of 15*120 sec exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565) We do not detect a source at the optical counterpart location (He et al., GCN 44780; Eyles-Ferris et al., GCN 44809; Bochenek et al., GCN 44811). We obtain the following 5-sigma upper limit: J = 19.1 mag (AB). WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research. View this GCN Circular online at https://gcn.nasa.gov/circulars/44829. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42959] GRB 260604C: LAST detection of optical counterpart candidate
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44828 SUBJECT: GRB 260604C: LAST detection of optical counterpart candidate DATE: 26/06/04 23:52:38 GMT FROM: Ruslan Konno at Weizmann Institute of Science <ruslankonno(a)gmail.com> R. Konno (WIS), S. Garrappa (WIS), E. A. Zimmerman (WIS), A. Horowicz (WIS), E. O. Ofek (WIS), S. Ben-Ami (WIS), D. Polishook (WIS), O. Yaron (WIS), S. Fainer (WIS), A. Krassilchtchikov (WIS), Y. M. Shani (WIS), E. Segre (WIS), A. Gal-Yam (WIS), and S. Spitzer (WIS) report on behalf of the LAST Collaboration. We report observations of GRB 260604C, detected by Fermi-GBM (Fermi GBM team, GCN 44822) and SVOM (Gotz et al, GCN 44823). Observations were conducted with the Large Array Survey Telescope (LAST; Ofek et al. 2023, PASP 135, 5001; Ben-Ami et al. 2023, PASP 135, 5002). Observations of GRB 260604C were taken over 4 sequential epochs in clear band (similar to the Gaia Bp band). The first epoch began at 2026-06-04 20:35:04 UTC (T-T0 = 0.275 h). Each epoch consists of 20x20s exposures per telescope. We detect one credible optical transient within the field reported by SVOM (Gotz et al, GCN 44823) consistent with the position of AT 2026ofi (TNS Report No. 307026) reported by MASTER (Lipunov et al, GCN 44827). The transient is well detected within each epoch and shows a rapid decay, consistent with afterglow emission. | Tmid-T0 (h) | Mag (AB) | | ------------ | ----------- | | 0.33 | 17.12 | | 0.45 | 16.85 | | 0.57 | 16.63 | | 0.75 | 16.42 | Previous observations of the field yield no detections on the source positions up to 2026-06-01 20:46:47 UTC (T0-T = 3d) with a 5-sigma limiting magnitude of 20.15 (AB). We encourage further follow-up observations. LAST is a survey telescope array of the Weizmann Astrophysical Observatory (https://www.weizmann.ac.il/wao/) View this GCN Circular online at https://gcn.nasa.gov/circulars/44828. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42958] GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44827 SUBJECT: GRB 260604C: MASTER OT J145749.59+284903.0 optical counterpart discovery DATE: 26/06/04 22:45:21 GMT FROM: Vladimir Lipunov at Lomonosov Moscow State University <lipunov(a)sai.msu.ru> MASTER OT J145749.59+284903.0 discovery MASTER-Tavrida auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 14h 57m 49.59s +28d 49m 03.0s on 2026-06-04.86020 UT. The OT magnitude (unfiltered) is 17.5m at04.86020UT (mlim=19.4). The OT is seen in 14 images. There is no minor planet at this place. We have reference image on 2020-09-17.71399 UT with unfiltered mlim= 18.1m. Spectral observations are required. View this GCN Circular online at https://gcn.nasa.gov/circulars/44827. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42957] Fermi GRB 260604C: Global MASTER-Net observations report
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44826 SUBJECT: Fermi GRB 260604C: Global MASTER-Net observations report DATE: 26/06/04 21:20:24 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko, G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU), O.Gress, N.Budnev (ISU), M. Segura, 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-Tavrida robotic telescope [1] located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 260604C ( Fermi GBM team, GCN 44822) errorbox 68 sec after notice time and 121 sec after trigger time at 2026-06-04 20:20:45 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 13 deg. The sun altitude is -20.4 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260604C errorbox 2607 sec after notice time and 2660 sec after trigger time at 2026-06-04 21:03:04 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 28 deg. The sun altitude is -23.8 deg. The galactic latitude b = 65 deg., longitude l = 54 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3361051 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 132 | 2026-06-04 20:20:45 | MASTER-Tavrida | (14h 45m 39.13s , +34d 23m 10.1s) | C | 20 | 18.2 | 159 | 2026-06-04 20:21:08 | MASTER-Tavrida | (14h 45m 39.22s , +34d 23m 08.2s) | C | 30 | 18.5 | 201 | 2026-06-04 20:21:45 | MASTER-Tavrida | (14h 45m 39.31s , +34d 23m 05.7s) | C | 40 | 18.7 | 244 | 2026-06-04 20:22:28 | MASTER-Tavrida | (14h 45m 39.40s , +34d 23m 03.5s) | C | 40 | 18.7 | 292 | 2026-06-04 20:23:11 | MASTER-Tavrida | (14h 45m 39.48s , +34d 23m 00.9s) | C | 50 | 18.9 | 351 | 2026-06-04 20:24:05 | MASTER-Tavrida | (14h 45m 39.57s , +34d 22m 58.3s) | C | 60 | 19.0 | 424 | 2026-06-04 20:25:08 | MASTER-Tavrida | (14h 45m 39.70s , +34d 22m 55.4s) | C | 80 | 19.9 | 512 | 2026-06-04 20:26:31 | MASTER-Tavrida | (14h 45m 39.83s , +34d 22m 52.2s) | C | 90 | 18.1 | 616 | 2026-06-04 20:28:05 | MASTER-Tavrida | (14h 45m 39.93s , +34d 22m 49.5s) | C | 110 | 18.8 | 753 | 2026-06-04 20:30:17 | MASTER-Tavrida | (14h 41m 46.90s , +33d 53m 19.6s) | C | 120 | 19.3 | 2690 | 2026-06-04 21:03:04 | MASTER-Kislovodsk | (14h 31m 34.56s , +34d 00m 31.5s) | C | 60 | 18.4 | 2780 | 2026-06-04 21:04:34 | MASTER-Kislovodsk | (14h 41m 05.21s , +33d 59m 44.5s) | C | 60 | 18.5 | 2868 | 2026-06-04 21:06:02 | MASTER-Kislovodsk | (14h 36m 52.22s , +35d 55m 19.9s) | C | 60 | 18.3 | 2957 | 2026-06-04 21:07:31 | MASTER-Kislovodsk | (14h 46m 41.72s , +35d 54m 08.3s) | C | 60 | 18.4 | 3046 | 2026-06-04 21:09:00 | MASTER-Kislovodsk | (14h 45m 53.08s , +34d 00m 34.0s) | C | 60 | 18.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/44826. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42956] Fermi GRB 260604C: Global MASTER-Net observations report
by GCN Circulars 05 Jun '26

05 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44825 SUBJECT: Fermi GRB 260604C: Global MASTER-Net observations report DATE: 26/06/04 21:18:02 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), M. Segura, 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-Tavrida robotic telescope [1] located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 260604C ( Fermi GBM team, GCN 44822) errorbox 68 sec after notice time and 121 sec after trigger time at 2026-06-04 20:20:45 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 13 deg. The sun altitude is -20.4 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260604C errorbox 2607 sec after notice time and 2660 sec after trigger time at 2026-06-04 21:03:04 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 28 deg. The sun altitude is -23.8 deg. The galactic latitude b = 65 deg., longitude l = 54 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3361051 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 132 | 2026-06-04 20:20:45 | MASTER-Tavrida | (14h 45m 39.13s , +34d 23m 10.1s) | C | 20 | 18.2 | 159 | 2026-06-04 20:21:08 | MASTER-Tavrida | (14h 45m 39.22s , +34d 23m 08.2s) | C | 30 | 18.5 | 201 | 2026-06-04 20:21:45 | MASTER-Tavrida | (14h 45m 39.31s , +34d 23m 05.7s) | C | 40 | 18.7 | 244 | 2026-06-04 20:22:28 | MASTER-Tavrida | (14h 45m 39.40s , +34d 23m 03.5s) | C | 40 | 18.7 | 292 | 2026-06-04 20:23:11 | MASTER-Tavrida | (14h 45m 39.48s , +34d 23m 00.9s) | C | 50 | 18.9 | 351 | 2026-06-04 20:24:05 | MASTER-Tavrida | (14h 45m 39.57s , +34d 22m 58.3s) | C | 60 | 19.0 | 424 | 2026-06-04 20:25:08 | MASTER-Tavrida | (14h 45m 39.70s , +34d 22m 55.4s) | C | 80 | 19.9 | 512 | 2026-06-04 20:26:31 | MASTER-Tavrida | (14h 45m 39.83s , +34d 22m 52.2s) | C | 90 | 18.1 | 616 | 2026-06-04 20:28:05 | MASTER-Tavrida | (14h 45m 39.93s , +34d 22m 49.5s) | C | 110 | 18.8 | 753 | 2026-06-04 20:30:17 | MASTER-Tavrida | (14h 41m 46.90s , +33d 53m 19.6s) | C | 120 | 19.3 | 2690 | 2026-06-04 21:03:04 | MASTER-Kislovodsk | (14h 31m 34.56s , +34d 00m 31.5s) | C | 60 | 18.4 | 2780 | 2026-06-04 21:04:34 | MASTER-Kislovodsk | (14h 41m 05.21s , +33d 59m 44.5s) | C | 60 | 18.5 | 2868 | 2026-06-04 21:06:02 | MASTER-Kislovodsk | (14h 36m 52.22s , +35d 55m 19.9s) | C | 60 | 18.3 | 2957 | 2026-06-04 21:07:31 | MASTER-Kislovodsk | (14h 46m 41.72s , +35d 54m 08.3s) | C | 60 | 18.4 | 3046 | 2026-06-04 21:09:00 | MASTER-Kislovodsk | (14h 45m 53.08s , +34d 00m 34.0s) | C | 60 | 18.5 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/44825. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42955] SVOM GRB260604.85: Global MASTER-Net observations report
by GCN Circulars 04 Jun '26

04 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44824 SUBJECT: SVOM GRB260604.85: Global MASTER-Net observations report DATE: 26/06/04 20:48:54 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), M. Segura, 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-Tavrida robotic telescope [1] located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the SVOM GRB260604.85 (trigger No 1780604437,14h 57m 12.77s , +28d 36m 26.6s, R=0.1738) errorbox 43 sec after notice time and 713 sec after trigger time at 2026-06-04 20:32:30 UT, with upper limit up to 19.4 mag. The observations began at zenith distance = 18 deg. The sun altitude is -21.0 deg. The galactic latitude b = 62 deg., longitude l = 43 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3361056 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 774 | 2026-06-04 20:32:30 | MASTER-Tavrida | (14h 57m 09.62s , +29d 05m 58.4s) | C | 120 | 19.4 | 897 | 2026-06-04 20:34:33 | MASTER-Tavrida | (14h 57m 09.73s , +29d 05m 54.0s) | C | 120 | 19.4 | 1019 | 2026-06-04 20:36:36 | MASTER-Tavrida | (14h 57m 09.83s , +29d 05m 50.2s) | C | 120 | 19.4 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. [1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp. http : // www.pereplet.ru/lipunov/625.html View this GCN Circular online at https://gcn.nasa.gov/circulars/44824. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42954] GRB 260604C: SVOM detection of a long burst
by GCN Circulars 04 Jun '26

04 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44823 SUBJECT: GRB 260604C: SVOM detection of a long burst DATE: 26/06/04 20:43:09 GMT FROM: Diego Gotz at CEA <diego.gotz(a)cea.fr> D. Gotz, D. Adrien, N. Dagoneau, S. Bisero (CEA Saclay) report on behalf of the SVOM mission team: At 2026-06-04T20:21:59 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260604C (SVOM burst-id sb26060404). 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 4 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 8.23 in the [5-20] keV energy band over a time window of 163.84 seconds starting at 2026-06-04T20:19:56 UTC. The localization of the best alert is R.A., Dec. 224.3461, 28.6558 degrees: R.A. (J2000) = 14h57m23s Dec. (J2000) = 28d39m20s with a 90% confidence level (C.L.) radius of 9.6 arcmin (including systematic error of 2 arcmin added in quadrature). This position is compatible with the GRB detected by Fermi/GBM GCN 44822 . SVOM slewed to the burst position. No X-ray observation could be performed by SVOM/MXT for the time being. Optical observations by VT will be published in a further circular. The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Sofia Bisero: sofia.bisero(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/44823. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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