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

[vsnet-grb-info 42913] Fermi GRB 260602B: Global MASTER-Net observations report
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44783 SUBJECT: Fermi GRB 260602B: Global MASTER-Net observations report DATE: 26/06/03 03:32:58 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-OAFA robotic telescope [1] located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 260602B ( Fermi GBM team, GCN 44779) errorbox 9521 sec after notice time and 9563 sec after trigger time at 2026-06-03 01:20:54 UT, with upper limit up to 20.0 mag. The observations began at zenith distance = 23 deg. The sun altitude is -46.3 deg. MASTER-OAGH robotic telescope located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) started inspect of the Fermi GRB 260602B errorbox 16498 sec after notice time and 16540 sec after trigger time at 2026-06-03 03:17:11 UT, with upper limit up to 17.3 mag. Observations started at twilight. The observations began at zenith distance = 45 deg. The sun altitude is -11.4 deg. The galactic latitude b = 46 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=3356506 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9594 | 2026-06-03 01:20:54 | MASTER-OAFA | (12h 27m 05.82s , -13d 47m 16.2s) | C | 60 | 19.1 | 9654 | 2026-06-03 01:20:54 | MASTER-OAFA | (12h 27m 05.83s , -13d 47m 16.2s) | C | 180 | 19.4 | Coadd 9670 | 2026-06-03 01:22:10 | MASTER-OAFA | (12h 35m 13.14s , -13d 48m 26.4s) | C | 60 | 18.9 | 9730 | 2026-06-03 01:22:10 | MASTER-OAFA | (12h 35m 13.13s , -13d 48m 26.4s) | C | 180 | 19.2 | Coadd 9750 | 2026-06-03 01:23:31 | MASTER-OAFA | (12h 27m 05.16s , -13d 47m 57.0s) | C | 60 | 19.0 | 9828 | 2026-06-03 01:24:48 | MASTER-OAFA | (12h 35m 17.15s , -13d 46m 53.5s) | C | 60 | 18.8 | 9903 | 2026-06-03 01:26:04 | MASTER-OAFA | (12h 27m 02.72s , -13d 48m 07.0s) | C | 60 | 18.7 | 9985 | 2026-06-03 01:27:26 | MASTER-OAFA | (12h 26m 59.87s , -13d 47m 08.8s) | C | 60 | 18.5 | 10045 | 2026-06-03 01:27:26 | MASTER-OAFA | (12h 26m 59.86s , -13d 47m 08.8s) | C | 180 | 19.1 | Coadd 10078 | 2026-06-03 01:28:59 | MASTER-OAFA | (12h 35m 14.02s , -13d 46m 18.6s) | C | 60 | 18.5 | 10154 | 2026-06-03 01:30:15 | MASTER-OAFA | (12h 27m 05.70s , -13d 47m 05.8s) | C | 60 | 18.5 | 10235 | 2026-06-03 01:31:36 | MASTER-OAFA | (12h 35m 14.80s , -13d 48m 15.9s) | C | 60 | 18.6 | 10295 | 2026-06-03 01:31:36 | MASTER-OAFA | (12h 35m 14.79s , -13d 48m 15.9s) | C | 180 | 19.6 | Coadd 10312 | 2026-06-03 01:32:53 | MASTER-OAFA | (12h 27m 05.42s , -13d 48m 01.8s) | C | 60 | 18.8 | 10390 | 2026-06-03 01:34:10 | MASTER-OAFA | (12h 25m 20.90s , -17d 35m 31.1s) | C | 60 | 18.9 | 10450 | 2026-06-03 01:34:10 | MASTER-OAFA | (12h 25m 20.90s , -17d 35m 31.1s) | C | 180 | 19.6 | Coadd 10467 | 2026-06-03 01:35:27 | MASTER-OAFA | (12h 33m 47.10s , -17d 34m 19.6s) | C | 60 | 18.7 | 10527 | 2026-06-03 01:35:27 | MASTER-OAFA | (12h 33m 47.11s , -17d 34m 19.6s) | C | 180 | 19.2 | Coadd 10547 | 2026-06-03 01:36:48 | MASTER-OAFA | (12h 33m 40.74s , -17d 34m 01.3s) | C | 60 | 18.1 | 10613 | 2026-06-03 01:37:54 | MASTER-OAFA | (12h 33m 40.67s , -17d 34m 00.6s) | C | 60 | 18.8 | 10684 | 2026-06-03 01:39:05 | MASTER-OAFA | (12h 25m 23.88s , -17d 34m 49.3s) | C | 60 | 19.0 | 10772 | 2026-06-03 01:40:33 | MASTER-OAFA | (12h 25m 23.93s , -17d 35m 34.0s) | C | 60 | 19.0 | 10848 | 2026-06-03 01:41:49 | MASTER-OAFA | (12h 33m 44.40s , -17d 34m 11.7s) | C | 60 | 18.7 | 10908 | 2026-06-03 01:41:49 | MASTER-OAFA | (12h 33m 44.40s , -17d 34m 11.7s) | C | 180 | 19.5 | Coadd 10925 | 2026-06-03 01:43:05 | MASTER-OAFA | (12h 25m 21.11s , -17d 35m 36.9s) | C | 60 | 18.5 | 11002 | 2026-06-03 01:44:23 | MASTER-OAFA | (12h 33m 48.05s , -17d 34m 23.8s) | C | 60 | 18.8 | 11098 | 2026-06-03 01:45:59 | MASTER-OAFA | (12h 25m 17.61s , -17d 34m 43.3s) | C | 60 | 18.8 | 11175 | 2026-06-03 01:47:16 | MASTER-OAFA | (12h 33m 50.32s , -19d 28m 49.0s) | C | 60 | 18.6 | 11235 | 2026-06-03 01:47:16 | MASTER-OAFA | (12h 33m 50.32s , -19d 28m 49.0s) | C | 180 | 19.1 | Coadd 11279 | 2026-06-03 01:49:00 | MASTER-OAFA | (12h 33m 50.36s , -19d 29m 26.5s) | C | 60 | 18.6 | 11356 | 2026-06-03 01:50:17 | MASTER-OAFA | (12h 42m 16.13s , -19d 28m 13.0s) | C | 60 | 19.0 | 11416 | 2026-06-03 01:50:17 | MASTER-OAFA | (12h 42m 16.13s , -19d 28m 13.0s) | C | 180 | 19.8 | Coadd 11432 | 2026-06-03 01:51:33 | MASTER-OAFA | (12h 33m 47.20s , -19d 29m 21.2s) | C | 60 | 18.2 | 11498 | 2026-06-03 01:52:39 | MASTER-OAFA | (12h 57m 10.66s , -17d 35m 20.6s) | C | 60 | 18.8 | 11558 | 2026-06-03 01:52:39 | MASTER-OAFA | (12h 57m 10.66s , -17d 35m 20.6s) | C | 180 | 19.7 | Coadd 12298 | 2026-06-03 02:05:59 | MASTER-OAFA | (13h 05m 37.50s , -17d 36m 14.8s) | C | 60 | 19.4 | 12358 | 2026-06-03 02:05:59 | MASTER-OAFA | (13h 05m 37.50s , -17d 36m 14.8s) | C | 180 | 19.8 | Coadd 12375 | 2026-06-03 02:07:16 | MASTER-OAFA | (12h 57m 18.25s , -17d 34m 48.1s) | C | 60 | 19.1 | 12453 | 2026-06-03 02:08:34 | MASTER-OAFA | (13h 05m 34.06s , -17d 35m 30.3s) | C | 60 | 19.1 | 12529 | 2026-06-03 02:09:50 | MASTER-OAFA | (12h 57m 11.85s , -17d 34m 15.1s) | C | 60 | 19.5 | 12607 | 2026-06-03 02:11:08 | MASTER-OAFA | (12h 35m 21.57s , -13d 46m 50.3s) | C | 60 | 19.5 | 12691 | 2026-06-03 02:12:32 | MASTER-OAFA | (12h 35m 17.62s , -13d 47m 19.1s) | C | 60 | 19.5 | 12783 | 2026-06-03 02:14:03 | MASTER-OAFA | (12h 33m 41.62s , -17d 35m 40.6s) | C | 60 | 19.5 | 12860 | 2026-06-03 02:15:20 | MASTER-OAFA | (12h 33m 48.15s , -17d 35m 16.2s) | C | 60 | 19.6 | 12920 | 2026-06-03 02:15:20 | MASTER-OAFA | (12h 33m 48.15s , -17d 35m 16.2s) | C | 180 | 20.0 | Coadd 12943 | 2026-06-03 02:16:44 | MASTER-OAFA | (12h 33m 44.94s , -17d 33m 47.4s) | C | 60 | 19.6 | 13038 | 2026-06-03 02:18:18 | MASTER-OAFA | (12h 33m 48.58s , -17d 33m 59.3s) | C | 60 | 19.3 | 13114 | 2026-06-03 02:19:34 | MASTER-OAFA | (12h 33m 41.07s , -17d 34m 36.6s) | C | 60 | 19.3 | 13193 | 2026-06-03 02:20:54 | MASTER-OAFA | (12h 33m 41.82s , -17d 33m 35.9s) | C | 60 | 19.4 | 13272 | 2026-06-03 02:22:13 | MASTER-OAFA | (12h 42m 13.61s , -19d 29m 40.3s) | C | 60 | 19.1 | 13351 | 2026-06-03 02:23:32 | MASTER-OAFA | (12h 42m 20.13s , -19d 29m 30.9s) | C | 60 | 19.2 | 13427 | 2026-06-03 02:24:48 | MASTER-OAFA | (12h 42m 16.91s , -19d 28m 04.8s) | C | 60 | 19.2 | 13503 | 2026-06-03 02:26:04 | MASTER-OAFA | (12h 33m 47.96s , -19d 29m 08.3s) | C | 60 | 19.5 | 13580 | 2026-06-03 02:27:20 | MASTER-OAFA | (12h 33m 50.86s , -19d 27m 42.5s) | C | 60 | 19.4 | 13680 | 2026-06-03 02:29:00 | MASTER-OAFA | (12h 35m 28.54s , -21d 21m 26.8s) | C | 60 | 19.6 | 13755 | 2026-06-03 02:30:16 | MASTER-OAFA | (12h 35m 36.14s , -21d 22m 26.3s) | C | 60 | 19.4 | 13839 | 2026-06-03 02:31:40 | MASTER-OAFA | (12h 49m 32.63s , -15d 39m 55.0s) | C | 60 | 19.4 | 13930 | 2026-06-03 02:33:11 | MASTER-OAFA | (12h 57m 44.22s , -15d 40m 57.7s) | C | 60 | 19.4 | 13990 | 2026-06-03 02:33:11 | MASTER-OAFA | (12h 57m 44.22s , -15d 40m 57.8s) | C | 180 | 19.8 | Coadd 14009 | 2026-06-03 02:34:30 | MASTER-OAFA | (12h 57m 51.10s , -15d 40m 56.7s) | C | 60 | 19.3 | 14092 | 2026-06-03 02:35:53 | MASTER-OAFA | (12h 57m 48.25s , -15d 40m 23.1s) | C | 60 | 19.5 | 14179 | 2026-06-03 02:37:19 | MASTER-OAFA | (12h 57m 48.26s , -15d 41m 48.9s) | C | 60 | 19.3 | 14261 | 2026-06-03 02:38:42 | MASTER-OAFA | (13h 05m 40.78s , -17d 34m 19.7s) | C | 60 | 19.5 | 14333 | 2026-06-03 02:39:54 | MASTER-OAFA | (13h 05m 35.77s , -17d 35m 00.3s) | C | 60 | 19.4 | 14415 | 2026-06-03 02:41:16 | MASTER-OAFA | (13h 05m 42.30s , -17d 34m 59.5s) | C | 60 | 18.8 | 14494 | 2026-06-03 02:42:35 | MASTER-OAFA | (12h 57m 12.14s , -17d 35m 48.3s) | C | 60 | 19.4 | 14554 | 2026-06-03 02:42:35 | MASTER-OAFA | (12h 57m 12.14s , -17d 35m 48.3s) | C | 180 | 19.9 | Coadd 14573 | 2026-06-03 02:43:54 | MASTER-OAFA | (12h 57m 18.62s , -17d 35m 22.0s) | C | 60 | 19.4 | 14648 | 2026-06-03 02:45:08 | MASTER-OAFA | (12h 57m 15.39s , -17d 34m 02.6s) | C | 60 | 19.3 | 14726 | 2026-06-03 02:46:27 | MASTER-OAFA | (12h 57m 15.42s , -17d 35m 38.7s) | C | 60 | 19.3 | 14819 | 2026-06-03 02:48:00 | MASTER-OAFA | (13h 05m 20.11s , -15d 40m 05.6s) | C | 60 | 19.3 | 16571 | 2026-06-03 03:17:11 | MASTER-OAGH | (12h 28m 33.45s , -14d 00m 32.3s) | C | 60 | 17.3 | 16671 | 2026-06-03 03:18:52 | MASTER-OAGH | (12h 33m 22.10s , -17d 46m 24.2s) | C | 60 | 17.3 | 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/44783. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42912] EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44782 SUBJECT: EP260530a: Xinglong optical spectroscopy of EP260530a / AT 2026nwl DATE: 26/06/03 03:03:14 GMT FROM: Xinglong Observatory at National Astronomical Observatories (NAOC), Chinese Academy of Sciences (CAS) <xinglong(a)nao.cas.cn> Xinglong optical observations Junjie-Jin (NAOC), Yiming-Mao (NAOC), Junjun-Jia (NAOC), Pengliang-Du (NAOC), Yu-Zhang (NAOC), Zhou-Fan (NAOC), Hong-Wu (NAOC) report: We obtained an optical spectrum of the Einstein Probe transient EP260530a (Wu et al., ATel #17824) using the Xinglong 2.16-m telescope. The observations targeted the optical counterpart candidate, AT 2026nwl, discovered by GOTO (TNS Astronomical Transient Report No. 306622). The observation was carried out on 2026 June 1 at 12:53:59 UT with BFOSC using the G4 grism and a 2.3-arcsec slit. The exposure time was 1800 s. The spectrum shows clear narrow emission lines from hydrogen and helium. View this GCN Circular online at https://gcn.nasa.gov/circulars/44782. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42911] EP260602a: SVOM/VT optical candidate
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44781 SUBJECT: EP260602a: SVOM/VT optical candidate DATE: 26/06/03 02:55:12 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> J. R. Xu, H. L. Li, C. Wu, Y. L. Qiu, L. P. Xin, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC) and J. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observations to the field of EP260602a triggered by Einstein Probe (Li et al., GCN 44770). The observation started at 2026-06-02T15:37:33 UTC, 7.44 hours post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. An uncatalogued optical source was detected within WXT's error box (Li et al., GCN 44770) in both VT channels, compared to the Legacy Survey. The position is at R.A., Dec. = 240.862173, 50.563348 degrees, equivalent to: R.A. (J2000) = +16:03:26.92 Dec. (J2000) = +50:33:48.05 with an uncertainty of 0.5 arcsec. The following measurements are in the AB magnitude without correction for Galactic extinction: Mid time | Band | Exposure Time | Brightness 9.49 h VT_B 93*50 s 23.2 +/- 0.3 mag 9.51 h VT_R 84*50 s 21.17 +/- 0.15 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/44781. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42910] EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44780 SUBJECT: EP-WXT trigger 01709266414 (EP260602b): JinShan optical counterpart detection DATE: 26/06/03 02:11:44 GMT FROM: L. B. He at NAOC <helb(a)bao.ac.cn> L.B. He, X. Liu, Z.P. Zhu, D. Xu, J. An, S.Q. Jiang (NAOC), S.Y. Fu, A.D. Zhu, L. Lei (HUST), J.Z. Liu (XAO) report: We observed the field of EP-WXT Trigger 01709266414 (presumably EP260602b) detected by Einstein Probe (EP), using the JinShan 100B and 100C telescopes located at Altay, Xinjiang, China. A series of r-band frames were obtained. An uncatalogued and decaying source is detected within the EP/WXT error circle at coordinates R.A. (J2000) = 18:13:53.7 (273.4738 deg) Dec. (J2000) = +07:34:16.4 (7.5712 deg) with an uncertainty of ~ 1.0 arcsec. The source had r ~ 19.0 mag at a median time of ~ 1.0 hr post-trigger, calibrated with Pan-STARRS DR2 and not corrected for Galactic extinction of A_V ~ 0.94 mag. We thus think the source is the optical counterpart. 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/44780. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42909] GRB 260602B: Fermi GBM Final Localization
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44779 SUBJECT: GRB 260602B: Fermi GBM Final Localization DATE: 26/06/03 01:14:31 GMT FROM: Lorenzo Scotton at UAH <lscottongcn(a)outlook.com> The Fermi GBM team reports the detection of a likely SHORT GRB "At 22:41:31.26 UT on 02 June 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260602B (trigger 802132896/260602945). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 187.55, Dec = -16.61 (J2000 degrees, equivalent to J2000 12h 30m, -16d 36'), with a statistical uncertainty of 4.88 degrees. The angle from the Fermi LAT boresight is 71 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260602945/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260602945/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260602945/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/44779. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42908] GRB 260601A: GECAM-B observation of a short burst
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44778 SUBJECT: GRB 260601A: GECAM-B observation of a short burst DATE: 26/06/03 00:54:14 GMT FROM: Yue Wang <m18509381757(a)163.com> Yue Wang, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team: GECAM-B was triggered in-flight by GRB 260601A at 2026-06-01T11:00:12.500 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #44755). According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of muplti-pulses with a duration (T90) of 0.78 +0.21/-0.57 s. The GECAM-B light curve can be found here: https://www.bursthub.cn//admin/static/gecambgrb260601A.png Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS). View this GCN Circular online at https://gcn.nasa.gov/circulars/44778. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42907] GRB 260601B/EP260601a: J-band upper limit with WINTER
by GCN Circulars 03 Jun '26

03 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44777 SUBJECT: GRB 260601B/EP260601a: J-band upper limit with WINTER DATE: 26/06/02 23:04:15 GMT FROM: Geoffrey Mo at Caltech / Carnegie Observatories <gmo(a)mit.edu> 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 GRB 260601B/EP260601a (Yang et al., GCN 44766; Yu et al., GCN 44767; Wang et al., GCN 44768; Waratkar et al., GCN 44771; Sugita et al., GCN 44773) 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 2026-06-02T11:12:20 UTC in the J band (~16 hr after the GRB trigger), consisting of 15 x 120 s 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 (Liu et al., GCN 44764; Guelfand et al., GCN 44765; Li et al., GCN 44769). We obtain the following 5-sigma upper limit: J = 18.8 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/44777. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42906] EP260530a/AT 2026nwl: COLIBRÍ optical follow up
by GCN Circulars 02 Jun '26

02 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44776 SUBJECT: EP260530a/AT 2026nwl: COLIBRÍ optical follow up DATE: 26/06/02 20:15:16 GMT FROM: Camila Angulo Valdez at UNAM <camiangulo(a)astro.unam.mx> Marion Guelfand (CPPM), Camila Angulo (UNAM), Noémie Globus (UNAM), Alan M. Watson (UNAM), Jean-Grégoire Ducoin (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We observed the field of the optical source AT 2026nwl, discovered by GOTO (Godson et al., TNS Astronomical Transient Report No. 306622), associated with EP260530a (Wu et al., ATel #17824), further observed by COLIBRÍ (Globus et al., GCN Circ. 44759) and KAIT (Zheng et al., GCN Circ. 44775), and classified as a CV (Pursiainen et al., TNS Classification Report No. 23885), with the DDRAGO two-channel wide-field imager mounted on the COLIBRÍ telescope. We observed from 2026-06-02 04:19 to 07:11 UTC (from 79.21 to 82.15 hours after the GOTO discovery) and obtained 24 minutes of exposure in each of the g, r, and i filters, and 72 minutes of exposure in the z filter. The data were reduced and coadded with the COLIBRÍ ASU pipeline. 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 continue to detect the source at the following preliminary magnitudes: g = 15.77 +/- 0.01, r = 15.87 +/- 0.01, i = 15.98 +/- 0.01, z = 16.07 +/- 0.01. We observe a quasi-periodic modulation of the light curve in the different photometric bands with a characteristic timescale of approximately 1 hour, typical of certain classes of accreting binary stars, and a peak-to-valley amplitude of about 0.1 mag Further observations and analysis are ongoing. We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM. 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/44776. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42905] EP260530a/AT 2026nwl: KAIT optical observations
by GCN Circulars 02 Jun '26

02 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44775 SUBJECT: EP260530a/AT 2026nwl: KAIT optical observations DATE: 26/06/02 18:47:59 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team: The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at Lick Observatory, observed the field of EP260530a (Wu et al., ATel #17824) on May 31 and again on Jun 02 UT. A set of clear (roughly R) filter images were obtained. We clearly detected the bright CV outburst associated with AT 2026nwl (TNS Astronomical Transient Report 306622, 306654; TNS Classification Reports 23885; Globus et al., GCN 44759). We measure its brightness decayed from 14.4 +/- 0.1 mag (Vega) at 0.98d after the burst, to 15.6 +/- 0.1 mag at 2.95d after the burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/44775. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42904] GRB 260602A: Fermi GBM Final Real-time Localization
by GCN Circulars 02 Jun '26

02 Jun '26

TITLE: GCN CIRCULAR NUMBER: 44774 SUBJECT: GRB 260602A: Fermi GBM Final Real-time Localization DATE: 26/06/02 18:40:24 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 18:29:53 UT on 2 Jun 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260602A (trigger 802117798.896848 / 260602771). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 26.3, Dec = 48.7 (J2000 degrees, equivalent to J2000 01h 45m, 48d 42'), with a statistical uncertainty of 2.0 degrees. The angle from the Fermi LAT boresight is 28.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260602771/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260602771/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260602771/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44774. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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