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

[vsnet-grb-info 40590] GRB 251028B: CALET Gamma-Ray Burst Monitor detection
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42505 SUBJECT: GRB 251028B: CALET Gamma-Ray Burst Monitor detection DATE: 25/10/28 16:08:21 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> Y. Akaike (Waseda U), A. Yoshida, T. Sakamoto, S. Sugita, Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), and the CALET collaboration: The long GRB 251028B (Fermi GBM Final Localization Correction: Fermi GBM team, GCN Circ. 42502) triggered the CALET Gamma-ray Burst Monitor (CGBM) at 07:48:06.24 UTC on 28 October 2025 (https://cgbm.calet.jp/cgbm_trigger/flight/1445672396/index.html) The burst signal was seen by all CGBM detectors. The burst light curve shows a multi-peaked structure that starts at T-0.5 sec, peaks at T+9.9 sec, and ends at T+11.5 sec. The T90 and T50 durations measured by the SGM data are 11.3 +/- 0.4 sec and 8.5 +/- 0.3 sec (40-1000 keV), respectively. The ground-processed light curve is available at https://cgbm.calet.jp/cgbm_trigger/ground/1445672396/ The CALET data used in this analysis are provided by the Waseda CALET Operation Center located at Waseda University. View this GCN Circular online at https://gcn.nasa.gov/circulars/42505. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40589] Fermi GRB 251028B: Global MASTER-Net observations report
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42504 SUBJECT: Fermi GRB 251028B: Global MASTER-Net observations report DATE: 25/10/28 14:00:39 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-Tunka robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 251028B ( Fermi GBM team, GCN 42502) errorbox 19936 sec after notice time and 19967 sec after trigger time at 2025-10-28 13:20:54 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 6 deg. The sun altitude is -33.5 deg. The galactic latitude b = -10 deg., longitude l = 99 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3025691 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 19998 | 2025-10-28 13:20:54 | MASTER-Tunka | (22h 31m 44.47s , +45d 04m 55.7s) | C | 60 | 18.6 | 19998 | 2025-10-28 13:20:54 | MASTER- | (22h 30m 56.32s , +45d 13m 01.0s) | C | 60 | 18.3 | 20070 | 2025-10-28 13:22:06 | MASTER-Tunka | (22h 34m 25.03s , +46d 58m 00.3s) | C | 60 | 17.5 | 20070 | 2025-10-28 13:22:06 | MASTER- | (22h 33m 35.14s , +47d 06m 10.6s) | C | 60 | 17.3 | 20146 | 2025-10-28 13:23:22 | MASTER-Tunka | (22h 30m 48.12s , +43d 08m 44.4s) | C | 60 | 13.9 | 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/42504. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40588] GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42503 SUBJECT: GRB 251025B: GROWTH-India Telescope continued multiband optical observations and rebrightening DATE: 25/10/28 12:33:26 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> T. Mohan, V. Swain, S. Patil, A.P. Saikia, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team: We observed the field of SVOM GRB 251025B (Hussein et al., GCN 42437), with 0.7m GROWTH-India Telescope (GIT). Our second epoch started at 2025-10-25 22:07:53 UT, i.e. about 7.73 hours after the SVOM trigger. Multiple exposures were obtained in the r′ and i' filters, and we detect the optical afterglow in our stacked images. The photometry result follows as: | MJD (mid) | tmid - t0 (hours) | Filter | Exposure (s) | Magnitude (AB) | | --------- | ----------------- | ------ | ------------ | -------------- | |60973.93279| 7.99 | r' | 5 x 360 | 19.97 +- 0.08 | |60973.95429| 8.5 | i' | 5 x 360 | 19.82 +- 0.16 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. The optical counterpart has rebrightened by ~0.4 mag over a period of about 5.8 hours since our earlier observation (Mohan et al., GCN 42447), consistent with other reports by Li et al., GCN 42453; Pereyra et al., GCN 42452; Freeberg et al., GCN 42474. The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/. View this GCN Circular online at https://gcn.nasa.gov/circulars/42503. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40587] GRB 251028B: Fermi GBM Final Localization Correction
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42502 SUBJECT: GRB 251028B: Fermi GBM Final Localization Correction DATE: 25/10/28 10:12:02 GMT FROM: Christian Malacaria at INAF-OAR <cmalacaria.astro(a)gmail.com> The Fermi GBM team reports the detection of a likely LONG GRB "At 07:48:06.71 UT on 28 October 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251028B (trigger 783330491/251028325). This trigger was initially classified as Distant Particles by the flight software, but is in fact a GRB. The on-ground calculated location, using the Fermi GBM trigger data, is RA = 337.82, Dec = 45.75 (J2000 degrees, equivalent to J2000 22h 31m, +45d 45'), with a statistical uncertainty of 3.69 degrees. The angle from the Fermi LAT boresight is 119 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028325/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028325/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028325/…" View this GCN Circular online at https://gcn.nasa.gov/circulars/42502. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40586] GRB251026B: PRIME H-band upper limit
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42501 SUBJECT: GRB251026B: PRIME H-band upper limit DATE: 25/10/28 10:04:28 GMT FROM: Massine El Kabir <m.elkabir(a)campus.unimib.it> M. El Kabir (U Rome), N. Passaleva (U Rome), J. Durbak (UMD), O. Guiffreda (UMD), E. Troja (U Rome), A. S. Kutyrev (NASA/GSFC), S. B. Cenko (NASA/GSFC) Following the detection of a candidate optical counterpart (Belkin et al., GCN 42470), we observed the field of GOTO GOTO25jgl/AT2025absf in the H filter with PRIME. Observations started ~ 2 d after the initial Fermi trigger (Dafčíková et al., GCN 42455). At the GOTO position (Belkin et al., GCN 42470), no obvious counterpart is detected on the top of the bright nearby galaxy. Due to the bright galaxy background, it is hard to assess the presence of a faint transient source without a template. Using GALFIT, we modelled the galaxy with a single Sersic profile and, after subtraction, derive a 3-sigma upper limit of H > 19 AB mag PRIME is a 1.8m telescope with 1.56 square degree FOV (0.5 arcsec/pixel) located in Sutherland, South Africa at the South African Astronomical Observatory (SAAO) (Kutyrev et al. 2023, Yama et al. 2023, Durbak et al. 2024). We thank the Osaka University observers at PRIME and the staff at SAAO for their support with these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/42501. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40585] GRB251025B: 3.6m DOT Optical Observations
by GCN Circulars 28 Oct '25

28 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42500 SUBJECT: GRB251025B: 3.6m DOT Optical Observations DATE: 25/10/28 07:35:28 GMT FROM: ANSHIKA GUPTA at ARIES <anshika05180(a)gmail.com> Anshika Gupta, Kumar Pranshu, Dhruv Jain, Debolina Kar, Pankaj Pawar, and Kuntal Misra (ARIES) report: We observed the field of GRB 251025B detected by SVOM/ECLAIRs (Hussein et al. 2025; GCN 42437) with the 3.6m Devasthal Optical Telescope (DOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-10-27 at 04:20:49.73 UT, i.e., ~1.58 days after the SVOM trigger. We have taken multiple frames with an exposure time of 300s in the R filter. We stacked the images after the alignment. We detect an optical counterpart in our stacked image within the error box of SVOM telescope (Hussein et al. 2025; GCN 42437) and Swift-XRT (Beardmore et al. 2025; GCN 42445). We obtain the following preliminary magnitude in the stacked image: Date Start_UT T_start-T0 (days) Filter Exp time (s) Magnitude ================================================================== 2025-10-27 04:20:49.73 ~1.58 ~ R 300s*8 20.866 +/-0.007 Our detection is consistent with Wu et al. 2025 (GCN 42438); Gress et al. 2025 (GCN 42439); Wu et al. 2025 (GCN 42440); Beardmore et al. 2025 (GCN 42445); Mohan et al. 2025 (GCN 42447); Hernández Fung et al. 2025 (GCN 42450); Pereyra et al. 2025 (GCN 42452); Li et al. 2025 (GCN 42453); Mo et al. 2025 (GCN 42459); Rakotondrainibe et al. 2025 (GCN 42460); Rajabov et al. 2025 (GCN 42466); Saccardi et al. 2025 (GCN 42472); Freeberg et al. 2025 (GCN 42474); Volnova et al. 2025 (GCN 42475). The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog. View this GCN Circular online at https://gcn.nasa.gov/circulars/42500. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40584] GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143)
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42499 SUBJECT: GRB 251028A: BALROG localization (Fermi Trigger 783314796 / GRB 251028143) DATE: 25/10/28 04:28:32 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 783314796 at 03:26:31 on 28 Oct. 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) = 145.7 deg Decl.(2000.0) = 16.8 deg The 1 sigma statistical error radius is 2.1 deg. We estimate an additional systematic error of 2 deg. Further details are available at: https://grb.mpe.mpg.de/grb/GRB251028143/ The Healpix map can be downloaded from: https://grb.mpe.mpg.de/grb/GRB251028143/healpix The location parameters are available as JSON at: https://grb.mpe.mpg.de/grb/GRB251028143/json View this GCN Circular online at https://gcn.nasa.gov/circulars/42499. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40583] GRB 251028A: MAXI/GSC detection
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42498 SUBJECT: GRB 251028A: MAXI/GSC detection DATE: 25/10/28 04:17:17 GMT FROM: Yuta Kawakubo at Aoyama Gakuin University <kawakubo(a)phys.aoyama.ac.jp> H. Sugai (Chuo U.), Y. Kawakubo, M. Serino (AGU), H. Negoro, M. Nakajima, K. Takagi, H. Takahashi, H. Nishio (Nihon U.), T. Mihara, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), T. Sakamoto, S. Sugita, H. Hiramatsu, Y. Kondo, A. Yoshida (AGU), Y. Tsuboi, N. Nagashima, Y. Ishihara (Chuo U.), M. Shidatsu, C. Kang, T. Nakamoto (Ehime U.), I. Takahashi, Y. Yatsu (Science Tokyo), S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, M. Kurihara (JAXA), Y. Ueda, K. Fujiwara (Kyoto U.), M. Yamauchi, M. Nishio, C. Hiraizumi (Miyazaki U.), K. Yamaoka (Nagoya U.), M. Sugizaki (Kanazawa U.), W. Iwakiri (Chiba U.), T. Kawamuro (Osaka U.), S. Yamada (Tohoku U) report on behalf of the MAXI team: The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray transient source at 03:27:06 UT on October 28, 2025. Assuming that the source flux was constant over the transit, we obtain the source position at (R.A., Dec) = (149.003 deg, 17.518 deg) = (09 56 00, +17 31 04) (J2000) with a statistical 90% C.L. elliptical error region with long and short radii of 0.27 deg and 0.21 deg, respectively. The roll angle of long axis from the north direction is 49.0 deg counterclockwise. There is an additional systematic uncertainty of 0.1 deg (90% containment radius). The X-ray flux averaged over the scan was 267 +- 43 mCrab (4.0-10.0keV, 1 sigma error). Without assumptions on the source constancy, we obtain a rectangular error box for the transient source with the following corners: (148.423, 18.362) deg = (09 53 41, +18 21 43) (J2000) (148.075, 17.954) deg = (09 52 17, +17 57 14) (J2000) (149.164, 17.109) deg = (09 56 39, +17 06 32) (J2000) (149.513, 17.514) deg = (09 58 03, +17 30 50) (J2000) There was no significant excess flux in the previous transit at 02:15 UT with an upper limit of 20 mCrab. View this GCN Circular online at https://gcn.nasa.gov/circulars/42498. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40582] GRB 251028A: Fermi GBM Final Real-time Localization
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42497 SUBJECT: GRB 251028A: Fermi GBM Final Real-time Localization DATE: 25/10/28 03:36:52 GMT FROM: Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply(a)GIOC.nsstc.nasa.gov> The Fermi GBM team reports the detection of a likely LONG GRB At 03:26:31 UT on 28 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251028A (trigger 783314796.860488 / 251028143). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 149.5, Dec = 20.2 (J2000 degrees, equivalent to J2000 09h 58m, 20d 11'), with a statistical uncertainty of 1.0 degrees. The angle from the Fermi LAT boresight is 53.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251028143/… View this GCN Circular online at https://gcn.nasa.gov/circulars/42497. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 40581] The EP-WXT trigger 01709247525 is not a real source
by GCN Circulars 27 Oct '25

27 Oct '25

TITLE: GCN CIRCULAR NUMBER: 42496 SUBJECT: The EP-WXT trigger 01709247525 is not a real source DATE: 25/10/28 01:44:18 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> J. H. Wu (GZHU), A. Li (BNU), H. Q. Cheng and H. Sun (NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709247525 at the time of 2025-10-27T03:28:52.59, is not a real source. View this GCN Circular online at https://gcn.nasa.gov/circulars/42496. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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