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

[vsnet-grb-info 42563] GRB 251013C: ABObservatory optical observations
by GCN Circulars 01 May '26

01 May '26

TITLE: GCN CIRCULAR NUMBER: 42251 SUBJECT: GRB 251013C: ABObservatory optical observations DATE: 25/10/14 10:53:56 GMT FROM: A. Brosio at ABObservatory Rosarno <antonino.brosio(a)gmail.com> A. Brosio (ABObservatory Rosarno), M. A. Tripodi (ABObservatory Rosarno), S. Savaglio (University of Calabria), G. Bracco, P. Cianfarra, L. Sangaletti, S. Tosi & S. Zappatore (University of Genoa), S. Benatti & M. G. Guarcello (INAF Palermo), L.Cabona, M. Rainer, F. M. Zerbi, M. Basilicata (INAF Brera), D. Ricci (INAF Padova), A. Di Dato (INAF Capodimonte), S. Masiero & A. Nastasi (GAL Hassin), D. Liguori (Osservatorio "G. Galilei" Cariati), L. Betti (Osservatorio Polifunzionale del Chianti), R. Nesci (Associazione Astronomica Antares APS di Foligno), for the NOCTIS team report We observed the field of GRB 251013C, which was detected by Fermi GBM team (GCN 42221) with the 30-cm automated telescope at ABObservatory (Rosarno, Italy) in V filter. The observations began on 2025 october 13 at 20:56:53 UT, approximately 2.38 hours after the trigger. The observation consisted of 50 exposures of 120 seconds each,with good sky conditions. The mid-exposure time was 22:12:46 UT, and the final exposure ended at 23:32:52 UT. From photometry, we detect the optical counterpart in our images at the following coordinates: R.A (J2000.0) = 23 03 19.712 Dec. (J2000.0) = -00 12 53.17 From the full photometric sequence, we obtained a mean magnitude of V = 17.244 +/- 0.213 at mean JD 2460962.42529 with SNR 14.98 (AB, calibrated with the GAIA DR3 on SIMBAD). We also performed time-series photometry and obtained a light curve of the optical counterpart during our observing run and the source shows a fading trend, reaching V = 17.848 ± 0.509 at JD 2460962.47774. View this GCN Circular online at https://gcn.nasa.gov/circulars/42251. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42562] GRB 260429A: SVOM/GRM observation of a short burst
by GCN Circulars 01 May '26

01 May '26

TITLE: GCN CIRCULAR NUMBER: 44439 SUBJECT: GRB 260429A: SVOM/GRM observation of a short burst DATE: 26/05/01 13:44:00 GMT FROM: yzh807926(a)163.com SVOM/GRM team: Zheng-Hang Yu, Chen-Wei Wang, Chao Zheng, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Sebastien Guillot, Olivier GODET (IRAP), Stéphane Schanne (CEA) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a burst GRB 260429A (SVOM trigger reference: sb26042902) at 2026-04-29T23:24:02.100 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #44425). 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 peak a T90 of 0.12 +0.12/-0.03 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260429A.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 283.9 deg, DEC= 18.1 deg, ERR=2.6 deg, GCN#44425), is located at about 99 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. Nevertheless, ECLAIRs detected the GRB through the shield above 50 keV. With this localization, the time-averaged spectrum from T0-0.2 to T0+0.5 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.19 +0.12/-0.14 and the cutoff energy, parameterized as Epeak, is 961 +672/-308 keV. The event fluence (10-1000 keV) in this time interval is (2.57 +/-0.16)E-06 erg/cm^2. The localization of GRB 260429A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/svgrb260429A_amati.png 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: Zheng-Hang Yu(IHEP)(zhyu(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/44439. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42561] SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China
by GCN Circulars 01 May '26

01 May '26

TITLE: GCN CIRCULAR NUMBER: 44438 SUBJECT: SN 2026kid: Optical follow-up with small-aperture telescopes in Spain and China DATE: 26/05/01 13:00:52 GMT FROM: Chenxi Bao at Peking University <2300011608(a)stu.pku.edu.cn> Chenxi Bao (PKU), Zhuokai Liu (PKU), Yacheng Kang (PKU) report on behalf of the Interestar Collaboration and the PKU HiTF (High-energy Transients Follow-up) group: We observed the field of SN 2026kid (ZTF26aatswhm), discovered and first reported by Yasuo Sano (TNS Discovery Report 300955; T0 = 2026-04-22T14:23:47.00). Observations began on 2026 Apr 24, approximately 2.2 days after the first detection of the SN, using a 13cm optical telescope located in Yanchi, China. We subsequently employed a 28cm optical telescope located in Castillejar, Spain, to continue monitoring SN 2026kid. In total, our observations spanned 3 nights in the Luminance filter and 2 nights in the Red filter. In the Luminance- and Red-band exposures, we clearly detect the Type II SN 2026kid in the nearby edge-on spiral galaxy NGC 5907, located at a distance of 16.5 Mpc (Rehemtulla et al.,TNS AstroNote 2026-114). Our observations show that SN 2026kid has brightened since discovery, reaching approximately 16.1 mag in the Luminance band and 15.5 mag in the Red band, indicating continued early-time photometric evolution. Preliminary photometry was derived from image subtraction using pre-explosion reference images, calibrated against nearby field stars, and is reported as approximate AB-equivalent magnitudes, without correction for Galactic extinction. The observation log is summarized below: | Date | Start_UT | T_mid - T0 (days) | Filter | Exposure (s) | Magnitude (AB) | | :--------: | :------: | :---------------: | :-------: | :----------: | :------------: | | 2026-04-24 | 18:04:42 | 2.15 | Luminance | 200 | 16.22 +/- 0.02 | | 2026-04-26 | 23:00:24 | 4.40 | Luminance | 6600 | 16.11 +/- 0.04 | | 2026-04-27 | 20:11:25 | 5.25 | Luminance | 1200 | 16.16 +/- 0.26 | | 2026-04-27 | 20:46:12 | 5.29 | Red | 3600 | 15.60 +/- 0.16 | | 2026-04-29 | 20:18:58 | 7.30 | Red | 8400 | 15.42 +/- 0.22 | Further analysis and follow-up observations are ongoing. The two small-aperture telescopes are operated by the Interestar Collaboration. The PKU HiTF group is dedicated to rapid follow-up observations of high-energy transients. View this GCN Circular online at https://gcn.nasa.gov/circulars/44438. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42560] EP260429a: Global MASTER-Net observations report
by GCN Circulars 01 May '26

01 May '26

TITLE: GCN CIRCULAR NUMBER: 44437 SUBJECT: EP260429a: Global MASTER-Net observations report DATE: 26/05/01 10:09:31 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-OAGH robotic telescope [1] located in Mexico (OAGH National Institute for Astrophysics, Optics and Electronics) was pointed to the EP260429a ( EP Team et al., GCN 44426) errorbox 1 days 24768 sec after notice time and 1 days 69627 sec after trigger time at 2026-05-01 10:01:38 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 44 deg. The sun altitude is -29.1 deg. The galactic latitude b = 30 deg., longitude l = 2 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3281864 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 156117 | 2026-05-01 10:01:38 | MASTER-OAGH | (16h 00m 56.52s , -09d 05m 48.0s) | C | 180 | 18.6 | 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/44437. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42559] EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations
by GCN Circulars 01 May '26

01 May '26

TITLE: GCN CIRCULAR NUMBER: 44436 SUBJECT: EP260430a: refined analysis of the EP-WXT and follow-up EP-FXT observations DATE: 26/05/01 07:13:34 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y. Wang (PMO, CAS; UCB), Y. L. Wang (NAO, CAS; ICE, CSIC), G. J. Yang, C.C Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: The X-ray transient EP260430a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Wang et al., GCN 44427) at 2026-04-30T02:32:47 (UTC). The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 0.3× 10^21 cm^-2, and a photon index of 0.84 (+0.19/-0.18). The derived average unabsorbed 0.5-4 keV flux is 4.63 (+2.54/-1.56) × 10^(-10) erg/s/cm^2. Follow-up observation by the Follow-up X-ray Telescope (FXT) on board EP was performed at 2026-04-30T02:34:41 (UTC). The exposure time of the observation is around 3 ks. The on-ground analysis of the FXT data found an uncatalogued source at R.A. = 178.3355, DEC = -10.2146 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The FXT light curve shows a raipd decay. The average FXT 0.5-10 keV spectra can be fitted with an absorbed power-law with a fixed Galactic hydrogen column density of 0.3× 10^21 cm^-2, and a photon index of 4.61 (+/-0.20). The derived average unabsorbed 0.5-10 keV flux is 1.27 (-0.16/+0.17) × 10^(-11) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. We note that follow-up observations were carried out by Lipunov et al. (GCN 44428), Fortin et al. (GCN 44431) and Chácon et al. (GCN 44432), but no optical counterpart was detected in these observation. 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/44436. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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