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[vsnet-grb-info 42786] GRB 260515A: further Liverpool Telescope observations
by GCN Circulars 17 May '26

17 May '26

TITLE: GCN CIRCULAR NUMBER: 44658 SUBJECT: GRB 260515A: further Liverpool Telescope observations DATE: 26/05/17 08:10:40 GMT FROM: A. Bochenek at Liverpool John Moores University <a.m.bochenek(a)2023.ljmu.ac.uk> A. Bochenek, D. A. Perley (LJMU), report: We observed the field of GRB 260515A (Brunetet al., GCN 44622) using the IO:O optical camera on the 2m robotic Liverpool Telescope. We obtained 5x110s exposures in SDSS r and i filters, starting at 2026-05-12 00:42:25 UT, approximately 5.55 hours after trigger. We detect a source in the stacked images in both filters at the position reported by He et al. (GCN 44623), and observed also by Saccardi et al., GCN 44624; Sosnovskij et al., GCN 44625; He et al., GCN 44626; Wu et al., GCN 44628, Dennefeld et al., GCN 44633; Li et al., GCN 44634, Antier et al., GCN 44643; Dimple et al. GCN 44646; and Moskvitin et al., GCN 44652: MJD (mid) T_mid-T_0 Filter Mag. (AB) 61176.03308 5.64 h r 21.32 ± 0.06 61176.04059 5.82 h i 21.26 ± 0.07 The photometry was calibrated using nearby PanSTARRS secondary standards and was not corrected for extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/44658. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42785] GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations
by GCN Circulars 17 May '26

17 May '26

TITLE: GCN CIRCULAR NUMBER: 44657 SUBJECT: GRB 260516D: SVOM/COLIBRÍ (FM-GFT) optical observations DATE: 26/05/17 06:24:29 GMT FROM: Leonardo Enrique García García <lgarcia(a)astro.unam.mx> Leonardo García García (UNAM), Francis Fortin (IRAP), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), 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), Antonio de Ugarte Postigo (LAM) and Andrea Saccardi (CEA) report: We imaged the field of the SVOM/ECLAIRs GRB 260516D (M. Brunet et al., GCN Circ. 44649) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-05-17 04:04 to 05:51 UTC (from to 7.48 to 9.25 hours after the trigger) and obtained 15 minutes of exposure in the r filter and 44 minutes of exposure in the z filter. The data were reduced, coadded, calibrated, and analysed 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 detect the source reported by Li et al. (GCN Circ. 44654) and de Ugarte Postigo et al. (GCN Circ. 44656) with preliminary unsubtracted magnitudes of: r = 21.65 +/- 0.07, z = 21.66 +/- 0.16. Using the combined r’ and r- band photometry from GCNs 44655 and 44656 together with our COLIBRI observations, we estimate the optical afterglow temporal decay index to be approximately alpha ≈ 1.4. 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/44657. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42784] GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801
by GCN Circulars 17 May '26

17 May '26

TITLE: GCN CIRCULAR NUMBER: 44656 SUBJECT: GRB 260516D: GTC/OSIRIS+ spectroscopic redshift z = 1.801 DATE: 26/05/17 04:17:13 GMT FROM: Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo(a)gmail.com> L. Izzo (INAF/OACN and DARK/NBI), D. B. Malesani (DAWN/NBI and Radboud), A. de Ugarte Postigo (LAM), S. Geier (GTC), A. Martin-Carrillo (UCD), C. C. Thoene (AbAO), M. A. Aloy (UV), J. P. U. Fynbo (DAWN/NBI), L. Galbany (IEEC-CSIC), G. Lombardi (GTC), N. A. Rakotondrainibe (LAM), B. Schneider (LAM), N. R. Tanvir (Univ. Leicester), F. Perez Toledo (GTC) report: We observed the optical counterpart (Li et al., GCN 44654; Mohan et al., GCN 44655) of GRB 260516D (Brunet et al., GCN 44649) using the Gran Telescopio Canarias (GTC) equipped with the OSIRIS+ instrument. In the 30-s acquisition image (beginning on 2026-05-17 at 02:54:51, that is 6.25 hr after trigger), the optical afterglow is well detected with a magnitude 21.0 ± 0.1 (AB), calibrated against nearby Pan-STARRS objects, and not corrected for Galactic extinction. A total of 3 spectra of 900 s were secured, starting at 03:06:24.010 UT (6.44 hr after trigger), using grism R1000B. Continuum is visible over the range 3650-7800 AA. A number of metal absorption features are detected, which we interpret as due to, among others, C II, C IV, Si II, Fe II, Al II, and Al III, all at a common redshift z = 1.801, which we suggest to be the redshift of GRB 260516D. This work has used the GRBspec database at http://grbspec.eu (de Ugarte Postigo et al. 2014, doi:10.1117/12.2055774). View this GCN Circular online at https://gcn.nasa.gov/circulars/44656. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42783] GRB 260516D: GROWTH-India Telescope optical counterpart discovery
by GCN Circulars 17 May '26

17 May '26

TITLE: GCN CIRCULAR NUMBER: 44655 SUBJECT: GRB 260516D: GROWTH-India Telescope optical counterpart discovery DATE: 26/05/17 01:33:09 GMT FROM: V. Swain at IIT Bombay <vishwajeet.s(a)iitb.ac.in> T. Mohan (IITB), V. Swain (IITB), A.P. Saikia (IITB), S. Patil (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team: We observed the field of GRB 260515D (Brunet et al., GCN 44649), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2026-05-16 22:19:57 (UTC), i.e., 1.67 hours after the trigger, and obtained multiple exposures in the r' filter. The observations were carried out at relatively high airmass (~2). We report the discovery of the possible counterpart whose coordinates are RA, Dec = 233.827989 (deg), 6.529308 (deg). No known minor planet was found at the source position during the time of observation. The photometric results are as follows: | MJD (mid) | Filter | tmid-t0 (minutes) | Exposure Time (sec) | Magnitude (AB) | | ------------ | ------ | ----------------- | ------------------- | -------------- | | 61176.93225 | r' | 102.62 | 1x300 | 19.17 +- 0.10 | | 61176.94497 | r' | 120.93 | 1x420 | 19.45 +- 0.09 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. Our results are consistent with other optical observations (Jelinek et al., GCN 44653) 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/44655. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42782] GRB 260516D: SVOM/VT optical bright candidate
by GCN Circulars 17 May '26

17 May '26

TITLE: GCN CIRCULAR NUMBER: 44654 SUBJECT: GRB 260516D: SVOM/VT optical bright candidate DATE: 26/05/17 01:27:37 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. N. Ma, C. Wu, Z. H. Yao, Y. L. Qiu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. R. Xu, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio and A. Saccardi (CEA/Irfu) report on behalf of the SVOM/VT team. SVOM/VT performed ToO observation to the field of possible short burst GRB 260516D detected by SVOM/ECLAIRs (Brunet et al., GCN 44619). The observation started at 2026-05-16T22:20:51 UTC, 1.69 hour post trigger in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. An uncatalogued optical source was clearly detected in single frames of both channels within the errobox of SVOM/ECLAIRs, compared to the Legacy Survey. The position is at R.A., Dec. = 233.827956, 6.529103 degrees, equivalent to: R.A. (J2000) = 15:35:18.71 Dec. (J2000) = +6:31:44.77 with an uncertainty of 0.5 arcsec. The measurements in AB magnitudes are given below: Mid_time Band Exposure Time Magnitude (AB) 1.71 hour VT_B 70 sec 19.62 +/- 0.05 mag 1.69 hour VT_R 70 sec 19.00 +/- 0.05 mag Our photometry was 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/44654. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42781] GRB 260516D: FRAM-ORM optical limit
by GCN Circulars 16 May '26

16 May '26

TITLE: GCN CIRCULAR NUMBER: 44653 SUBJECT: GRB 260516D: FRAM-ORM optical limit DATE: 26/05/16 23:59:09 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek(a)asu.cas.cz> Martin Jelinek, Filip Novotny and Jan Strobl (ASU CAS Ondrejov, CZ), Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza (Institute of Physics, Prague, CZ) report: The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically to the SVOM/ECLAIRs alert of GRB 260516D (Brunet et al., GCNC 44649), obtaining a series of unfiltered 60s images starting at 20:54:16 UT, i.e. ~948s post trigger. We do not detect any new or strongly variable source in comparison to the ATLAS REFCAT2 catalog. In single images the detection limit gradually improved from R_C > 17.1 in the first frame (midtime ~978s post trigger), stabilizing at R_C > ~18.3–18.4 around ~2000s post trigger and remaining there for the rest of the ~one hour sequence. Combining images in groups of 10 (10x60s), we reach limits of R_C > ~20 (R_C > ~19.3 for the first combined frame). View this GCN Circular online at https://gcn.nasa.gov/circulars/44653. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42780] GRB 260515A: CrAO ZTSh BVRI optical observations
by GCN Circulars 16 May '26

16 May '26

TITLE: GCN CIRCULAR NUMBER: 44652 SUBJECT: GRB 260515A: CrAO ZTSh BVRI optical observations DATE: 26/05/16 23:52:00 GMT FROM: Alexander Moskvitin at SAO RAS <mosk(a)sao.ru> A. Moskvitin (SAO RAS), A. Pozanenko (IKI), V. Rumyantsev (CrAO), N. Pankov (IKI), A. Volnova (IKI) report on behalf of IKI GRB-FuN. We observed the field of the GRB 260515A (Brunet et al., GCN 44622; Wang et al., GCN 44642; Frederiks et al., GCN 44647) with the Shajn 2.6-meter telescope (ZTSh) of the Crimean Astrophysical Observatory (CrAO). We obtained series of 120 s exposures in BVRI filters starting on 2026-05-15 22:10:11 UT (about 3 hours after trigger). The OT (He et al., GCN 44623; Saccardi et al., GCN 44624; Sosnovskij et al., GCN 44625; He et al., GCN 44626; Wu et al., GCN 44628; Malesani et al., GCN 44629; Dennefeld et al., GCN 44633; Li et al., GCN 44634; Antier et al., GCN 44643; Pérez-Fournon et al., GCN 44645; Dimple et al., GCN 44646) is clearly detected in the stacked frames. Details of the photometry is the following. Start_UT, t_mid-T0, exp, filter, mag, err, UL(3 sigma) 2026-05-15T22:54:33 4.79 15*120 B 21.53 0.04 23.9 2026-05-15T22:56:41 4.75 13*120 V 21.30 0.05 23.7 2026-05-15T22:10:11 3.12 5*120 R 20.56 0.04 23.4 2026-05-15T22:20:40 3.29 5*120 R 20.57 0.04 23.4 2026-05-15T22:31:09 3.46 5*120 R 20.65 0.04 23.5 2026-05-15T22:41:44 3.66 6*120 R 20.64 0.03 23.6 2026-05-15T22:56:41 4.26 7*120 R 20.87 0.03 23.7 2026-05-15T23:58:56 5.35 8*120 R 21.03 0.04 23.4 2026-05-15T23:00:57 4.89 15*120 I 20.75 0.05 22.8 This preliminary photometry is based on nearby SDSS stars (using Lupton 2005 transformation equations) and not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/44652. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42779] Fermi GRB 260516C: Global MASTER-Net observations report
by GCN Circulars 16 May '26

16 May '26

TITLE: GCN CIRCULAR NUMBER: 44651 SUBJECT: Fermi GRB 260516C: Global MASTER-Net observations report DATE: 26/05/16 22:15:42 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 [1] located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 260516C ( Fermi GBM team, GCN 44648) errorbox 31 sec after notice time and 63 sec after trigger time at 2026-05-16 19:35:42 UT, with upper limit up to 18.7 mag. The observations began at zenith distance = 27 deg. The sun altitude is -48.6 deg. The galactic latitude b = 1 deg., longitude l = 293 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3319181 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 68 | 2026-05-16 19:35:42 | MASTER-SAAO | (11h 28m 29.01s , -56d 15m 46.9s) | C | 10 | 17.3 | 68 | 2026-05-16 19:35:42 | MASTER-SAAO | (11h 31m 55.60s , -56d 31m 08.1s) | C | 10 | 17.5 | 102 | 2026-05-16 19:36:11 | MASTER-SAAO | (11h 28m 28.89s , -56d 15m 46.7s) | C | 20 | 17.7 | 102 | 2026-05-16 19:36:11 | MASTER-SAAO | (11h 31m 55.42s , -56d 31m 08.1s) | C | 20 | 18.0 | 155 | 2026-05-16 19:36:58 | MASTER-SAAO | (11h 22m 44.28s , -59d 38m 52.0s) | C | 30 | 17.1 | 200 | 2026-05-16 19:36:58 | MASTER-SAAO | (11h 22m 44.28s , -59d 38m 52.0s) | C | 120 | 17.4 | 155 | 2026-05-16 19:36:58 | MASTER-SAAO | (11h 26m 31.14s , -59d 54m 11.9s) | C | 30 | 17.4 | 200 | 2026-05-16 19:36:58 | MASTER-SAAO | (11h 26m 31.15s , -59d 54m 11.8s) | C | 120 | 17.8 | 209 | 2026-05-16 19:37:47 | MASTER-SAAO | (11h 22m 44.18s , -59d 38m 51.3s) | C | 40 | 17.1 | 209 | 2026-05-16 19:37:47 | MASTER-SAAO | (11h 26m 31.02s , -59d 54m 11.2s) | C | 40 | 17.5 | 273 | 2026-05-16 19:38:46 | MASTER-SAAO | (11h 22m 44.06s , -59d 38m 50.3s) | C | 50 | 17.1 | 273 | 2026-05-16 19:38:46 | MASTER-SAAO | (11h 26m 30.89s , -59d 54m 10.4s) | C | 50 | 17.5 | 347 | 2026-05-16 19:39:55 | MASTER-SAAO | (11h 22m 43.88s , -59d 38m 48.6s) | C | 60 | 17.3 | 347 | 2026-05-16 19:39:55 | MASTER-SAAO | (11h 26m 30.80s , -59d 54m 08.8s) | C | 60 | 17.6 | 626 | 2026-05-16 19:44:34 | MASTER-SAAO | (11h 24m 24.54s , -59d 37m 32.6s) | C | 60 | 17.4 | 686 | 2026-05-16 19:44:34 | MASTER-SAAO | (11h 24m 24.54s , -59d 37m 32.6s) | C | 180 | 17.5 | 626 | 2026-05-16 19:44:34 | MASTER-SAAO | (11h 28m 06.66s , -59d 53m 08.5s) | C | 60 | 17.7 | 686 | 2026-05-16 19:44:34 | MASTER-SAAO | (11h 28m 06.70s , -59d 53m 08.6s) | C | 180 | 17.9 | 705 | 2026-05-16 19:45:53 | MASTER-SAAO | (11h 24m 24.42s , -59d 37m 32.0s) | C | 60 | 17.4 | 705 | 2026-05-16 19:45:53 | MASTER-SAAO | (11h 28m 06.55s , -59d 53m 07.8s) | C | 60 | 17.6 | 784 | 2026-05-16 19:47:13 | MASTER-SAAO | (11h 24m 24.31s , -59d 37m 30.4s) | C | 60 | 17.4 | 784 | 2026-05-16 19:47:13 | MASTER-SAAO | (11h 28m 06.41s , -59d 53m 06.3s) | C | 60 | 17.6 | 863 | 2026-05-16 19:48:31 | MASTER-SAAO | (11h 24m 24.22s , -59d 37m 28.7s) | C | 60 | 17.3 | 863 | 2026-05-16 19:48:31 | MASTER-SAAO | (11h 28m 06.25s , -59d 53m 04.6s) | C | 60 | 17.6 | 1850 | 2026-05-16 20:04:28 | MASTER-SAAO | (11h 24m 04.79s , -59d 36m 36.8s) | C | 120 | 17.5 | 1850 | 2026-05-16 20:04:28 | MASTER-SAAO | (11h 27m 46.76s , -59d 52m 15.2s) | C | 120 | 17.8 | 2004 | 2026-05-16 20:07:02 | MASTER-SAAO | (11h 37m 54.80s , -59d 44m 27.2s) | C | 120 | 17.6 | 2004 | 2026-05-16 20:07:02 | MASTER-SAAO | (11h 41m 37.73s , -60d 00m 05.4s) | C | 120 | 17.8 | 2157 | 2026-05-16 20:09:35 | MASTER-SAAO | (11h 37m 55.16s , -59d 43m 25.3s) | C | 120 | 17.6 | 2157 | 2026-05-16 20:09:35 | MASTER-SAAO | (11h 41m 37.91s , -59d 59m 03.3s) | C | 120 | 17.9 | 2310 | 2026-05-16 20:12:09 | MASTER-SAAO | (11h 37m 59.95s , -59d 44m 22.1s) | C | 120 | 17.6 | 2310 | 2026-05-16 20:12:09 | MASTER-SAAO | (11h 41m 42.75s , -60d 00m 00.1s) | C | 120 | 17.8 | 2463 | 2026-05-16 20:14:41 | MASTER-SAAO | (11h 38m 07.66s , -57d 45m 21.9s) | C | 120 | 18.2 | 2463 | 2026-05-16 20:14:41 | MASTER-SAAO | (11h 41m 38.03s , -58d 01m 00.6s) | C | 120 | 18.5 | 2616 | 2026-05-16 20:17:15 | MASTER-SAAO | (11h 38m 13.31s , -57d 45m 08.0s) | C | 120 | 18.2 | 2616 | 2026-05-16 20:17:15 | MASTER-SAAO | (11h 41m 43.61s , -58d 00m 46.9s) | C | 120 | 18.5 | 2769 | 2026-05-16 20:19:47 | MASTER-SAAO | (11h 38m 10.50s , -57d 43m 18.7s) | C | 120 | 18.2 | 2769 | 2026-05-16 20:19:47 | MASTER-SAAO | (11h 41m 40.63s , -57d 58m 57.8s) | C | 120 | 18.5 | 2922 | 2026-05-16 20:22:21 | MASTER-SAAO | (11h 22m 13.66s , -57d 44m 42.9s) | C | 120 | 17.7 | 2922 | 2026-05-16 20:22:21 | MASTER-SAAO | (11h 25m 44.03s , -58d 00m 21.7s) | C | 120 | 17.9 | 3076 | 2026-05-16 20:24:54 | MASTER-SAAO | (11h 22m 15.81s , -57d 42m 54.4s) | C | 120 | 17.8 | 3076 | 2026-05-16 20:24:54 | MASTER-SAAO | (11h 25m 46.05s , -57d 58m 33.5s) | C | 120 | 18.0 | 3229 | 2026-05-16 20:27:28 | MASTER-SAAO | (11h 22m 10.17s , -57d 43m 35.0s) | C | 120 | 17.8 | 3229 | 2026-05-16 20:27:28 | MASTER-SAAO | (11h 25m 40.54s , -57d 59m 14.2s) | C | 120 | 18.0 | 3383 | 2026-05-16 20:30:01 | MASTER-SAAO | (11h 13m 44.65s , -61d 42m 13.8s) | C | 120 | 18.2 | 3383 | 2026-05-16 20:30:01 | MASTER-SAAO | (11h 17m 41.85s , -61d 57m 51.5s) | C | 120 | 18.6 | 3536 | 2026-05-16 20:32:34 | MASTER-SAAO | (11h 13m 50.07s , -61d 43m 09.6s) | C | 120 | 18.2 | 3536 | 2026-05-16 20:32:34 | MASTER-SAAO | (11h 17m 47.42s , -61d 58m 47.3s) | C | 120 | 18.7 | 3689 | 2026-05-16 20:35:07 | MASTER-SAAO | (11h 13m 44.81s , -61d 44m 05.2s) | C | 120 | 18.2 | 3689 | 2026-05-16 20:35:07 | MASTER-SAAO | (11h 17m 42.30s , -61d 59m 42.9s) | C | 120 | 18.7 | 3842 | 2026-05-16 20:37:41 | MASTER-SAAO | (11h 24m 03.00s , -59d 37m 40.6s) | C | 120 | 17.5 | 3842 | 2026-05-16 20:37:41 | MASTER-SAAO | (11h 27m 45.41s , -59d 53m 19.5s) | C | 120 | 17.6 | 3995 | 2026-05-16 20:40:14 | MASTER-SAAO | (11h 23m 59.91s , -59d 35m 52.6s) | C | 120 | 17.5 | 3995 | 2026-05-16 20:40:14 | MASTER-SAAO | (11h 27m 42.09s , -59d 51m 31.5s) | C | 120 | 17.6 | 4149 | 2026-05-16 20:42:48 | MASTER-SAAO | (11h 23m 59.68s , -59d 37m 31.9s) | C | 120 | 17.5 | 4149 | 2026-05-16 20:42:48 | MASTER-SAAO | (11h 27m 42.06s , -59d 53m 11.0s) | C | 120 | 17.6 | 4303 | 2026-05-16 20:45:21 | MASTER-SAAO | (11h 24m 02.31s , -59d 35m 54.7s) | C | 120 | 17.5 | 4303 | 2026-05-16 20:45:21 | MASTER-SAAO | (11h 27m 44.51s , -59d 51m 33.8s) | C | 120 | 17.6 | 4456 | 2026-05-16 20:47:54 | MASTER-SAAO | (11h 27m 39.44s , -59d 52m 02.8s) | C | 120 | 17.6 | 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/44651. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42778] SVOM GRB260516.86: Global MASTER-Net observations report
by GCN Circulars 16 May '26

16 May '26

TITLE: GCN CIRCULAR NUMBER: 44650 SUBJECT: SVOM GRB260516.86: Global MASTER-Net observations report DATE: 26/05/16 21:14:44 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-Tavrida robotic telescope [1] located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the SVOM GRB260516.86 (trigger No 1778963908,15h 35m 23.71s , +06d 22m 21.4s, R=0.1937) errorbox 767 sec after notice time and 1684 sec after trigger time at 2026-05-16 21:06:32 UT, with upper limit up to 18.6 mag. The observations began at zenith distance = 39 deg. The sun altitude is -25.7 deg. The galactic latitude b = 45 deg., longitude l = 13 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3319281 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 1714 | 2026-05-16 21:06:32 | MASTER-Tavrida | (15h 35m 16.63s , +06d 23m 55.5s) | C | 60 | 18.6 | 1783 | 2026-05-16 21:07:41 | MASTER-Tavrida | (15h 35m 20.66s , +06d 25m 06.4s) | C | 60 | 18.6 | 1852 | 2026-05-16 21:08:50 | MASTER-Tavrida | (15h 35m 12.84s , +06d 24m 31.1s) | C | 60 | 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/44650. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42777] GRB 260516D: SVOM possible detection of a short faint burst
by GCN Circulars 16 May '26

16 May '26

TITLE: GCN CIRCULAR NUMBER: 44649 SUBJECT: GRB 260516D: SVOM possible detection of a short faint burst DATE: 26/05/16 21:08:26 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> M. Brunet, O. Godet (IRAP), H. Goto (RIKEN/CEA), A. Saccardi (CEA/Irfu) report on behalf of the SVOM mission team: At 2026-05-16T20:39:50 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260516D (SVOM burst-id sb26051616). 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 6.73 in the [5-20] keV energy band over a time window of 81.92 seconds starting at 2026-05-16T20:38:28. The localization of the best alert is R.A., Dec. 233.849, 6.373 degrees: R.A. (J2000) = 15h35m23.71s Dec. (J2000) = 6d22m21.34s with a 90% confidence level (C.L.) radius of 11.62 arcmin (including systematic error of 2 arcmin added in quadrature). Due to the detection significance being below the slew threshold, no immediate slew was performed on this burst. A Svom ToO has been scheduled. 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 Andrea Saccardi (CEA): 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/44649. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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