March 2025 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 37938] GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate
by GCN Circulars 29 Mar '25

29 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39920 SUBJECT: GRB 250328A: SVOM/COLIBRÍ (F-GFT) optical afterglow candidate DATE: 25/03/29 11:09:27 GMT FROM: COLIBRI at COLIBRI Consortium <gcn(a)colibri-obs.org> Benjamin Schneider (LAM), Jean-Grégoire Ducoin (CPPM), Sarah Antier (OCA/IJCLAB), Ramandeep Gill (UNAM), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Francesco Magnani (CPPM), Diego López-Cámara (UNAM), Dalya Akl (AUS), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Antonio de Ugarte Postigo (LAM) report: We observed the field of the SVOM/ECLAIRs GRB 250328A (Brunet et al., GCN 39910) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (F-GFT) telescope. We obtained 50 min of exposures in the i-band starting at 06:57:58 UT on 2025-03-29 (14.0 hr after the SVOM trigger). In the stacked image, we detect a source at the near-infrared afterglow candidate position reported by Schneider et al., GCN 39919 and consistent with the XRT source #2. At that position, no source is visible either in the PanSTARRS survey or the Legacy Survey. The preliminary magnitude derived for that source is i = 22.04 +/- 0.24 mag (AB). The data were coadded with the Colibri pipeline and analyzed with STDWeb/STDPipe (Karpov 2021). The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitude is not corrected for Galactic extinction. Further observations are ongoing. We acknowledge the excellent support from the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/39920. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37937] GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate
by GCN Circulars 29 Mar '25

29 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39919 SUBJECT: GRB 250328A: VLT/HAWK-I near-infrared afterglow candidate DATE: 25/03/29 09:37:08 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> B. Schneider (LAM), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), G. Corcoran (UCD), report on behalf of the Stargate collaboration: We observed the location of the SVOM/ECLAIRs GRB 250328A (Brunet et al., GCN 39910) using the ESO/VLT UT4 (Yepun) equipped with the HAWK-I camera. Observations started on March 29 at 07:13:31 UT (14.3 hr after the SVOM trigger). A series of 15 images of 60 s were obtained in the J-band. Consistent with the location of the X-ray Swift/XRT [source #2](https://www.swift.ac.uk/SVOM/SVOM_FIELD00006/), we detect an object which is not visible in the Legacy Survey, at coordinates: RA(J2000) = 14:23:50.41 = 215.9601 Dec(J2000) = +25:55:55.0 = +25.9319 We measure J = 21.9 +/- 0.1 (AB) calibrated against nearby stars in the 2MASS catalogue. This object is a viable afterglow candidate for GRB 250328A, although we note that we lack deep enough reference imaging in the J band, and the X-ray light curve of XRT source #2 does not show obvious fading. Further observations are thus required to robustly confirm the nature of this NIR and X-ray source. We acknowledge excellent support from the ESO observing staff in Paranal. View this GCN Circular online at https://gcn.nasa.gov/circulars/39919. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37936] GRB 250329A: VLT/X-shooter redshift z = 2.921
by GCN Circulars 29 Mar '25

29 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39918 SUBJECT: GRB 250329A: VLT/X-shooter redshift z = 2.921 DATE: 25/03/29 08:38:33 GMT FROM: Antonio Martin-Carrillo at UCD,Space Science Group <antonio.martin-carrillo(a)ucd.ie> B. Schneider (LAM), G. Corcoran (UCD), E. Le Floc’h (CEA), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), N. R. Tanvir (Leicester), report on behalf of the Stargate collaboration: We observed the optical counterpart (Watson et al., GCN 39915, Wang et al. GCN 39917) of the SVOM/ECLAIRs GRB 250329A (Wang et al., GCN 39916) using the ESO/VLT UT3 (Melipal) equipped with the X-shooter spectrograph. In a 10-s r-band exposure taken with the acquisition camera (1.58 hr after the SVOM trigger), a source is well detected at the location of the counterpart reported by Watson et al., GCN 39915 with a magnitude r = 21.9 +/- 0.1 (AB, calibrated against a single Pan-STARRS object). Our measurement is consistent with Wang et al. GCN 39917 and confirms the fast fading nature of this source and its likely association with GRB 250329A. Our spectra, covering the wavelength range 3000-21000 AA, consist of 4 exposures of 600 s each. The observation mid time was on 2025 Mar 29.2611 UT (1.97 hr after the SVOM trigger). In a preliminary reduction of the spectra, a break is visible at ~4775 AA, which we identify as due to HI Lyman-alpha absorption. From the detection of multiple narrow absorption features, including OI, Si II, C II, Si IV, C IV, Fe II, Al II, Al III, Mg I, Ni II*, Fe II*, Mg II, Ca II, we infer a redshift of z = 2.921. We acknowledge excellent support from the ESO observing staff in Paranal, in particular Martina Baratella, Felipe Gaete, Rob van Holstein, and Vincent Megevand. We would like to thank especially the two visitors at UT3, Helmut Wiesemeyer and Mario van den Ancker for their patience while our observation was being taken. View this GCN Circular online at https://gcn.nasa.gov/circulars/39918. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37935] GRB 250329A: SVOM/VT optical counterpart confirmation
by GCN Circulars 29 Mar '25

29 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39917 SUBJECT: GRB 250329A: SVOM/VT optical counterpart confirmation DATE: 25/03/29 08:01:15 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> B.-T. Wang (YNAO, CAS), Y.H. Cheng (SWIFAR, YNU), W.J. Xie, L.P. Xin, Y. L. Qiu, H. L. Li, C. Wu (NAOC), J. T. Palmerio(CEA/Irfu), Z. H. Yao, Y. Xu, P. P. Zhang, J. Wang, X. H. Han, Y. J. Xiao, H. B. Cai, J. Y. Wei (NAOC) report on behalf of the SVOM team: SVOM performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Wang et al., GCN 39916). SVOM/VT began observing the field automatically with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. With VHF downlinked data, an uncatalogued source was found in VT_R channel, and fading for about 0.4 mag in the third and fourth sequences. The coordinates are R.A (J2000) =13:09:47.23 (197.44674 deg) DEC.(J2000) = +09:29:43.2 (+9.49532 deg) Error=0.5 arcseconds. The coordinates are consistent with the candidate reported (Watson et al., GCN 39915). The magnitude is VT_R=20.1+/- 0.04 mag(AB) and VT_B>22.0 mag(AB,3sigma) with the mid time of 1.25 hours after the burst. We propose it is possible a medium/high redshift GRB, given on red coulor (Wang et al., 2020). 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/39917. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37934] GRB 250329A: SVOM detection of a burst
by GCN Circulars 29 Mar '25

29 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39916 SUBJECT: GRB 250329A: SVOM detection of a burst DATE: 25/03/29 05:34:15 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> B.-T.Wang(YNAO, CAS), Y.H. Cheng (SWIFAR, YNU), W.J. Xie, D.H. Zhao (NAOC), C.W. Wang (IHEP), and D. Götz (CEA) on behalf of the SVOM mission team. At 2025-03-29T04:17:54 UTC (Tb) SVOM/ECLAIRs triggered on the gamma-ray burst GRB 250329A (SVOM burst-id sb25032901). 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 Count-Rate Trigger (CRT), which produced a sequence of 17 alerts. CRT provided the alert with the best signal-to-noise-ratio (SNR) of 37.28 in the [8-50] keV energy band over a time window of 5.10 seconds starting at Tb. The localization of the best alert is R.A., Dec 197.4374, 9.4849 degrees (J2000) with a 90% C.L.radius of 2.88 arcmin (including systematic error of 2 arcmin added in quadrature). The burst was also detected by GRM. The GRM light curve shows that this burst consists of a single main pulse. The SVOM/GRM lightcurve can be found here: https://www.bursthub.cn//admin/static/svgrb250329A.png SVOM slewed to the burst position. MXT began observing the field at 2025-03-29T04:20:20 UTC, 146 seconds after Tb. Using onboard processed data we found a faint uncatalogued X-ray source located at R.A., Dec 197.4168, 9.5412 degrees: RA (J2000) = 13h09m40s DEC (J2000) = 9d32m28s with a 90% C.L. radius of 2.5 arc minutes. This location is 3.59 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received. VT began observing the field after the slew. The analysis of the recorded images will be published in a future circular gathering information on the follow-up of the SVOM optical instruments. 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. The Burst Advocate (BA) on shift for this burst is Boting Wang: wangbaiting(a)ynao.ac.cn. Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/39916. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37933] GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate
by GCN Circulars 29 Mar '25

29 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39915 SUBJECT: GRB 250329A: SVOM/COLIBRÍ (F-GFT) Detection of a Bright Optical Counterpart Candidate DATE: 25/03/29 05:20:22 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Alan M. Watson (UNAM), Ramandeep Gill (UNAM), Sarah Antier (OCA/IJCLAB), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Francesco Magnani (CPPM), Diego López-Cámara (UNAM), Benjamin Schneider (LAM), Dalya Akl (AUS), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the SVOM/ECLAIRs GRB 250329A (sb25032901) with the DDRAGO wide-field imager on the SVOM/COLIBRÍ (F-GFT) telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico. We observed from 2025-03-29 04:18 to 04:55 UTC (55 to 2256 seconds after the trigger) and obtained 26 minutes of exposure in the i filter. The data were coadded with custom software and analyzed in STDWeb/STDPipe (Karpov 2024), with photometric calibration against Pan-STARRS DR1. Our photometry is in the AB system and is not corrected for Galactic extinction. Within the SVOM/ECLAIRs error box, we detect a bright uncatalogued source at RA = 197.44679 and Dec = 9.49533 (J2000) with a magnitude of i = 17.91 +/- 0.03 Further observations are planned. We warmly thank the COLIBRÍ and DDRAGO engineering teams and the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/39915. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37932] GRB 250327B: J-band observations with WINTER
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39914 SUBJECT: GRB 250327B: J-band observations with WINTER DATE: 25/03/28 20:44:14 GMT FROM: Geoffrey Mo at MIT <gmo(a)mit.edu> Geoffrey Mo (MIT), Benjamin Schneider (LAM), Tomas Ahumada (Caltech), Danielle Frostig (CfA), Viraj Karambelkar (Caltech), Robert Stein (UMD), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of GRB 250327B (Bouchet et al., GCN 39888) in the near-infrared J-band with the Palomar 1-m telescope, equipped with the 1-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations began under poor weather conditions at 2025-03-28T10:04:53 UTC (12.9 hours after the GRB), consisting of 13 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 and X-ray counterpart location (Moskvitin et al., GCN 39889; Xin et al., GCN 39890; O’Neill et al., GCN 39891; Malesani et al., GCN 39893; Lian et al., GCN 39894; Page et al., GCN 39895; Shrestha et al., GCN 39896; Duncoin et al., GCN 39897; Perley et al., GCN 39902; Kumar et al., GCN 39904; Dennefeld et al., GCN 39905; Pankov et al., GCN 39906; Pérez-Fournon et al., GCN 39912). We obtain the following 5-sigma upper limit: J ~ 17.5 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/39914. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37931] GRB 250327B: MASTER detection of OT rebrightening
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39913 SUBJECT: GRB 250327B: MASTER detection of OT rebrightening DATE: 25/03/28 20:43:27 GMT FROM: Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov(a)xray.sai.msu.ru> A.Tarasenkov, V.Lipunov, A.Kuznetsov, G.Antipov, K..Zhirkov, P.Balanutsa, N.Tyurina, E.Gorbovskoy, Ya.Kechin, A.Chasovnikov, V.Topolev, V.Senik, K.Labzina (Lomonosov MSU), C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA), D.Buckley (SAAO), A.Sosnovskij (Crao RAS), O.Gress, N.Budnev, O.Ershova (ISU), A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory), A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity), R.Rebolo (The Instituto de Astrofisica de Canarias), L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino,J.Martinez,A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory) MASTER-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina, started SVOM GRB 250327B (Bouchet et al. GCN 39888, Ttrigger=2025-03-27T21:11:27UT) at 2025-03-28 06:46:31UT with mlim=21m at 600s summary exposition. There is optical source with m_OT=19.9 +-0.3m(by GAIA reference stars) at two single images and at summary one at Moskvitin et al. (GCN 39889) position (also observed by SVOM/VT (GCN 39890), GOTO (GCN 398901), NOT (39893), Mephisto (GCN 39894), LCOGT (GCN 39896, GCN 39912, GCN 39904), COLIBRI (GCN 39897), LT (GCN 39902), OHP (GCN 39905), CrAO/SAORAS (GCN 39906)). that means rebrightening 9.5h after trigger time This message may by cited View this GCN Circular online at https://gcn.nasa.gov/circulars/39913. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37930] GRB 250327B: LCO optical counterpart detection
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39912 SUBJECT: GRB 250327B: LCO optical counterpart detection DATE: 25/03/28 18:04:55 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf(a)iac.es> I. Pérez-Fournon, F. Poidevin (IAC and ULL), D. Cano-Morales, I. Correa-Plasencia, A.E. Hernández-Díaz (ULL), and A. López-Oramas (IAC and ULL) We report Las Cumbres Observatory Global Telescope network (LCOGT) observations of GRB 250327B, detected by SVOM ECLAIRs and MXT (Bouchet et al., GCN circ. 39888) and VT (Xin et al., GCN circ. 39890) and Swift XRT (Page et al., GCN circ. 39895) at a redshift of z = 3.035 (Malesani et. al, GCN circ. 39893; Dennefeld et al., GCN circ. 39905). We observed the field of GRB 250327B with the two LCOGT 1-m telescopes, equipped with Sinistro cameras, located at the LCOGT node at Teide Observatory (Tenerife, Spain) in the SDSS r, g, and i filters, starting at 2025-03-27 23:55:43 UT, about 2.74 hours after the SVOM trigger. An uncatalogued source is clearly detected at the position of the optical counterpart reported by Moskvitin et al., GCN circ. 39889; Xin et al., GCN circ. 39890; O’Neill et al., GCN circ. 39891; Malesani et al., GCN circ. 39893; Lian et al., GCN circ. 39894; Shrestha et al., GCN circ. 39896; Ducoin et al., GCN circ. 39897; Perley and Bochenek, GCN circ. 39902; Kumar et al., GCN circ. 39904; Dennefeld et al., GCN circ. 39905; and Pankov et al., GCN circ. 39906). We measure the following magnitudes, calibrated against Pan-STARRS DR2 stars and not corrected for Galactic extinction: Date | UT start | mag | error | filter | exposure time (sec) --------------------------------------------------------------------- 2025-03-27 23:55:43 18.24 0.02 r 180 2025-03-28 00:31:11 20.07 0.06 g 180 2025-03-28 00:34:41 18.19 0.04 i 180 2025-03-28 02:12:57 18.79 0.06 i 180 2025-03-28 03:04:23 19.35 0.05 r 300 2025-03-28 03:09:13 21.25 0.14 g 180 This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF). View this GCN Circular online at https://gcn.nasa.gov/circulars/39912. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 37929] GRB 250328A: GWAC-F50A optical upper limit
by GCN Circulars 28 Mar '25

28 Mar '25

TITLE: GCN CIRCULAR NUMBER: 39911 SUBJECT: GRB 250328A: GWAC-F50A optical upper limit DATE: 25/03/28 17:58:43 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> L. P. Xin(NAOC), Y. G. Yang(HNU), X. H. Han, C. WU, Y. L. Qiu, J. Wang, H. L. Li, X .M. Lu, R. S. Zhang, Y. Xu, L. Huang, H. B. Cai, Y. J. Xiao, P. P. Zhang, L. Lan, W. J. Xie, Z. H. Yao, J. Y. Wei(NAOC), X. G. Wang, E. W. Liang(GXU) report on behalf of the SVOM/F50A team: We began to observe GRB 250328A (Brunet et al., GCN 39910) with 50cm telescope (GWAC-F50A) at Xinglong station, China, at 2025-03-28T16:59:19 (UT), about 145s after the burst. With the first observations with exposure time of 6*100 sec, no any uncatalogued source was detected in our stacked image down to a 3 sigma limit magnitude of 19.0 mag in R band, at the mid time of 7.5 min after the burst, comparing to several nearby USNO B1.0 stars. We acknowledge the excellent support from observation assistant Yangtong Zheng and Winlong Dong. View this GCN Circular online at https://gcn.nasa.gov/circulars/39911. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

2025

2024

2023

2022

2021

vsnet-grb-info March 2025