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

[vsnet-grb-info 42874] AT 2026nuz: COLIBRÍ optical observations
by GCN Circulars 30 May '26

30 May '26

TITLE: GCN CIRCULAR NUMBER: 44745 SUBJECT: AT 2026nuz: COLIBRÍ optical observations DATE: 26/05/30 16:56:24 GMT FROM: Alan Watson at UNAM <alan(a)astro.unam.mx> Francesco Magnani (CPPM), Margarita Pereyra (UNAM), Alan M. Watson (UNAM), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Enrique Moreno Méndez (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), and Antonio de Ugarte Postigo (LAM) report: We imaged the field of the AT 2026nuz (Habeeb et al., GCN Circ. 44737) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-05-30 08:34 to 11:17 UTC (from 30.4 to 32.4 hours after the trigger for GRB 260529A; Fermi GBM team, GCN 44733) and obtained 30, 30, 62, and 122 minutes of exposure in the g, r, i, and z filters. 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 detected the optical transient AT 2026nuz reported by Habeeb et al. (GCN Circ. 44737) at preliminary magnitudes of: g = 18.29 +/- 0.01 r = 18.32 +/- 0.01 i = 18.46 +/- 0.01 z = 18.51 +/- 0.01 The blue colors suggest that this is not the afterglow of GRB 260529A but could be CV, as suggested by Habeeb et al., or possibly an FBOT. That said, in addition to the reasons given by Habeeb et al., the lack of an obvious host in Legacy Survey imaging (Dey et al. 2019) argues against this being an FBOT. Nevertheless, we encourage spectroscopic observation to determine the nature of this source. 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/44745. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42873] IPN triangulation of GRB 260527A / EP260527a
by GCN Circulars 30 May '26

30 May '26

TITLE: GCN CIRCULAR NUMBER: 44744 SUBJECT: IPN triangulation of GRB 260527A / EP260527a DATE: 26/05/30 14:35:28 GMT FROM: Dmitry Svinkin at Ioffe Institute <dmitrysvinkin(a)gmail.com> A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin on behalf of the HEND/Mars Odyssey team, D. Svinkin, D. Frederiks, A. Lysenko, A. Ridnaia, and T. Cline on behalf of the Konus-Wind team, E. Burns on behalf of the IPN, Y. Kawakubo, A. Yoshida, T. Sakamoto, S. Sugita (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC), M. L. Cherry (LSU), S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena), on behalf of the CALET collaboration, Chen-Wei Wang (IHEP), Shao-Lin Xiong (IHEP), Shuang-Nan Zhang (IHEP) on behalf of the Insight-HXMT team, Zheng-Hang Yu, Chen-Wei Wang, Shao-Lin Xiong, Chao Zheng, Cheng-Kui Li (IHEP) on behalf of GECAM team, and W. Boynton, C. Fellows, K. Harshman, H. Enos, R. Starr, and A.S. Gardner on on behalf of the GRS-Odyssey GRB team, report: The short-duration GRB 260527A (Konus-Wind detection: Svinkin et al., GCN 44722; GECAM-B detection: Yu et al., GCN 44724; CALET-GBM detection: Kawakubo et al., GCN 44726; Insight-HXMT detection: Wang et al., GCN 44735) was detected by Konus-Wind, CALET (GBM trigger 1463897683), GECAM-B, Insight-HXMT(HE), and Mars-Odyssey (HEND) at about 22570 s UT (06:16:10). We have triangulated it to a preliminary, 3 sigma error box whose coordinates are: --------------------------------------------- RA(2000), deg Dec(2000), deg --------------------------------------------- Center: 192.924 (12h 51m 42s) +1.318 ( +1d 19' 03") Corners: 192.308 (12h 49m 14s) +0.301 ( +0d 18' 02") 192.793 (12h 51m 10s) +1.224 ( +1d 13' 25") 193.417 (12h 53m 40s) +2.085 ( +2d 05' 08") 193.052 (12h 52m 13s) +1.406 ( +1d 24' 23") --------------------------------------------- The error box area is 457 sq. arcmin, and its maximum dimension is 2.1 deg (the minimum one is 6.4 arcmin). The Sun distance was 125 deg. This localization may be improved. The fast X-ray transient EP260527a (Yang et al., GCN 44718) is inside the box strengthen the association of the transient and GRB 260527A. A triangulation map is posted at http://www.ioffe.ru/LEA/GRBs/GRB260527_T22572/IPN/ View this GCN Circular online at https://gcn.nasa.gov/circulars/44744. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42872] EP260527a/GRB 260527A: further FTW optical and NIR observations
by GCN Circulars 30 May '26

30 May '26

TITLE: GCN CIRCULAR NUMBER: 44743 SUBJECT: EP260527a/GRB 260527A: further FTW optical and NIR observations DATE: 26/05/30 13:40:09 GMT FROM: Ziyuan.Zhu(a)campus.lmu.de Ziyuan Zhu (LMU), Malte Busmann (LMU), Brendan O'Connor (CMU), Julius Gassert (LMU/CMU), Daniel Gruen (LMU), Xander Hall (CMU), and Antonella Palmese (CMU) report: We observed the counterpart of EP260527a/GRB 260527A (Yang et al., GCN 44718; Aguilar-Ruiz et al., GCN 44719; Li et al., GCN 44720; Svinkin et al., GCN 44722; Yu et al., GCN 44724; Yang et al., GCN 44725; Kawakubo et al., GCN 44726; Mo et al., GCN 44727; Busman et al., GCN 44728) with the Three Channel Imager (3KK) at the Fraunhofer Telescope at Wendelstein Observatory (FTW) in the r, i, and J bands for 48x 180s starting at starting at 2026-05-29 20:47 UT (2.6 days after the trigger). In the r band, we do not detect the counterpart down to a limiting magnitude of r > 24.0 AB mag. The magnitude is calibrated against the PS1 catalog and not corrected for Galactic extinction. We thank Christoph Ries from the Wendelstein Observatory for obtaining these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/44743. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42871] GRB 260530B: SVOM/GRM detection of a possible bright short GRB
by GCN Circulars 30 May '26

30 May '26

TITLE: GCN CIRCULAR NUMBER: 44742 SUBJECT: GRB 260530B: SVOM/GRM detection of a possible bright short GRB DATE: 26/05/30 13:26:56 GMT FROM: Chenwei Wang at IHEP <cwwang(a)ihep.ac.cn> SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Marius Brunet (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered in-flight by a bright short burst GRB 260530B (SVOM trigger reference: sb26053001) at 2026-05-30T06:00:05.600 UTC (T0). 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 symmetrical smooth pulse with a T90 of 1.55 +0.20/-0.15 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb260530B.png ECLAIRs was not collecting data at the time of this burst. We note that this signal was detected near the NWC transmitter and may be associated with the artificial electron belt, so it is not yet clear whether it is a genuine astrophysical burst. 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: Chen-Wei Wang (IHEP)(cwwang(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/44742. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42870] GRB 260530A: Fermi GBM Final Real-time Localization
by GCN Circulars 30 May '26

30 May '26

TITLE: GCN CIRCULAR NUMBER: 44741 SUBJECT: GRB 260530A: Fermi GBM Final Real-time Localization DATE: 26/05/30 06:21:32 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 06:10:52 UT on 30 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260530A (trigger 801814257.752724 / 260530258). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 93.0, Dec = 12.7 (J2000 degrees, equivalent to J2000 06h 12m, 12d 41'), with a statistical uncertainty of 6.4 degrees. The angle from the Fermi LAT boresight is 87.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260530258/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260530258/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260530258/… View this GCN Circular online at https://gcn.nasa.gov/circulars/44741. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42869] GRB 260527A / EP260527a: VLA radio detection
by GCN Circulars 29 May '26

29 May '26

TITLE: GCN CIRCULAR NUMBER: 44740 SUBJECT: GRB 260527A / EP260527a: VLA radio detection DATE: 26/05/29 16:53:30 GMT FROM: Genevieve Schroeder at Cornell University <genevieveschroeder(a)u.northwestern.edu> G. Schroeder (Cornell), J. Rastinejad (UMD), W. Fong (Northwestern) report: We observed the location of the short-duration GRB 260527A / EP260527a (Yang et al. GCN 44718, Svinkin et al. GCN 44722, Yu et al. GCN 44724) with the Karl G. Jansky Very Large Array (VLA) in A configuration under program 26A-062 (PI Schroeder) at a mid time of 2026 May 29 at 04:47 UT (1.9 days post-burst) for 0.75 hours at a mean frequency of 6 GHz. In preliminary analysis, we detect a 3-sigma radio source with a flux density of ~50 microJy at the position: RA(J2000) = 12:52:13.141 Dec(J2000) = +01:28:56.47 with an uncertainty of ~0.1" in each coordinate. This position is offset by ~0.4" from the optical counterpart (Aguilar-Ruiz et al. GCN 44719). At the proposed event redshift of z=0.8 (Yang et al. GCN 44736), this corresponds to a rest-frame luminosity of ~ 9e29erg/s/Hz, on the bright end of typical short-duration Gamma-ray burst radio afterglow luminosities at a similar rest-frame time (e.g., Laskar et al. 2022, Anderson et al. 2025, Belkin et al. 2026). Further observations are planned to assess the variability of the radio source and its connection to GRB 260527A and EP260527a. We thank the VLA staff for quickly approving and executing these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/44740. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42868] EP260527a/GRB 260527A: optical upper limit with Kinder observations
by GCN Circulars 29 May '26

29 May '26

TITLE: GCN CIRCULAR NUMBER: 44739 SUBJECT: EP260527a/GRB 260527A: optical upper limit with Kinder observations DATE: 26/05/29 15:40:44 GMT FROM: Amar Aryan at National Central University, Institute of Astronomy (NCUIA) <amararyan941(a)gmail.com> K. N.-T. Ho, A. Aryan, T.-W. Chen, W.-J. Hou, H.-Y. Hsiao (all NCU), A. K. H. Kong (NTHU), S. J. Smartt, J. Gillanders (both Oxford), S. Yang(HNAS), Y.-H. Lee, A. Sankar.K, M.-H. Lee, A. Dutta, Y.-C. Pan, C.-C. Ngeow, C.-H. Lai, H.-C. Lin, C.-S. Lin, J.-K. Guo (all NCU), Z. N. Wang, D. C. Qiang, L. L. Fan (all HNAS), Y. J. Yang (NYUAD), H.-W. Lin (UMich), H. F. Stevance, S. Srivastav, L. Rhodes (all Oxford), M. Nicholl, M. Fulton, K. W. Smith, C. Angus, A. Aamer (all QUB), T. Moore (STScI), A. Schultz and M. Huber (both IfA, Hawaii) report: We observed the field of the fast X-ray transient EP260527a (Yang et al., GCN 44718, GCN 44725; Svinkin, GCN 44722; Yu et al., GCN 44724; Kawakubo et al., GCN 44726; Wang et al., GCN 44735) using the 1m LOT at the Lulin Observatory in Taiwan as part of the Kinder collaboration (Chen & Yang et al., 2025, ApJ, 983, 86). The first SLT epoch of observations started at 16:02 UTC on 28th May 2026 (MJD 61188.6683), 33.71 hr after the EP-WXT trigger. We utilized the astroalign (Beroiz et al. 2020, A&C, 32, 100384) and astropy (Astropy Collaboration et al. 2022, ApJ, 935, 167) packages to align and stack the individual frames. Neither in the individual frames nor in the stacked frame did we detect the reported optical/NIR counterpart candidate (Aguilar-Ruiz et al., GCN 44719; Li et al., GCN 44720; Mo et al., GCN 44727; Busmann et al., GCN 44728; Corcoran et al., GCN 44729; Kabir et al., GCN 44730; O'Connor et al., GCN 44731; Yang et al., GCN 44736). The details of the observations and measured PSF magnitude with template subtraction (in the AB system) of the possible counterpart of EP260507a are as follows: -------------------------------------------------------------------------------------------------- Telescope | Filter | MJD (start) | t-t0 (hr) | Exposure (s) | Magnitude | avg. Seeing | med. Airmass LOT | r | 61188.6683 | 33.71 | 120 * 15 | >21.1 | 1".24 | 2.02 The presented magnitudes are calibrated using the field stars from the Pan-STARRS catalogue. The reported upper limit is not corrected for an expected galactic extinction of A_r = 0.04 mag, in the direction of the transient (Schlafly & Finkbeiner 2011). The methodology, details on the Lulin observatory telescopes, and a compilation of our optical follow-up campaign for FXTs discovered within the first year of operation of the Einstein-Probe mission are presented in Aryan et al. 2025, ApJS, 281, 20, doi:10.3847/1538-4365/adfc69. View this GCN Circular online at https://gcn.nasa.gov/circulars/44739. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42867] GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate
by GCN Circulars 29 May '26

29 May '26

TITLE: GCN CIRCULAR NUMBER: 44738 SUBJECT: GRB 260429B / EP260429a: COLIBRÍ optical counterpart candidate DATE: 26/05/29 15:17:32 GMT FROM: F. Fortin at IRAP <ffortin.sci.edu(a)gmail.com> Francis Fortin (IRAP), Enrique Moreno Méndez (UNAM), Rosa L. Becerra (UNAM), 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), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), 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), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM) report: We reimaged the field of GRB 260429B / EP260429a (Wang et al., GCN Circ. 44426, Arya et al., GCN Circ. 44443) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-05-27 06:34 to 08:42 UTC (from 27.7 to 27.8 days after the trigger) and obtained 1.57 hours of exposure in the r and z filters. The data were reduced and coadded with the ASU COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. By comparing these observations with our first epoch reported by Fortin et al. (GCN Circ. 44434), we found that an uncatalogued optical source located at: RA (J2000) = 240.58812 (16:02:21.15) Dec (J2000) = -9.60116 (-09:36:04.2) and with an uncertainty of 0.5”, is no longer detected in this second epoch down to the following (3-sigma) limits: r > 23.90 z > 23.07 In our first epoch, for this source, we measured: r = 21.95 +/- 0.05 z = 21.08 +/- 0.04 Given the fading nature of the source, the spatial coincidence with the source EPF J160221.2-093607 reported in by the EP team (Wang et al., GCN Circ. 44445), and the absence of any known minor planet at this position, we suggest this is the optical counterpart of GRB 260429B / EP260429a. 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/44738. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42866] GRB 260529A: GOTO tentative optical afterglow candidate
by GCN Circulars 29 May '26

29 May '26

TITLE: GCN CIRCULAR NUMBER: 44737 SUBJECT: GRB 260529A: GOTO tentative optical afterglow candidate DATE: 26/05/29 12:21:36 GMT FROM: Nusrin Habeeb at University of Leicester <nh312(a)leicester.ac.uk> N. Habeeb, A. Kumar, D. O’Neill, R. Starling, B. Gompertz, G. Ramsay, S. Belkin, K. Ackley, M. Dyer, J. Lyman, K. Ulaczyk, D. Steeghs, D. Galloway, V. Dhillon, P. O'Brien, K. Noysena, R. Kotak, R. Breton, J. Casares, L. Nuttall, B. Godson, T. Killestein, M. Pursiainen, on behalf of the GOTO collaboration We report on optical observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022, Dyer et al. 2024) in response to the Fermi/GBM detected GRB 260529A (fermi_801715802, Fermi GBM team, GCN 44733). Observations covering the GBM localization began at 2026-05-29 03:00:27 UT (+0.18h post trigger) and continued through to 2026-05-29 04:55:50 UT(+2.10 h post trigger). Images consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline (Lyman et al. 2026) and difference imaging was performed using deeper template observations. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs. Human vetting was carried out in real time on any candidates that passed the above checks. A new optical transient, GOTO26fez (AT 2026nuz), is identified within the 90% localization region of the Fermi/GBM trigger. The source was detected in the GOTO L-band with magnitudes of 17.85 ± 0.06 and 17.90 ± 0.04 AB mag at +0.23 h and +1.3 h post-trigger, respectively. We would like to caution that, given the source location close to the Galactic plane, we cannot exclude the possibility that the transient is of Galactic origin, such as a stellar flare or a CV. We find no evidence of this source prior to the GRB trigger time in previous GOTO observations, in the archival ATLAS forced photometry server (Shingles et al. 2021) to a magnitude limit of m_o > 18.06 AB mag ~26.3h prior to the trigger, nor in archival ZTF observations provided by the Lasair broker (Smith et al. 2019). We note, however, that the most recent pre-trigger observations from GOTO were obtained approximately one month prior to the burst, and therefore do not provide constraints on shorter-timescale pre-burst variability. GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester, the University of Birmingham and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/44737. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 42865] GRB 260527A/EP260527a: VLT/X-shooter tentative redshift
by GCN Circulars 29 May '26

29 May '26

TITLE: GCN CIRCULAR NUMBER: 44736 SUBJECT: GRB 260527A/EP260527a: VLT/X-shooter tentative redshift DATE: 26/05/29 10:15:04 GMT FROM: Yu-Han Yang at University of Rome Tor Vergata <yyang(a)roma2.infn.it> Y.-H. Yang, E. Troja, M. El Kabir (U Rome) report on behalf of the ERC BHianca team: We observed the field of EP260527a (Yang et al., GCN 44718), likely associated with the short GRB 260527A (Svinkin et al., GCN 44722, Yu et al., GCN 44724; Kawakubo et al., GCN 44726, Wang et al., GCN 44735) with the X-shooter spectrograph on the ESO Very Large Telescope (VLT). Observations were performed beginning at 41 hours after the GRB trigger, at an average airmass of 1.3 and in excellent conditions. Our spectra cover the wavelength range 3000-25000 AA, and consist of 4x600 s exposures. Using a nearby bright star for blind offsets, we placed the 1 arcsec slit at the position of the optical counterpart (Aguilar-Ruiz et al., GCN 44719; Li et al., GCN 44720; Busmann et al.44728; Corcoran et al. GCN 44729, El Kabir et al. GCN 44730, O’Connor et al. GCN 44731). Based on a preliminary analysis, we report the identification of weak emission features consistent with the [OII] 3727 doublet at z ~ 0.80, which we propose as the tentative redshift of the EP transient and its underlying host galaxy. Further observations to confirm this value are planned. We thank the staff at the VLT for the rapid execution of these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/44736. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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