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

[vsnet-grb-info 39040] GRB 250706B: TRT bright optical counterpart detection
by GCN Circulars 06 Jul '25

06 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40991 SUBJECT: GRB 250706B: TRT bright optical counterpart detection DATE: 25/07/06 18:32:19 GMT FROM: Dong Xu at NAOC/CAS <dxu(a)nao.cas.cn> Z.P. Zhu (NAOC), K. Noysena, S. Tinyanont, K. Chanchaiworawit (NARIT), S.Q. Jiang, X. Liu, J. An, L.B. He, D. Xu (NAOC), S.Y. Fu (HUST) report on behalf of a large collaboration: We observed the field of GRB 250706B detected by SVOM/ECLAIRs (Palmerio et al., GCN 40989) using the 0.7-m telescope of the Thai Robotic Telescope network (TRT), located at New South Wales, Australia (SBO). Observations started at 17:41:58 UTC on 2025-07-06, i.e., 35.9 min after the SVOM trigger and a series of frames in the R band were obtained. An uncatalogued and varying optical transient is detected within the SVOM/MXT error circle (Palmerio et al., GCN 40989) at coordinates R.A. (J2000) = 02:44:55.45 Dec. (J2000) = -50:03:40.32 with an uncertainty of ~0.5 arcsec. It has R ~ 15.5 mag in the first R-band frame, calibrated with Legacy Survey DR-10 and not corrected for Galactic extinction. We thus think this is the optical afterglow of the GRB. View this GCN Circular online at https://gcn.nasa.gov/circulars/40991. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39039] GRB 250706A: GROWTH-India Telescope optical upper limit
by GCN Circulars 06 Jul '25

06 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40990 SUBJECT: GRB 250706A: GROWTH-India Telescope optical upper limit DATE: 25/07/06 18:21:04 GMT FROM: Varun Bhalerao at IIT Bombay <varunb(a)iitb.ac.in> T. Mohan, A.P. Saikia, A. Salgundi, V. Swain, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team: We observed the field of Swift GRB 250706A (Moss et al., GCN 40988), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2025-07-06 16:04:55 UT, i.e., 16.4 min after the GRB trigger. We obtained multiple exposures each in r' and g' filters. After performing image subtraction using PanSTARRS reference images, we do not detect any afterglow candidates at the XRT localization. The photometric upper limits are as follows: | MJD (mid) | Filter | tmid-t0 (min) | Exposure Time (sec) | Upper limit (AB) | | ------------ | ------ | ------------- | ------------------- | ---------------- | | 60862.670081 | r' | 18.9 | 300 | 20.0 | | 60862.682546 | g' | 34.4 | 300 | 20.3 | | 60862.699537 | r' | 61.3 | 300 | 20.5 | The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction. The result is consistent with Swift UVOT upper limit (Moss et al., GCN 40988). 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/40990. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39038] GRB 250706B: SVOM detection of a long burst
by GCN Circulars 06 Jul '25

06 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40989 SUBJECT: GRB 250706B: SVOM detection of a long burst DATE: 25/07/06 17:33:22 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Jesse Palmerio, Dylan Adrien, Nicolas Dagoneau (CEA), Marius Brunet (IRAP), Maria Grazia Bernardini (INAF-OAB, LUPM), Charlotte Van Hove (IJCLab), Pierre Maggi (ObAS) report on behalf of the SVOM mission team: At 2025-07-06T17:06:04 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250706B (SVOM burst-id sb25070609). 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 7 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 10.09 in the [5-20] keV energy band over a time window of 81.92 seconds starting at 2025-07-06T17:05:23. The localization of the best alert is R.A., Dec. 41.1337, -50.1172 degrees (J2000) with a 90% confidence level (C.L.) radius of 7.89 arcmin (including systematic error of 2 arcmin added in quadrature). SVOM slewed to the burst. SVOM/MXT began observing the field at 2025-07-06T17:08:42 UTC, 158 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 41.2300, -50.0621 degrees: R.A. (J2000) = 2h44m55.20s Dec. (J2000) = -50d03m43.51s with a 90% C.L. radius of 38 arcseconds. This location is 4.97 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 data will be published in a future circular. 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 Jesse Palmerio: palmerio(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/40989. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39037] GRB 250706A: Swift detection of a burst
by GCN Circulars 06 Jul '25

06 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40988 SUBJECT: GRB 250706A: Swift detection of a burst DATE: 25/07/06 16:05:46 GMT FROM: Mike Moss at NASA GSFC <mikejmoss3(a)gmail.com> M. J. Moss (GSFC), E. Ambrosi (INAF-IASFPA), R. Gupta (NASA GSFC), J. A. Kennea (PSU), A. Melandri (INAF-OAR), K. L. Page (U Leicester) and M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 15:48:30.96 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 250706A (trigger=1330958). Swift slewed immediately to the burst. The BAT on-board calculated location is RA, Dec 284.007, +32.287 which is RA(J2000) = 18h 56m 1.6s Dec(J2000) = +32d 17' 13" with an uncertainty of 3 arcmin (radius, 90% containment, including systematic uncertainty). The BAT light curve showed a complex structure with a duration of about 35 sec. The peak count rate was ~750 counts/sec (15-350 keV), at ~7 sec after the trigger. The XRT began observing the field at 15:50:53.1 UT, 142.2 seconds after the BAT trigger. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 284.01755, 32.32120 which is equivalent to: RA(J2000) = 18h 56m 04.21s Dec(J2000) = +32d 19' 16.3" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This location is 127 arcseconds from the BAT onboard position, within the BAT error circle. This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density consistent with the Galactic value of 1.20 x 10^21 cm^-2 (Willingale et al. 2013). The initial flux in the 2.5 s image was 5.25e-10 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of 250 seconds with the U filter starting 147 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18.0 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.093. Burst Advocate for this burst is M. J. Moss (mikejmoss3 AT gmail.com) Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/40988. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39036] GRB 250704B: Swift-XRT refined Analysis
by GCN Circulars 06 Jul '25

06 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40987 SUBJECT: GRB 250704B: Swift-XRT refined Analysis DATE: 25/07/06 11:00:24 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> C. Salvaggio (INAF-OAB), M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), S. Dichiara (PSU), J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi (INAF-IASF PA) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: We have analysed 3.3 ks of XRT data for GRB 250704B, from 2.0 ks to 97.7 ks after the Einstein Probe/WXT trigger. The data are entirely in Photon Counting (PC) mode. Using 1717 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 300.87238, +12.02301 which is equivalent to: RA (J2000): 20h 03m 29.37s Dec(J2000): +12d 01' 22.9" with an uncertainty of 2.7 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=0.9 (+0.4, -0.3). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.96 (+0.16, -0.13). The best-fitting absorption column is consistent with the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.6 x 10^-11 (4.3 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.47 (+/-0.25) x 10^21 cm^-2 Galactic foreground: 1.5 x 10^21 cm^-2 Excess significance: <1.6 sigma Photon index: 1.96 (+0.16, -0.13) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00019908. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40987. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39035] GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope
by GCN Circulars 05 Jul '25

05 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40986 SUBJECT: GRBs 250702B,C,D,E / EP250702a: J band upper limit by SYSU 80cm infrared telescope DATE: 25/07/06 04:15:00 GMT FROM: lixia76(a)mail2.sysu.edu.cn Xia Li, Chun Chen, Zhong-nan Dong, Duo-le Cao, Wei-Sen Huang, Jin-Ji Li, Jia-Qi Lin, Pu Lin, Yan Yu, Hao-Nan Yang, Hao-Ran Zhang, Xiang-Tao Zeng, P H Thomas Tam, Rong-Feng Shen, Bin Ma (Sun Yat-sen University) report on behalf of the SYSU 80cm infrared telescope team: We observed the field of GRBs 250702B,C,D,E / EP250702a (H. Q. Cheng et al., GCN 40906; Y. Kawakubo et al., GCN 40910; D. Frederiks et al., GCN 40914; H. Q. Cheng et al., GCN 40917; J. A. Kennea et al., GCN 40919; Chen-Wei Wang et al., GCN 40923; E. Neights et al., GCN 40931) using the Sun Yat-sen University 80cm infrared telescope with 58 x 20 s exposures in J band. The calculated position is RA. = 18:58:45.61, DEC =-07:52:26.9 J2000, from Swift/XRT observation (J. A. Kennea et al., GCN 40919). Our observations began at 2025-7-3 19:36:00 UTC (29.67 hours after the first Fermi trigger, GRB 250702B). We do not detect any optical counterpart (A. Kumar et al., GCN 40908; V.Lipunov et al., GCN 40912; Rosa L. Becerra et al., GCN 40918; I. Pérez-García et al., GCN 40929; Yan-Long Hua et al., GCN 40943; Malte Busmann et al., GCN 40949; M. H. Siegel, GCN 40952) at the position of the near-infrared afterglow (A. Martin-Carrillo et al., GCN 40924; A. J. Levan et al., GCN 40961), down to a 5-sigma depth of J~ 17.5 Vega magnitudes. The SYSU 80cm infrared telescope is operated and managed by the Department of Astronomy, Sun Yat-sen University. View this GCN Circular online at https://gcn.nasa.gov/circulars/40986. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39034] EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart
by GCN Circulars 05 Jul '25

05 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40985 SUBJECT: EP250702a/GRB250702 B,E,D: MeerKAT radio counterpart DATE: 25/07/05 23:18:15 GMT FROM: Joe Bright at U of Oxford <joe.bright(a)physics.ox.ac.uk> Authors: J. Bright (Oxford), F. Carotenuto (INAF, Rome), P. G. Jonker (Radboud), on behalf of a larger collaboration We observed the field of EP250702a (GCN 40906; associated with GRBs 250702/B/D/E) with the MeerKAT radio telescope from 2025-07-04 17:37:32 UTC to 2025-07-04 18:39:55 UTC (with a total time on source of 44 minutes) using the S band receiver at a central frequency of 3.06 GHz. Analysing the SARAO Science Data Processor output continuum image we detect a source at the position of EP250702a with a flux density of around 100uJy/beam, with a typical image noise of around 8uJy/beam. Our detection is consistent with the upper limit reported by the Allen Telescope Array (GCN 40979). Under the assumption of a source distance of 10 kpc we infer a radio luminosity of around 3.5e28 erg/s, consistent with X-ray binaries during the less luminous phases of their outburst cycles. The extragalactic/galactic nature of EP250702a is therefore not clarified by these observations. Further observations will be conducted to check for variability. We thank the SARAO staff for rapidly scheduling these observations. The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. This work has made use of the "MPIfR S-band receiver system" designed, constructed and maintained by funding of the MPI für Radioastronomie and the Max-Planck-Society. View this GCN Circular online at https://gcn.nasa.gov/circulars/40985. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39033] GRB 250703A: EIRSAT-1 GMOD Detection
by GCN Circulars 05 Jul '25

05 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40984 SUBJECT: GRB 250703A: EIRSAT-1 GMOD Detection DATE: 25/07/05 22:38:57 GMT FROM: Laura Cotter at University College Dublin <laura.cotter(a)ucdconnect.ie> L. Cotter,C. McKenna, D. Murphy, C. de Barra, A. Ulyanov, P. McDermott, G. Finneran, M. Doyle, R. Dunwoody, J. Mangan, G. Corcoran, A. Empey, J. Fisher, F. Gibson Kiely, J. Thompson, D. McKeown, A. Martin-Carrillo, L. Hanlon, S. McBreen, on behalf of the EIRSAT-1 team: EIRSAT-1 reports the detection of the long gamma-ray burst GRB250703A (Fermi-GBM detection GCN 40909; IPN localization GCN 40976; Kounus Wind GCN 40977) by the Gamma-ray Module (GMOD) instrument. The GMOD detection was made, starting at 2025-07-03 09:07:31.6 UTC. The GMOD light-curve for GRB250703A with 1.2s binning shows a single bright pulse starting at 09:07:31.6 UTC, also visible on the Fermi light-curve. The spacecraft location at the time of detection was 47.364º N, 32.160º E, at an altitude of 361.2 km. The GMOD light curve for this event can be found here: [https://grb.eirsat1.ie/250703A/250703A_LC_onboard_preliminary.png]() EIRSAT-1 is Ireland’s first satellite (Doyle et al. Proceedings of the 4th SSEA, 2022). It is a 2U CubeSat and carries onboard a number of experiments, including the Gamma-Ray Module (GMOD), a novel, compact, gamma-ray detector (Murphy et al, Experimental Astronomy, 53, 961–990, 2022). GMOD consists of a 25 mm × 25 mm × 40 mm Cerium Bromide scintillator coupled to SiPMs and is designed to detect gamma-ray bursts in the ~ 60 keV - 1.5 MeV range. EIRSAT-1 was developed at University College Dublin with support from ESA’s Fly Your Satellite! programme and was launched on 1st December 2023. View this GCN Circular online at https://gcn.nasa.gov/circulars/40984. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39032] EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST
by GCN Circulars 05 Jul '25

05 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40983 SUBJECT: EP250702a/GRB 250702B,C,D,E: Archival radio observations from ASKAP VAST DATE: 25/07/05 22:26:12 GMT FROM: akashjanaki98(a)gmail.com Akash Anumarlapudi (UNC Chapel Hill), David Kaplan (UWM), Igor Andreoni (UNC Chapel Hill), Dougal Dobie (U. Sydney/OzGrav), Tara Murphy (U. Sydney) on behalf of the VAST collaboration. Fermi Gamma-ray Burst Monitor (GBM) reported the discovery of four possible long-durational GRBs, GRB 250702B,C,D,E, that might likely be coming from the same source (GCN #40891). Further X-ray observations by the Einstein Probe (EP; GCN #40906), MAXI (GCN #40910), Konus-WIND (GCN #40914), and SVOM (GCN #40923) resulted in the discovery of an X-ray counterpart. Data from the Wide-field X-ray Telescope (WXT) aboard EP revealed that the source was active in X-rays even a day before the Fermi GBM discovery. Follow-up observations from the Follow-up X-ray Telescope on EP (FXT, GCN #40906) constrained the position of the source to 20 arcseconds (90% confidence). No optical counterparts were reported down to i=22.0 (GCN #40918), but infrared observations have resulted in the discovery of a candidate counterpart (GCN #40924) with Ks~17.3 Vega, which is very red in color and rapidly fading (GCN #40961). Subsequent analysis of GBM data suggested that the burst GRB 250702C is likely not related to GRB 250702 B/D/E, but an unrelated short GRB (GCN #40931). Here we report the archival radio observations of this source taken at the Australian SKA Pathfinder (ASKAP) observations as part of the Variable And Slow Transients Survey (VAST; Murphy et al. 2021) at 887.5 MHz. The position of the source was observed for 13 epochs, roughly with a two-week cadence between March 2024 and December 2024. Each observation lasted approximately 12 minutes, reaching a sensitivity (noise level) of 250 uJy. The source was not detected in any of the single-epoch images. We stacked the individual exposures, which also resulted in a non-detection. The 1-sigma noise level at the location of the source is 75 uJy, and hence we place a limit on the persistent radio flux density (5-sigma) of the source to be < 375 uJy. View this GCN Circular online at https://gcn.nasa.gov/circulars/40983. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39031] GRB 250704B: Swift/UVOT Upper Limits
by GCN Circulars 05 Jul '25

05 Jul '25

TITLE: GCN CIRCULAR NUMBER: 40982 SUBJECT: GRB 250704B: Swift/UVOT Upper Limits DATE: 25/07/05 18:41:26 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) reports on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250704B 2.0 ks after the SVOM/GRM trigger (Wang et al., GCN Circ. 40940). No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 40951) or the reported optical counterparts (Malesani et al., GCN Circ. 40945; Gillanders et al., GCN Circ. 40958; Xin et al., GCN Circ. 40960) is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) are: Filter T_start(s) T_stop(s) Exp(s) Mag u 2024 7891 1944 20.02+/-0.12 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.115 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40982. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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