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

[vsnet-grb-info 39200] SVOM J195836+32283/sb25072103: Second VT observation
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41144 SUBJECT: SVOM J195836+32283/sb25072103: Second VT observation DATE: 25/07/23 16:24:40 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> L. P. Xin, Y. L. Qiu, C. Wu, H. L. Li, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei, D.H. Zhao (NAOC), J. Palmerio (CEA) report on behalf of the SVOM team: SVOM/VT performed a second ToO observation for the galactic transient SVOM J195836+32283 (sb25072103) (Gotz et al., GCN 41131) detected by SVOM/MXT. The VT conducted observations between July 22, 2025, 11:23:37 UT and 15:18:41 UT, from 26.7 hours 30.6 hours after trigger time in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. For the optical source identified in VT observation (Gotz et al., GCN 41131), its brightness was 22.2+/-0.3 mag in our second observations. No apparent variability was detected compared to the first VT observation. Given the constant brightness in our twice observations, it is likely that this object is the extended source as noticed by Mo et al. (GCN 41138) and Eyles-Ferris et al. (GCN 41143). 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/41144. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39199] SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41143 SUBJECT: SVOM J195836+32283/sb25072103: Liverpool Telescope detection of an extended source DATE: 25/07/23 14:57:46 GMT FROM: Rob Eyles-Ferris at U of Leicester <raje1(a)leicester.ac.uk> R. A. J. Eyles-Ferris and N. Habeeb (U of Leicester) report on behalf of a larger collaboration: We observed the field of the SVOM transient SVOM J195836+32283 / sb25072103 (Götz et al., GCN 41131) with the 2m Liverpool Telescope using the IO:O instrument. We obtained 6x150s exposures in each of the SDSS g’, r’, i’ and z’ filters starting at 23:43:39 UT on 2025-07-22, approximately 41 hours after the ECLAIRs trigger. No sources consistent with the SVOM/VT position are identified in the g’ or r’ images and we obtain 3-sigma upper limits of g’ > 22.7 and r’ > 22.9 calibrated to Pan-STARRS and not corrected for Galactic extinction. In the i’ and z’ images, we do identify a source, the morphology of which is inconsistent with a single point source. Instead, it appears to be extended, consistent with the suggestion of Mo et al. (GCN 41138), or may be a combination of several components. We measure i’ = 22.9 +/- 0.3 and z’ = 21.9 +/- 0.2 for the source, again calibrated to Pan-STARRS and not corrected for Galactic extinction. The relative contributions of the transient and possible host to this flux are currently unknown and we encourage further observations of this source. View this GCN Circular online at https://gcn.nasa.gov/circulars/41143. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39198] GRB 250723B: Fermi GBM Final Real-time Localization
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41142 SUBJECT: GRB 250723B: Fermi GBM Final Real-time Localization DATE: 25/07/23 14:56:17 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 14:45:37 UT on 23 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250723B (trigger 774974742.499166 / 250723615). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 358.0, Dec = 50.6 (J2000 degrees, equivalent to J2000 23h 52m, 50d 36'), with a statistical uncertainty of 3.1 degrees. The angle from the Fermi LAT boresight is 114.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250723615/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250723615/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250723615/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41142. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39197] GRB 250721A: Fermi GBM Observation
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41141 SUBJECT: GRB 250721A: Fermi GBM Observation DATE: 25/07/23 14:43:37 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 09:37:46.53 UT on 21 July 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250721A (trigger 774783471/250721401). which was also detected by MAXI (M. Nakajima et al. 2025, GCN 41129). The Fermi GBM on-ground location is consistent with the MAXI position. The angle from the Fermi LAT boresight is 70 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 54 s (50-300 keV). The time-averaged spectrum from T0-3.1 to T0+1.5 s is best fit by a simple power law function with index -1.46 +/- 0.07. The event fluence (10-1000 keV) in this time interval is (9.8 +/- 1.6)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.5 s in the 10-1000 keV band is 1.7 +/- 0.2 ph/s/cm^2. The spectral analysis results presented above are preliminary; final results will be published in the GBM GRB Catalog: https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html For Fermi GBM data and info, please visit the official Fermi GBM Support Page: https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/" View this GCN Circular online at https://gcn.nasa.gov/circulars/41141. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39196] GRB 250723A: Fermi GBM Final Real-time Localization
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41140 SUBJECT: GRB 250723A: Fermi GBM Final Real-time Localization DATE: 25/07/23 13:23:34 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 13:13:04 UT on 23 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250723A (trigger 774969189.599836 / 250723551). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 65.3, Dec = 38.4 (J2000 degrees, equivalent to J2000 04h 21m, 38d 23'), with a statistical uncertainty of 6.2 degrees. The angle from the Fermi LAT boresight is 54.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250723551/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250723551/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250723551/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41140. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39195] SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41139 SUBJECT: SVOM J195836+32283/sb25072103: Swift XRT/UVOT upper limits DATE: 25/07/23 12:34:20 GMT FROM: noelklin(a)umbc.edu Noel Klingler (NASA-GSFC / UMBC / CRESST II), Brendan O'Connor (CMU), and Alexander Lange (GWU) report: Swift has performed follow-up observations of SVOM J195836+32283 / sb25072103 (Götz et al; GCN Circ. 41131) between 2025-07-22T14:24:46 and 2025-07-22T14:40:52, which corresponds to 106.9 ks and 107.9 ks post-trigger. The XRT collected 956 s of data. No counts (0.3-10 keV) are detected within a 25 arcsecond radius of the SVOM/MXT position (19h 58m 36s, +32° 28’ 20”). The UVOT collected 950 s of data in the U-band. No source is seen at the position obtained by SVOM/VT (19h 58m 36.29s, +32° 28’ 25.7”); the 3 sigma limiting magnitude (AB) is 21.55. View this GCN Circular online at https://gcn.nasa.gov/circulars/41139. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39194] SVOM J195836+32283/sb25072103: NIR observations with WINTER
by GCN Circulars 23 Jul '25

23 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41138 SUBJECT: SVOM J195836+32283/sb25072103: NIR observations with WINTER DATE: 25/07/23 01:26:48 GMT FROM: Geoffrey Mo at MIT <gmo(a)mit.edu> Geoffrey Mo (MIT), Tomas Ahumada (Caltech), Viraj Karambelkar (Caltech), Benjamin Schneider (LAM), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report: We observed the field of SVOM J195836+32283 (Götz et al., GCN 41131) in the near-infrared J and Hs bands with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024). Observations began at 2025-07-22T03:36:20 UTC in the J band and 2025-07-22T04:09:09 in the Hs band (~19 hours after the SVOM trigger), consisting of 15 x 120 s and 30 x 60 s exposures respectively. 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 any source at the SVOM/VT optical candidate location (Götz et al., GCN 41131). We obtain the following 5-sigma upper limits: J ~ 18.1 mag, Hs ~ 18.4 mag (AB). We note the presence of a faint, unresolved, possibly extended source at the position of the SVOM/VT candidate in archival UKIRT UKIDSS J, H, and K-band imaging (Lawrence et al., 2007). We encourage further observations in the IR. 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/41138. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39193] Swift-BAT trigger 1334535 is not a GRB
by GCN Circulars 22 Jul '25

22 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41137 SUBJECT: Swift-BAT trigger 1334535 is not a GRB DATE: 25/07/22 14:22:25 GMT FROM: Mike Moss at NASA GSFC <mikejmoss3(a)gmail.com> M. Moss (GSFC) on behalf of the Swift-BAT team: The Swift-BAT trigger (trigger=1334535) at 00:14:02 UT on 18 Aug 2025 is not a GRB. All photons in the peak are simultaneous within the 100 us timing of the detector plane. This is indicative of a cosmic ray shower. View this GCN Circular online at https://gcn.nasa.gov/circulars/41137. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39192] GRB 250721A: Swift-XRT observations
by GCN Circulars 22 Jul '25

22 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41136 SUBJECT: GRB 250721A: Swift-XRT observations DATE: 25/07/22 13:46:07 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB), M.G. Bernardini (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the MAXI-detected burst GRB 250721A in a series of observations tiled on the sky. The total exposure time is 1.4 ks, distributed over 5 tiles; the maximum exposure at a single sky location in the tiling was 569 s. The data were collected between T0+16.2 ks and T0+22.9 ks, and are entirely in Photon Counting (PC) mode. No X-ray sources have been detected. The 3-sigma upper limit in the field (not including the regions where the tiles overlap) ranges from ~0.02 to ~0.05 ct s^-1, corresponding to a 0.3-10 keV observed flux of 6.5e-13 to 2.2e-12 erg cm^-2 s^-1 (assuming a typical GRB spectrum). The results of the XRT-team automatic analysis of the tiled XRT observations, including a position-specific upper limit calculator, are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00137. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41136. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39191] GRB 250722A: Fermi GBM Final Real-time Localization
by GCN Circulars 22 Jul '25

22 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41135 SUBJECT: GRB 250722A: Fermi GBM Final Real-time Localization DATE: 25/07/22 11:19:47 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 11:09:07 UT on 22 Jul 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250722A (trigger 774875352.002704 / 250722465). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 313.5, Dec = -63.3 (J2000 degrees, equivalent to J2000 20h 53m, -63d 17'), with a statistical uncertainty of 12.6 degrees. The angle from the Fermi LAT boresight is 2.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250722465/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250722465/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250722465/… View this GCN Circular online at https://gcn.nasa.gov/circulars/41135. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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