July 2026 - vsnet-grb-info - ooruri.kusastro.kyoto-u.ac.jp

[vsnet-grb-info 43441] GRB 260727A: AstroSat CZTI detection
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45225 SUBJECT: GRB 260727A: AstroSat CZTI detection DATE: 26/07/27 09:56:45 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910(a)gmail.com> Harsha K. H. (IUCAA), S.Salunke(IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260727A which was also detected by SVOM/ECLAIRs (An Li et.al., GCN Circ. 45220). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-07-27 00:22:10.26 UTC. The measured peak count rate associated with the burst is 72 (+26, -7) counts/s above the background in the combined data of two quadrants (out of four), with a total of 743 (+158, -105) counts. The local mean background count rate was 118 (+1, -2) counts/s. We measure a T90 of 20 (+3, -1) s from the cumulative CZT light curve. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-07-27 00:22:01.23 UTC. The measured peak count rate associated with the burst is 149 (+43, -18) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1666 (+284, -314) counts. The local mean background count rate was 476 (+3, -4) counts/s. We measure a T90 of 20 (+2, -3) s from the cumulative Veto light curve. CZTI data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/ET20260727T002157/ET20260727T0… CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/45225. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43440] GRB 260727A: Kilonova-Catcher optical upper limit
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45224 SUBJECT: GRB 260727A: Kilonova-Catcher optical upper limit DATE: 26/07/27 08:53:05 GMT FROM: Damien Turpin at CEA-Saclay <dturpin-astro(a)hotmail.com> M. Freeberg (KNC), D. Turpin (CEA-Saclay/Irfu), C. Andrade(UMN), S. Antier (IJCLab), M. Coughlin (UMN), S. Karpov (FZU), P. Hello (IJCLAB), M. Pillas (IAP) on behalf of the GRANDMA/Kilonova-Catcher collaboration: We observed the field of GRB 260627A detected by SVOM/ECLAIRs (Li et al., GCN 45220) with the GRANDMA citizen science project Kilonova-catcher (KNC). Our observations were performed with a TEC 180 telescope operated by M. Freeberg. Our observations started at TGRB+3.12 hours and were taken with the sdssr filter. In our stacked frames, subtracted from the PanSTARRS DR2 template image, we do not detect any optical counterpart. We report our follow-up results in the table below: | Tmid-TGRB (hr)| Exp (s) | Filter | Magnitude | Instrument | | ------------ | ------------ |------------ |------------ |------------ | | 3.38 | 10 x 180s | r (AB) | 19.8 (5 sigma) | TEC180 | All the data have been reduced by a single data processing pipeline, STDPipe (Karpov et al., 2022). Images obtained with the Sloan filters were calibrated using the PanSTARRS DR1 catalog. We use the SkyPortal application (skyportal.io) to monitor our observational campaign (Coughlin et al. 2023). GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr) devoted to the observation of transients in the context of multi-messenger astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/) View this GCN Circular online at https://gcn.nasa.gov/circulars/45224. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43439] GRB 260727A: LCO optical upper limits
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45223 SUBJECT: GRB 260727A: LCO optical upper limits DATE: 26/07/27 07:34:00 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Y.Y. Shi (GXU), C. Wu, L.P. Xin (NAOC), A. Saccardi, D. Turpin (CEA/Irfu), Z.M. Wang, R.Z. Li (BA-F) report on behalf of the SVOM mission team: We observed the field of GRB 260727A (SVOM burst-id sb26072701) detected by SVOM (Li et al., GCN 45220) with the LCO 1m telescope at Tenerife Observatory equipped with the Sinistro instrument. Our observation started on 2026-07-27 at 02:31:21 UT (about 2.16 hr after the trigger) and we obtained 3x200 s exposures in the Pan-STARRS z filters. In the stacked image, we do not detect any new source within the SVOM/ECLAIRs error box. We measure the following upper limit calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction: z > 20.2 AB (5-sigma, mid-time 2.25 hr after the trigger). This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/45223. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43438] GRB 260727B: Fermi GBM Final Real-time Localization
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45222 SUBJECT: GRB 260727B: Fermi GBM Final Real-time Localization DATE: 26/07/27 03:28:02 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 03:17:30 UT on 27 Jul 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260727B (trigger 806815055.083858 / 260727137). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 191.4, Dec = -24.5 (J2000 degrees, equivalent to J2000 12h 45m, -24d 30'), with a statistical uncertainty of 10.6 degrees. The angle from the Fermi LAT boresight is 80.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260727137/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260727137/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260727137/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45222. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43437] Fermi GRB 260726A: Global MASTER-Net observations report
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45221 SUBJECT: Fermi GRB 260726A: Global MASTER-Net observations report DATE: 26/07/27 01:46:31 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), M. Segura, 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 260726A ( Fermi GBM team, GCN 45218) errorbox 3746 sec after notice time and 3782 sec after trigger time at 2026-07-27 00:47:51 UT, with upper limit up to 17.5 mag. The observations began at zenith distance = 78 deg. The sun altitude is -59.0 deg. The galactic latitude b = -10 deg., longitude l = 127 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3444915 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3812 | 2026-07-27 00:47:51 | MASTER-SAAO | (00h 33m 08.03s , +40d 42m 54.8s) | C | 60 | 17.4 | 4815 | 2026-07-27 01:04:33 | MASTER-SAAO | (00h 53m 12.92s , +40d 41m 37.6s) | C | 60 | 17.4 | 4915 | 2026-07-27 01:06:13 | MASTER-SAAO | (01h 11m 16.44s , +38d 48m 24.2s) | C | 60 | 17.1 | 5018 | 2026-07-27 01:07:57 | MASTER-SAAO | (00h 34m 12.82s , +42d 36m 13.8s) | C | 60 | 17.4 | 5327 | 2026-07-27 01:13:06 | MASTER-SAAO | (00h 14m 01.29s , +44d 30m 13.1s) | C | 60 | 17.3 | 5926 | 2026-07-27 01:23:05 | MASTER-SAAO | (01h 13m 23.75s , +40d 41m 40.4s) | C | 60 | 17.1 | 6024 | 2026-07-27 01:24:42 | MASTER-SAAO | (01h 30m 51.35s , +38d 49m 10.7s) | C | 60 | 16.9 | 6121 | 2026-07-27 01:26:19 | MASTER-SAAO | (00h 54m 59.03s , +42d 36m 51.3s) | C | 60 | 17.5 | 6426 | 2026-07-27 01:31:24 | MASTER-SAAO | (00h 35m 31.56s , +44d 32m 11.3s) | C | 60 | 17.3 | 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/45221. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43436] GRB 260727A: SVOM detection of a bright long burst
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45220 SUBJECT: GRB 260727A: SVOM detection of a bright long burst DATE: 26/07/27 00:58:53 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> An Li (BNU), Yifang Liang (PMO), Wenjin Xie (NAOC), Donghua Zhao (NAOC), Clara Plasse (HKU), Ruizhi Li (YNAO), Ziming Wang (BNU) report on behalf of the SVOM mission team: At 2026-07-27T00:22:02 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260727A (SVOM burst-id sb26072701). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 41 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 111.24 in the [8-120] keV energy band over a time window of 81.92 seconds starting at 2026-07-27T00:21:34. The localization of the best alert is R.A., Dec. 331.6445, 74.5406 degrees: R.A. (J2000) = 22h06m34.69s Dec. (J2000) = 74d32m25.98s with a 90% confidence level (C.L.) radius of 2.12 arcmin (including systematic error of 2 arcmin added in quadrature). The SVOM/ECLAIRs light curve showed a multiple peak structure with long duration. The SVOM/GRM light curve showed a multiple broad peak structure with long duration. Due to another ongoing GRB observation, no immediate slew was performed on this burst. No X-ray observation could be performed by SVOM/MXT for the time being.No optical observation could be performed by SVOM/VT for the time being. 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 Ziming Wang: 202421101144(a)mail.bnu.edu.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45220. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43435] GRB 260726A: SVOM detection of a burst
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45219 SUBJECT: GRB 260726A: SVOM detection of a burst DATE: 26/07/27 00:23:38 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Yifang Liang(PMO), Wenjin Xie (NAOC), Ruizhi Li (YNAO), Ziming Wang (BNU), Clara Plasse (HKU) report on behalf of the SVOM mission team: At 2026-07-26T23:45:23 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260726A (SVOM burst-id sb26072614), which was also detected by Fermi/GBM (Fermi GBM team, GCN 45218). The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network. The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 13 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 14.47 in the [8-50] keV energy band over a time window of 40.96 seconds starting at 2026-07-26T23:45:03. The localization of the best alert is R.A., Dec. 356.3179, 53.1360 degrees (J2000) with a 90% confidence level (C.L.) radius of 5.68 arcmin (including systematic error of 2 arcmin added in quadrature). This burst was also detected by SVOM/GRM. SVOM slewed to the burst. MXT and 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 Rui-Zhi Li: liruizhi(a)ynao.ac.cn Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45219. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43434] GRB 260726A: Fermi GBM Final Real-time Localization
by GCN Circulars 26 Jul '26

26 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45218 SUBJECT: GRB 260726A: Fermi GBM Final Real-time Localization DATE: 26/07/26 23:55:25 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 23:44:49 UT on 26 Jul 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260726A (trigger 806802294.070584 / 260726989). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 19.0, Dec = 52.4 (J2000 degrees, equivalent to J2000 01h 15m, 52d 23'), with a statistical uncertainty of 11.9 degrees. The angle from the Fermi LAT boresight is 13.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260726989/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260726989/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260726989/… View this GCN Circular online at https://gcn.nasa.gov/circulars/45218. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43433] IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova
by GCN Circulars 26 Jul '26

26 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45217 SUBJECT: IceCube-260722A: Classification of ZTF26abjbxfs/SN 2026vts as a Type Ia Supernova DATE: 26/07/26 15:58:08 GMT FROM: Robert David Stein at JSI <rdstein(a)umd.edu> Robert Stein (UMD/JSI/NASA GSFC), Avinash Singh (Stockholm), and Jesper Sollerman (Stockholm) report: We observed ZTF26abjbxfs / SN 2026vts, reported as a possible counterpart (Necker et al., GCN 45198) to IceCube-260722A (Zilleruelo Cañas et. al, GCN 45194). We obtained spectroscopic observations using the Alhambra Faint Object Spectrograph and Camera (ALFOSC) on the Nordic Optical Telescope (NOT), beginning at 2026-07-24 21:14:1 UTC. Data were reduced using PypeIt (Prochaska et al. 2020). The spectrum matches well to templates of a Type Ia supernova, and the transient is therefore unrelated to the neutrino. The spectrum is available on TNS. The data presented here were obtained with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOT. View this GCN Circular online at https://gcn.nasa.gov/circulars/45217. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0

[vsnet-grb-info 43432] EP260723a: further EP-FXT follow-up observation
by GCN Circulars 26 Jul '26

26 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45216 SUBJECT: EP260723a: further EP-FXT follow-up observation DATE: 26/07/26 12:17:29 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> K. R. Ni (CCNU), Y. J. Zhang (PKU), X. H. Tang (THU), and H. Sun (NAOC) report on behalf of the Einstein Probe (EP) team: EP-FXT performed a second follow-up observation of EP260723a, which was detected by EP-WXT (Zhang et al., GCN 45201) and previously followed up by EP-FXT (Ni et al., GCN 45209). The observation started at 2026-07-25T11:52:47 UTC, about 40.9 hr after the WXT detection, with an exposure time of approximately 6.0 ks. On-ground analysis of the FXT data identified an uncatalogued X-ray source within the WXT error circle at R.A. (J2000) = 2.9759 deg and Dec. (J2000) = -12.1022 deg, with an uncertainty of 10 arcsec in radius (90% confidence level, including both statistical and systematic uncertainties). The source position is consistent with the optical counterpart reported by the Liverpool Telescope (Eyles-Ferris et al., GCN 45202, 45212), the Nordic Optical Telescope (He et al., GCN 45203), COLIBRÍ (Basa et al., GCN 45204), and SVOM/VT (Ma et al., GCN 45205), and also with the weak X-ray excess reported in the first EP-FXT follow-up observation (Ni et al., GCN 45209). The average FXT spectrum in the 0.5-10 keV band can be fitted with an absorbed power-law model, with the hydrogen column density fixed at the Galactic value of 2.0 x 10^20 cm^-2 and a photon index of 2.96 (+1.53, -1.21). The derived average unabsorbed 0.5-10 keV flux is 3.1 (+3.0, -1.4) x 10^(-14) erg cm^-2 s^-1. The uncertainties quoted above are at the 90% confidence level. Further EP-FXT follow-up observations will be arranged. Continued multi-band follow-up observations are encouraged. Launched on January 9, 2024, EP is a space X-ray observatory designed to monitor the dynamic soft X-ray sky and perform follow-up observations of newly discovered transients (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/45216. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

1 0