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[vsnet-grb-info 43444] GRB 260727A / SVOM sb26072702: RAPAS optical non-detection
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45228 SUBJECT: GRB 260727A / SVOM sb26072702: RAPAS optical non-detection DATE: 26/07/27 15:20:56 GMT FROM: Thierry Midavaine at SAF - RAPAS <thierrymidavaine(a)sfr.fr> Pierre-Yves Lechapelain and Thierry Midavaine report on behalf of the RAPAS network: We observed the field of GRB 260727A (SVOM/ECLAIRs trigger sb26072701; Li et al., GCN 45220) in response to the overlapping SVOM broker alert sb26072702 (RA = 331.626 deg, Dec = +74.549 deg, J2000, 2.5 arcmin error radius). Observations were obtained with the RAPAS 0.25 m f/3 robotic telescope and IMX533 sensor at Observatoire de Bretagne Sud (Y80), using RAPAS filters matched to the Gaia G, Gbp, and Grp bands. Data were reduced with the STDPipe/stdweb pipeline; photometry and astrometry are calibrated to Gaia DR3 with spatially varying zero points and color terms. Observations began at 2026-07-27 00:48 UTC (T_GRB + 26 min, with T_GRB = 2026-07-27 00:22:02 UTC from GCN 45220) and continued in a G / Gbp / Grp cycle with 30 s exposures until approximately 02:44 UTC (T_GRB + 2.4 hr). We detect no optical afterglow at the sb26072702 position. Forced aperture photometry at RA = 331.626 deg, Dec = +74.549 deg shows no significant excess on the earliest G exposure (flux S/N = 1.8) or on the deep G co-add (flux S/N = 3.6, below our 5σ detection threshold). No Gaia-uncatalogued source is found within the 2.5 arcmin SVOM error circle. A comparison to Gaia DR3 in a 12 arcmin (0.2 deg) radius around the alert on the first G frame yields five marginal transient candidates at 7–11 arcmin offset; none are confirmed in deeper co-added images. Searches over the full unvignetted RAPAS field (~0.62 deg radius) reveal no plausible afterglow at the SVOM coordinates. We report 5σ limiting magnitudes (Vega, Gaia-calibrated) from the global detection limits of each reduction: Earliest epoch per band (single frame or shortest stack in the sequence): | T_mid - T_GRB | Exp | Band | Limit (5σ) | Note | |---------------|------------|------|------------|-------------| | +25 min | 1 × 30 s | G | >18.3 | | | +31 min | 2 × 30 s | G_BP | >18.6 |2-frame stack| | +36 min | 2 × 30 s | G_RP | >17.4 |2-frame stack| Co-added images from the ToO night: | Band | Co-add | Limit (5σ) | |------|-------------|------------| | G | 17 × 30 s | >20.1 | | G_BP | 18 × 30 s | >19.9 | | G_RP | 14 × 30 s | >18.6 | Mid-exposure times correspond to the first useful epoch in each band and to the weighted mean epoch of each co-added stack, respectively. Acknowledgements : RAPAS ( https://gemini.obspm.fr/20220101-rapas/ ) is a ProAm collaboration created by T. Midavaine (SAF), W. Thuillot (LTE, Obs. de Paris-PSL) and M. Dennefeld (IAP/CNRS and Sorbonne Univ.) and funded by the Paris Observatory under API ProAm of the Scientific Council. It aims at homogenizing observing procedures and filters, and is delivering to a network of french amateur observatories a set of 3 filters which have been chosen to meet the Gaia G, Gbp and Grp spectral bands. This network produces data on astrophysical alerts delivered by various Alert systems (Gaia Alerts, Atlas, ZTF, etc…) and collected by Astro-COLIBRI ( https://astro-colibri.science ). It is similarly progressing towards an homogeneous spectroscopic equipment to deliver SED. Paris Observatory PADC which is on the way to archive all the FITS files with attached processing pipeline. View this GCN Circular online at https://gcn.nasa.gov/circulars/45228. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43443] EP260723a: SVOM/ECLAIRs Upper Limit
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45227 SUBJECT: EP260723a: SVOM/ECLAIRs Upper Limit DATE: 26/07/27 13:44:17 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> H. Yang, M. Brunet, O. Godet, S. Guillot (IRAP) report on behalf of the SVOM team: We performed a targeted search of the X-ray transient EP260723a, detected by EP-WXT at 2026-07-23T18:56:01 UTC (T0) with a duration of about 100 s (EP team, GCN 45201), using the SVOM/ECLAIRs event-by-event data downloaded through the X-band ground station. At T0, the transient position was within the ECLAIRs field of view. No statistically significant signal was identified in the [T0 - 500 s, T0 + 3000 s] interval by the ECLAIRs image trigger performed on multiple timescales and energy bands. For the interval from T0 to T0 + 100 s, we derive a 3-sigma upper limit of 2.4e-9 erg/cm^2/s in the 4-120 keV energy band, assuming a power-law spectrum with a photon index of 1.4, as measured by EP-WXT (GCN 45201). Alternatively, assuming a “soft” spectral template (a Band function with Epeak = 25 keV, alpha = -1.5, beta = -3.0), we derive a 3-sigma upper limit of 1.5e-9 erg/cm^2/s. The Space 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. ECLAIRs was developed jointly by APC, CEA, CNES, and IRAP. The SVOM/ECLAIRs point of contact for this event is : Hui Yang (hui.yang(a)cnrs.fr) View this GCN Circular online at https://gcn.nasa.gov/circulars/45227. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43442] GRB 260727A: GOTO early optical upper limit
by GCN Circulars 27 Jul '26

27 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45226 SUBJECT: GRB 260727A: GOTO early optical upper limit DATE: 26/07/27 11:30:59 GMT FROM: Rhaana Starling at U of Leicester <rlcs1(a)leicester.ac.uk> R. Starling, M. Kennedy, D. O'Neill, B. P. Gompertz, G. Ramsay, A. Kumar, 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, I. Worssam 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 SVOM/ECLAIRs detected GRB 260727A (sb26072701, Li et al. 2026, GCN 45220), also detected by AstroSat (Harsha et al.2026, GCN 45225). Observations at the ECLAIRs position began at 2026-07-27 00:27:22 UT (+5.8 minutes post trigger) and continued to 2026-07-27 01:47:11 UT (+1.4h 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. Difference imaging was performed using deeper template observations. Any source candidates are initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogs (Lyman et al. 2026). We found no new transients that could be credibly associated with 260727A within the localisation down to a 5-sigma depth of L<20.2 AB mag. 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/45226. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[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…

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[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…

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[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…

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[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…

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[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…

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[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…

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[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…

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