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[vsnet-grb-info 43402] Fermi trigger No 806104130: Global MASTER-Net observations report
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45186 SUBJECT: Fermi trigger No 806104130: Global MASTER-Net observations report DATE: 26/07/18 22:31:13 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 GRB260718.91 (trigger No 806104130,00h 29m 02.40s , -00d 33m 00.0s, R=11.89) errorbox 792 sec after notice time and 803 sec after trigger time at 2026-07-18 22:02:09 UT, with upper limit up to 17.1 mag. The observations began at zenith distance = 72 deg. The sun altitude is -75.6 deg. The galactic latitude b = -63 deg., longitude l = 112 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3433519 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 834 | 2026-07-18 22:02:09 | MASTER-SAAO | (23h 54m 05.72s , -03d 01m 04.2s) | C | 60 | 15.0 | 1139 | 2026-07-18 22:07:14 | MASTER-SAAO | (00h 09m 13.60s , -01d 06m 25.9s) | C | 60 | 14.8 | 1244 | 2026-07-18 22:08:59 | MASTER-SAAO | (00h 09m 20.07s , -01d 07m 24.0s) | C | 60 | 14.8 | 1350 | 2026-07-18 22:10:46 | MASTER-SAAO | (00h 09m 13.69s , -01d 06m 25.2s) | C | 60 | 13.2 | 1459 | 2026-07-18 22:12:34 | MASTER-SAAO | (00h 09m 19.04s , -01d 07m 06.4s) | C | 60 | 15.4 | 1565 | 2026-07-18 22:14:20 | MASTER-SAAO | (00h 09m 12.41s , -01d 06m 25.3s) | C | 60 | 15.6 | 1666 | 2026-07-18 22:16:01 | MASTER-SAAO | (00h 24m 32.56s , -03d 01m 04.1s) | C | 60 | 12.2 | 2184 | 2026-07-18 22:24:39 | MASTER-SAAO | (00h 09m 13.55s , -03d 00m 26.1s) | C | 60 | 16.4 | 2282 | 2026-07-18 22:26:17 | MASTER-SAAO | (00h 09m 15.33s , -04d 55m 25.9s) | C | 60 | 17.1 | 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/45186. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43401] Fermi GRB 260718A: Global MASTER-Net observations report
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45185 SUBJECT: Fermi GRB 260718A: Global MASTER-Net observations report DATE: 26/07/18 20:46:39 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 260718A ( A. Holzmann Airasca et al., GCN 45181) errorbox 30093 sec after notice time and 30129 sec after trigger time at 2026-07-18 19:38:45 UT, with upper limit up to 16.1 mag. The observations began at zenith distance = 79 deg. The sun altitude is -47.9 deg. The galactic latitude b = -70 deg., longitude l = 272 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=3433050 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 30160 | 2026-07-18 19:38:45 | MASTER-SAAO | (00h 43m 50.40s , -54d 15m 03.4s) | C | 60 | 15.0 | 30564 | 2026-07-18 19:45:29 | MASTER-SAAO | (01h 17m 13.48s , -58d 01m 45.8s) | C | 60 | 16.1 | 30772 | 2026-07-18 19:48:57 | MASTER-SAAO | (00h 41m 49.87s , -52d 21m 34.2s) | C | 60 | 14.7 | 31386 | 2026-07-18 19:59:10 | MASTER-SAAO | (00h 40m 00.33s , -50d 27m 42.3s) | C | 60 | 15.5 | 31486 | 2026-07-18 20:00:50 | MASTER-SAAO | (01h 13m 14.66s , -56d 07m 02.2s) | C | 60 | 15.4 | 31895 | 2026-07-18 20:07:40 | MASTER-SAAO | (01h 09m 43.51s , -54d 13m 28.2s) | C | 60 | 13.7 | 32004 | 2026-07-18 20:09:28 | MASTER-SAAO | (01h 09m 45.18s , -54d 14m 59.8s) | C | 60 | 15.1 | 32521 | 2026-07-18 20:18:06 | MASTER-SAAO | (01h 06m 29.78s , -52d 20m 35.2s) | C | 60 | 12.7 | 32725 | 2026-07-18 20:21:29 | MASTER-SAAO | (01h 03m 42.42s , -50d 26m 49.3s) | C | 60 | 14.7 | 33229 | 2026-07-18 20:29:53 | MASTER-SAAO | (01h 40m 19.62s , -56d 07m 30.7s) | C | 60 | 13.7 | 33327 | 2026-07-18 20:31:31 | MASTER-SAAO | (01h 35m 37.77s , -54d 14m 35.3s) | C | 60 | 12.8 | 33429 | 2026-07-18 20:33:14 | MASTER-SAAO | (01h 35m 33.23s , -54d 13m 49.2s) | C | 60 | 14.4 | 33947 | 2026-07-18 20:41:51 | MASTER-SAAO | (01h 31m 17.62s , -52d 21m 15.0s) | C | 60 | 13.6 | 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/45185. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43400] GRB 260718A: LCO optical upper limits
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45184 SUBJECT: GRB 260718A: LCO optical upper limits DATE: 26/07/18 19:44:16 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> D. Turpin, A. Saccardi (CEA/Irfu), S.-J. Yin (GXU), C. Wu, L.-P. Xin (NAOC), W. Zhang (PMO), Y. Ma (NAOC) report on behalf of the SVOM mission team: We observed the field of GRB 260718A detected by SVOM (Antier et al., GCN 45177) and Fermi/GBM (Holzmann Airasca et al., GCN 45181) with the LCO 1m telescope at the Siding Spring Observatory (SAAO) equipped with the Sinistro instrument. Our observation started at 2026-07-18T18:35:32 about 7.3 hours after the SVOM/ECLAIRs trigger time. We obtained 3x200 s exposures in the PanSTARRS z filters. No any uncatalogued source was identified in our stacked frames in the ECLAIRs localisation region as also reported by SVOM/VT (Ma et al., GCN 45178; Li et al., GCN 45179) and GRANDMA/KNC (Jacquesson et al., GCN 45180) . We measure the following upper limits (5 sigma) calibrated against the SkyMapper DR4 catalog, and not corrected for Galactic extinction: z = 20.1 (AB) T_mid - T0 = 7.4hr This project is funded by the SVOM collaboration. View this GCN Circular online at https://gcn.nasa.gov/circulars/45184. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43399] GRB 260711A: SVOM/GRM observation
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45183 SUBJECT: GRB 260711A: SVOM/GRM observation DATE: 26/07/18 18:23:24 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> SVOM/GRM team: Xue-Yuan Zao, Chen-Wei Wang, Yue Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Hui Yang (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground by GRB 260711A at 2026-07-11T06:05:23.000 UTC (T0). With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of GRB 260711A. The GRM light curve shows that this burst consists of multiple pulses with a T90 of 12.5 +4.5/-3.5 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here： https://www.bursthub.cn/gcn/2026/svgrb260711A.png 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/GRM point of contact for this burst is: Xue-Yuan Zao (IHEP) (zaoxy(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/45183. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43398] GRB 260710A: SVOM/GRM observation
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45182 SUBJECT: GRB 260710A: SVOM/GRM observation DATE: 26/07/18 18:22:10 GMT FROM: xueyuan zao <zaoxueyuan(a)gmail.com> SVOM/GRM team: Xue-Yuan Zao, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP) SVOM/ECLAIRs team: Olivier Godet, Sebastien Guillot (IRAP) Report on behalf of the SVOM team: SVOM/GRM was triggered on-ground and in-flight by GRB 260710A at 2026-07-10T12:58:43.450 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #45131 and M. Dafcikova et al., GCN #45138). With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of GRB 260710A. The GRM light curve shows that this burst consists of a single pulse with a T90 of 2.60 +1.00/-0.60 s in the 15-5000 keV band. The SVOM/GRM light curve can be found here： https://www.bursthub.cn/gcn/2026/svgrb260710A.png In addition, the position of this burst, as determined by Fermi/GBM (RA= 5.6, DEC=-85.0, ERR= 1.8 degrees, GCN #45131), is located at about 60 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. With this localization, the time-averaged spectrum from T0-0.25 to T0+2.75 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.27 +/-0.12 and the cutoff energy, parameterized as Epeak, is 161 +41/-25 keV. The event fluence (10-1000 keV) in this time interval is (2.26 +0.21/-0.17) E-06- erg/cm^2. The 1s peak spectrum, measured from T0-0.05 to T0+0.95 s, is also fitted by a power law function with an exponential high-energy cutoff, the power law index is -0.91 +/- 0.10 and the cutoff energy, parameterized as Epeak, is 153 +16/-12 keV. The flux (10-1000 keV) in this time interval is (1.74 +0.09/-0.08) E-06 erg/cm^2/s. The localization of GRB 260710A in the 'Amati' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/svgrb260710A_amati.png The localization of GRB 260710A in the 'Yonetoku' relation diagram is shown at: https://www.bursthub.cn/gcn/2026/svgrb260710A_yonetoku.png 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/GRM point of contact for this burst is: Xue-Yuan Zao (IHEP) (zaoxy(a)ihep.ac.cn) View this GCN Circular online at https://gcn.nasa.gov/circulars/45182. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43397] GRB 260718A: Fermi GBM Observation
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45181 SUBJECT: GRB 260718A: Fermi GBM Observation DATE: 26/07/18 17:24:01 GMT FROM: A. Holzmann Airasca at University of Trento and INFN Bari <a.holzmannairasca(a)unitn.it> A. Holzmann Airasca (UniTrento and INFN Bari) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 11:16:35.01 UT on 18 July 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260718A (trigger 806066200/260718470), which was also detected by SVOM/ECLAIRs (S. Antier et al. 2026, GCN 45177). The Fermi GBM on-ground location is consistent with the SVOM/ECLAIRs position. The angle from the Fermi LAT boresight is 31 degrees. The GBM light curve consists of a single emission episode with a duration (T90) of about 19 s (50-300 keV). The time-averaged spectrum from T0-3.8 to T0+16.3 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.29 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 68 +/- 3 keV. The event fluence (10-1000 keV) in this time interval is (6.8 +/- 0.6)E-07 erg/cm^2. The 1-sec peak photon flux measured starting from T0-2.4 s in the 10-1000 keV band is 2.1 +/- 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/45181. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43396] GRB 260718A : GRANDMA and KNC upper limits
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45180 SUBJECT: GRB 260718A : GRANDMA and KNC upper limits DATE: 26/07/18 17:08:36 GMT FROM: Alex Jacquesson <jacquessonalex179(a)gmail.com> GRB 260718A : GRANDMA and KNC upper limits A. Jacquesson (IJCLab), S. Antier (IJCLab), D. Turpin (CEA/Irfu), P. Hello (IJCLab), M. Freeberg (KNC), N. Kochiashvili (Ilia State University), M. Molham (NRIAG), C. Douzet (IJCLab), N. Jasmin (IJCLab), R. Le Montagner (IJCLab), K. Agabi (OCA), L. Abe (OCA), T. Guillot (OCA) on behalf of GRANDMA. We observed the field of GRB 260718A detected by SVOM/ECLAIRs (GCN 45177). The observations started with ASTEP at 2026-07-18T14-47-18 UTC on the 18th of July 2026 about 4h post ECLAIRs T0. We didn't detect any optical counterpart within a region centered on ECLAIRs localization error box and with a radius above 8 arcmin with the GRANDMA network with ASTEP at Concordia and KNC-T30. We reported our upper limit in the public ACME service Skyportal/ICARE https://skyportal-icare.ijclab.in2p3.fr/source/GCN-260718_111632. To access, one simply needs to create an account using your ORCID id. Our upper limit are coherent with SVOM/VT (GCN 45178 and 45179) The data were 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. Images obtained with the Johnson-Cousins filters were calibrated using the Gaia DR3 Synphot catalog. The observations are performed under the P7 campaign of GRANDMA to monitor SVOM alerts and LSST alerts from explosive fast transients filtered by BOOM/Babamul and FINK. 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/) Astrophysics Center for Multimessenger studies in Europe is supported Skyportal/ICARE (contact camille.douzet(a)ijclab.in2p3.fr, skyportal.io). View this GCN Circular online at https://gcn.nasa.gov/circulars/45180. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43395] GRB 260718A: SVOM/VT optical upper limits
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45179 SUBJECT: GRB 260718A: SVOM/VT optical upper limits DATE: 26/07/18 16:56:45 GMT FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn> H. L. Li, Y. N. Ma, C. Wu, Y. L. Qiu, L. P. Xin, Z. H. Yao, J. R. Xu, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA/Irfu), W. L. Zhang (PMO) report on behalf of the SVOM/VT team. SVOM/VT performed observations with automatic slew to the field of GRB 260718A triggered by SVOM/ECLAIRs (sb26071802, Antier et al., GCN 45177). The observations started at 2026-07-18T12:00:14 UTC, about 44.08 minutes post trigger in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously. No credible sources were detected within the error box of ECLAIRs (Antier et al., GCN 45177), compared to the Legacy Survey catalog. The 3σ upper limits of AB magnitudes without corrections for Galactic extinction are as follows: Mid time | Band | Exposure Time | 3 sigma upper limit 1.05 hr VT_B 42*50 s > 23.2 mag 1.05 hr VT_R 38*50 s > 23.0 mag This non-detection is consistent with VT VHF upper limits (Ma et al., GCN 45178). 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/45179. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43394] GRB 260718A: SVOM/VT optical upper limits from VHF data
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45178 SUBJECT: GRB 260718A: SVOM/VT optical upper limits from VHF data DATE: 26/07/18 14:52:36 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> Y. N. Ma (NAOC), W. L. Zhang (PMO), C. Wu, L. P. Xin, Y.L. Qiu (NAOC), D. Turpin, A. Saccardi, J. T. Palmerio (CEA/Irfu) report on behalf of the SVOM/VT team. After the trigger by SVOM/ECLAIRs at 2026-07-18T11:16:34 UTC (T0), SVOM performed an automatic slew on the burst location (Antier et al., GCN 45177). SVOM/VT took images of the field in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. From a preliminary analysis of the 1-bit subimage and source list downloaded via VHF network, no uncatalogued optical source was detected at the ECLAIRs position (Antier et al., GCN 45177) in our two sequence images, compared to the Legacy Survey DR10. The 5-sigma upper limits are: Mid time | Band | Exposure Time | 5 sigma upper limit 44.5 min | VT_B | 6*50 sec | > 21.5 mag 44.5 min | VT_R | 6*50 sec | > 21.5 mag 49.5 min | VT_R | 6*50 sec | > 21.5 mag The subimage and source list cover 100% of the SVOM/ECLAIRs R90 uncertainty region. Given the lack of detection in VT_B and VT_R at an early phase, deeper or redder follow-ups are encouraged to investigate the nature of the burst. 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/VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS. The Burst Advocate (BA) on shift for this alert is Yinuo Ma: mayn(a)bao.ac.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45178. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 43393] GRB 260718A: SVOM detection of a burst
by GCN Circulars 18 Jul '26

18 Jul '26

TITLE: GCN CIRCULAR NUMBER: 45177 SUBJECT: GRB 260718A: SVOM detection of a burst DATE: 26/07/18 11:57:28 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> S. Antier (IJCLAB), D. Zhao (NAOC), W. Zhang (PMO), Y. Ma (NAOC), C. Wang (IHEP) report on behalf of the SVOM mission team: At 2026-07-18T11:16:34 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 260718A (SVOM burst-id sb26071802). 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 19 alerts. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 20.86 in the [5-20] keV energy band over a time window of 20.40 seconds starting at 2026-07-18T11:16:31. The localization of the best alert is R.A., Dec. 37.2660, -56.0993 degrees: R.A. (J2000) = 2h29m03.85s Dec. (J2000) = -56d05m57.31s with a 90% confidence level (C.L.) radius of 4.20 arcmin (including systematic error of 2 arcmin added in quadrature). The SVOM/ECLAIRs light curve showed a broad peak structure. This burst was also detected by SVOM/GRM. : https://www.bursthub.cn/gcn/2026/svgrb260718A.png SVOM slewed to the burst. No immediate MXT and VT observation could be carried out due to Earth occultation. Later observations will be reported in future GCN Circulars. 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 Wenlong Zhang: wlzhang(a)pmo.ac.cn. Please contact the BA by email if you require additional information. View this GCN Circular online at https://gcn.nasa.gov/circulars/45177. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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