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

[vsnet-grb-info 38717] GRB 250610B: SVOM/VT optical counterpart
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40678 SUBJECT: GRB 250610B: SVOM/VT optical counterpart DATE: 25/06/10 23:35:24 GMT FROM: Liping Xin at NAOC, SVOM <xlp(a)nao.cas.cn> H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, Y. N. Ma, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), A. Saccardi, J. Rodriguez, N. Dagoneau (CEA), C. Van Hove (IJCLab) report on behalf of the SVOM mission team. SVOM performed a Target of Opportunity observation of GRB 250610B detected by SVOM/Eclairs (Saccardi et al., GCN 40671). SVOM/VT began observing the field at 2025-06-10 17:04:26 UTC, 0.52 hours after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously. An uncatalogued source, compared to legacy survey, is found using VT X-band data, within the error box of Swift/XRT1 at R.A., Dec 200.179739, 31.10496 degrees: RA (J2000) = 13:20:43.1 Dec (J2000) = +31:06:17.9 with an uncertainty of 0.5 arcsec. The source is detected in both VT_R and VT_B, and was fading by 0.3 mag in 2 orbits, the magnitudes are: Mid-time after the burst | exposure time (s) | band | mag (AB) | mag err --------------------|-------------------|------|----------|-------- 1.234 hour | 70 | VT_B | 20.7 ｜ 0.1 1.234 hour | 70 | VT_R | 20.3 ｜ 0.1 This position and the brightness is consistent with the reports (Schneider et al., GCN 40676, Gompertz et al., GCN 40677) The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre 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. The Burst Advocate (BA) on shift for this alert is Andrea Saccardi(a)cea.fr. View this GCN Circular online at https://gcn.nasa.gov/circulars/40678. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38716] GRB 250610B: LT detection of the optical counterpart
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40677 SUBJECT: GRB 250610B: LT detection of the optical counterpart DATE: 25/06/10 23:30:06 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz (U. Birmingham), Dimple (U. Birmingham), A. Martin-Carrillo (UCD) and G. Corcoran (UCD) report on behalf of a larger collaboration: We initiated follow-up observations of GRB 250610B (Saccardi et al., GCN 40671) with the IO:O camera on the 2m robotic Liverpool Telescope (LT). Observations began at 22:24:56 UT, ~5.85 hr after the SVOM/ECLAIRs trigger, and consisted of 7x120 s and 10x120 s exposures in the SDSS g and i filters, respectively. We detect the optical counterpart (Schneider et al., GCN 40676) with AB magnitudes of g = 21.38 ± 0.11 and i = 21.02 ± 0.06. Magnitudes are calibrated against nearby Pan-STARRS stars and are not corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/40677. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38715] GRB 250610B: optical counterpart candidate
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40676 SUBJECT: GRB 250610B: optical counterpart candidate DATE: 25/06/10 23:26:37 GMT FROM: Benjamin Schneider at MIT <bschn(a)mit.edu> B. Schneider (LAM), A. de Ugarte Postigo (LAM), C. Adami (LAM/Pytheas/AMU), J.P Troncin (Pytheas/OHP), A. Martin-Carrillo (UCD), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), report on behalf of a larger collaboration: We observed the field of the GRB 250610B (Saccardi et al., GCN 40671) using the T120cm telescope at Observatoire de Haute-Provence (France). We obtained 30 minutes of exposure in the r-band starting at 20:31:03.29 UT on 2025-06-10 (3.97 hr after the trigger). In the stacked image, we detected a new source at RA, DEC (J2000) 200.1796, +31.1047, not visible in the Legacy Survey and consistent with the XRT error: RA(J2000) = 13:20:43.11 DEC(J2000) = +31:06:16.8 with an uncertainty of 0.5 arcsec. The preliminary magnitude derived for that source is: r = 20.96 +/- 0.15 mag (AB) The photometric calibration was performed using nearby stars from the SDSS catalog and the magnitude is not corrected for Galactic extinction. We acknowledge the excellent support from Observatoire de Haute-Provence and in particular the students and professors from the summer camp OHP 2025. View this GCN Circular online at https://gcn.nasa.gov/circulars/40676. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38714] GRB 250610C: Fermi GBM Final Real-time Localization
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40675 SUBJECT: GRB 250610C: Fermi GBM Final Real-time Localization DATE: 25/06/10 23:21:44 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 23:11:04 UT on 10 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250610C (trigger 771289869.772446 / 250610966). The on-ground calculated location, using the Fermi GBM trigger data, is RA = 26.8, Dec = 59.7 (J2000 degrees, equivalent to J2000 01h 47m, 59d 42'), with a statistical uncertainty of 2.5 degrees. The angle from the Fermi LAT boresight is 64.0 degrees. The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610966/… The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610966/… The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250610966/… View this GCN Circular online at https://gcn.nasa.gov/circulars/40675. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38713] GRB 250610B: GOTO optical upper limit
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40674 SUBJECT: GRB 250610B: GOTO optical upper limit DATE: 25/06/10 21:43:38 GMT FROM: Ben Gompertz at U of Birmingham <b.gompertz(a)bham.ac.uk> B. P. Gompertz, D. O’Neill, D. Steeghs, R. Starling, K. Ackley, M. J. Dyer, J. Lyman, K. Ulaczyk, A. Kumar, B. Godson, D. K. Galloway, V. Dhillon, P. O'Brien, G. Ramsay, K. Noysena, R. Kotak, R. P. Breton, L. K. Nuttall, and J. Casares report 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 250610B (Saccardi et al., GCN 40671). Targeted observations were performed with GOTO-North centred at 2025-06-10 21:13:20 UT (+4.66h post trigger). Observations 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. We detect no new sources within the ECLAIRS localisation region down to a 3-sigma limiting magnitude of L > 19.92 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 and the Instituto de Astrofisica de Canarias (IAC). View this GCN Circular online at https://gcn.nasa.gov/circulars/40674. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38712] EP250610a: Global MASTER-Net observations report
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40673 SUBJECT: EP250610a: Global MASTER-Net observations report DATE: 25/06/10 19:36:20 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), C.Francile, 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-OAFA robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Argentina (OAFA observatory of San Juan National University) was pointed to the EP250610a ( EP Team et al., GCN 40660) errorbox 972 sec after notice time and 9094 sec after trigger time at 2025-06-10 06:57:24 UT, with upper limit up to 17.6 mag. The observations began at zenith distance = 82 deg. The sun altitude is -57.2 deg. MASTER-Kislovodsk robotic telescope located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the EP250610a errorbox 44872 sec after notice time and 52993 sec after trigger time at 2025-06-10 19:09:03 UT, with upper limit up to 17.4 mag. The observations began at zenith distance = 15 deg. The sun altitude is -18.3 deg. The galactic latitude b = 42 deg., longitude l = 61 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2898181 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 9229 | 2025-06-10 06:57:24 | MASTER-OAFA | (16h 33m 32.66s , +38d 48m 08.6s) | C | 270 | 17.6 | Coadd 53024 | 2025-06-10 19:09:03 | MASTER-Kislovodsk | (16h 31m 32.68s , +38d 50m 44.6s) | C | 60 | 17.0 | 53210 | 2025-06-10 19:12:09 | MASTER-Kislovodsk | (16h 31m 34.53s , +38d 48m 49.2s) | C | 60 | 17.4 | 53547 | 2025-06-10 19:17:46 | MASTER-Kislovodsk | (16h 31m 41.01s , +38d 50m 51.7s) | C | 60 | 17.1 | 53720 | 2025-06-10 19:20:40 | MASTER-Kislovodsk | (16h 31m 35.46s , +38d 50m 56.6s) | C | 60 | 16.0 | 53893 | 2025-06-10 19:23:32 | MASTER-Kislovodsk | (16h 31m 32.13s , +38d 48m 59.5s) | C | 60 | 17.0 | Filter C is a clear (unfiltred) band. The observation and reduction will continue. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/40673. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38711] GRB 250610B : SVOM/GWAC-F60A and F50 observations
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40672 SUBJECT: GRB 250610B : SVOM/GWAC-F60A and F50 observations DATE: 25/06/10 18:53:15 GMT FROM: Weikang Zheng at UC Berkeley <weikang(a)berkeley.edu> J. Wang, W. L. Dong, L. P. Xin(NAOC), L. J. Chen(GXU), Y. G. Yang(HNU), X. H. Han, C. WU, Y. L. Qiu, H. L. Li, X .M. Lu, R. S. Zhang, Y. Xu, L. Huang, H. B. Cai, Y. J. Xiao, P. P. Zhang, L. Lan, W. J. Xie, Z. H. Yao, J. Y. Wei(NAOC), X. G. Wang, E. W. Liang(GXU) and W. Zheng (UCB) report on behalf of the SVOM follow-up team: We observed the field of SVOM GRB 250610B (Saccardi et al., GCN 40671) with the GWAC-F60A and GWAC-F50 at Xinglong Observatory, China. F60A started observing at 2025-06-10T17:14:17.39 UTC with a set of 34 images in R-band. F50 started observing at 2025-06-10T17:14:17.39 UTC and with a set of 9 images in R-band. After coadding the images, we do not find any uncatalog candidate within the SVOM/ECLAIRs error box. We estimate the upper limit of 16.0 mag for GWAC-F60A at mid time of 54.5 minutes after brust, and upper limit of 17.5 mag for GWAC-F50 at mid time of 54.0 minutes after brust. Two 60cm GWAC-F60(A/B) are operated by Guangxi University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 19*19 arcmin. The 50cm telescope (F50A) is operated by Huaibei Normal University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 27*27 arcmin. View this GCN Circular online at https://gcn.nasa.gov/circulars/40672. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38710] GRB 250610B: SVOM detection of a long burst
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40671 SUBJECT: GRB 250610B: SVOM detection of a long burst DATE: 25/06/10 17:27:30 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> A. Saccardi, J. Rodriguez, N. Dagoneau (CEA), C. Van Hove (IJCLab) report on behalf of the SVOM mission team. At 2025-06-10T16:32:58 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250610B (SVOM burst-id sb25061018). 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 40 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 30.55 in the [8-50] keV energy band over a time window of 81.92 seconds starting at 2025-06-10T16:33:19. The localization of the best alert is R.A., Dec. 200.1831, 31.1028 degrees: R.A. (J2000) = 13h20m43.94s Dec. (J2000) = 31d06m10.04s with a 90% confidence level (C.L.) radius of 3.22 arcmin (including systematic error of 2 arcmin added in quadrature). The ECLAIRs light curve may show a double narrow peak structure with a T90 duration of about 134.368 (-13.465 +23.518) s. The ECLAIRs peak count rate was ~496.6503 ± 191.3858 counts/sec in the band [20-50] keV, ~5.6 seconds after the trigger. This burst was also detected by SVOM/GRM with a significance of 14.30. The GRM light curve showed a single broad peak structure with a T90 duration of about 69.237 (-6.343 +6.558) s. The GRM peak count rate was ~470.4469 ± 82.6942 counts/sec in the band [4-5000] keV, ~34.4 seconds after the trigger. A SVOM ToO has been executed for follow-up and started to observe at 2025-06-10T16:59 UTC. 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. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE. The Burst Advocate (BA) on shift for this alert is Andrea Saccardi: andrea.saccardi(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/40671. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38709] Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40670 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771256110/250610575 is not a GRB DATE: 25/06/10 14:25:40 GMT FROM: eliza.neights(a)gmail.com E. Neights (GWU, NASA GSFC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771256110/250610575 at 13:48:25.58 UT on 10 June 2025, tentatively classified as a GRB, is in fact not due to a GRB. This trigger is likely due to local particles." View this GCN Circular online at https://gcn.nasa.gov/circulars/40670. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38708] EP250610a: refined analysis of the EP-WXT and EP-FXT observations
by GCN Circulars 10 Jun '25

10 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40669 SUBJECT: EP250610a: refined analysis of the EP-WXT and EP-FXT observations DATE: 25/06/10 14:16:44 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> T.Y. Lian, H. Q. Cheng (NAO, CAS), Y. J. Zhang (THU) and C. C. Jin (NAO, CAS) report on behalf of the Einstein Probe team: The fast X-ray transient EP250610a was detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Zhang et al., GCN 40660), and followed up by several optical and X-ray telescopes (Schneider et al., GCN 40661, Brivio et al., GCN 40665, Evans et al., GCN 40662). Refined analysis of the WXT data shows that the event started at T0=2025-06-10T04:23:24 (UTC) and lasted for about 140s before the interruption by the autonomous follow-up observation. The peak flux (0.5-4 keV) is estimated to be 2.2 x 10^-9 erg/s/cm^2. The averaged 0.5-4 keV spectrum can be fitted with an absorbed power-law with a Galactic hydrogen column density of 9.5 x 10^19 cm^-2 and a photon index of 0.7 (-/+0.8). The derived average unabsorbed 0.5-4 keV flux is 5.2 (-2.3, +4.2) x 10^-10 erg/s/cm^2. The Follow-up X-ray Telescope (FXT) on board EP observed this source autonomously at 2025-06-10T04:26:32, about 3 minutes after T0, with an exposure time of 3946 seconds. Within the WXT error circle, on-ground analysis of the FXT data found an uncatalogued source at R.A. = 248.3567, DEC = 38.5362 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic), which is spatially consistent with the candidate X-ray counterpart detected by Swift/XRT (Source 1 in Evans et al., GCN 40662). The averaged 0.5-10 keV FXT spectrum can be fitted with an absorbed power-law with a Galactic hydrogen column density of 9.5 x 10^19 cm^-2 and a photon index of 2.34 (-0.12, +0.12). The derived unabsorbed 0.5-10 keV flux is 1.87 (-0.17, +0.19) x 10^-12 erg/s/cm^2. The uncertainties are at the 90% confidence level for all the above parameters. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). The contact TAs of this source are Tianying Lian and Huaqing Cheng, please contact them via the email tylian(a)nao.cas.cn and hqcheng(a)nao.cas.cn if needed. View this GCN Circular online at https://gcn.nasa.gov/circulars/40669. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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