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

[vsnet-grb-info 39060] GRB 250706A: Swift-XRT refined Analysis
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41010 SUBJECT: GRB 250706A: Swift-XRT refined Analysis DATE: 25/07/07 16:05:07 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> R. Brivio (INAF-OAB), D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 5.7 ks of XRT data for GRB 250706A, from 131 s to 55.6 ks after the trigger. The data comprise 285 s in Windowed Timing (WT) mode (the first 10 s were taken while Swift was slewing) with the remainder in Photon Counting (PC) mode. The refined XRT position is RA, Dec = 284.0176, +32.3216 which is equivalent to: RA (J2000): 18 56 04.22 Dec(J2000): +32 19 17.6 with an uncertainty of 3.5 arcsec (radius, 90% confidence). The light curve can be modelled with an initial power-law decay with an index of alpha=0.76 (+0.12, -0.13), followed by a break at T+427 s to an alpha of 2.27 (+0.18, -0.14). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.87 (+/-0.09). The best-fitting absorption column is 2.6 (+/-0.4) x 10^21 cm^-2, in excess of the Galactic value of 1.2 x 10^21 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 3.8 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1. A summary of the WT-mode spectrum is thus: Total column: 2.6 (+/-0.4) x 10^21 cm^-2 Galactic foreground: 1.2 x 10^21 cm^-2 Excess significance: 6.4 sigma Photon index: 1.87 (+/-0.09) If the light curve continues to decay with a power-law decay index of 2.27, the count rate at T+24 hours will be 3.3 x 10^-5 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.3 x 10^-15 (1.7 x 10^-15) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01330958. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/41010. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39059] GRB 250706B: refined SVOM/MXT data analysis
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41009 SUBJECT: GRB 250706B: refined SVOM/MXT data analysis DATE: 25/07/07 15:24:57 GMT FROM: SVOM_group <svomgroup(a)bao.ac.cn> P. Maggi (ObAS), D. Götz (CEA), H. Goto (Kanazawa University/CEA), M. Moita (CEA), C. Plasse (CEA), F. Robinet (IJCLab), C. Van Hove (IJCLab) report of behalf of the SVOM/MXT Team: GRB 250706B (Palmerio et al. GCN 40989) was observed by SVOM/MXT after an automatic SVOM slew, starting at T0 = 2025-07-06T17:08:42.6 (158 s after trigger time Tb). MXT observed during 6 orbits for 13.6 ks effective exposure time. Using the full X-band dataset, the X-ray source afterglow is located at R.A., Dec = 41.239, -50.065 degrees: R.A. (J2000) = 02h44m57.45s Dec. (J2000) = -50d03m55.6s with a 90% C.L. radius of 31 arcseconds (including 30 arcseconds systematic error added in quadrature) and consistent with the reported optical VT position (Palmerio et al. GCN 40992). The spectrum is modelled with an absorbed power law. Across the full data set the absorption column NH is consistent within uncertainties, between 2 and 3 x 1e22 /cm2 (all uncertainties are at the 90% C.L.). The photon index evolves from 2.25 (-0.16/+0.18) within 1200s of trigger time, to 2.53 (-0.25/+0.28) at Tb + 5 ks < t < Tb+ 20 ks, and softens further to 3.43 (-1.04/+1.45) at t > Tb + 25 ks. The 0.3-10 keV flux is 8.24e-10 (-0.91/+0.82) x 1e-10 erg/cm2/s, 8.9 (-1.0/+1.2) x 1e-11 erg/cm2/s, and down to <1.0 x 1e-11 erg/cm2/s during the same intervals. We observe a complex light curve with at least 3 power-law segments with count rate proportional to t^alpha, with: alpha = -0.42 +/-0.02 until Tb+5031s +/-277s alpha = -1.57 +/-0.07 until Tb+24326s +/-3479s alpha = -3.05 +/-1.62 afterwards The SVOM/MXT light curve can be found here: https://seafile.unistra.fr/f/909c01d644774417897e/. With the spectrum reported in the first interval, a count rate of 1 count/s corresponds to a flux of 1.89x1e-10 erg/cm2/s. Follow-up observations at other wavelengths are encouraged. 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. MXT was developed jointly by CEA, CNES, University of Leicester, IJCLab and MPE. The SVOM point of contact for this burst is Jesse Palmerio: palmerio(a)cea.fr Please contact the BA by email if you require additional information regarding the SVOM follow-up of this burst. View this GCN Circular online at https://gcn.nasa.gov/circulars/41009. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39058] GRB 250706A: Swift/UVOT Upper Limits
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41008 SUBJECT: GRB 250706A: Swift/UVOT Upper Limits DATE: 25/07/07 12:51:03 GMT FROM: Mike Siegel at PSU/Swift MOC <mhs18(a)psu.edu> M. H. Siegel (PSU) and M. J. Moss (GSFC) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250706A 147 s after the BAT trigger (Moss et al., GCN Circ. 40988). No optical afterglow consistent with the XRT position is detected in the initial UVOT exposures. Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first finding chart (FC) exposure and subsequent exposures are: Filter T_start(s) T_stop(s) Exp(s) Mag u_FC 147 397 246 >19.5 v 453 473 19 >16.8 b 403 423 19 >18.0 u 147 397 246 >19.5 w1 502 509 6 >18.2 m2 477 497 19 >17.9 w2 429 449 19 >19.9 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.093 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/41008. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39057] GRB 250706B: REM optical observations
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41007 SUBJECT: GRB 250706B: REM optical observations DATE: 25/07/07 10:23:35 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of GRB 250706B detected by SVOM/ECLAIRs (Palmerio et al., GCN 40989) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, and z bands, started on 2025 July 07 at 05:14:01 UT (i.e. 12.1 hr after the burst), and lasted for about 1 hour. From preliminary inspection, we do not detect any counterpart at the position of the optical afterglow (Zhu et al., GCN 40991; Romanov, GCN 40995) down to the following 3sigma limit: r > 19.2 (AB; calibrated against the SkyMapper catalogue), at a mid-time of 13.0 hr after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/41007. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39056] GRB 250706A: REM optical/NIR observations
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41006 SUBJECT: GRB 250706A: REM optical/NIR observations DATE: 25/07/07 10:22:00 GMT FROM: Riccardo Brivio at INAF-OAB <riccardo.brivio(a)inaf.it> R. Brivio, M. Ferro, P. D'Avanzo, S. Covino, D. Fugazza (INAF-OAB) report on behalf of the REM team: We observed the field of GRB 250706A detected by Swift/BAT (Moss et al., GCN 40988) with the REM 60 cm robotic telescope located at the ESO observatory of La Silla (Chile). The observations were carried in the g, r, i, z, and H bands, started on 2025 July 07 at 06:21:07 UT (i.e. 14.5 hr after the burst), and lasted for about 1 hour. From preliminary inspection, we do not detect any optical/NIR counterpart within the Swift/XRT error region down to the following 3sigma limits: r > 19.8 (AB; calibrated against the Pan-STARRS catalogue), at a mid-time of 15.1 hr after the trigger; H > 15.3 (Vega; calibrated against the 2MASS catalogue), at a mid-time of 14.6 hr after the trigger. View this GCN Circular online at https://gcn.nasa.gov/circulars/41006. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39055] EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41005 SUBJECT: EP250706a/GRB 250706A: EP-WXT detection of a fast X-ray transient DATE: 25/07/07 09:25:55 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Q. C. Liu (THU), J. W. Hu, D. Y. Li, B. B. Zhang (NAO,CAS), Y. H. Cheng (YNU), P. Y. Han (HUST), W. Yuan (NAO,CAS) on behalf of the Einstein Probe team We report on the detection of a fast X-ray transient, designated EP250706a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient event started at 2025-07-06T15:48:25 (UTC). The position of the source is R.A. = 284.02 deg, DEC = 32.329 deg (J2000) with an uncertainty of 2.2 arcmin in radius (90% C.L. statistical and systematic). The trigger time and position of this X-ray transient are consistent with that of GRB 250706A (#GCN 40988, #GCN 40990, #GCN 40998, #GCN 41000, #GCN 41001). The transient event lasts for more than 250 seconds. No automated follow-up X-ray observation was performed due to that EP was performing a ToO observation of higher priority. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a photon index of 2.7 (+1.2/-1.0) with a column density value of 0.7 (+0.4/-0.3) x 10^22 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 0.8 (+1.0/-0.3) x 10^-9 erg/s/cm^2. The peak flux is around 4.6 x 10^-9 erg/s/cm^2. The uncertainties are at the 90% confidence level for 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). View this GCN Circular online at https://gcn.nasa.gov/circulars/41005. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39054] IceCube-250416A: DDOTI Optical Upper Limit
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41004 SUBJECT: IceCube-250416A: DDOTI Optical Upper Limit DATE: 25/07/07 09:22:40 GMT FROM: Rosa L. Becerra at Tor Vergata, Roma <rosa.becerra(a)roma2.infn.it> Rosa L. Becerra (U Roma), Sahil Atri (U Roma), Alan M. Watson (UNAM), Eleonora Troja (U Roma), Camila Angulo Valdez (UNAM), Nat Butler (ASU), Simone Dichiara (Penn State University), Tsvetelina Dimitrova (ASU), Alexander Kutyrev (GSFC/UMD), William H. Lee (UNAM), Océlotl López (UNAM) and Margarita Pereyra (UNAM) report: We observe the field of the IceCube250706A (gold) event (IceCube Collaboration, GCN Circ. 40994) with the DDOTI/OAN wide-field imager at the Observatorio Astronómico Nacional on the Sierra of San Pedro Martir (http://ddoti.astroscu.unam.mx) on the night of 2025-07-07 UTC. DDOTI observed from 06:32 UTC to 07:43 UTC (from T+17.3 h to T+18.5 h after the trigger) with a total exposure of 38 min, covering the total error region reported by IceCube (IceCube Collaboration, GCN Circ 40994). Comparing our observations to the USNO-B1 and PanSTARRS PS1 DR2 catalogues and after performed image subtraction against PanSTARRS PS1 DR2, we detect no uncatalogued sources within the observed field to a 10-sigma limiting AB magnitude of: w > 20.2. This upper limit is consistent with the non-detection reported by COLIBRI (Globus et al., GCN Circ. 41003). This value is not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra of San Pedro Mártir. View this GCN Circular online at https://gcn.nasa.gov/circulars/41004. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39053] IceCube-250706A: COLIBRÍ optical upper limits
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41003 SUBJECT: IceCube-250706A: COLIBRÍ optical upper limits DATE: 25/07/07 08:47:45 GMT FROM: Sarah Antier at OCA <sarah.antier(a)oca.eu> Noémie Globus (UNAM), Sarah Antier (OCA/IJCLAB), Rosa L. Becerra (U Roma), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Alan M. Watson (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), N. A. Rakotondrainibe (LAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM) report: We observed the field of the IceCube-250706A (GCN 40994) (goldtrack) event with the DDRAGO wide-field imager on the COLIBRÍ telescope at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir in Mexico on the night of 2025-07-07 UTC. COLIBRÍ tiled the IceCube error region, starting at 03:43:42 UTC, e.g T+14.5 h after the trigger, for about 1h distributed over 4 tiles (26x26 arcmin); the maximum exposure at a single sky location was 16x60 s. The data were coadded with the COLIBRÍ pipeline and analysed in STDWeb/STDPipe (Karpov 2025). Comparing our observations (and after performing image subtraction) against Pan-STARRS DR2, we detect no evident uncatalogued sources within the observed field to a 5-sigma limiting AB magnitude of: i > 21.6 for the first tile (3 min exp.), centered on (RA, Dec) = (17:43:12.00, +38:46:11.6) i > 21.1 for the second tile (3 min exp.), centered on (RA, Dec) = (17:43:12.00 +39:10:12.0) i > 21.9 for the third tile (16 min exp.), centered on (RA, Dec) = (17:44:48.00, +39:10:12.0) i > 22.3 for the fourth tile (16 min exp.), centered on (RA, Dec) = (17:44:48.00, +38:46:12.0) These values are not corrected for the Galactic extinction. We thank the staff of the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir and the COLIBRÍ and DDRAGO engineering teams. View this GCN Circular online at https://gcn.nasa.gov/circulars/41003. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39052] Swift GRB 250706A: Global MASTER-Net observations report
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41002 SUBJECT: Swift GRB 250706A: Global MASTER-Net observations report DATE: 25/07/07 08:24:35 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 Swift GRB 250706A ( M. J. Moss et al., GCN 40988) errorbox 46980 sec after notice time and 47035 sec after trigger time at 2025-07-07 04:52:26 UT, with upper limit up to 18.0 mag. The observations began at zenith distance = 64 deg. The sun altitude is -81.1 deg. The galactic latitude b = 13 deg., longitude l = 63 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2927564 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 47126 | MASTER-OAFA | C | 180 | 17.7 | 47319 | MASTER-OAFA | C | 180 | 17.8 | 49913 | MASTER-OAFA | C | 180 | 18.0 | 50108 | MASTER-OAFA | C | 180 | 18.0 | 51188 | MASTER-OAFA | C | 180 | 17.8 | 51392 | MASTER-OAFA | C | 180 | 17.9 | 52485 | MASTER-OAFA | C | 180 | 17.8 | 52679 | MASTER-OAFA | C | 180 | 17.6 | 53664 | MASTER-OAFA | C | 180 | 17.6 | 53965 | MASTER-OAFA | C | 180 | 17.7 | 54883 | MASTER-OAFA | C | 180 | 17.7 | 55239 | MASTER-OAFA | C | 180 | 17.7 | 56730 | MASTER-OAFA | C | 180 | 17.4 | 56924 | MASTER-OAFA | C | 180 | 17.2 | 57911 | MASTER-OAFA | C | 180 | 17.4 | 58211 | MASTER-OAFA | C | 180 | 17.1 | 59205 | MASTER-OAFA | C | 180 | 16.4 | 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/41002. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 39051] GRB 250706A: JinShan optical upper limits
by GCN Circulars 07 Jul '25

07 Jul '25

TITLE: GCN CIRCULAR NUMBER: 41001 SUBJECT: GRB 250706A: JinShan optical upper limits DATE: 25/07/07 07:17:13 GMT FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn> Z.P. Zhu, S.Q. Jiang, X. Liu, J. An, L.B. He, D. Xu (NAOC), S.Y. Fu(HUST), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB250706A detected by Swift/BAT (Moss et al., GCN 40988), using the 100cm-C telescope (100C) of the JinShan project, located at Altay, Xinjiang, China. Observations began at 15:55:19 UT on 2025-07-06, i.e., 6.8 minutes after the BAT trigger, and a series of frames were obtained in the Sloan r- and z-band. No new optical source is detected within the XRT error circle (Moss et al., GCN 40988), consistent with the reported results (Mohan et al., GCN 40990; Wu et al., GCN 40998), down to 5-sigma upper limits of r ~ 21.4 and z ~21.1, calibrated with nearby Pan-STARRS stars and not corrected for Galactic extinction. We acknowledge the excellent support from T.Q. Chen for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/41001. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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