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

[vsnet-grb-info 38787] GRB 250615A: Swift/UVOT Upper Limits
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40747 SUBJECT: GRB 250615A: Swift/UVOT Upper Limits DATE: 25/06/16 11:38:35 GMT FROM: Paul Kuin at MSSL <npkuin(a)gmail.com> N.P.M.Kuin (UCL/MSSL) and S. Dichiara (PSU) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250615A 152 s after the BAT trigger (Dichiara et al., GCN Circ. 40736). No optical afterglow consistent with the enhanced XRT position (Goad et al., GCN Circ. 40739) 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 152 402 246 >19.8 white 432 1722 284 >21.0 v 483 1772 156 >19.5 b 408 1697 136 >20.7 u 152 1672 363 >20.0 w1 532 1821 136 >19.5 w2 804 1747 78 >19.2 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 1.165 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40747. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38786] Konus-Wind detection of GRB 250612C (short/hard with extended emission)
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40746 SUBJECT: Konus-Wind detection of GRB 250612C (short/hard with extended emission) DATE: 25/06/16 11:33:32 GMT FROM: Dmitry Frederiks at Ioffe Institute <fred(a)mail.ioffe.ru> D. Frederiks, A.Lysenko, A. Ridnaia, D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline, on behalf of the Konus-Wind team, report: The bright GRB 250612C (Fermi GBM detection: Fermi GBM team, GCN 40704; Neights & Meegan, GCN 40713; SVOM/GRM observation: Wang et al., GCN 40708; GRID detection: Yang et al., GCN 40732) triggered Konus-Wind (KW) at T0=53591.512 s UT (14:53:11.512). The burst light curve shows a very bright, multi-peaked emission episode, which starts at ~T0-0.05 s and has a duration of ~1.3 s. This episode is followed by a much weaker extended emission tail visible to ~T0+25 s. The emission is seen up to ~15 MeV. The Konus-Wind light curve of this GRB is available at http://www.ioffe.ru/LEA/GRBs/GRB250612_T53591/ As observed by Konus-Wind, the burst had the total fluence of (6.92 ± 0.50)x10^-5 erg/cm^2 and a 16-ms peak energy flux, measured from T0+0.016, of (3.01 ± 0.38)x10^-4 erg/cm^2/s (both in the 20 keV - 10 MeV energy range). The time-integrated spectrum of the initial episode (measured from T0 to T0+1.280 s) is best fit in the 20 keV - 20 MeV range by a power law with exponential cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep) with alpha = -0.90(-0.03,+0.02) and Ep = 2084 (-97,+103) keV (chi2 = 91.8/74 dof). Fitting this spectrum by a Band function yields similar, within errors, values of alpha and Ep, and an upper limit on the high energy photon index beta of -4.0 (chi2 = 91.7/73 dof). The spectrum near the peak count rate (measured from T0 to T0+0.064 s) is best fit in the 20 keV - 20 MeV range by a CPL model with alpha = -0.14(-0.13,+0.14) and Ep = 2073 (-214,+263) keV (chi2 = 38.7/35 dof). Fitting this spectrum by a Band function yields the same values of alpha and Ep, and an upper limit on the high energy photon index beta of -2.0 (chi2 = 38.4/34 dof). The spectrum of the extended emission, measured from T0+1.280 s to T0+25.856 s, is best fit in the 20 keV - 20 MeV range by a simple power law (PL) function with the photon PL index of -1.68 ± 0.12. All the quoted errors are estimated at the 68% confidence level. All the presented results are preliminary. View this GCN Circular online at https://gcn.nasa.gov/circulars/40746. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38785] GRB 250615A: Swift-XRT refined Analysis
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40745 SUBJECT: GRB 250615A: Swift-XRT refined Analysis DATE: 25/06/16 10:56:50 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> D.N. Burrows (PSU), M.A. Williams (PSU), S. Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-OAR) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.2 ks of XRT data for GRB 250615A, from 93 s to 40.3 ks after the trigger. The data comprise 106 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a power-law decay with a decay index of alpha=1.62 (+0.07, -0.06). A spectrum formed from the WT mode data can be fitted with an absorbed power-law with a photon spectral index of 1.62 (+0.27, -0.26). The best-fitting absorption column is 2.4 (+0.6, -0.5) x 10^22 cm^-2, in excess of the Galactic value of 5.5 x 10^21 cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index of 2.0 (+0.4, -0.3) and a best-fitting absorption column of 2.4 (+0.7, -0.6) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 6.7 x 10^-11 (1.5 x 10^-10) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 2.4 (+0.7, -0.6) x 10^22 cm^-2 Galactic foreground: 5.5 x 10^21 cm^-2 Excess significance: 5.3 sigma Photon index: 2.0 (+0.4, -0.3) If the light curve continues to decay with a power-law decay index of 1.62, the count rate at T+24 hours will be 2.2 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.5 x 10^-14 (3.3 x 10^-14) erg cm^-2 s^-1. The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/01324646. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40745. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38784] sb25061207/SVOM: T120 OHP optical upper limit
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40744 SUBJECT: sb25061207/SVOM: T120 OHP optical upper limit DATE: 25/06/16 10:28:28 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), Y. Degot-Longui (Pytheas/OHP), 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 SVOM sb25061207 X-ray transient (Zhang et al., GCN 40697; Li et al., GCN 40707; Evans et al.,GCN 40711; Li et al., GCN 40707; Zhang et al., GCN 40697) using the T120cm telescope at Observatoire de Haute-Provence (France). We obtained 54.5 minutes in the r-band, from 2025-06-12T20:32:03.91 to 2025-06-12T21:44:45.14 (from 9.9 to 11.3 hr after the trigger). In the stacked image, we do not detect the VT optical counterpart (Li et al., GCN 40707) down to the following 3-sigma limit (AB): r > 22.1 The photometric calibration was performed using nearby stars from the PanStarrs 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 (Institut Origines). View this GCN Circular online at https://gcn.nasa.gov/circulars/40744. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38783] EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40743 SUBJECT: EP250615a/GRB 250615A: EP-WXT detection of a fast X-ray transient DATE: 25/06/16 09:31:10 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> G. J. Yang, M. J. Liu (NAO, CAS), Y. Q. Zhao (USTC,PRIC), Y. P. Zhou (NJU), X. L. Chen (YNU), Q. Y. Wu, C. C. Jin (NAO,CAS) on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient, designated EP250615a, by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission. The transient event started at 2025-06-15T22:25:17 (UTC). The position of the source is R.A. = 290.379 deg, DEC = 4.678 deg (J2000) with an uncertainty of 2.181 arcmin in radius (90% C.L. statistical and systematic). The transient event lasts for more than 50 seconds. The lightcurve of the transient observed by the WXT exhibits a rapid brightening profile. The average 0.5-4 keV spectrum can be fitted by an absorbed power law with a photon index of 2.2 (+1.5/-1.4) with a column density value of 2.1 (+1.7/-1.6) x 10^22 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 1.0 (+4.3/-0.6) x 10^-8 erg/s/cm^2. The peak flux is around 6.3 x 10^-7 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. The trigger time and position of this X-ray transient are consistent with that of GRB 250615A (GCN 40736, GCN 40737, GCN 40739). 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/40743. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38782] Fermi trigger No 771752663: Global MASTER-Net observations report
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40742 SUBJECT: Fermi trigger No 771752663: Global MASTER-Net observations report DATE: 25/06/16 09:15:27 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) started inspect of the Fermi GRB250616.32 (trigger No 771752663,19h 04m 43.92s , -07d 46m 01.2s, R=27.15) errorbox 2889 sec after notice time and 2923 sec after trigger time at 2025-06-16 08:33:01 UT, with upper limit up to 17.0 mag. The observations began at zenith distance = 48 deg. The sun altitude is -37.2 deg. The galactic latitude b = -7 deg., longitude l = 28 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2903763 We obtain a following upper limits. Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment _________|_____________________|_____________________|____________________________________|_____|_______|_______|________ 3013 | 2025-06-16 08:33:01 | MASTER-OAFA | (19h 20m 17.19s , +04d 53m 38.9s) | C | 180 | 17.0 | 3152 | 2025-06-16 08:36:20 | MASTER-OAFA | (19h 21m 22.31s , +04d 51m 02.3s) | C | 60 | 16.9 | 3239 | 2025-06-16 08:37:47 | MASTER-OAFA | (19h 21m 16.18s , +04d 50m 03.8s) | C | 60 | 16.9 | 3315 | 2025-06-16 08:39:03 | MASTER-OAFA | (19h 21m 21.58s , +04d 50m 26.3s) | C | 60 | 16.9 | 3395 | 2025-06-16 08:40:22 | MASTER-OAFA | (19h 21m 19.40s , +04d 51m 42.4s) | C | 60 | 17.0 | 3468 | 2025-06-16 08:41:36 | MASTER-OAFA | (19h 21m 19.35s , +04d 50m 15.0s) | C | 60 | 17.0 | 3546 | 2025-06-16 08:42:54 | MASTER-OAFA | (19h 21m 21.84s , +04d 51m 40.9s) | C | 60 | 17.0 | 3623 | 2025-06-16 08:44:11 | MASTER-OAFA | (19h 21m 16.42s , +04d 51m 07.8s) | C | 60 | 17.0 | 3699 | 2025-06-16 08:45:27 | MASTER-OAFA | (19h 21m 17.11s , +04d 52m 08.6s) | C | 60 | 17.0 | 3779 | 2025-06-16 08:46:47 | MASTER-OAFA | (19h 21m 21.43s , +04d 51m 09.2s) | C | 60 | 17.0 | 3861 | 2025-06-16 08:48:09 | MASTER-OAFA | (19h 21m 15.96s , +04d 50m 10.0s) | C | 60 | 17.0 | 3938 | 2025-06-16 08:49:26 | MASTER-OAFA | (19h 21m 22.10s , +04d 50m 10.0s) | C | 60 | 17.0 | 4012 | 2025-06-16 08:50:40 | MASTER-OAFA | (19h 21m 19.19s , +04d 52m 05.4s) | C | 60 | 17.0 | 4530 | 2025-06-16 08:59:18 | MASTER-OAFA | (19h 21m 32.36s , +04d 51m 07.1s) | C | 60 | 16.7 | 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/40742. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38781] EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40741 SUBJECT: EP-WXT trigger 01709178875: confirmation of a stellar flare by BOOTES-6 DATE: 25/06/16 06:51:28 GMT FROM: I. Perez-Garcia at Institute of Astrophysics of Andalusia <ipg(a)iaa.es> I. Perez-Garcia, S.-Y. Wu, A. J. Castro-Tirado, E. J. Fernandez-Garcia, M.D. Caballero-Garcia, S. Guziy, G. Garcia-Segura, R. Sanchez-Ramirez (IAA-CSIC), Y.-D. Hu (INAF-OAB), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), , M. Gritsevich (Univ. of Helsinki), D.-R. Xiong (Yunnan Observatories of CAS), B.-B. Zhang (Nanjing Univ.), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland), on behalf of a larger collaboration, report: Following the detection of trigger 01709178875 by EP-WXT (Zhao et al. GCN 40740), the 0.6m robotic telescope BOOTES-6/DPRT at Boyden Observatory in Maselspoort (South Africa) responded to the alert on June 15, 16:35 UT (i.e. 23 min after notification and 29 min after the detection). Within the reported EP error circle we find the star SZ 67 decreasing 1.6 mag in brightness (g filter) and 1 mag (r filter) during a 240 min time interval, confirming the EP X-ray trigger due to a stellar flare. We thank the staff at Boyden Observatory for their excellent support. View this GCN Circular online at https://gcn.nasa.gov/circulars/40741. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38780] The EP-WXT trigger 01709178875 is likely a flaring star
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40740 SUBJECT: The EP-WXT trigger 01709178875 is likely a flaring star DATE: 25/06/16 04:17:09 GMT FROM: EP Team at NAOC/CAS <ep_ta(a)bao.ac.cn> Y.Q.Zhao(USTC,PRIC),Y.P.Zhou(NJU),X.L.Chen(YNU),M.J.Liu,C.C.Jin(NAO, CAS) on behalf of the Einstein Probe (EP) team: The EP-WXT trigger 01709178875 at the time of 2025-06-15T16:06:24, is likely a stellar flare associated with T Tauri Star SZ 67. The estimated flux of the flare is around 1.18e-10 erg/s/cm^2 in 0.5-4.0 keV, corresponding to an X-ray luminosity of around 1.51e32 erg/s. 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/40740. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38779] GRB 250615A: Enhanced Swift-XRT position
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40739 SUBJECT: GRB 250615A: Enhanced Swift-XRT position DATE: 25/06/16 02:49:06 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team. Using 1622 s of XRT Photon Counting mode data and 1 UVOT images for GRB 250615A, we find an astrometrically corrected X-ray position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 290.38565, +4.68515 which is equivalent to: RA (J2000): 19h 21m 32.56s Dec (J2000): +04d 41' 06.5" with an uncertainty of 2.3 arcsec (radius, 90% confidence). This position may be improved as more data are received. The latest position can be viewed at http://www.swift.ac.uk/xrt_positions. Position enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans et al. (2009, MNRAS, 397, 1177). This circular was automatically generated, and is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40739. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38778] Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB
by GCN Circulars 16 Jun '25

16 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40738 SUBJECT: Fermi Gamma-ray Burst Monitor trigger 771718064/250615922 is not a GRB DATE: 25/06/16 01:58:38 GMT FROM: sumanbala2210(a)gmail.com S. Bala (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team: "The Fermi Gamma-ray Burst Monitor (GBM) trigger 771718064/250615922 at 22:07:39.34 UT on 15 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/40738. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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