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[vsnet-grb-info 38881] GRB 250625A: Swift/UVOT Upper Limits
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40840 SUBJECT: GRB 250625A: Swift/UVOT Upper Limits DATE: 25/06/26 11:21:27 GMT FROM: Alice Breeveld at MSSL-UCL <a.breeveld(a)ucl.ac.uk> A.A. Breeveld (UCL-MSSL) and M. Ferro (INAF-OAB) report on behalf of the Swift/UVOT team: The Swift/UVOT began settled observations of the field of GRB 250625A 125 s after the BAT trigger (Ferro et al., GCN Circ. 40825). The optical afterglow reported by Moskvitin et al. (GCN Circ. 40828), Xin et al. (GCN Cir. 40830), Zhu et al. (GCN Circ. 40834) Fortin et al. (GCN Circ. 40837), Adami et al. (GCN Circ. 40838) and Brosio et al. (GCN Circ. 40839) is not 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 white_FC 125 275 147 >20.9 u_FC 283 533 246 >20.5 white 125 1529 392 >21.7 v 613 1579 117 >19.2 b 539 1505 97 >20.4 u 283 1480 324 >20.6 w1 662 1628 117 >19.6 m2 637 1431 78 >20.1 w2 589 1383 97 >20.6 The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.054 in the direction of the burst (Schlegel et al. 1998). View this GCN Circular online at https://gcn.nasa.gov/circulars/40840. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38880] GRB 250625A: ABObservatory afterglow detection
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40839 SUBJECT: GRB 250625A: ABObservatory afterglow detection DATE: 25/06/26 11:06:58 GMT FROM: A. Brosio at ABObservatory Rosarno <antonino.brosio(a)gmail.com> A. Brosio (ABObservatory Rosarno), S. Savaglio (University of Calabria), G. Bracco, P. Cianfarra, L. Sangaletti, S. Tosi & S. Zappatore (University of Genoa), S. Benatti & M. G. Guarcello (INAF Palermo), L. Cabona, M. Rainer & F. M. Zerbi (INAF Brera), D. Ricci (INAF Padova), A. Di Dato (INAF Capodimonte), S. Masiero & A. Nastasi (GAL Hassin), D. Liguori (Osservatorio "G. Galilei" Cariati), L. Betti (Osservatorio Polifunzionale del Chianti), R. Nesci (Associazione Astronomica Antares APS di Foligno), for the NOCTIS team report We observed the field of GRB 250625A, which was detected by Swift-BA (Ferro et al., GCN 40825) and Fermi-GBM (GCN #40824) with the 30-cm automated telescope at ABObservatory (Rosarno, Italy) in clear filter. The observations began on 2025 june 25 at 19:34:37 UT, approximately 3.34 hours after the trigger. The observation consisted of 85 exposures of 90 seconds each, with good sky condictions. The mid-exposure time was 20:21:42 UT, and the final exposure ended at 21:09:59 UT. From photometry, we detect the optical counterpart in our images at the at the following coordinates: R.A (J2000.0) = 17:26:01.56 Dec. (J2000.0) = +22 16 12.3 The measured magnitude is: V = 21.13 +/- 0.28 with SNR 5.4 (AB, calibrated against the Pan-STARRS catalogue on SIMBAD). View this GCN Circular online at https://gcn.nasa.gov/circulars/40839. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38879] GRB 250625A: OHP/T193 optical detection
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40838 SUBJECT: GRB 250625A: OHP/T193 optical detection DATE: 25/06/26 11:02:44 GMT FROM: Christophe Adami at LAM <christophe.adami(a)lam.fr> C. Adami (LAM/Pytheas/AMU), S. Basa (LAM/OHP/Pytheas/AMU), B. Schneider (LAM), E. Le Floc'h (CEA/Irfu), A. Ugarte Postigo (LAM), M. Dennefeld (IAP/CNRS/Sorbonne U.), report on behalf of a larger collaboration: We observed the field of the GRB 250625A (Fermi GBM Team, GCN 40824; Ferro et al., GCN 40825; Beardmore et al., GCN 40827; Dichiara et al., GCN 40835; Di Lalla et al., GCN 40836) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 8 exposures (for a total of 81min) in the r-band starting at 20:34:39 UT on 2025-06-25 (4.50 hours after the trigger). We also obtained 2 exposures (for a total of 30min) in the i-band starting at 22:28:55 UT on 2025-06-25 (6.40 hours after the trigger). In the stacked images, we detected the optical counterpart reported/followed by Moskvitin et al., GCN 40828, Xin et al., GCN 40830; Malesani et al., GCN 40831; Lipunov et al., GCN 40826/40832; Zhu et al., GCN 40834, Fortin et al., GCN 40837; in the r-band image. The preliminary magnitude derived for that source is: r = 22.95 +/- 0.23 mag (AB) We do not detect the optical counterpart in the i-band image with a 3-sigma upper limit of: i < 22.2 The photometric calibration was performed using nearby stars from the PanSTARRS catalog and the magnitudes are not corrected for Galactic extinction. We used the STDWeb/STDPipe tools (Karpov 2025). We acknowledge the excellent support from the Observatoire de Haute-Provence and in particular Jean Balcaen and R.P. Nelson for the MISTRAL observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40838. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38878] GRB 250625A: COLIBRÍ optical observations
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40837 SUBJECT: GRB 250625A: COLIBRÍ optical observations DATE: 25/06/26 09:35:11 GMT FROM: F. Fortin at IRAP <ffortin.sci.edu(a)gmail.com> Francis Fortin (IRAP), Alan M. Watson (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Fredd Alvarez (UNAM), Camila Angulo (UNAM), Dalya Akl (AUS), Sarah Antier (OCA), Rosa L. Becerra (U Roma), Nathaniel R. Butler (ASU) , Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Leonardo García García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Ny Avo Rakotondrainibe (LAM), Benjamin Schneider (LAM) and Antonio de Ugarte Postigo (LAM): We imaged the field of the Fermi/Swift co-detection of GRB 250625A (Fermi GBM Team, GCN Circ. 40824, Ferro et al., GCN Circ. 40825) using the DDRAGO wide-field imager on the COLIBRÍ telescope. We observed from 2025-06-26T03:42:43 to 05:49:43 UTC (from 11.41 to 13.53 hours after the trigger) and obtained 32 minutes of exposure in each of the g, r and i filters. The data were reduced and coadded with the COLIBRÍ pipeline and analysed with STDWeb/STDPipe (Karpov 2025). The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction. We detected the optical counterpart reported by Moskvitin et al. (GCN 40828), Xin et al. (GCN 40830), and Zhu et al. (GCN 40834), at a magnitude of: g = 24.22 +/- 0.34 r = 23.43 +/- 0.21 i = 24.01 +/- 0.58 Further observations are ongoing. 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/40837. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38877] GRB 250625A: Fermi-LAT detection
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40836 SUBJECT: GRB 250625A: Fermi-LAT detection DATE: 25/06/26 08:10:58 GMT FROM: Davide Depalo at Politecnico and INFN Bari <davide.depalo(a)ba.infn.it> N. Di Lalla (Stanford Univ.), A. Holzmann Airasca (UniTrento and INFN Bari), R. Gupta (NASA GSFC), and D. Depalo (Politecnico and INFN Bari) report on behalf of the Fermi-LAT Collaboration: On June 25, 2025, Fermi-LAT detected high-energy emission from GRB 250625A, which was also detected by Fermi-GBM (trigger 772560301 / 250625670, GCN 40824), Swift-BAT/XRT (GCN 40825) and SVOM/VT (GCN 40830). The best LAT on-ground location is found to be: RA, Dec = 261.2, 22.4 (J2000) with an error radius of 0.6 deg (90 % containment, statistical error only). This was 32 deg from the LAT boresight at the time of the GBM trigger (T0 = 16:04:57.51 UT). The data from the Fermi-LAT shows a significant increase in the event rate that is spatially and temporally correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0 - 100 s after the GBM trigger is (1.12 ± 0.48) E-5 ph/cm2/s. The estimated photon index above 100 MeV is -2.00 ± 0.38. The highest-energy photon is a 580 MeV event which is observed ~ 27 seconds after the GBM trigger. The Fermi-LAT point of contact for this burst is Davide Depalo (d.depalo2(a)phd.poliba.it). The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden. View this GCN Circular online at https://gcn.nasa.gov/circulars/40836. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38876] GRB 250625A: Swift-XRT refined Analysis
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40835 SUBJECT: GRB 250625A: Swift-XRT refined Analysis DATE: 25/06/26 05:57:53 GMT FROM: Phil Evans at U of Leicester <pae9(a)star.le.ac.uk> S. Dichiara (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M. Capalbi (INAF-OAR), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), J.A. Kennea (PSU), D.N. Burrows (PSU) and P.A. Evans report on behalf of the Swift-XRT team: We have analysed 6.0 ks of XRT data for GRB 250625A, from 123 s to 45.1 ks after the trigger. The data comprise 58 s in Windowed Timing (WT) mode with the remainder in Photon Counting (PC) mode. The light curve can be modelled with a series of power-law decays. The initial decay index is alpha=0.8 (+1.1, -1.2). At T+174 s the decay steepens to an alpha of 6.3 (+/-1.7) before breaking again at T+238 s to a final decay with index alpha=1.19 (+0.17, -0.15). A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 1.68 (+0.32, -0.29). The best-fitting absorption column is 1.7 (+1.3, -1.0) x 10^21 cm^-2, in excess of the Galactic value of 5.5 x 10^20 cm^-2 (Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 4.3 x 10^-11 (5.2 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.7 (+1.3, -1.0) x 10^21 cm^-2 Galactic foreground: 5.5 x 10^20 cm^-2 Excess significance: 1.9 sigma Photon index: 1.68 (+0.32, -0.29) If the light curve continues to decay with a power-law decay index of 1.19, the count rate at T+24 hours will be 5.0 x 10^-4 count s^-1, corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.2 x 10^-14 (2.6 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/01327910. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/40835. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38875] GRB 250625A: JinShan optical observations
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40834 SUBJECT: GRB 250625A: JinShan optical observations DATE: 25/06/26 04:25:58 GMT FROM: Zipei Zhu at NAOC <zpzhu(a)nao.cas.cn> Z.P. Zhu, S.Q. Jiang, X. Liu, J. An, D. Xu (NAOC), S.Y. Fu (HUST), J.Z. Liu (XAO) report on behalf of a large collaboration: We observed the field of GRB 250625A detected by the Fermi/GBM and Swift/BAT (the Fermi GBM Team, GCN 40824; Ferro et al., GCN 40825), using the 100cm-C telescope (100C) of the JinShan project, located at Altay, Xinjiang, China. Observations started at 16:11:04 UT on 2025-06-25, i.e., 6.1 min after the BAT trigger, and a series of frames were obtained in the Sloan r-, i-, z-bands. In the first round of r-band exposures, an uncatalogued optical source is marginally detected within the Swift/XRT enhanced error circle (Beardmore et al., GCN 40827), which is consistent with the reported optical counterpart by SAO RAS (Moskvitin et al., GCN 40828) and SVOM/VT (Xin et al., GCN 40830). The source is not detected in i-band and z-band (see also Malesani et al., GCN 40831), as well as in the second r-band exposures. Our preliminary results are summarized as follows: T-mid (hr) | Filter | Mag 0.387 | r | 22.5 +/- 0.3 1.237 | i | > 21.7 (5$\sigma$) 1.935 | z | > 20.5 (5$\sigma$) 2.761 | r | > 21.1 (5$\sigma$) calibrated with nearby Pan-STARRS stars without the Galactic extinction correction. We acknowledge the excellent support from T.Q. Chen and J.L. He for enabling these observations. View this GCN Circular online at https://gcn.nasa.gov/circulars/40834. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38874] GRB250625A: Fermi GBM Observation
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40833 SUBJECT: GRB250625A: Fermi GBM Observation DATE: 25/06/26 03:47:05 GMT FROM: Matt Godwin <msg0028(a)uah.edu> Matt Godwin (UAH), O. Mukherjee (USRA) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team: "At 16:04:57.51 UT on 25 June 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB250625A (trigger 772560302/250625670). Which was also detected by Swift BAT/XRT (Ferro et al. 2025, GCN 40825) and SVOM/VT (Xin et al. 2025, GCN 40830). The Fermi GBM on-ground location is consistent with the Swift position. The angle from the Fermi LAT boresight is 32 degrees. The GBM light curve consists of one strong peak and a few weaker peaks with a duration (T90) of about 5.4 s (50-300 keV). The time-averaged spectrum from T0-2.0 to T0+5.0 s is best fit by a power law function with an exponential high-energy cutoff. The power law index is -1.27 +/- 0.05 and the cutoff energy, parameterized as Epeak, is 1301.00 +/- 1190.00 The event fluence (10-1000 keV) in this time interval is (1.8 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured starting from T0-0.13 s in the 10-1000 keV band is 3 +/- 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/40833. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38873] Swift GRB 250625A: Global MASTER-Net observations report
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40832 SUBJECT: Swift GRB 250625A: Global MASTER-Net observations report DATE: 25/06/26 02:24:25 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-Tavrida robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 250625A ( M. Ferro et al., GCN 40825) errorbox 16240 sec after notice time and 16278 sec after trigger time at 2025-06-25 20:36:14 UT, with upper limit up to 14.7 mag. The observations began at zenith distance = 22 deg. The sun altitude is -20.8 deg. MASTER-OAFA robotic telescope located in Argentina (OAFA observatory of San Juan National University) was pointed to the Swift GRB 250625A errorbox 35307 sec after notice time and 35345 sec after trigger time at 2025-06-26 01:54:01 UT, with upper limit up to 18.9 mag. The observations began at zenith distance = 60 deg. The sun altitude is -53.1 deg. The galactic latitude b = 28 deg., longitude l = 45 deg. Real time updated cover map and OT discovered available here: https://master.sai.msu.ru/site/master2/observ.php?id=2916460 We obtain a following upper limits. Tmid-T0 | Site |Filt.| Expt. | Limit| Comment _________|_____________________|_____|_______|______|________ 16368 | MASTER-Tavrida | C | 180 | 14.7 | 35435 | MASTER-OAFA | C | 180 | 18.5 | 35630 | MASTER-OAFA | C | 180 | 18.2 | 35825 | MASTER-OAFA | C | 180 | 18.9 | 36026 | MASTER-OAFA | C | 180 | 18.6 | 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/40832. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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[vsnet-grb-info 38872] GRB 250625A: NOT z-band upper limit
by GCN Circulars 26 Jun '25

26 Jun '25

TITLE: GCN CIRCULAR NUMBER: 40831 SUBJECT: GRB 250625A: NOT z-band upper limit DATE: 25/06/26 00:25:21 GMT FROM: Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani(a)nbi.ku.dk> D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), A. de Ugarte Postigo (LAM), G. Corcoran (UCD), B. P. Gompertz (Birmingham), D. Xu (NAOC), M. A. Diaz Teodori (NOT and Turku Univ.), report on behalf of a larger collaboration: We observed the position of the X-ray and optical afterglow (Beardmore et al., GCN 40827; Moskvitin & Spiridonova, GCN 40828) of GRB 250625A (Ferro et al., GCN 40825; Fermi GBM team, GCN 40824) using the Nordic Optical Telescope, using the “standby” StanCam instrument. In a sequence of 3 exposures of 200 s each, with mean time 2025 Jun 25.948 UT (6.67 hr after the trigger), we detect no object consistent with the X-ray afterglow, down to a limiting magnitude z > 21 AB, calibrated against the Pan-STARRS catalog. View this GCN Circular online at https://gcn.nasa.gov/circulars/40831. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0L…

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