GRB 250625A
GCN Circular 40860
Subject
GRB 250625A: VLT/X-shooter spectroscopic observations at the afterglow position
Date
2025-06-28T14:57:40Z (6 months ago)
From
J. An <jiean0813@foxmail.com>
Via
Web form
J. An (NAOC), B. Schneider (LAM), L. Izzo (INAF/OAC), R. Brivio (INAF/OABr), G. Corcoran (UCD), A. de Ugarte Postigo (LAM), B. P. Gompertz (Birmingham), A. J. Levan (Radboud and Warwick), D. B. Malesani (DAWN/NBI and Radboud), A. Martin-Carrillo (UCD), report on behalf of a larger collaboration:
We observed the optical afterglow of GRB 250625A detected by Fermi/GBM (Godwin et al., GCN 40833) and Swift/BAT (Ferro et al., GCN 40825) using the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra cover the wavelength range 3000-21000 AA, and consist of 4 exposures of 1200 s each. The observation mid time was 2025 Jun 27.128 UT (34.98 hr after the GRB).
The slit was aligned to cover the optical afterglow (Moskvitin et al., GCN 40828; Xin et al., GCN 40830; Zhu et al., GCN 40834; Fortin et al., GCN 40837; Adami et al., GCN 40838; Brosio et al., GCN 40839; de Ugarte Postigo et al., GCN 40486). In a preliminary reduction of the spectra, we detect no obvious continuum nor any emission lines across the entire covered wavelength range. This could simply indicate that the emission lines of the actual (faint) GRB host galaxy are below our detection sensitivity, or, alternatively, would be consistent with an association with the nearby galaxy at z = 0.655 reported by de Ugarte Postigo et al. (GCN 40486).
We acknowledge excellent support from the ESO observing staff in Paranal, in particular Célia Desgrange, Rodrigo Palominos, and Boris Häußler. We also thank Liping Xin (NAOC) and the SVOM/VT team for sharing accurate coordinates of the afterglow (see also GCN 40830).
GCN Circular 40852
Subject
GRB 250625A: Swift-BAT refined analysis
Date
2025-06-27T23:16:03Z (6 months ago)
From
Amy <yarleen@gmail.com>
Via
email
A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), M. Ferro (INAF-OAB), R. Gupta
(GSFC), H. A. Krimm (NSF), S. Laha (GSFC/UMBC), C. B. Markwardt (GSFC), M.
J. Moss (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC), D. Sadaula
(GSFC/UMBC), T. Sakamoto (AGU) (i.e. the Swift-BAT team):
Using the data set from T-239 to T+100 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 250625A (trigger #1327910)
(Ferro et al., GCN Circ. 40825). The BAT ground-calculated position is
RA, Dec = 261.517, 22.245 deg which is
RA(J2000) = 17h 26m 04.1s
Dec(J2000) = +22d 14' 40.7"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 68%.
The mask-weighted light curve shows a single-pulse structure that starts at
~T0, peaks at ~T+2 s, and ends at ~T+6 s. T90 (15-350 keV) is 4.00 +- 1.41
sec (estimated error including systematics).
The time-averaged spectrum from T-0.35 to T+3.65 sec is best fit by a
simple power-law model. The power law index of the time-averaged spectrum
is 1.00 +- 0.22. The fluence in the 15-150 keV band is 2.8 +- 0.4 x 10^-07
erg/cm2. The 1-sec peak photon flux measured from T+1.65 sec in the 15-150
keV band is 0.8 +- 0.2 ph/cm2/sec. All the quoted errors are at the 90%
confidence level.
The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/batgrbcat/BAT_refined_circular/1327910
GCN Circular 40851
Subject
GRB 250625A: Leavitt Observatory afterglow detection
Date
2025-06-27T19:20:11Z (6 months ago)
From
leavittob@gmail.com
Via
Web form
L. Moretti, E. Pavoni (Leavitt Observatory, Italy)
Members of:
GRB/UAI - Gamma Ray Burst Section of Unione Astrofili Italiani
ATA - Associazione Tuscolana di Astronomia
In a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy), K. Kalinowski (Aarhus University, Department of Physics and Astronomy), report:
We imaged the field of GRB 250625A, which was detected by Swift-BA (Ferro et al., GCN 40825) and Fermi-GBM (GCN 40824) with our RC telescope (D=250 mm, F/D=8) of Leavitt Observatory.
The observations began approximately 4.6 hours after the trigger, with good weather conditions, stacking a series of 12 exposures of 120 seconds each. All images are unfiltered and were processed by a single data processing pipeline based on astropy package (Astropy Collaboration et al., 2022ApJ...935..167A).
In the stacked frame, we detected a very faint object at the following position:
R.A. (J2000) = 17:26:01.92
Dec. (J2000) = +22:16:04.31
with the following photometry:
Date UT at mid-exposure Filter Mag. Err.
2025-06-25 20:58:29 UTC CR 21.4 +/-0.2
CR magnitude is unfiltered with R zero point.
Magnitudes were estimated with the Pan-STARRS cat. and are derived using Lupton (2005) equations. Not corrected for galactic dust extinction.
This measure is consistent with the optical afterglow reported by Moskvitin et al. (GCN 40828), Xin et al. (GCN 40830), Zhu et al. (GCN 40834), Fortin et al. (GCN 40837), Adami et al. (GCN 40838), Brosio et al. (GCN 40839), Wang et al. (GCN 40841), Ruocco et al. (GCN 40843), de Ugarte Postigo et al. (GCN 40846).
The message may be cited.
Reference:
https://leavittobservatory.altervista.org
GCN Circular 40848
Subject
GRB 250625A: AbAO and INASAN Kislovodsk Optical Observations
Date
2025-06-27T11:55:09Z (6 months ago)
From
Nicolai Pankov at HSE, IKI RAS <colinsergesen@gmail.com>
Via
Web form
N. Pankov (HSE, IKI), R. Ya. Inasaridze (AbAO), A. Tarasenkov (INASAN), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of 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 0.7-meter AS-32 telescope of Abastumani Observatory (AbAO) and the 0.5-meter RC-500 telescope of INASAN Kislovodsk Observatory. The observations at AbAO started on 2025-06-25 at 17:41:35 UT and consisted of 71*60 sec exposures. The observations at RC-500 were carried out between 2025-06-25 18:19:40 UT and 2025-06-26 00:09:04 UT using 120 sec exposures. We do not detect the optical afterglow 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; Adami et. al, GCN 40838; Brosio et. al, GCN 40839; Breeveld & Ferro, GCN 40840; WU et. al, GCN 40842; Ruocco et. al, GCN 40843; de Ugarte Postigo et. al, GCN 40846) in the R-band co-add images.
The preliminary photometry is as follows:
Date UT start t-T0 Exp. Filter OT Err. UL Telescope
(mid, days) (n*s) (3sigma)
2025-06-25 17:41:35 0.09176 71*60 R n/d n/d 20.0 AS-32
2025-06-25 18:38:08 0.14735 59*120 R n/d n/d 21.5 RC-500
The photometry has calibrated using stars from USNO-B1.0 (see Moskvitin et al., GCN 40828) and has not corrected for the Galactic extinction.
GCN Circular 40846
Subject
GRB 250625A: GTC/OSIRIS+ spectroscopic observations of the potential host galaxy
Date
2025-06-26T23:08:02Z (6 months ago)
Edited On
2025-07-09T13:26:27Z (6 months ago)
From
Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo@gmail.com>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo@gmail.com>
Via
email
A. de Ugarte Postigo (LAM), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), J. F. Agui Fernandez (CAHA), M. A. Aloy (UV), J. P. U. Fynbo (DAWN/NBI), L. Galbany (IEEC-CSIC), S. Geier (GTC), B. Schneider (LAM), L. Izzo (INAF/OACN and DARK/NBI), G. Lombardi (GTC), N. A. Rakotondrainibe (LAM), N. R. Tanvir (Univ. Leicester), C. C. Thoene (AbAO), F. Pérez (GTC), D. Pérez Valladares (GTC) and A. Cabrera Lavers (GTC) report:
We observed the optical afterglow of the GRB 250625A detected by Fermi/GBM and Swift/BAT (Fermi GBM team, GCN 40824; Ferro et al., GCN 40825) using the 10.4 m GTC located at the Roque de los Muchachos Observatory in the island of La Palma (Spain) equipped with the OSIRIS+ instrument.
In a 3x30 s acquisition image in the z-band, with a mean time of 2025-06-26T01:09:07 (~9.07 hr after the Swift trigger), we detect two objects consistently with the Swift/XRT position (Beardmore et al. GCN 40827). The first is the optical afterglow reported by Moskvitin et al. (GCN 40828), Xin et al. (GCN 40830), Zhu et al. (GCN 40834), Fortin et al. (GCN 40837), Adami et al. (GCN 40838) and Brosio et al. (GCN 40839), for which we measure a magnitude z = 23.75 +/- 0.20 (AB, calibrated against nearby Legacy Survey objects). The second (at RA =17:26:02.17, Dec = +22:16:02.8) has an AB magnitude z = 23.69 +/- 0.18, with a separation of ~1.4" from the afterglow.
Our spectroscopic observations started on 2025-06-26T01:44:27.5 UT (9.67 hr after the Swift trigger) and consisted of 3x1200 s exposures using grism R1000R, covering the range between 5100 and 10,000 AA.
In the acquisition process, the slit was placed on top of this second object, not the afterglow. For this target, in a preliminary reduction of the spectra, we detect a continuum and a few emission lines, including the [O II] doublet, [O III] 5008 and H-beta, from which we infer a redshift of z = 0.655. At this distance, if this galaxy is associated with the optical afterglow, the offset between the galaxy and the optical afterglow would be ~10 kpc.
We note that the probability of chance coincidence is not negligible (~2.5%). We cannot thus conclude that GRB 250625A is at redshift z = 0.655. Further observations to confirm their association are planned and encouraged.
We thank Liping Xin (NAOC) for sharing accurate coordinates of the afterglow from SVOM/VT.
GCN Circular 40843
Subject
GRB 250625A: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an optical counterpart
Date
2025-06-26T17:11:34Z (6 months ago)
From
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>
Via
Web form
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), Y. Niino (Tokyo University, Institute of Astronomy) and K. Kalinowski (Aarhus University, Department of Physics and Astronomy) report:
Following the Swift trigger no. 1327910 (GCN 40825 M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), J. J. DeLaunay (PSU),R. Gupta (NASA GSFC), J. A. Kennea (PSU), D. M. Palmer (LANL),B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf ofthe Neil Gehrels Swift Observatory Team) from the Swift Burst Alert Telescope (BAT), we pointed at the coordinates RA(J2000)=17h 26m 02.09s: Dec(J2000)= +22d 16' 03.5" and started our observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of:
AAVSO - American Association of Variable Star Observers.
GRB/UAI Gamma Ray Burst Section of Unione Astrofili Italiani.
The observations started at 19:30 UT of 2025/06/25, after about 3.30 hours after the GRB trigger, with clear sky, with principal telescope SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 13 unfiltered images of 120 sec .
Start End
19:30:01 UT 19:56:45 UT
All images, calibrated with masterdark and masterflat have been measured with Thycho Tracker software
We have detected a faint source at the enhanced position reported by Swift Burst Alert Telescope (BAT) at following position
RA (J2000.0) 17 26 02.13
Dec (J2000.0) +22 16 07.7
with the following photometry and astrometry:
GRB 250625A 17 26 02.13 +22 16 07.7 20.2 V C82
Magnitudes were estimated with the ATLAS cat. and are not corrected for galactic dust extinction.
The message may be cited.
GCN Circular 40842
Subject
GRB 250625A: SVOM/C-GFT upper limit in early phase
Date
2025-06-26T15:29:45Z (6 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Chao WU (NAOC), Zhe Kang (CHO), Liping Xin(NAOC), Xuhui Han(NAOC), Pinpin Zhang (NAOC), Xiaomeng Lu (NAOC), Zhenwei Li (CHO), You Lv (CHO), Ruosong Zhang (NAOC), Yujie Xiao(NAOC), Yulei, Qiu(NAOC), Jing Wang (NAOC), Jinsong Deng(NAOC), Lei Huang(NAOC), Jianyan Wei (NAOC), report on behalf of the SVOM/C-GFT team:
We observed the field of GRB 250625A detected by Swift-BAT（Ferro et al., GCN 40825) and Fermi-GBM (GCN 40824) with LATIOS on SVOM/C-GFT. Observations started at 2025-06-25T16:06:18 UTC, ~82 seconds after the trigger.
A series of g, r, and i band images were obtained. The optical afterglow reported by Moskvitin et al. (GCN 40828), Xin et al. (GCN 40830), Zhu et al. (GCN 40834), Fortin et al. (GCN 40837), Adami et al. (GCN 40838) and Brosio et al. (GCN 40839) is not detected in the images after preliminary processing. The three sigma upper limits are:
| date-obs|mid-time | exposure time (s) | band | upper limit (AB) |
|--------------------|-------------------|------|-------------------|
|2025-06-25T16:08:18 | 170 | i | 20.00 |
|2025-06-25T16:27:53 | 180 | g | 20.59 |
|2025-06-25T16:31:28 | 180 | r | 20.52 |
The photometry was calibrated with nearby UCAC4 catalogue. This result is consistent with the report by Breeveld & Ferro (GCN 40840).
We thank the observation assistants Chunlei Guo and Shuai Liu at Jilin observatory for their excellent support.
The Chinese Ground Follow-up Telescope (C-GFT) for the SVOM mission is located at Jilin Station, Changchun Observatory, National Astronomical Observatories, CAS. It features two instruments: (1) CATCH at the Cassegrain focus with a 21 arcsec x 21 arcsec FOV for simultaneous g/r/i-band imaging, and (2) LATIOS, a 4k x 4k CMOS camera at the prime focus with a 1.28 deg x 1.28 deg FOV that images in g, r, and i bands via filter switching.
GCN Circular 40841
Subject
GRB 250625A: GECAM-B detection
Date
2025-06-26T14:18:47Z (6 months ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered on-ground by GRB 250625A at 2025-06-25T16:04:56 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#40824), Swift/BAT (David Palmer et al., GCN#40825), Fermi/LAT (Davide Depalo et al., GCN#40836). According to the GECAM-B light curves in about 40-6000 keV, this burst mainly consists of a single pulse with a duration (T90) of 6.0 +3.5/-5.5 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecamgrb250625A.png
The time-averaged spectrum from T0 to T0+4 s is best fitted by a power law function. The power law index is -1.52 +0.29/-0.20. The event fluence (10-1000 keV) in this time interval is (1.39 +/-0.24)E-06 erg/cm^2.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 40840
Subject
GRB 250625A: Swift/UVOT Upper Limits
Date
2025-06-26T11:21:27Z (6 months ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
Via
email
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).
GCN Circular 40839
Subject
GRB 250625A: ABObservatory afterglow detection
Date
2025-06-26T11:06:58Z (6 months ago)
From
A. Brosio at ABObservatory Rosarno <antonino.brosio@gmail.com>
Via
Web form
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).
GCN Circular 40838
Subject
GRB 250625A: OHP/T193 optical detection
Date
2025-06-26T11:02:44Z (6 months ago)
From
Christophe Adami at LAM <christophe.adami@lam.fr>
Via
Web form
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.
GCN Circular 40837
Subject
GRB 250625A: COLIBRÍ optical observations
Date
2025-06-26T09:35:11Z (6 months ago)
From
F. Fortin at IRAP <ffortin.sci.edu@gmail.com>
Via
Web form
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.
GCN Circular 40836
Subject
GRB 250625A: Fermi-LAT detection
Date
2025-06-26T08:10:58Z (6 months ago)
Edited On
2025-06-26T13:04:34Z (6 months ago)
From
Davide Depalo at Politecnico and INFN Bari <davide.depalo@ba.infn.it>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Davide Depalo at Politecnico and INFN Bari <davide.depalo@ba.infn.it>
Via
Web form
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@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.
GCN Circular 40835
Subject
GRB 250625A: Swift-XRT refined Analysis
Date
2025-06-26T05:57:53Z (6 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
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.
GCN Circular 40834
Subject
GRB 250625A: JinShan optical observations
Date
2025-06-26T04:25:58Z (6 months ago)
From
Zipei Zhu at NAOC <zpzhu@nao.cas.cn>
Via
Web form
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.
GCN Circular 40833
Subject
GRB250625A: Fermi GBM Observation
Date
2025-06-26T03:47:05Z (6 months ago)
From
Matt Godwin <msg0028@uah.edu>
Via
Web form
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/"
GCN Circular 40832
Subject
Swift GRB 250625A: Global MASTER-Net observations report
Date
2025-06-26T02:24:25Z (6 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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.
GCN Circular 40831
Subject
GRB 250625A: NOT z-band upper limit
Date
2025-06-26T00:25:21Z (6 months ago)
Edited On
2025-06-26T13:04:04Z (6 months ago)
From
Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Daniele Bjørn Malesani at Cosmic Dawn Center, Niels Bohr Institute <daniele.malesani@nbi.ku.dk>
Via
Web form
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; Xin et al., GCN 40830) 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.
GCN Circular 40830
Subject
GRB 250625A: SVOM/VT optical confirmation
Date
2025-06-26T00:20:46Z (6 months ago)
Edited On
2025-06-26T13:04:19Z (6 months ago)
From
Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Liping Xin at NAOC, SVOM <xlp@nao.cas.cn>
Via
Web form
L. P. Xin, H. L. Li, Y. L. Qiu, C. Wu, Y.N. Ma, Z. H. Yao, X. H. Han, Y. Xu, J. Wang, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, L. Lan, J. S. Deng, J. Y. Wei (NAOC), J. Palmerio (CEA), A. Li (BNU) report on behalf of the SVOM/VT team
SVOM/VT performed a Target of Opportunity observation of GRB 250625A detected by Swift-BAT（Ferro et al., GCN 40825) and Fermi-GBM (GCN #40824). The observation began at 2025-06-25T16:50:36 UTC, 45.7 minutes after the trigger, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
The optical counterpart (Moskvitin et al., GCN 40828) within the errorbox of Swift/XRT (Beardmore et al., GCN 40827) was detected in the 38*70 sec stack image with a magnitude of VT_B=22.5+/-0.15 mag in AB magnitude at the mid time of 69 min after the burst.
The counterpart is also detected in VT_R band in the stack image, but it has some contaimination from the blooming light from the nearby bright source. More detailed data analysis is on going.
Our photometry was not corrected for Galactic extinction.
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.
GCN Circular 40828
Subject
GRB 250625A: SAO RAS possible optical afterglow
Date
2025-06-25T21:47:40Z (6 months ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
Web form
A. Moskvitin, O. Spiridonova (SAO RAS),
report on behalf of a GRB follow-up collaboration.
We observed the field of the GRB 250625A (The Fermi GBM team,
GCN 40824; Ferro et al., GCN 40825) with SAO RAS 1-m telescope
Zeiss-1000 equipped with CCD-photometer. We obtained 6 x 300 sec.
exposures in Rc band on June 25, 20:39:03--21:12:11 UT
(t_mid - T0 = 4.8447 hours).
Withtin the enhanced XRT error circle (Beardmore et al., GCN 40827)
we detect single object with the coordinates:
R.A. (J2000.0) = 17:26:02.1
Dec. (J2000.0) = +22:16:03.6 +/- 0".3
and brightness of R = 22.97 +/- 0.17, possible GRB OT.
Observations are ongoing to confirm variability of the object.
Preliminary photometry is based on the nearby USNO-B1.0
and has not corrected for the Galactic extinction.
R.A. Dec. (2000) R2
17:26:06.4 +22:16:29.4 14.75
17:26:03.7 +22:15:09.9 15.42
17:26:10.0 +22:13:56.8 15.03
17:26:01.4 +22:18:39.0 14.59
GCN Circular 40827
Subject
GRB 250625A: Enhanced Swift-XRT position
Date
2025-06-25T21:43:16Z (6 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester)
report on behalf of the Swift-XRT team.
Using 2454 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 250625A, 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 = 261.50887, +22.26729 which is equivalent
to:
RA (J2000): 17h 26m 2.13s
Dec (J2000): +22d 16' 02.3"
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.
GCN Circular 40826
Subject
Fermi GRB 250625A: Global MASTER-Net observations report
Date
2025-06-25T21:15:24Z (6 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
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) started inspect of the Fermi GRB 250625A ( Fermi GBM team, GCN 40824) errorbox 16256 sec after notice time and 16277 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.
The galactic latitude b = 33 deg., longitude l = 49 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2916483
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
16367 | 2025-06-25 20:36:14 | MASTER-Tavrida | (17h 25m 02.21s , +22d 17m 15.8s) | C | 180 | 14.7 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 40825
Subject
GRB 250625A: Swift detection of a burst
Date
2025-06-25T16:20:37Z (6 months ago)
From
David Palmer at LANL <palmer@lanl.gov>
Via
email
M. Ferro (INAF-OAB), R. Brivio (INAF-OAB), J. J. DeLaunay (PSU),
R. Gupta (NASA GSFC), J. A. Kennea (PSU), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB) and M. H. Siegel (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:
At 16:04:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 250625A (trigger=1327910). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 261.519, +22.265 which is
RA(J2000) = 17h 26m 04s
Dec(J2000) = +22d 15' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a complex
structure with a duration of about 8 sec. The peak count rate
was ~2200 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 16:06:56.2 UT, 119.8 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 261.50871, 22.26763
which is equivalent to:
RA(J2000) = 17h 26m 02.09s
Dec(J2000) = +22d 16' 03.5"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 35 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. We
cannot determine whether the source is fading at the present time.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (5.47 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 8
(+10.81/-7.26) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 124 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag.
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.055.
This is co-detection with Fermi/GBM (GCN #40824).
Burst Advocate for this burst is M. Ferro (matteo.ferro AT inaf.it).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)
GCN Circular 40824
Subject
GRB 250625A: Fermi GBM Final Real-time Localization
Date
2025-06-25T16:15:37Z (6 months ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 16:04:57 UT on 25 Jun 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250625A (trigger 772560302.510236 / 250625670).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 257.2, Dec = 27.0 (J2000 degrees, equivalent to J2000 17h 08m, 27d 00'), with a statistical uncertainty of 6.9 degrees.
The angle from the Fermi LAT boresight is 28.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250625670/quicklook/glg_skymap_all_bn250625670.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250625670/quicklook/glg_healpix_all_bn250625670.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250625670/quicklook/glg_lc_medres34_bn250625670.gif