GRB 250713A
GCN Circular 41134
Subject
GRB 250713A : SVOM/ECLAIRs refined analysis
Date
2025-07-22T11:09:53Z (2 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
M. Brunet, L. Bouchet (IRAP), F. Cangemi (APC), P. Maggi (ObAS)
Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of the long GRB 250713A (SVOM burst-id sb25071320),
The burst that triggered ECLAIRs [onboard/ onground] (GCN #41078) consists of a single peak with a duration of at least 60s visible in the 4-60 keV energy band.
The time-averaged spectrum from T0-10s s to T0+32s (T0 = 2025-07-13T17:06:26) in the energy range 4-60 keV is best fitted by a black body model with kT = 4.91 +0.32/-0.30 keV . With this model, the total 4-120 keV fluence is 1.10 +0.07/-0.10 e-8 erg/cm^2.
A Broken Power-law also gives a decent fit with a photon index of 1.08 +0.16/-0.18 before the break, a break energy of 21.50 +3.41/-2.76 keV and a photon index of 3.23 +0.81/-0.53 after the break. In that case, the total 4-120 keV fluence is 1.25 +0.06/-0.18 e-8 erg/cm^2.
A preliminary time-resolved spectral analysis shows a decrease in the black body temperature from kT = 6.73 +0.72/-0.64 keV to kT =2.72 +0.45/-0.36 keV over the first 42 seconds of the burst duration. At the same time the source radius increases by a factor 4.3 +1.3/-1.7.
All the quoted errors are at the 68% confidence level.
We note that the calibration of SVOM/ECLAIRs is undergoing thus these results are preliminary.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC.
The SVOM/ECLAIRs point of contact for this burst is: Marius Brunet (mbrunet at irap.omp.eu)
GCN Circular 41094
Subject
GRB 250713A: Mephisto optical upper limits
Date
2025-07-15T05:31:26Z (2 months ago)
From
Brajesh Kumar at SWIFAR, YNU <brajesh@ynu.edu.cn>
Via
Web form
Helong Guo, Yuan Fang, Yuze Zhao, Runnan Jiang, Guowang Du, Xingzhu Zou, Xinlei Chen, Yu Pan, Xufeng Zhu, Tao Wang, Jinghua Zhang, Brajesh Kumar, Edorardo Lagioia, Dezi Liu, Chenxu Liu, Shiyan Zhong, Weikang Lin, Jianhui Lian, Yuanpei Yang, Xiangkun Liu, Xiaowei Liu (all SWIFAR, YNU) report on behalf of the Mephisto Team:
Simultaneous multi-band photometric observations of the SVOM GRB 250713A (Maggi et al., GCN 41078) were performed with the 1.6m Multi-channel Photometric Survey Telescope (Mephisto) of Yunnan University located at Lijiang Observatory. The observations started from 17:11:19 2025-07-13 UT (~5 minutes after the trigger), and several frames were obtained in uvgr bands. In our stacked images, no new optical source was detected within the SVOM/MXT error region and in particular at the EP/FXT Source 2 position (Liang et al., GCN 41085). The 3-sigma upper limits are below:
Start_Time(UT) Band Exp (sec) LimMag(AB)
2025-07-13T17:11:19 u 45*6 >20.53
2025-07-13T17:32:27 v 45*6 >20.65
2025-07-13T17:11:19 g 45*6 >21.17
2025-07-13T17:32:27 r 45*6 >21.32
Our results are consistent with Fu et al. (GCN 41079), Wu et al. (GCN 41089), Braun et al. (GCN 41090), Saccardi et al. (GCN 41091) and Li et al. (GCN 41092).
----------------------------------------------------------------------------
Mephisto (Multi-channel Photometric Survey Telescope) is a 1.6m wide-field multi-channel telescope, the first of its type in the world, capable of imaging the same field of view in three optical bands simultaneously. It provides real-time, high-quality colors of stellar objects. The on-site telescope assemblage and commissioning were carried out in September 2022. The first light in all three channels was achieved on 2023 December 21.
----------------------------------------------------------------------------
GCN Circular 41092
Subject
GRB 250713A: SVOM/VT optical upper limit
Date
2025-07-14T11:38:39Z (2 months ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, L. P. Xin, Y. L. Qiu, C. Wu, Y. N. Ma, Z. H. Yao, X. H. Han, J. Wang, Y. Xu, P. P. Zhang, W. J. Xie, Y. J. Xiao, H. B. Cai, J. S. Deng, J. Y. Wei (NAOC), P. Maggi (ObAS), M. Brunet(IRAP), report on behalf of the SVOM mission team.
SVOM performed an automatic slew on the burst triggered by SVOM/ECLAIRs (Maggi
et al., GCN 41078). SVOM/VT began observing the field at 2025-07-13T17:09:14
UTC, 168 seconds after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
No uncatalogued candidate was detected in our single or stacked images within the errorbox of the SVOM/MXT position (Maggi et al., GCN 41078) or FXT (Liang et al., 41085) or XRT (Evens et al., GCN 41086) .
The 3-sigma upper limits are:
[T-T0, mid-time] | exposure time (s) | band | upper limit (AB)
----------- --------|-------------------|------|-----------------
20.7 min | 44*50 | VT_B | 23.5
20.7 min | 44*50 | VT_R | 23.2
Our results are consistent with Fu et al. (GCN 41079), Wu et al. (GCN 41089), and Braun et al. (GCN 41090) and Saccardi et al. (GCN 41091).
NIR follow-ups are encouraged to investigate the nature of the burst.
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Centre for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. VT was jointly developed by Xi'an Institute of Optics and Precision Mechanics (XIOPM), CAS and National astronomical observatories (NAOC), CAS.
The Burst Advocate (BA) on shift for this alert is Pierre Maggi: pierre.maggi@astro.unistra.fr
GCN Circular 41091
Subject
GRB 250713A: NOT optical upper limits
Date
2025-07-14T10:43:55Z (2 months ago)
From
Andrea Saccardi at CEA/Irfu <andrea.saccardi@cea.fr>
Via
Web form
A. Saccardi (CEA/Irfu), A. Martin-Carrillo (UCD), D. B. Malesani (DAWN/NBI and Radboud), A. de Ugarte Postigo (LAM), G. Corcoran (UCD), J. T. Palmerio (CEA/Irfu), L. Izzo (INAF/OACN and DARK/NBI), B. P. Gompertz (Birmingham), N. Pyykkinen (Univ. of Turku and NOT), K. Valeckas (NBI and NOT), report on behalf of a larger collaboration:
We observed the field of GRB 250713A detected by SVOM/ECLAIRs (Maggi et al., GCN 41078), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT) centered at the X-ray source detected by SVOM/MXT. We obtained 5x200 s exposures in each of the SDSS i and z bands, starting at 23:46:40 UT on 2025-07-13 (6.67 hr after the SVOM/ECLAIRs trigger).
No new optical source is detected at a position consistent with the SVOM/MXT error region and in particular with the EP/FXT Source 2 (Liang et al., GCN 41085) in the stacked images of either band, down to the 5-sigma limiting AB magnitudes of i > 22.9 and z > 22.5, calibrated against nearby stars from the Pan-STARRS catalog and not corrected for Galactic extinction. Our results are consistent with Fu et al. (GCN 41079), Wu et al. (GCN 41089), and Braun et al. (GCN 41090).
We note the presence of an object just north of EP/FXT Source 2, at coordinates (J2000):
RA = 22:27:34.17
Dec = +38:46:23.8
This is just 11" away from the centre of the 10"-radius EP/FXT error circle. This point-like object is detected in both our images and in the archival Pan-STARRS images of the field. It is fainter in the NOT images, by ~0.3 and 0.2 mag in the i and z bands, respectively, indicating long-term variability. It is also listed in the Gaia catalog (doi:10.1051/0004-6361/202243940) as having a ~68% probability of being a QSO. It is thus possible that this object is responsible for the EP/FXT X-ray source, which would be then unrelated to GRB 250713A. We encourage further EP/FXT observations to test for variability of this X-ray source.
Further NOT images are planned at a later date to test for short-term variability of objects in the field.
GCN Circular 41090
Subject
GRB 250713A: OHP/T193 upper limit
Date
2025-07-14T09:21:22Z (2 months ago)
From
Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa@lam.fr>
Via
Web form
O. Braun (LAM/OHP/Pytheas/AMU), C. Adami (LAM/Pytheas/AMU), B. Schneider (LAM), S. Basa (LAM/OHP/Pytheas/AMU), E. Le Floc'h (CEA/Irfu), report on behalf of a larger collaboration:
We observed the field of the GRB 250713A (Maggi et al., GCN 41078; Fu et al., GCN 41079) using the T193cm telescope at Observatoire de Haute-Provence (France) equipped with the MISTRAL spectro-imager. We obtained 14 exposures (for a total of 60 min) in the r-band starting at 22:26:02 UT on 2025-07-13 (5.3 hours after the trigger).
In the stacked images, we do not detect any new source at the MXT position (Maggi et al., GCN 41078). The preliminary upper limit is r > 22.3 mag (AB) at 3 sigma.
No other credible source compatible with a GRB is detected in MISTRAL's field of view up to r > 21.7 mag (AB) at 5 sigma.
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 for the MISTRAL observations.
GCN Circular 41089
Subject
GRB 250713A: SVOM/C-GFT upper limit
Date
2025-07-14T07:50:58Z (2 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), P. Maggi (ObAS) report on behalf of the SVOM/C-GFT team:
We observed the field of GRB250713A (sb25071320) detected by SVOM/ECLAIRs (GCN 41078) with LATIOS on SVOM/C-GFT. Observations started at 2025-07-13T17:07:44 UTC, ~78 seconds after the trigger.
A series of g, r, and i band images were obtained under brighter Moon. No credible candidate was detected within the error box provided by SVOM/MXT(GCN 41078), EP/FXT (GCN 41085), and Swift/XRT(GCN 41086) in our images after preliminary processing, the three sigma upper limits are:
| Date-Obs (mid-time) | Mid_t - T0 (s) | Exposure Time (s) | Band | Upper Limit (AB) |
|---|---|---|---|---|
| 2025-07-13T17:09:13 | 167 | 6×10 | i | 18.12 |
| 2025-07-13T17:20:51 | 864 | 6×30 | g | 18.84 |
| 2025-07-13T17:24:26 | 1080 | 6×30 | r | 18.38 |
This result is consistent with GCN 41079. The photometry was calibrated with UCAC4 catalogue.
We thank the observation assistants Chunlei Guo and Guangsheng Zhang 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 41086
Subject
GRB 250713A: Swift-XRT observations
Date
2025-07-14T05:58:35Z (2 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
P.A. Evans (U. Leicester), J.A. Kennea (PSU), E. Ambrosi (INAF-IASFPA) , A.P.
Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), R. Brivio (INAF-OAB), D.N.
Burrows (PSU), S. Campana (INAF-OAB), M. Capalbi (INAF-OAR), A. D'Ai (INAF-IASFPA),
P. D'Avanzo (INAF-OAB), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU), M. Ferro
(INAF-OAB), A. Melandri (INAF-OAR), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), M. Perri (SSDC & INAF-OAR), C. Salvaggio (INAF-OAB), T. Sbarrato
(INAF-OAB), B. Sbarufatti (INAF-OAB), M.A. Williams (PSU) report on behalf of the
Swift-XRT team:
Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected source
GRB 250713A, collecting 2.0 ks of Photon Counting (PC) mode data between T0+429 s
and T0+6.4 ks after the trigger. We have detected 1 source. This has been
automatically classified as an uncatalogued X-ray source.
Uncatalogued X-ray sources
--------------------------
Source 1 (SWIFT J222820.3+385214):
==================================
RA (J2000.0): 337.0847 = 22h 28m 20.33s
Dec (J2000.0): +38.8706 = +38d 52' 14.2"
Error: 7.0 (arcsec, radius, 90% confidence).
Detect flag: GOOD
Distance: 8.2 arcmin from the SVOM/ECLAIRs position.
Mean rate: (7.7 [+2.8, -2.3])e-3 ct s^-1
Mean flux: (2.94 [+1.07, -0.88])e-13 erg cm^-2 s^-1
Peak rate: (7.7 [+2.8, -2.3])e-3 ct s^-1
Peak flux: (2.94 [+1.07, -0.88])e-13 erg cm^-2 s^-1
ECF: 3.84e-11 erg cm^-2 ct^-1, assuming NH=1.27e+21 cm^-2,
gamma=1.63; determined from a spectral fit.
XMM UL: 2.2e-12 erg cm^-2 s^-1, (0.3-10 keV)
so the source is 19.2-sigma above this 3-sigma upper limit.
There is no evidence for fading.
This source is not spatially consistent with any of those detected by EP-FXT (Circ.
41085).
All fluxes are 0.3-10 keV, observed. For all flux conversions and comparisons with
catalogues and upper limits from other missions, we assumed a power-law spectrum
with NH=3x10^20 cm^-2 and photon index (Gamma)=1.7 unless otherwise stated.
The results of the XRT-team automatic analysis of the XRT observations, including a
position-specific upper limit calculator, are available at
https://www.swift.ac.uk/SVOM.
This circular is an officicial product of the Swift-XRT team.
GCN Circular 41085
Subject
GRB 250713A: EP-FXT counterpart detection
Date
2025-07-14T03:06:19Z (2 months ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y. F. Liang (PMO, CAS), M. H. Zhang (NAO, CAS), C. Y. Dai (NJU), Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team:
EP-FXT performed a follow-up observation of the SVOM/ECLAIRs-detected burst GRB 250713A (SVOM/sb25071320) at 2025-07-13T18:52:11 (UTC), about 2 hours after the SVOM/ECLAIRs trigger, with an exposure time of 4919s. Five uncatalogued sources are detected within the ECLAIRs error circle, among which Source 2 is spatially consistent with the candidate counterpart detected by SVOM/MXT (Maggi et al. GCN #41078). Preliminary analysis on these source are automatically conducted, and the details are listed as follows.
Source 1: EPF_J222746.7+384738
RA (J2000): 336.9445
Dec (J2000): 38.7939
Flux: 2.68 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev)
Flux_err: 4.65 x 10^-14 erg/s/cm^2 (1 sigma)
Source 2: EPF_J222734.0+384613
RA (J2000): 336.8919
Dec (J2000): 38.7702
Flux: 1.05 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev)
Flux_err: 4.09 x 10^-14 erg/s/cm^2 (1 sigma)
Note: This source is spatially consistent with the candidate counterpart detected by SVOM/MXT.
Source 3: EPF_J222734.3+384800
RA (J2000): 336.8931
Dec (J2000): 38.8000
Flux: 1.39 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev)
Flux_err: 3.05 x 10^-14 erg/s/cm^2 (1 sigma)
Source 4: EPF_J222729.6+384709
RA (J2000): 336.8733
Dec (J2000): 38.7859
Flux: 9.13 x 10^-13 erg/s/cm^2 (observed, 0.5-10 kev)
Flux_err: 2.37 x 10^-13 erg/s/cm^2 (1 sigma)
Source 5: EPF_J222815.4+384825
RA (J2000): 337.0641
Dec (J2000): 38.8070
Flux: 8.94 x 10^-14 erg/s/cm^2 (observed, 0.5-10 kev)
Flux_err: 3.54 x 10^-14 erg/s/cm^2 (1 sigma)
The Source 1, 2, and 3 were detected by both FXT-A and FXT-B, while Source 4 and 5 were detected only by FXT-B. The positional uncertainty of the sources are about 10 arcsec in radius (90% C.L. statistical and systematic).
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).
GCN Circular 41079
Subject
GRB 250713A: JinShan optical upper limits
Date
2025-07-13T19:06:10Z (2 months ago)
From
syfu@nao.cas.cn
Via
Web form
S.Y. Fu(HUST), S.Q. Jiang, J. An, X. Liu, Z.P. Zhu, L.B. He, D. Xu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:
We observed the field of GRB250713A (sb25071320) detected by SVOM/ECLAIRs (Maggi et al., GCN 41078), using the 50cm & 100cm telescopes of the JinShan project, located at Altay, Xinjiang, China. Observations began at 17:08:08 UT on 2025-07-13, i.e., 102 seconds after the trigger, and a series of frames were obtained in the Sloan r, i and z-band.
No new optical source is detected within the SVOM/MXT error circle, down to 5-sigma upper limits of r ~ 21.0, i ~ 17.7 and z ~ 20.8, 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.
GCN Circular 41078
Subject
GRB 250713A: SVOM detection of a long burst
Date
2025-07-13T17:46:03Z (2 months ago)
Edited On
2025-07-15T17:04:22Z (2 months ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
P. Maggi (ObAS), M. Brunet, L.Bouchet (IRAP), D. Gotz (CEA) report on behalf of the SVOM mission team:
At 2025-07-13T17:06:26 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 250713A (SVOM burst-id sb25071320).
The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was detected both by the Count-Rate Trigger (CRT) and the Image Trigger (IMT), which produced a sequence of 7 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 14.04 in the [8-120] keV energy band over a time window of 40.96 seconds starting at 2025-07-13T17:06:02.
The localization of the best alert is R.A., Dec. 336.9666, 38.7686 degrees (J2000) with a 90% confidence level (C.L.) radius of 5.84 arcmin (including systematic error of 2 arcmin added in quadrature).
SVOM slewed to the burst.
SVOM/MXT began observing the field at 2025-07-13T17:08:48 UTC, 142 seconds after T0. Using onboard processed data we found an uncatalogued X-ray source located at R.A., Dec. 336.9045, 38.7670 degrees:
R.A. (J2000) = 22h27m37.09s
Dec. (J2000) = 38d46m01.31s
with a 90% C.L. radius of 55 arcseconds (including systematic error of 25 arcsec added in quadrature).
This location is 2.90 arcminutes from the ECLAIRs onboard position. This position may be improved as more data is received.
VT began observing the field after the slew. The analysis of the data will be published in a future circular.
The Space-based multi-band astronomical Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA), French Space Agency (CNES), and the Chinese Academy of Sciences (CAS), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. SVOM/ECLAIRs was developed jointly by CNES, CEA-IRFU, CNRS-IRAP, CNRS-APC. SVOM/GRM was developed by the Institute of High Energy Physics (IHEP) of CAS. SVOM/MXT was developed jointly by CNES, CEA-IRFU, CNRS-IJCLab, University of Leicester, MPE.
The Burst Advocate (BA) on shift for this alert is Pierre Maggi: pierre.maggi@astro.unistra.fr.
Please contact the BA by email if you require additional information.