TITLE: GCN CIRCULAR
NUMBER: 41078
SUBJECT: GRB 250713A: SVOM detection of a long burst
DATE: 25/07/13 17:46:03 GMT
FROM: SVOM_group <svomgroup(a)bao.ac.cn>
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 …
[View More]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(a)astro.unistra.fr.
Please contact the BA by email if you require additional information.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41078.
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TITLE: GCN CIRCULAR
NUMBER: 41096
SUBJECT: EP250702a / GRB 250702B,D,E: Hubble Space Telescope Observations
DATE: 25/07/15 12:48:10 GMT
FROM: Andrew Levan at Radboud University <a.levan(a)astro.ru.nl>
EP250702a / GRB 250702BD,D,E: Hubble Space Telescope Observations
A. J. Levan (Radboud and Warwick), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud Univ.), A. Saccardi (CEA/Irfu), P. O’Brien (Univ. of Leicester), R. A. J. Eyles-Ferris (…
[View More]Univ. of Leicester), A. de Ugarte Postigo (LAM), G. Corcoran (UCD), S. D. Vergani (LUX-Paris Obs.), N. R. Tanvir (U. Leicester), B. P. Gompertz (U. Birmingham) report for the Stargate collaboration:
We observed the location of EP250702a / GRB 250702B,D,E (Cheng et al., GCNs 40906, 40917; Fermi GBM Team, GCNs 40883, 40886, 40890; DeLaunay et al., GCN 40903; Frederiks et al., GCN 40914) with the Hubble Space Telescope on 15 July 2025. A total of 2196 s of observations were obtained using WFC3 and the F160W (broad-band H) filter.
At the location of the infrared counterpart (Martin-Carrillo et al., GCN 40924; Levan et al., GCN 40961) we clearly resolve a galaxy, whose nucleus is offset 0.7” from the transient location. The galaxy has an edge-on morphology, and either a disturbed disc or prominent dust lane. The transient lies on the stellar field of this galaxy, and the low probability of chance alignment (0.05%: Levan et al., GCN 40961) strongly implies that EP250702a / GRB 250702BDE is indeed an extragalactic transient. A weak excess of emission over the smooth disc is present at the transient location, but it appears likely the flux is now dominated by galaxy light.
If extragalactic in origin the very long duration of the outburst is extremely unusual. Only relativistic TDEs have been seen to have such long-lived emission in gamma-rays. However, the non-nuclear nature of the transient is not in keeping with the expected location of a supermassive black hole, although is consistent with the expectations for white-dwarf - intermediate mass black hole disruptions.
We thank Bill Januszewski, Joel Green, Claus Leitherer and Jennifer Lotz for their rapid work in approving and scheduling these observations.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41096.
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TITLE: GCN CIRCULAR
NUMBER: 41095
SUBJECT: GRB 250702B,D,E / EP250702a: H.E.S.S. very-high-energy gamma-ray observations
DATE: 25/07/15 09:19:06 GMT
FROM: Mathieu de Naurois at Laboratoire Leprince Ringuet, CNRS, Deputy Director of the H.E.S.S. Collaboration <denauroi(a)in2p3.fr>
The H.E.S.S. array of imaging atmospheric Cherenkov telescopes conducted follow-up observations of the transient EP250702a, at the localization provided by the EP-WXT (Cheng et al., GCN 40906). H.E.S.S.…
[View More] observed this source position for a total of 6 hours over 4 consecutive nights, starting on 2025-07-04, under fairly good observing conditions. A preliminary off-site analysis shows no evidence for a significant signal in either the full dataset or the four nights individually, consistent with the non-detection reported by the LST-1 and MAGIC telescopes (Paneque et al., GCN 41067). Our upper limits are expected to be compatible with the H.E.S.S. sensitivity curves (e.g., Fig. 6 of https://doi.org/10.22323/1.236.0847), scaled to the observation duration.
The observations took place during the following times:
2025-07-04, 00:06 - 03:01 UTC
2025-07-05, 00:48 - 02:19 UTC
2025-07-06, 01:41 - 03:08 UTC
2025-07-07, 02:36 - 03:00 UTC
H.E.S.S. is an array of five imaging atmospheric Cherenkov telescopes that detects very-high-energy gamma rays (>100 GeV) and is located in the Khomas Highland in Namibia. It was constructed and is operated by researchers from Armenia, Australia, Austria, France, Germany, Ireland, Japan, the Netherlands, Poland, South Africa, Sweden, UK, and the host country, Namibia. For more details see https://hess.in2p3.fr/.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41095.
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TITLE: GCN CIRCULAR
NUMBER: 41094
SUBJECT: GRB 250713A: Mephisto optical upper limits
DATE: 25/07/15 05:31:26 GMT
FROM: Brajesh Kumar at SWIFAR, YNU <brajesh(a)ynu.edu.cn>
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 …
[View More]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).
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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.
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View this GCN Circular online at https://gcn.nasa.gov/circulars/41094.
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TITLE: GCN CIRCULAR
NUMBER: 41092
SUBJECT: GRB 250713A: SVOM/VT optical upper limit
DATE: 25/07/14 11:38:39 GMT
FROM: Huali Li at at NAOC, SVOM <lhl(a)nao.cas.cn>
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/…
[View More]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(a)astro.unistra.fr
View this GCN Circular online at https://gcn.nasa.gov/circulars/41092.
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TITLE: GCN CIRCULAR
NUMBER: 41091
SUBJECT: GRB 250713A: NOT optical upper limits
DATE: 25/07/14 10:43:55 GMT
FROM: Andrea Saccardi at CEA/Irfu <andrea.saccardi(a)cea.fr>
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 …
[View More]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.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41091.
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TITLE: GCN CIRCULAR
NUMBER: 41090
SUBJECT: GRB 250713A: OHP/T193 upper limit
DATE: 25/07/14 09:21:22 GMT
FROM: Stephane Basa at UAR Pytheas/OHP, LAM <stephane.basa(a)lam.fr>
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 …
[View More]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.
View this GCN Circular online at https://gcn.nasa.gov/circulars/41090.
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