GRB 251111A
GCN Circular 42710
Subject
GRB 251111A: Mondy optical upper limit
Date
2025-11-17T08:05:29Z (4 days ago)
From
Alina Volnova at IKI RAS <alinusss@gmail.com>
Via
Web form
A. Volnova (IKI), E. Klunko (ISTP), A. Pozanenko (IKI) report on behalf of IKI-GRB-FuN:
We observed the field of the GRB 251111A (Cheng et al., GCN 42637) with the AZT-33IK 1.5m telescope of the Sayan Solar Observatory (Mondy) in the R-filter starting Nov., 11, 2025, UT 16:26:22, and taking several frames with 120 s exposures. In the stacked frame we do not detect the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCNs 42639, 42641; Ma et al., GCN 42647). Preliminary photometry is the following:
Date UT start t-T0 Exp. Filter OT Err. UL
(mid,days) (n*s) (3sigma)
2025-11-11 16:26:22 0.48686 25*120 R n/d n/d 22.1
The photometry is based on several nearby SDSS stars (R-magnitudes Lupton's transformation) and is not corrected for the Galactic extinction, all magnitudes are in Vega system.
GCN Circular 42670
Subject
GRB 251111A: SVOM/ECLAIRs refined analysis
Date
2025-11-13T15:34:26Z (8 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
H. Yang, M. Brunet, O. Godet (IRAP), W.-J. Xie (NAOC), S. Schanne, B. Hubert (CEA), Y.-H. Cheng (SWIFAR,YNU), B.-T. Wang (YNAO)
Using the event-by-event data downloaded through the X-band ground station, we report further analysis of ECLAIRs observations of GRB 251111A (SVOM burst-id sb25111101, GCN 42637) detected at T0 = 2025-11-11T05:10:18.26.
The burst that triggered ECLAIRs consists of a single peak mostly seen in the 4-30 keV, with a duration of T90 = 5.31 (-0.68 / +2.36) s in the 4-20 keV energy band.
The time-averaged spectrum from the peak (T0-5.3 s to T0+5 s) in the 5-30 keV energy range is well fitted by a power-law model with a photon index of 2.4 +/-0.2.The large photon index suggests that the peak energy is below 4 keV, indicating that this event is an X-ray flash. A blackbody model is also tested but does not provide a good fit. With the power-law model, the total 4-120 keV fluence is (1.5+/-0.2)e-07 erg/cm^2.
All the quoted errors are at the 68% confidence level.
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: Hui Yang (IRAP) (hui.yang@irap.omp.eu).
GCN Circular 42651
Subject
GRB251111A: 1.3m DFOT optical upper limit
Date
2025-11-12T16:45:38Z (9 days ago)
From
ANSHIKA GUPTA at ARIES <anshika05180@gmail.com>
Via
Web form
Anshika Gupta, Kumar Pranshu, Debolina Kar, Dhruv Jain, Pankaj Pawar and Kuntal Misra (ARIES) report:
We observed the field of GRB251111A detected by SVOM (Cheng et al. 2025, GCN 42637), with the 1.3m Devasthal Fast Optical Telescope (DFOT), located at the Devasthal Observatory of the Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2025-11-11 at 15:37:41 UT, i.e., ~10.45 hours after the SVOM trigger. We have taken multiple frames with an exposure time of 300 s in the R filter. We stacked the images after the alignment. We could not detect the optical emission in our stacked image within the error box of SVOM/COLIBRÍ (López-Cámara et al. 2025, GCN 42638) & Swift-XRT (Campana et al. 2025, GCN 42648). We obtain the following 3-sigma upper limit in the stacked image:
Date Start_UT T_start-T0 (hour) Filter Exp time (s) Magnitude
===============================================================
2025-11-11 15:37:41 ~10.45 R 300s*24 >23.2
The upper limit of the burst is consistent with López-Cámara et al. 2025 (GCN 42638); Wu et al. 2025 (GCN 42639); Zheng et al. 2025 (GCN 42640); Wu et al. 2025 (GCN 42641); Ma et al. 2025 (GCN 42647).
The magnitude is not corrected for the Galactic extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalogue.
GCN Circular 42648
Subject
GRB 251111A: Swift-XRT afterglow detection
Date
2025-11-12T10:51:12Z (9 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
S. Campana (INAF-OAB), D.N. Burrows (PSU), S. Lanava (PSU), S. Dichiara
(PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.
Melandri (INAF-OAR), T. Sbarrato (INAF-OAB) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of GRB 251111A. We
searched for X-ray sources in 2.1 ks of Photon Counting (PC) mode
data. The total exposure at the position of the afterglow (see below)
is 2.1 ks, obtained between T0+7.6 ks and T0+36.9 ks.
An uncatalogued X-ray source is detected and is believed to be the
afterglow. Using 305 s of PC mode data and 1 UVOT image, we find an
enhanced XRT position (using the XRT-UVOT alignment and matching UVOT
field sources to the USNO-B1 catalogue): RA, Dec = 32.36166, +5.22815
which is equivalent to:
RA (J2000): 02h 09m 26.80s
Dec(J2000): +05d 13' 41.3"
with an uncertainty of 5.1 arcsec (radius, 90% confidence). The
observed count rate was 2.5 (+1.2, -0.9)e-02 count/s at T0+7.7 ks,
falling to 5.2 (+2.6, -1.9)e-03 at T0+33.8 ks, which indicates the
X-ray source is fading.
The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/03000189.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/SVOM/SVOM_FIELD00049.
This circular is an official product of the Swift-XRT team.
GCN Circular 42647
Subject
GRB 251111A: SVOM/VT optical observations with X-band data
Date
2025-11-12T07:32:30Z (9 days ago)
From
Yinuo Ma <mayn@bao.ac.cn>
Via
Web form
Y. N. Ma, H. L. Li, L. P. Xin, Z. H. Yao, Y. L. Qiu, C. Wu, 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), Y. H. Cheng (SWIFAR, YNU), B. T. Wang(YNAO) report on behalf of the SVOM/VT team.
SVOM/VT performed an automatic slew on the burst GRB 251111A (sb25111101) triggered by SVOM/ECLAIRs (Cheng et al., GCN 42637). SVOM/VT began observing the field at 2025-11-11 06:01:57 UTC, 51.656 minutes after T0, in the VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
With X-band data available, the optical counterpart (López-Cámara et al., GCN 42638; Wu et al., GCN 42639; Zheng et al., GCN 42640; Wu et al., GCN 42641) was detected in VT_R band within XRT's error box (Evans et al., GCN 42645) and EP-FXT's error box (Cheng et al., GCN 42643) at the mid time of 1.34 hour, followed with a decay slope of -0.7. The measurements are:
mid time (h) | exposure time (s) | band | mag (AB)
-------------|-------------------|------|----------------
1.34 | 28*50 | VT_R | 22.3+/-0.2
6.10 | 14*100 | VT_R | 23.5+/-0.3
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 Center 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 42645
Subject
GRB 251111A: Swift-XRT observations
Date
2025-11-11T14:02:01Z (10 days 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 251111A, collecting 288 s of Photon Counting (PC) mode data between T0+7.4 ks
and T0+7.8 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 J020926.8+051342):
==================================
RA (J2000.0): 32.3618 = 02 09 26.83
Dec (J2000.0): +5.2284 = +05 13 42.2
Error: 5.7 (arcsec, radius, 90% confidence).
Detect flag: GOOD
Distance: 2.0 arcmin from the SVOM/ECLAIRs position.
Mean rate: 0.0264 [+0.0127, -0.0096] ct s^-1
Mean flux: (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1
Peak rate: 0.0264 [+0.0127, -0.0096] ct s^-1
Peak flux: (7.2 [+3.5, -2.6])e-13 erg cm^-2 s^-1
ECF: 2.73e-11 erg cm^-2 ct^-1
assuming NH=5.07e+20 cm^-2, gamma=2.63
determined from a spectral fit.
XMM UL: 2.6e-12 erg cm^-2 s^-1, (0.3-10 keV)
so the source is not above this 3-sigma upper limit.
There is no evidence for fading.
The XRT position is consistent the optical counterpart reported by the SVOM/COLIBRÍ
(FM-GFT; López-Cámara et al., GCN Circ. 42638), LCO 1m (Wu et al., GCN Circ.
42639) and SVOM/VT (Wu et al., GCN 42641) telescopes, as well as the Einstein Probe
FXT X-ray detection (Cheng et al. 42643).
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/SVOM_FIELD00049.
This circular is an official product of the Swift-XRT team.
GCN Circular 42643
Subject
GRB 251111A: EP-FXT counterpart detection
Date
2025-11-11T13:12:22Z (10 days ago)
From
EP Team at NAOC/CAS <ep_ta@bao.ac.cn>
Via
Web form
Y.H. Cheng (SWIFAR,YNU), Z. M. Wang (BNU), Y. J. Zhang (THU), C. L. Guo, J. W. Hu, 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 251111A (SVOM/sb25111101, Cheng et al., GCN #42637) at 2025-11-11 06:06:55 (UTC), about 0.93 hours after the SVOM/ECLAIRs trigger, with an exposure time of 1939 s. One uncatalogued source is detected within the ECLAIRs error circle, and the source is spatially consistent with the counterpart reported in optical band (López-Cámara et al., GCN #42638; Wu et al., GCN #42639, Zheng et al., GCN #42640, Wu et al., GCN #42641). Preliminary analysis on this source is automatically conducted, and the details are listed as follows.
Source 1 ：EPF_J020926.9+051342
RA (J2000): 32.362
Dec (J2000): 5.228
Flux: 1.24 x 10^-12 erg/s/cm2 (observed, 0.5-10 keV)
Flux_err: 3.53 x 10^-13 erg/s/cm2 (1 sigma)
The position uncertainty of the source is 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 42641
Subject
GRB 251111A: SVOM/VT optical observations with VHF data
Date
2025-11-11T09:01:37Z (10 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
C. Wu (NAOC), J. T. Palmerio (CEA), L.P. Xin (NAOC), H.L. Li, Y. L. Qiu, Yehao Cheng (SWIFAR,YNU), Boting Wang(YNAO) report on behalf of the SVOM team.
SVOM/VT performed an automatic slew on the burst of GRB 251111A (sb25111101) triggered by SVOM/ECLAIRs (Cheng et al. GCN 42637). SVOM/VT began observing the field automatically at 2025-11-11T06:01:57 UTC, 51.65 minutes after the T0, with the slew of the platform triggered on-board, in VT_B (400nm-650nm) and VT_R (650nm-1000nm) channels simultaneously.
We confirm the detection of the source reported by López-Cámara et al. (GCN 42638) and Wu et al. (GCN 42639) in the VT_R band with the downlinked VHF data.
The AB magnitude was derived as follows:
--------------------------------------------
(T-T0)_mid exptime band mag
54.15 min 300 sec VT_R 21.32 +/-0.11
No correction for Galactic extinction was applied to the photometry.
This result is consistent with the report by Zheng et al. (GCN 42640)
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center 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 42640
Subject
GRB 251111A: KAIT optical upper limit
Date
2025-11-11T08:13:13Z (10 days ago)
From
Weikang Zheng at UC Berkeley <weikang@berkeley.edu>
Via
email
WeiKang Zheng (UCB), Xuhui Han (NAOC), Pinpin Zhang (NAOC) and
Alexei V. Filippenko (UCB) report on behalf of the KAIT GRB team:
The 0.76-m Katzman Automatic Imaging Telescope (KAIT), located at
Lick Observatory, automatically responded to the SVOM GRB
251111A (Cheng et al., GCN 42637) starting at 05:12:13, 115 seconds
after the burst. Observations were performed in 3 x 3 tiling mode,
and a set of clear (roughly R) filter images were obtained. The first
image covered the reported afterglow (López-Cámara et al., GCN 42638;
Wu et al., GCN 42639) position was at 05:14:50, 272 seconds after
the burst. We did not detect the afterglow in our clear images with
the following upper limit:
mid t-t0(s) exp(s) UL(mag)
---------------------------
282 20 >18.5
561 20 >18.5
763 20 >18.5
1042 20 >18.5
1323 20 >18.5
1690 40 >19.0
2156 40 >19.0
2613 40 >19.0
3168 60 >19.5
3813 60 >19.5
4442 60 >19.5
GCN Circular 42639
Subject
GRB 251111A: LCO optical observation
Date
2025-11-11T07:59:03Z (10 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
C. Wu (NAOC), L. P. Xin, Xuhui Han, J. T. Palmerio (CEA/Irfu), D. Turpin, A. Saccardi, B. Cordier report on behalf of the SVOM mission team:
We observed the field of GRB 251111A (SVOM/ECLAIRs, Cheng et al. GCN 42637) with the LCO 1m telescope at Cerro Tololo Inter-American Observatory equipped with the Sinistro instrument. Our observation started at 2025-11-11T05:31:30.632 about 21.21 minutes after the SVOM/ECLAIRs T0 time.
We obtained a sequence of 3x200 s exposures in the SDSS r band. The optical counterpart reported by SVOM/COLIBRÍ (FM-GFT) (López-Cámara et al., GCN 42638) is clearly detected in our stacked image. We measure an AB magnitude of r = 21.52 ± 0.15 at a midtime of Tmid − T0 = 26.63 min after the trigger.
The photometry was calibrated against nearby Pan-STARRS1 stars and no correction for Galactic dust extinction was applied.
This project is funded by the SVOM collaboration.
GCN Circular 42638
Subject
GRB 251111A: SVOM/COLIBRÍ (FM-GFT) optical counterpart detection
Date
2025-11-11T06:23:52Z (10 days ago)
From
Antonio de Ugarte Postigo at LAM, CNRS <adeugartepostigo@gmail.com>
Via
email
Diego López-Cámara (UNAM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), Benjamin Schneider (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Jean-Luc Atteia (IRAP), Camila Angulo (UNAM), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Rosa L. Becerra (UNAM), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Kin Ocelotl López (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), N. A. Rakotondrainibe (LAM), Fredd Sánchez Álvarez (UNAM), Yehao Cheng (SWIFAR,YNU), Boting Wang (YNAO):
We imaged the field of the SVOM GRB 251111A (Cheng et al., GCN Circ. 42637) using the DDRAGO two-channel wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2025-11-11 05:21:36 to 05:37:03 UTC (from 11.4 to 26.8 minutes after the trigger) and obtained 13 minutes of simultaneous exposure in the r and z filters.
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 detect an uncatalogued source revealed by image subtraction using PanSTARRS as template and consistent with the ECLAIRs 7.55 arcmin error circle (Cheng et al., GCN Circ. 42637) at:
RA(J2000) = 02:09:26.82 = 32.361770 degrees
Dec(J2000) = 05:13:40.4 = 5.227888 degrees
with an uncertainty of 0.5 arcsec.
The preliminary magnitude derived for that source is:
r = 21.35 +/- 0.05
z = 20.27 +/- 0.05
The source fades during our observations, confirming that it is the optical afterglow of the GRB. The red r-z color might indicate a moderately high redshift or extinction due to dust.
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.
COLIBRÍ is an astronomical observatory developed and operated jointly by France (AMU, CNES and CNRS) and Mexico (UNAM and SECIHTI). It is located at the Observatorio Astronómico Nacional on the Sierra de San Pedro Mártir, Baja California, Mexico.
GCN Circular 42637
Subject
GRB 251111A: SVOM detection of a soft burst
Date
2025-11-11T05:40:11Z (10 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Yehao Cheng (SWIFAR,YNU), Boting Wang (YNAO), Wenjin Xie, Donghua ZHAO (NAOC), Hatsunegoto Goto (Kanazawa Univ./CEA) report on behalf of the SVOM mission team:
At 2025-11-11T05:10:18 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 251111A (SVOM burst-id sb25111101).
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. CRT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 10.57 in the [5-20] keV energy band over a time window of 5.10 seconds starting at 2025-11-11T05:10:15.
The localization of the best alert is R.A., Dec. 32.3783, 5.2567 degrees:
R.A. (J2000) = 2h09m30.79s
Dec. (J2000) = 5d15m24.04s
with a 90% confidence level (C.L.) radius of 7.55 arcmin (including systematic error of 2 arcmin added in quadrature).
SVOM slewed to this burst, but MXT and VT were in the occultation of the Earth.
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 Yehao Cheng: yhcheng@mail.ynu.edu.cn.
Please contact the BA by email if you require additional information.