GRB 261110A
GCN Circular 46228
Subject
GRB 261110A: CrAO ZTSh optical observations
Date
2026-11-11T17:26:22Z (4 hours ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
email
A. Moskvitin (SAO), V. Rumyantsev (CrAO), A. Pozanenko (IKI),
A. Volnova (IKI), N. Pankov (IKI), O. Spiridonova (SAO) report
on behalf of IKI GRB-FuN and SAO GRB follow-up team.
We observed the field of the SVOM GRB 261110A (Wang et al., GCN 46215)
with the Shajn 2.6-meter telescope (ZTSh) of the Crimean Astrophysical
Observatory (CrAO) on November 10 and obtained two series in R band
(t_mid - T0 = 6.12 and 10.81 hours respectively).
The afterglow (Wu et al., GCN 46218; Li et al., GCN 46219; Moskvitin
et al., GCN 46220; Angulo et al., GCN 46223) is clearly detected
in stacked images of the two epochs with the following parameters.
Date UT start t-T0 Exp, Filter Obj Err UL
(mid, d) (n*s) (3sigma)
2026-11-10 17:51:58 0.25498 5*120 R 22.30 +/- 0.10 23.7
2026-11-10 21:43:16 0.45050 53*120 R 22.80 +/- 0.09 24.3
The photometry (Vega) is preliminary and based on nearby SDSS stars
(Lupton 2005 transformation) and not corrected for Galactic extinction.
GCN Circular 46223
Subject
GRB 261110A: SVOM/COLIBRÍ (FM-GFT) optical observations
Date
2026-11-11T07:53:50Z (14 hours ago)
From
Massimiliano Lincetto at Aix Marseille Univ, CNRS/IN2P3, CPPM <lincetto@cppm.in2p3.fr>
Via
Web form
Camila Angulo (UNAM), Massimiliano Lincetto (CPPM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), 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), Asuka Kuwata (UNAM), Marion Guelfand (CPPM), Nikos Mandarakas (LAM), Diego López-Cámara (UNAM), Francesco Magnani (CPPM), Enrique Moreno Méndez (UNAM), Margarita Pereyra (UNAM), Fredd Sánchez Álvarez (UNAM), Benjamin Schneider (LAM), Antonio de Ugarte Postigo (LAM), Alan M. Watson (UNAM), Wen-Jun Tan (PKU) and J. X. Cao (GXU) report:
We imaged the field of the SVOM GRB 261110A (Wang et al., GCN Circ. 46215) using the DDRAGO wide-field imager on the SVOM/COLIBRÍ (FM-GFT) telescope. We observed from 2026-11-11 02:23:36 to 04:42:13 UTC (from 14.57 to 16.88 hours after the trigger) and obtained 138.6 minutes of exposure in the r filter.
The data were reduced and coadded with the CPPM COLIBRÍ pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR2 catalog, is in the AB system, and is not corrected for Galactic extinction.
After subtracting the template Legacy Survey image, we detected the optical counterpart reported by Wu et al. (GCN Circ 46218), Li et al (GCN Circ. 46219) and Moskvitin et al. (GCN Circ. 46220) at a preliminary magnitude of:
r = 23.60 +/- 0.19
Further observations are ongoing.
We thank the staff of the Observatorio Astronómico Nacional at Sierra de San Pedro Mártir, as well as the technical and engineering teams at CEA, CPPM, IRAP, LAM, OHP, OSU Pytheas, and UNAM.
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 46222
Subject
GRB 261110A : MITSuME Akeno optical upper limits
Date
2026-11-11T07:29:52Z (14 hours ago)
From
J. Yonamine at Institute of Science Tokyo <yonamine.j.21c9@m.isct.ac.jp>
Via
Web form
J. Yonamine, I. Takahashi, M. Sasada, H. Hagio, A. Ochi, Y. Kubo, R. Kato, N. Hosoya, Y. Yatsu and N. Kawai (Science Tokyo) report on behalf of the MITSuME collaboration:
We observed the field of GRB 261110A detected by SVOM/ECLAIRs (Wang et al., GCN 46215) with the optical three-color (g', Rc, and Ic) CCD cameras attached to the MITSuME 50-cm telescope Akeno.
The observation started at 2026-11-10 11:58:39 UT (8.7 min after the trigger). We stacked the images taken under good conditions. We did not detect any optical point source at the reported position (Wu et al., GCN 46218; Li et al., GCN 46219; Moskvitin et al., GCN 46220). We obtained 5-sigma detection limits of the stacked images as follows.
T0+[sec] | MID-UT | T-EXP[sec] | 5-sigma limits
------------------------------------------------------------------------------------------------
929 | 2026-11-10 12:05:29 | 600 | g'>19.4, Rc>19.5, Ic>18.6
2311 | 2026-11-10 12:28:31 | 3000 | g'>20.2, Rc>20.3, Ic>19.3
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the trigger
T-EXP: Total exposure time
We used the PS1 catalog for flux calibration. The catalog magnitudes in PS1 g, r and i bands were converted to our g', Rc and Ic band magnitudes following Tonry et al. (2012), Table 6. The magnitudes are expressed in the AB system. The images were processed in real-time through the MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ; https://github.com/MNiwano/Eclaire).
GCN Circular 46221
Subject
GRB 261110A: LCO optical upper limits
Date
2026-11-11T02:57:39Z (19 hours ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Y.Y. Shi (GXU), A. Saccardi, D. Turpin (CEA/Irfu), C. Wu, L.P. Xin (NAOC), S.J. Yin, Y.X. Guan (GXU), W.Jun. Tan (PKU), J.X. Cao (GXU) report on behalf of the SVOM mission team:
We observed the field of GRB 261110A (SVOM burst-id sb26111002) detected by SVOM (Wang et al., GCN 46215) with the LCO 1m telescope at Cerro Tololo Inter-American Observatory equipped with the Sinistro instrument.
Our observation started on 2026-11-11T00:46:09 UTC (about 12.94 hr after the trigger) and we obtained 3x200 s exposures in the SDSS r and Pan-STARRS z filter.
We do not detect the optical counterpart (Wu et al., GCN 46218; Li et al., GCN 46219; Moskvitin et al., GCN 46220) in our stacked image. We measure the following upper limits calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
r > 22.3 AB (3-sigma, mid-time 13.03 hr after the trigger),
z > 20.2 AB (3-sigma, mid-time 13.07 hr after the trigger).
This project is funded by the SVOM collaboration.
GCN Circular 46220
Subject
GRB 261110A: SAO RAS optical observations
Date
2026-11-10T23:00:13Z (a day ago)
From
Alexander Moskvitin at SAO RAS <mosk@sao.ru>
Via
email
A. Moskvitin (SAO), O. Spiridonova (SAO), V. Rumyantsev (CrAO),
A. Pozanenko (IKI), A. Volnova (IKI), N. Pankov (IKI) report
on behalf of SAO GRB follow-up team and IKI GRB-FuN.
We observed the field of the SVOM GRB 261110A (Wang et al., GCN 46215)
with the Zeiss-1000, 1-m telescope of SAO RAS on November 10,
19:54:00--21:00:26 UT (t_mid - T0 = 8.62 hours after the trigger).
The OT (Wu et al., GCN 46218; Li et al., GCN 46219) is detected
in our stacked frame with the following brightness.
Date UT start t-T0 Exp, Filter Obj Err UL
(mid, d) (n*s) (3sigma)
2026-11-10 19:54:00 0.35918 12*300 Rc 23.0 +/- 0.2 23.6
This preliminary photometry (Vega) is based on nearby SDSS stars
(Lupton 2005 transformation) and not corrected for Galactic
extinction.
_____________________________________________
Alexander Sergeevich Moskvitin, Ph. D., researcher,
Optical Transient Physics Laboratory (#523), SAO RAS,
369167, Nizhnij Arkhyz, Karachai-Cherkessia, Russia,
+7(928)3946958, mosk@sao.ru
GCN Circular 46219
Subject
GRB 261110A: SVOM/VT optical observations
Date
2026-11-10T19:48:30Z (a day ago)
From
Huali Li at at NAOC, SVOM <lhl@nao.cas.cn>
Via
Web form
H. L. Li, C. Wu, Y. L. Qiu, Y. N. Ma, L. P. Xin, L. J. Chen, Z. H. Yao, J. R. Xu, 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), J. T. Palmerio, W. J. Tan (PKU), J. X. Cao (GXU) report on behalf of the SVOM/VT team.
SVOM/VT performed observation with automatic slew on the field of GRB 261110A detected by SVOM/ECLAIRs (sb26111002, Wang et al., GCN 46215). Our observation started on 2026-11-10T11:55:06 UT, 306 seconds in the VT_B (400-650 nm) and VT_R (650-1000 nm) channels simultaneously .
With the limited X-band data available, the optical candidate from Xinglong 2.16m telescope (Chen et al., GCN 46218) was detected in both channels. It shows a shallow decay with the slope index of -0.13 over our 2-hour observation span. The following measurements are in AB magnitudes and are not corrected for Galactic extinction:
Mid time | Band | Exposure Time | Brightness
16.7 m VT_B 20*70 s 22.3 +/- 0.2 mag
17.3 m VT_R 21*70 s 22.0 +/- 0.2 mag
More observations are ongoing.
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 46218
Subject
GRB 261110A: Xinglong 2.16m optical candidate
Date
2026-11-10T19:00:15Z (a day ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
C. Wu, L. J. Chen, Y. N. Ma, L. P. Xin, H.L. Li, Y. L. Qiu, J. Wang, X. H. Han, P. P. Zhang, J. Zheng, J. J. Jia, Z. Fan, J. Y. Wei (NAOC), W. J. Tan (PKU), J. X. Cao (GXU) report on behalf of SVOM follow-up team:
We observed the field of GRB 261110A triggered by SVOM/ECLAIRs (sb26111002, Wang et al., GCN 46215) using the 2.16m telescope located at Xinglong observatory, China, equipped with the BFOSC camera. We obtained 4*60s frames in R-band, starting at 12:12:11 UT on 2026-11-10, about 22.18 min after the trigger.
We found a candidate at RA = 350.8530709 deg, Dec = 33.0630451 deg with R ~ 21.4 within the ECLAIRs error box (Wang et al., GCN 46215). We notice there is a faint catalogued source in the Legacy Survey at this position with the brightness: g=24.07, r=23.61, z=23.06.
We thank the staff at Xinglong observatory for their excellent support.
GCN Circular 46216
Subject
GRB 261110A : SVOM/GWAC-F60 optical upper limit
Date
2026-11-10T15:44:40Z (a day ago)
Edited On
2026-11-10T16:04:05Z (a day ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Edited By
K.L. Page at U Leicester <klp5@leicester.ac.uk> on behalf of SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Y.X. Guan, S.J. Yin (GXU), L.P. Xin, C. Wu, X.H. Han, P.P. Zhang, J.L. Wang (NAOC), Y.Y. Shi, J.X. Cao(GXU), W.J. Tan(PKU), X.G. Wang, E.W. Liang(GXU) report on behalf of the SVOM follow-up team:
We observed the field of GRB261110A detected by SVOM/ECLAIRs (Wang et al., GCN 46215), with the GWAC-F60 at Xinglong Observatory, China. F60 started observing at 2026-11-10T11:52:02 UTC, ~ 122 s after trigger.
After coadding the images of R band, we do not find any uncataloged candidate within the SVOM/ECLAIRs error box (Wang et al., GCN 46215). We measure the following upper limit calibrated against the USNO-B1.0 catalog, and not corrected for Galactic extinction:
R > 20.15 mag (5-sigma, mid-time 16.03 min after the trigger).
Two 60cm GWAC-F60(A/B) are operated by Guangxi University and NAOC, CAS, at Xinglong Observatory, China. The field of view is 19*19 arcmin.
GCN Circular 46215
Subject
GRB 261110A: SVOM detection of a burst
Date
2026-11-10T12:19:20Z (a day ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
Chen-Wei Wang (THU), Li Zhang (IHEP), Wen-Jun Tan (PKU), S. Schanne, A. Saccardi, B. Cordier, D. Turpin (CEA/Irfu) report on behalf of the SVOM mission team:
At 2026-11-10T11:50:00 UTC (T0), SVOM/ECLAIRs triggered and located the gamma-ray burst GRB 261110A (SVOM burst-id sb26111002).
The following trigger information was received on the ground with low latency by the SVOM VHF Alert Network.
The burst was only detected by the Image Trigger (IMT), which produced a sequence of 3 alerts. IMT provided the alert with the best signal-to-noise-ratio in the image (SNR) of 7.60 in the [5-20] keV energy band over a time window of 40.96 seconds starting at 2026-11-10T11:49:19.
The localization of the best alert is R.A., Dec. 350.7538, 33.0385 degrees:
R.A. (J2000) = 23h23m00.91s
Dec. (J2000) = 33d02m18.62s
with a 90% confidence level (C.L.) radius of 10.33 arcmin (including systematic error of 2 arcmin added in quadrature).
The SVOM/ECLAIRs light curve showed a weak peak structure with a T90 duration of about 21.891 (-8.717 +8.734).
SVOM slewed to the burst.
MXT and 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 Wenjun Tan: tanwj@pku.edu.cn.
Please contact the BA by email if you require additional information.