GRB 260922A
GCN Circular 45729
Subject
Konus-Wind detection of GRB 260922A
Date
2026-09-24T16:37:49Z (5 hours ago)
From
Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>
Via
Web form
A. Ridnaia, D. Frederiks, A. Lysenko, V. Panteleeva,
D. Svinkin, A. Tsvetkova, M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:
The long-duration GRB 260922A
(Swift detection: Page et al., GCN 45690;
Sakamoto et al., GCN 45703;
CALET-GBM detection: Ricciarini et al., GCN 45716;
NuSTAR detection: Waratkar & Grefenstette, GCN 45728)
triggered Konus-Wind at T0=36035.366 s UT (10:00:35.366).
The burst light curve shows a multi-peaked emission pulse,
which starts at ~T0-3.5 s and has a total duration of ~15.6 s.
The emission is seen up to ~2 MeV.
The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB260922_T36035/
As observed by Konus-Wind, the burst
had the total fluence of 6.88(-0.28,+0.29)x10^-6 erg/cm2,
and the 64-ms peak flux, measured from T0+1.552 s,
of 2.15(-0.35,+0.35)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).
The time-averaged spectrum of the burst
(measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.31(-0.19,+0.21)
and Ep = 151(-9,+10) keV (chi2 = 101/98 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 101/97 dof).
The spectrum near the maximum count rate
(measured from T0+0.256 to T0+8.448 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with alpha = -0.39(-0.15,+0.16)
and Ep = 153(-8,+8) keV (chi2 = 63/83 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.9
(chi2 = 62/82 dof).
All the quoted errors are at the 68% confidence level.
All the quoted values are preliminary.
GCN Circular 45728
Subject
GRB 260922A: NuSTAR detection of prompt emission
Date
2026-09-24T15:41:00Z (6 hours ago)
From
Gaurav Waratkar at Caltech <gauravwaratkar@iitb.ac.in>
Via
Web form
G. Waratkar (Caltech) and B. Grefenstette (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:
The NuSTAR SINGS working group reports the detection of prompt emission from the long-duration GRB 260922A in both the NuSTAR CsI anti-coincidence shields. Details of the search algorithm will be described in a future paper.
The NuSTAR SINGS algorithm, triggered at 2026-09-22T10:00:33.95 UTC, shows a detection of GRB 260922A, also detected by Swift-BAT (GCN 45690) and CALET-GBM (GCN 45716).
The NuSTAR CsI shield data are recorded at 1 Hz. We detect a single peak lasting for about 10-s. The peak count rate is ~1500-cps with a baseline rate of ~1000-cps during this time period. We do not see any evidence in the signal above 100 keV in the CZT detectors.
The Swift-XRT localization (GCN 45696) at RA = 227.90847, Dec = 14.21907 implies an offset from the NuSTAR boresight of 44-deg (i.e. from the side) and an offset from the geocenter of 141-deg.
Lightcurves and analysis for this GRB can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2026/260922A
Information on NuSTAR SINGS can be found here:
https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/
NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASA's Science Mission Directorate in Washington.
GCN Circular 45724
Subject
GRB 260922A: COLIBRÍ Confirmation of the Optical Counterpart
Date
2026-09-24T14:20:41Z (7 hours ago)
From
Rosa Leticia Becerra Godínez at Instituto de Astronomía, UNAM <rbecerra@astro.unam.mx>
Via
Web form
Rosa L. Becerra (UNAM), Antonio de Ugarte Postigo (LAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Camila Angulo (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), Nathaniel R. Butler (ASU), Damien Dornic (CPPM), Jean-Grégoire Ducoin (CPPM), Francis Fortin (IRAP), Leonardo García-García (UNAM), Ramandeep Gill (UNAM), Noémie Globus (UNAM), Marion Guelfand (CPPM), Asuka Kuwata (UNAM), Massimiliano Lincetto (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) and Alan M. Watson (UNAM) report:
We continued our observations of the field of the Swift GRB 260922A (Page et al., GCN Circ. 45690) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-09-24 02:29 to 03:51 UTC (from 40.48 to 41.86 hours after the trigger) and obtained 64 minutes of simultaneous exposure in the r and z filters.
The data were reduced, coadded and analyzed with the ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
At the position of the optical counterpart reported in Angulo et al. (GCN Circ. 45699), we do not detect the source in the r band down to the following 3-sigma limit:
r > 23.8.
In the z band, we marginally detect the source with a preliminary magnitude of:
z = 23.15 +/- 0.34.
The observed fading between our two epochs confirms the transient nature of the source and supports its identification as the optical counterpart of GRB 260922A.
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 45716
Subject
GRB 260922A: CALET Gamma-Ray Burst Monitor detection
Date
2026-09-24T05:34:09Z (16 hours ago)
From
Yuta Kawakubo at Aoyama Gakuin University <kawakubo@phys.aoyama.ac.jp>
Via
Web form
S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto, S. Sugita,
Y. Kawakubo (AGU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U), Y. Shimizu,
T. Tamura (Kanagawa U), N. Cannady (GSFC), M. L. Cherry (LSU),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:
The CALET Gamma-ray Burst Monitor (CGBM) detected GRB 260922A
at 10:00:33.96 UTC on 22 September 2026 (trigger #1474106408;
https://cgbm.calet.jp/cgbm_trigger/flight/1474106408/index.html).
A CGBM Notice was distributed in near real time.
This event was also reported by Swift-BAT (Page et al., GCN #45690;
Sakamoto et al., GCN #45703) .
The burst signal was seen by only the SGM detector.
The burst light curve shows a double-peaked structure starting
at T+0.4 s, peaking at T+5.8 s, and ending at T+ 7.5 s.
The T90 and T50 durations measured with the SGM data are 6.2 +/- 0.5 s
and 2.8 +/- 0.4 s in the 40-1000 keV band, respectively.
The ground-processed light curve is available at:
https://cgbm.calet.jp/cgbm_trigger/ground/1474106408/
The CALET data used in this analysis were provided by
the Waseda CALET Operation Center located at Waseda University.
GCN Circular 45707
Subject
GRB 260922A: Ondrejov D50 optical limit
Date
2026-09-23T15:10:54Z (a day ago)
From
Filip Novotný at Masaryk University <filip.novotny@talentovani.cz>
Via
Web form
F. Novotny, J. Strobl, M. Jelinek and R. Hudec (ASU CAS Ondrejov) report:
We observed the field of GRB 260922A (Page et al., GCN 45690; Beardmore et al., GCN 45696), detected by Swift (trigger=1512686), with the 50 cm D50 telescope of the Astronomical Institute Ondrejov, Czech Republic. We obtained 3x300 s Sloan r'-band exposures starting at 2026-09-22 18:24 UT, 8.39 h after the trigger.
We do not detect any source at the position of the COLIBRÍ candidate optical counterpart (RA, Dec = 227.90767, +14.21923; Angulo et al., GCN 45699), neither in the individual images (3-sigma limit r' > 19.3) nor in the combined 900 s image (mean epoch T0+8.5 h, 3-sigma limit r' > 20.2). This limit is consistent with the fainter COLIBRÍ detection (r = 22.44) obtained at a later epoch.
Magnitudes are calibrated in Sloan r' (AB) against ATLAS-RefCat2 field stars and are not corrected for Galactic extinction.
GCN Circular 45703
Subject
GRB 260922A: Swift-BAT refined analysis
Date
2026-09-23T13:36:37Z (a day ago)
From
Amy <yarleen@gmail.com>
Via
email
T. Sakamoto (AGU), S. D. Barthelmy (GSFC), R. Gupta (GSFC), H. A. Krimm
(NSF), S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
M. J. Moss (GSFC), D. M. Palmer (LANL), K. L. Page (U Leicester), T.
Parsotan (GSFC), D. Sadaula (GSFC/UMBC) (i.e. the Swift-BAT team):
Using the data set from T-61 to T+242 sec from the recent telemetry
downlink,
we report further analysis of BAT GRB 260922A (trigger #1512686)
(Page et al., GCN Circ. 45690). The BAT ground-calculated position is
RA, Dec = 227.909, 14.216 deg which is
RA(J2000) = 15h 11m 38.1s
Dec(J2000) = +14d 12' 57.8"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 21%.
The mask-weighted light curve shows a multi-pulse structures that starts at
~T-5 s and ends at ~T+80 s. The main peak occurs at ~T+1 s. T90 (15-350
keV) is 63.96 +- 12.79 sec (estimated error including systematics).
The time-averaged spectrum from T-4.90 to T+80.24 sec is best fit by a
simple power-law model. The power law index of the time-averaged spectrum
is 1.42 +- 0.09. The fluence in the 15-150 keV band is 4.7 +- 0.2 x 10^-06
erg/cm2. The 1-sec peak photon flux measured from T+0.72 sec in the 15-150
keV band is 5.7 +- 0.6 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/1512686
GCN Circular 45701
Subject
GRB 260922A: J-band upper limit with WINTER
Date
2026-09-23T10:30:25Z (a day ago)
From
tanishk.mohan@iitb.ac.in
Via
Web form
Tanishk Mohan (IITB), Geoffrey Mo (Caltech/Carnegie), Viraj Karambelkar (Columbia), Benjamin Schneider (LAM), Tomas Ahumada (NOIRLab), Robert Stein (UMD), Danielle Frostig (CfA), Nathan Lourie (MIT), Robert Simcoe (MIT), and Mansi Kasliwal (Caltech) report:
We observed the field of GRB 260922A (Page et al., GCN 45690; also see Beardmore et al., GCN 45696) in the near-infrared J band with the Palomar 1-m telescope, equipped with the 1.2-square degree WINTER camera (Lourie et al. 2020, Frostig et al. 2024).
Observations began on 2026-09-23 at 02:21:59.754 UTC in the J band (16.36 hr after the BAT trigger), consisting of 15*120 sec exposures. The images were processed using the WINTER data reduction pipeline implemented with mirar (https://github.com/winter-telescope/mirar, https://doi.org/10.5281/zenodo.13352565).
We do not detect the optical counterpart (Angulo et al., GCN 45699) in our stacked image.(Yin et al., GCN 45691; Shilling et al., GCN 45700)
We obtain the following 5-sigma upper limit: J = 18.8 mag (AB).
WINTER (Wide-field INfrared Transient ExploreR) is a partnership between MIT and Caltech, housed at Palomar Observatory, and funded by NSF MRI, NSF AAG, the David and Lucile Packard Foundation, and the MIT Kavli Institute for Astrophysics and Space Research.
GCN Circular 45700
Subject
GRB 260922A: Swift/UVOT Upper Limits
Date
2026-09-23T06:26:09Z (2 days ago)
From
s.shilling@lancaster.ac.uk
Via
Web form
S. P. R. Shilling (Lancaster U.) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 260922A
118.5 s after the BAT trigger (Page et al., GCN Circ. 45690).
No optical afterglow consistent with the enhanced XRT position
(Beardmore et al., GCN Circ. 45696) is 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 118 268 147 >20.2
white 118 4697 530 >20.8
v 661 1062 58 >18.3
b 587 1161 58 >19.2
u_FC 331 581 246 >19.7
u 331 1135 285 >19.8
w1 710 1111 19 >18.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.035 in the direction of the burst
(Schlegel et al. 1998).
GCN Circular 45699
Subject
GRB 260922A: COLIBRÍ Optical Counterpart Candidate (correction to GCN 45698)
Date
2026-09-23T05:54:41Z (2 days ago)
From
Camila Angulo Valdez at UNAM <camiangulo@astro.unam.mx>
Via
Web form
Camila Angulo (UNAM), Marion Guelfand (CPPM), Rosa L. Becerra (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (UNAM), Jean-Luc Atteia (IRAP), Dalya Akl (NYUAD), Sarah Antier (IJCLAB), 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), Massimiliano Lincetto (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) report:
We re-analysed our images of the field of Swift GRB 260922A (Page et al., GCN Circ. 45690) previously reported by Angulo et al. (GCN Circ. 45698).
In the same stacked images, we detect an uncatalogued source consistent with the XRT error circle (Beardmore et al., GCN Circ. 45696) and not identified in the DESI Legacy Survey catalog (Dey et al. 2019) at:
RA(J2000) = 15:11:37.84 = 227.90767 degrees,
Dec(J2000) = +14:13:09.2 = +14.21923 degrees
with an uncertainty of 1 arcsec. The preliminary magnitude derived for that source is:
r = 22.44 +/- 0.13,
z = 22.35 +/- 0.25.
We suggest this is the optical counterpart of the GRB.
We apologize for the omission of this source in our previous GCN Circular.
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 45698
Subject
GRB 260922A: COLIBRÍ optical upper limits
Date
2026-09-23T04:24:13Z (2 days ago)
From
Camila Angulo Valdez at UNAM <camiangulo@astro.unam.mx>
Via
Web form
Camila Angulo (UNAM), Marion Guelfand (CPPM), Noémie Globus (UNAM), Stéphane Basa (UAR Pytheas), William H. Lee (UNAM), Edilberto Aguilar-Ruiz (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), Asuka Kuwata (UNAM), Massimiliano Lincetto (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) report:
We imaged the field of the Swift GRB 260922A (Page et al., GCN Circ. 45690) using the DDRAGO two-channel wide-field imager on the COLIBRÍ telescope. We observed from 2026-09-23 02:46:11 to 03:44:26 UTC (from 16.76 to 17.75 hours after the trigger) and obtained 90 minutes of simultaneous exposure in the r and z filters.
The data were reduced, coadded and analyzed with the ASU pipeline. The photometry was calibrated using nearby stars from the PanSTARRS DR1 catalog, is in the AB system, and is not corrected for Galactic extinction.
In the stacked image, we do not detect any new source at the XRT source position (Beardmore et al., GCN Circ. 45696) down to the following 3-sigma limit:
r > 23.06,
z > 22.38.
This upper limit is consistent with the one reported by Yin et al. (GCN Circ. 45691).
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 45697
Subject
GRB 260922A: Swift-XRT refined Analysis
Date
2026-09-23T02:13:55Z (2 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), S. Lanava (PSU), S.
Dichiara (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB) and P.A. Evans report
on behalf of the Swift-XRT team:
We have analysed 6.9 ks of XRT data for GRB 260922A, from 97 s to 33.8
ks after the trigger. The data comprise 192 s in Windowed Timing (WT)
mode (the first 10 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode.
The light curve can be modelled with an initial power-law decay with an
index of alpha=2.80 (+0.11, -0.10), followed by a break at T+463 s to
an alpha of 0.77 (+0.06, -0.07).
A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.18 (+0.11, -0.10). The
best-fitting absorption column is 5.1 (+2.0, -1.8) x 10^20 cm^-2, in
excess of the Galactic value of 2.9 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.70 (+0.15, -0.10)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum is 3.9 x 10^-11 (4.1 x 10^-11) erg
cm^-2 count^-1.
A summary of the PC-mode spectrum is thus:
Total column: 2.9 (+3.3, -0.0) x 10^20 cm^-2
Galactic foreground: 2.9 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index: 1.70 (+0.15, -0.10)
If the light curve continues to decay with a power-law decay index of
0.77, the count rate at T+24 hours will be 0.025 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 9.6 x
10^-13 (1.0 x 10^-12) erg cm^-2 s^-1.
The results of the XRT-team automatic analysis are available at
https://www.swift.ac.uk/xrt_products/01512686.
This circular is an official product of the Swift-XRT team.
GCN Circular 45696
Subject
GRB 260922A: Enhanced Swift-XRT position
Date
2026-09-22T21:26:30Z (2 days 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 2765 s of XRT Photon Counting mode data and 7 UVOT
images for GRB 260922A, 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 = 227.90847, +14.21907 which is equivalent
to:
RA (J2000): 15h 11m 38.03s
Dec (J2000): +14d 13' 08.7"
with an uncertainty of 2.0 arcsec (radius, 90% confidence).
This position may be improved as more data are received. The latest
position can be viewed at https://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 45691
Subject
GRB 260922A: SVOM/C-GFT optical upper limit
Date
2026-09-22T15:06:13Z (2 days ago)
From
SVOM_group <svomgroup@bao.ac.cn>
Via
Web form
S.J. Yin(GXU), Z. Kang (CHO), C. Wu , L.P. Xin, X.H. Han, P.P. Zhang, X.M. Lu (NAOC), Z.W. Li, Y. Lv (CHO), R.S. Zhang, Y.J. Xiao, Y.L. Qiu, J. Wang, J.S. Deng, L. Huang, J.Y. Wei (NAOC) report on behalf of the SVOM/C-GFT team:
We observed the field of GRB 260922A detected by Swift/XRT (Page et al., GCN 45690) with LATIOS on SVOM/C-GFT. Observations started at 2026-09-22T10:39:18 UTC, ~ 38.6 min after the trigger.
We obtained follow-up imaging in g,r, and i bands. After preliminary analysis, no credible candidate was detected within the error box provided by Swift/XRT (Page et al., GCN 45690) in our images. We measure the following upper limit calibrated against the Pan-STARRS DR1 catalog, and not corrected for Galactic extinction:
g > 19.4 AB (3-sigma, mid-time 0.8 hr after the trigger).
r > 19.3 AB (3-sigma, mid-time 1.04 hr after the trigger).
i > 19.3 AB (3-sigma, mid-time 0.92 hr after the trigger).
We thank the observation assistants Y.-H. Hao and C.-L. Guo 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 arcmin x 21 arcmin 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 45690
Subject
GRB 260922A: Swift detection of a burst
Date
2026-09-22T10:19:04Z (2 days ago)
From
K.L. Page at U Leicester <klp5@leicester.ac.uk>
Via
email
K. L. Page (U Leicester), P. A. Evans (U Leicester) and
A. Y. Lien (U Tampa) report on behalf of the Neil Gehrels Swift
Observatory Team:
At 10:00:39.44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 260922A (trigger=1512686). Swift slewed immediately to the
burst.
The BAT on-board calculated location is
RA, Dec = 227.904, +14.207 deg, which is
RA(J2000) = 15h 11m 37s
Dec(J2000) = 14d 12' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a multi-peaked
structure with a duration of about 50 sec. The peak count rate
was ~3000 counts/sec (15-350 keV), at ~1 sec after the trigger.
The XRT began observing the field at 10:02:28.3 UT, 108.9 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
227.90885, 14.21924 which is equivalent to:
RA(J2000) = 15h 11m 38.12s
Dec(J2000) = +14d 13' 09.3"
with an uncertainty of 2.4 arcseconds (radius, 90% containment). This
location is 47 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.
A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.88 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.1
(+2.88/-2.57) x 10^21 cm^-2 (90% confidence).
The initial flux in the 2.5 s image was 2.31e-09 erg cm^-2 s^-1 (0.2-10
keV).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 122 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 extinction.
Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk).
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/)