GRB 260115A
GCN Circular 43453
Subject
GRB 260115A: AstroSat CZTI detection
Date
2026-01-19T16:33:28Z (2 months ago)
Edited On
2026-01-20T14:31:01Z (a month ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Edited By
Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Arya (IITB), A. Goyal (IITB), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:
Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a GRB 260115A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 43417), and GECAM-B (Zhang et. al., GCN Circ. 43434).
The source was weakly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-01-15 17:46:47.72 UTC. The measured peak count rate associated with the burst is 252 (+64, -69) counts/s above the background in the combined data of all quadrants, with a total of 270 (+117, -120) counts. The local mean background count rate was 1327 (+9, -12) counts/s. Due to the low count rate of the burst, we cannot reliably measure T90 for this event.
CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 43434
Subject
GRB 260115A: GECAM-B observation
Date
2026-01-17T00:47:57Z (2 months ago)
From
zhangjinpeng@ihep.ac.cn
Via
Web form
Jin-Peng Zhang, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by GRB 260115A, at 2026-01-15T17:46:45.900 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #43417).
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of a bright pulse and some fainter emissions, with a duration (T90) of 4.8 +2.4/-1.4 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260115A.png
The time-averaged spectrum from T0 - 1.0 to T0 + 4.0 s is best fitted by a power law function. The power law index is -2.2 +0.3/-0.4. The event fluence (10-1000 keV) in this time interval is (2.8 +0.7/-0.4)E-06 erg/cm^2.
Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission originally consists of two micro-satellites (GECAM-A and GECAM-B) launched in Dec. 2020. As the third member of GECAM constellation, GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. GECAM mission is funded by the Chinese Academy of Sciences (CAS).
GCN Circular 43420
Subject
GRB 260115A: BALROG localization (Fermi Trigger 790192010 / GRB 260115741)
Date
2026-01-15T19:22:56Z (2 months ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
at 17:46:45 on 15 Jan. 2026 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).
The best-fit position is:
RA(2000.0) = 112.0 deg
Decl.(2000.0) = 7.9 deg
The 1 sigma statistical error radius is 4.6 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB260115741/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB260115741/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB260115741/json
GCN Circular 43418
Subject
Fermi GRB 260115A: Global MASTER-Net observations report
Date
2026-01-15T18:45:39Z (2 months ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
MASTER-Kislovodsk robotic telescope [1] located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 260115A ( Fermi GBM team, GCN 43417) errorbox 45 sec after notice time and 77 sec after trigger time at 2026-01-15 17:48:03 UT, with upper limit up to 18.5 mag. The observations began at zenith distance = 59 deg. The sun altitude is -41.0 deg.
MASTER-Tunka robotic telescope located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 260115A errorbox 548 sec after notice time and 580 sec after trigger time at 2026-01-15 17:56:26 UT, with upper limit up to 19.5 mag. The observations began at zenith distance = 49 deg. The sun altitude is -59.1 deg.
The galactic latitude b = 9 deg., longitude l = 214 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3103145
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
88 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 36m 40.06s , +03d 42m 42.1s) | C | 20 | 17.2 |
113 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 36m 40.06s , +03d 42m 42.1s) | C | 70 | 17.9 | Coadd
88 | 2026-01-15 17:48:03 | MASTER-Kislovodsk | (07h 40m 49.00s , +03d 19m 43.0s) | C | 20 | 17.3 |
128 | 2026-01-15 17:48:44 | MASTER-Kislovodsk | (07h 36m 40.13s , +03d 42m 39.9s) | C | 20 | 17.3 |
128 | 2026-01-15 17:48:44 | MASTER-Kislovodsk | (07h 40m 49.04s , +03d 19m 39.7s) | C | 20 | 17.3 |
174 | 2026-01-15 17:49:24 | MASTER-Kislovodsk | (07h 36m 40.22s , +03d 42m 38.6s) | C | 30 | 17.5 |
174 | 2026-01-15 17:49:24 | MASTER-Kislovodsk | (07h 40m 49.10s , +03d 19m 38.3s) | C | 30 | 17.6 |
229 | 2026-01-15 17:50:15 | MASTER-Kislovodsk | (07h 36m 40.26s , +03d 42m 37.7s) | C | 40 | 17.7 |
289 | 2026-01-15 17:50:15 | MASTER-Kislovodsk | (07h 36m 40.26s , +03d 42m 37.7s) | C | 160 | 18.5 | Coadd
295 | 2026-01-15 17:51:15 | MASTER-Kislovodsk | (07h 36m 40.31s , +03d 42m 37.5s) | C | 50 | 17.8 |
295 | 2026-01-15 17:51:15 | MASTER-Kislovodsk | (07h 40m 49.19s , +03d 19m 36.6s) | C | 50 | 18.0 |
385 | 2026-01-15 17:52:36 | MASTER-Kislovodsk | (07h 36m 40.38s , +03d 42m 37.5s) | C | 70 | 18.0 |
391 | 2026-01-15 17:52:42 | MASTER-Kislovodsk | (07h 40m 49.30s , +03d 19m 36.9s) | C | 70 | 18.2 |
611 | 2026-01-15 17:56:26 | MASTER-Tunka | (07h 20m 16.73s , +03d 41m 02.8s) | C | 60 | 19.5 |
611 | 2026-01-15 17:56:26 | MASTER-Tunka | (07h 19m 45.70s , +03d 47m 07.0s) | C | 60 | 19.2 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
[1] - V.M. Lipunov, V.G. Kornilov, E.S. Gorbovskoy, N.A. Tiurina & A.S.Kuznetsov, 2023, Astronomical Robotic Networks and Operative Multichanel Astrophysics, Lomonosov MSU PRESS, 591pp.
http : // www.pereplet.ru/lipunov/625.html
GCN Circular 43417
Subject
GRB 260115A: Fermi GBM Final Real-time Localization
Date
2026-01-15T17:57:28Z (2 months ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 17:46:45 UT on 15 Jan 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260115A (trigger 790192010.88085 / 260115741).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.2, Dec = 3.3 (J2000 degrees, equivalent to J2000 07h 20m, 3d 17'), with a statistical uncertainty of 5.1 degrees.
The angle from the Fermi LAT boresight is 83.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/quicklook/glg_skymap_all_bn260115741.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/quicklook/glg_healpix_all_bn260115741.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260115741/quicklook/glg_lc_medres34_bn260115741.gif