GRB 260523B
GCN Circular 44702
Subject
GRB 260523B: AstroSat CZTI detection
Date
2026-05-25T11:38:44Z (5 days ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Arya (IITB), A. Goyal (IITB), Harsha K. H. (IUCAA), S. Salunke (IUCAA), M. Tembhurnikar (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 short GRB 260523B which was also detected by Fermi/GBM (Fermi GBM team, GCN Circ. 44699).
The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-05-23 19:26:02.85 UTC. The measured peak count rate associated with the burst is 259 (+123, -28) counts/s above the background in the combined data of three quadrants (out of four), with a total of 259 (+56, -54) counts. The local mean background count rate was 184 (+4, -7) counts/s. Using cumulative rates, we measure a T90 of 1.74 (+0.57, -0.46) s.
The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-05-23 19:26:02.79 UTC. The measured peak count rate associated with the burst is 318 (+68, -53) counts/s above the background in the combined data of all quadrants, with a total of 408 (+166, -174) counts. The local mean background count rate was 1282 (+11, -12) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 for our detection.
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 data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/517260365.54/ET20260523T192602_details.html
CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb
GCN Circular 44701
Subject
GRB 260523B: GECAM-B observation
Date
2026-05-24T12:00:37Z (6 days ago)
Edited On
2026-05-25T23:48:04Z (4 days ago)
From
Xinghao Luo at IHEP <2952704891@qq.com>
Edited By
Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of Xinghao Luo at IHEP <2952704891@qq.com>
Via
Web form
Xing-Hao Luo, Chen-Wei Wang, Shao-Lin Xiong (IHEP) report on behalf of GECAM team:
GECAM-B was triggered in-flight by GRB 260523B, at 2026-05-23T19:26:02.800 UTC (denoted as T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #44699).
According to the GECAM-B light curves in about 70-6000 keV, this burst mainly consists of multiple pulses with a duration (T90) of 1.6 +0.4/-0.6 s.
The GECAM-B light curve can be found here:
https://www.bursthub.cn//admin/static/gecambgrb260523B.png
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 44699
Subject
GRB 260523B: Fermi GBM Final Real-time Localization
Date
2026-05-23T19:36:40Z (6 days 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 SHORT GRB
At 19:26:02 UT on 23 May 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260523B (trigger 801257167.544222 / 260523810).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 34.1, Dec = -63.1 (J2000 degrees, equivalent to J2000 02h 16m, -63d 06'), with a statistical uncertainty of 3.1 degrees.
The angle from the Fermi LAT boresight is 121.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523810/quicklook/glg_skymap_all_bn260523810.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/bn260523810/quicklook/glg_healpix_all_bn260523810.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260523810/quicklook/glg_lc_medres34_bn260523810.gif