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GRB 260920A

GCN Circular 45672

Subject

GRB 260920A: AstroSat CZTI detection

Date

2026-09-21T09:20:58Z (a day 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), 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 260920A which was also detected by Fermi (Fermi GBM team, GCN Circ. 45658Loading...
 
 ).

The source was detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-09-20 10:32:38.06 UTC. The measured peak count rate associated with the burst is 234 (+37, -40) counts/s above the background in the combined data of all quadrants, with a total of 1301 (+278, -299) counts. The local mean background count rate was 306 (+4, -4) counts/s. We measure a T90 of 17 (+4, -3) s from the cumulative CZT light curve.

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-09-20 10:32:37.72 UTC. The measured peak count rate associated with the burst is 750 (+60, -66) counts/s above the background in the combined data of all quadrants, with a total of 3370 (+383, -418) counts. The local mean background count rate was 694 (+4, -5) counts/s. We measure a T90 of 16 (+3, -2) s from the cumulative Veto light curve.

CZTI data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/527596334.22/S527596334.22_details.html

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 45658

Subject

GRB 260920A: Fermi GBM Final Real-time Localization

Date

2026-09-20T10:42:45Z (2 days ago)

From

Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

Via

The Fermi GBM team reports the detection of a likely LONG GRB

At 10:32:24 UT on 20 Sep 2026, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 260920A (trigger 811593149.787088 / 260920439).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 293.0, Dec = -31.8 (J2000 degrees, equivalent to J2000 19h 32m, -31d 48'), with a statistical uncertainty of 1.1 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/bn260920439/quicklook/glg_skymap_all_bn260920439.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/bn260920439/quicklook/glg_healpix_all_bn260920439.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2026/bn260920439/quicklook/glg_lc_medres34_bn260920439.gif