GCN Circular 44469

Harsha K. H. (IUCAA), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), A. Goyal (IITB), A. Arya (IITB), 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 long GRB 260430B.

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-04-30 16:04:26.34 UTC. The measured peak count rate associated with the burst is 100 (+32, -10) counts/s above the background in the combined data of three quadrants (out of  four), with a total of 1436 (+290, -227) counts. The local mean background count rate was 219 (+1, -2) counts/s. Using cumulative rates, we measure a T90 of 47 (+2, -4) 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 2026-04-30 16:04:22.5 UTC. The measured peak count rate associated with the burst is 417 (+77, -26) counts/s above the background in the combined data of all quadrants, with a total of 6007 (+912, -928) counts. The local mean background count rate was 1271 (+6, -6) counts/s. We measure a T90 of 40 (+11, -6) s from the cumulative Veto light curve.

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/515261050.0/S515261050.0_details.html

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb