TITLE: GCN CIRCULAR NUMBER: 36711 SUBJECT: GRB 240619C: AstroSat CZTI detection DATE: 24/06/20 05:56:11 GMT FROM: Gaurav Waratkar at IIT Bombay gauravwaratkar@iitb.ac.in
J. Joshi (IUCAA), G. Waratkar (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-duration GRB 240619C. Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst.
The source was clearly 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 2024-06-19 23:44:51.50 UTC. The measured peak count rate associated with the burst is 186 (+34, -37) counts/s above the background in the combined data of three quadrants (out of four), with a total of 694 (+196, -209) counts. The local mean background count rate was 268 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 17 (+1, -5) s.
The source was also 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 2024-06-19 23:44:51.11 UTC. The measured peak count rate associated with the burst is 1471 (+90, -96) counts/s above the background in the combined data of all quadrants, with a total of 5520 (+402, -429) counts. The local mean background count rate was 1481 (+7, -8) counts/s. We measure a T90 of 14 (+1, -1) s from the cumulative Veto light curve.
Note that we see an additional peak in INTEGRAL/SPI-ACS data about 70 s after the main episode of this GRB. These peaks are very faint in our data; hence, we do not include them in our T90 calculations.
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
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