TITLE: GCN CIRCULAR NUMBER: 37505 SUBJECT: EP240913A / GRB 240913C: AstroSat CZTI detection DATE: 24/09/14 13:31:29 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in> A. Dasgupta (BITS Pilani, Hyderabad), S. Srijan (IITB), G. Waratkar (IITB), J. Joshi (IUCAA), 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 240913C, a burst potentially related to EP240913A, which was also detected by Fermi/GBM (Yin et al., GCN Circ. 37493). Our detection time is consistent with that of Fermi/GBM, which is about 180 s after the EP/WXT detection time (Li et al., GCN Circ. 37492). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-09-13 11:42:36.46 UTC. The measured peak count rate associated with the burst is 352 (+59, -62) counts/s above the background in the combined data of all quadrants, with a total of 510 (+142, -155) counts. The local mean background count rate was 294 (+4, -5) counts/s. Using cumulative rates, we measure a T90 of 5.2 (+3.1, -2.3) s. We also had a faint detection in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-09-13 11:42:36.8 UTC. The measured peak count rate is 132 (+64, -65) counts/s above the background in the combined Veto data of all quadrants, with a total of 639 (+522, -561) counts. The local mean background count rate was 1216 (+12, -13) counts/s. We measure a T90 of 6.9 (+1.8, -4.1) 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 GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb View this GCN Circular online at https://gcn.nasa.gov/circulars/37505. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...