{
  "editedBy": "Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of ABHINAV GOYAL at Indian Institute of Technology Bombay <abhigoyale2003@gmail.com>",
  "circularId": 45859,
  "eventId": "GRB 261007A",
  "eventType": [
    "GRB",
    "Gamma-ray Transient",
    "X-ray Transient"
  ],
  "version": 2,
  "submitter": "ABHINAV GOYAL at Indian Institute of Technology Bombay <abhigoyale2003@gmail.com>",
  "editedOn": 1791470118361,
  "subject": "GRB 261007A / EP261007a: AstroSat CZTI detection",
  "createdOn": 1791465097199,
  "body": "Harsha K. H. (IUCAA), S. Salunke (IUCAA), S. Puri (IITB), A. Goyal (IITB), A. Arya (IITB), G. Waratkar (Caltech/IITB), V. Bhalerao (IITB),  A. Vibhute (IUCAA), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:\n\nAnalysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a GRB 261007A which was also detected by Fermi (Fermi GBM team, GCN Circ. 45830), SVOM/ECLAIRs (Goto et. al., GCN Circ. 45824), associated with EP261007a detected by Einstein Probe (Wen et. al., GCN Circ. 45828), and NuSTAR (Waratkar et. al., GCN Circ. 45846).\n\nThe 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 2026-10-07 05:40:02.36 UTC. The measured peak count rate associated with the burst is 1427 (+79, -36) counts/s above the background in the combined data of all quadrants, with a total of 15823 (+333, -396) counts. The local mean background count rate was 307 (+3, -3) counts/s. We measure a T90 of 22.9 (+0.3, -0.4) s from the cumulative CZT light curve. \n\nThe source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2026-10-07 05:40:11.67 UTC. The measured peak count rate associated with the burst is 2125 (+88, -77) counts/s above the background in the combined data of all quadrants, with a total of 21607 (+536, -496) counts. The local mean background count rate was 772 (+6, -5) counts/s. We measure a T90 of 22.4 (+0.3, -0.3) s from the cumulative Veto light curve.\n\nIn the preliminary analysis, we find 1822 Compton events associated with this event.\n\nCZTI data products like interactive and downloadable light curves for this GRB can be found at: \nhttps://astrosat.iucaa.in/cift/cift_products/ET20261007T053949/ET20261007T053949_details.html\n\nCZTI 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.\n\nCZTI GRB detections are reported regularly on the payload site at:\nhttp://astrosat.iucaa.in/czti/?q=grb\n",
  "format": "text/plain",
  "submittedHow": "web"
}