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GCN Circular 34649

Subject
GRB 230906A: AstroSat CZTI detection
Date
2023-09-10T05:39:19Z (10 months ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
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P. K. Navaneeth (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 the short GRB 230906A which was also detected by Fermi (Fermi GBM team, GCN Circ. 34631), Konus-Wind (Frederiks et al., GCN Circ. 34638) with IPN localization (Kozyrev et al., GCN Circ. 34637).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a multi-peak structure that peaked at 2023-09-06 12:55:07.82 UTC. The measured peak count rate associated with the burst is 3406 (+1081, -773) counts/s above the background in the combined data of all quadrants, with a total of 163 (+35, -34) counts. The local mean background count rate was 545 (+43, -67) counts/s. Using cumulative rates, we measure a T90 of 0.09 (+0.03, -0.03) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detectors in the 100-500 keV energy range. The light curve peaks at 2023-09-06 12:55:07.01 UTC. The measured peak count rate associated with the burst is 1048 (+81, -90) counts/s above the background in the combined data of all quadrants, with a total of 823 (+634, -729) counts. The local mean background count rate was 1430 (+7, -8) counts/s. Due to the intrinsic 1 s binning of Veto data, we cannot reliably estimate a T90 from it.

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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