GCN Circular 20969
V. Sharma (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed clear detection of GRB 170330A (Swift burst detection: P. D'Avanzo et al., GCN Circ. 20944) in the 40-200 keV energy range. The light curve shows multiple peak structure with peak counts at 22:27:36.000 UT, around ~35 s after the Swift trigger time i.e. ~T-170 s (Swift-BAT refined analysis: A. Y. Lien et al., GCN Circ. 20968) and it also coincides with the Swift main peak. The light curve doesn't show excess counts above the background for last ~100 s. The measured peak count rate is 163.2 counts/s above the background in combined data of four quadrants, with a total 1389 counts. The local mean background count rate was 358.8 counts/s. Using cumulative rates, we measure a T90 of 15.6 s. It was clearly detected in the CsI anticoincidence detector (Veto) also as bright detection in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.