GCN Circular 31793
Subject
GRB 220325A: 1.3m DFOT Optical upper limit
Event
Date
2022-03-26T09:35:16Z (4 years ago)
From
Rahul Gupta at ARIES, India <rahulbhu.c157@gmail.com>
Rahul Gupta, Amit Ror, Amit Kumar, Dimple, Ankur Ghosh, Amar Aryan, Krishan
Chand, S. B. Pandey, and Kuntal Misra (ARIES) report:
We observed the Swift-BAT and Fermi-GBM Sub-Threshold detected GRB 220325A (
Ferro et al., GCN 31787; Wood, GCN 31791) with 1.3m Devasthal Fast
Optical Telescope
(DFOT) located at Devasthal observatory of Aryabhatta Research Institute of
Observational Sciences (ARIES), India. The observations were started on
2022-03-25 at ~ 22:15 UT, i.e., ~ 5 hours after the BAT trigger. We have
taken multiple frames having an exposure time of 300 sec in the R filter.
We stacked the images after the alignment. We did not detect any new
optical source
within the Swift XRT uncertainty circle (Osborne et al., GCN 31790) in our
stacked image.
We obtain the following 3-sigma upper limit in the stacked image.
Date Start_UT T_start-T0 (hour) Filter Exp time (sec) Limiting magnitude
====================================================
2022-03-25 22:15 ~5 R 300*20 > 21.7
The magnitude is not corrected for the Galactic extinction in the direction
of the burst. Photometric calibration is performed using the standard stars
from the USNO-B1.0 catalog.
This circular may be cited.