[vsnet-grb-info 25373] GRB 200325B: Optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27473
SUBJECT: GRB 200325B: Optical upper limit
DATE:    20/04/02 10:08:41 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515 at gmail.com>

TITLE:   GCN CIRCULAR
NUMBER:  27472
SUBJECT: GRB 200325B: Optical upper limit
DATE:    20/04/02 9:44:53 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515 at gmail.com,amit at aries.res.in>

A. Kumar (ARIES), A. Aryan (ARIES),  S. B. Pandey (ARIES), R. Gupta
(ARIES), A. Ghosh
(ARIES), Dimple (ARIES), and K. Misra (ARIES) report:

We observed the optical afterglow field of the Fermi GRB 200325B
(Fermi GBM team, GCN 27441, Lipunov et al., GCN 27446)
with 1.3m Devsthal Fast Optical Telescope (DFOT) at Aryabhatta
Research Institute of Observational Sciences (ARIES), Nainital
(India),
from 2020-03-30 UT 19:37:08 to 2020-03-30 UT 20:59:28. We observed 16
frames each of 300 seconds in Bessell I filter.
No new optical source was detected within the Swift XRT enhanced error
circle in any individual as well as stacked frame.


The 3-sigma upper limit is as follows:

T_start-T0 (days)   Start Date (UTC)             End Date (UTC)
      Filter        3-sigma upper limit (mag)
---------------------------------------------------------------------------------------------------------------
5.21                2020-03-30 19:37:08          2020-03-30 20:59:28
        I               >23.2

Photometry is done based on the standard star PB 2256 and USNO-B1.0
catalog. The quoted magnitude is not corrected for Galactic
extinction.