TITLE:   GCN CIRCULAR
NUMBER:  27764
SUBJECT: GRB 200519A: 1.3m DFOT Optical Afterglow Detection
DATE:    20/05/20 01:58:43 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515@gmail.com>

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

We observed the optical afterglow of the Swift detected GRB 200519A (GCN
27756, GCN 27761 and GCN 27763) with the 1.3m Devsthal Fast Optical
Telescope (DFOT) at
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital
(India), from 2020-05-19T19:17:27 to 2020-05-19T22:01:38 UTC.
We observed 11 frames each of 300 seconds in Bessell R filter, whereas, a
serious of 7x300 seconds exposure in Bessell I filter.
In the stacked images, we clearly detected the optical afterglow of GRB
200519A in both Bessell R and I filters within the Swift XRT enhanced error
circle (Osborne et al. GCN 27761).
The estimated magnitudes are consistent with optical detections by Kong et
al. GCN 27757, Strausbaugh et al. GCN 27759, and Hu et al. 27760.


The observed magnitudes are as follows:

T_start-T0 (hours)   Start Date (UTC)              Filter
 Magnitudes (mag)
---------------------------------------------------------------------------------------------------------------
7.95               2020-05-19T19:17:27                 R               19.4
+- 0.1
9.98               2020-05-19T21:19:27                 I
18.2 +- 0.1


Photometry is done based on the USNO-B1.0 catalog. The quoted magnitudes
are not corrected for Galactic extinction.