[vsnet-grb-info 25503] GRB 200410A: Optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  27603
SUBJECT: GRB 200410A: Optical upper limit
DATE:    20/04/18 07:14:21 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515 at gmail.com>

TITLE:   GCN CIRCULAR
NUMBER:  27602
SUBJECT: GRB 200410A: Optical upper limit
DATE:    20/04/18 07:11:53 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515 at gmail.com,
amit at aries.res.in>

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

We observed the field of Swift GRB 200410A (Simpson et al., GCN Circ.
27518, Gropp et al., GCN 27523, Kuin et al., GCN 27532, Pizzuto et al., GCN
27552, Laha et al., GCN Circ. 27578, Valentin et al., GCN 27584) with the
1.3m Devsthal Fast Optical Telescope (DFOT) at Aryabhatta Research
Institute of Observational Sciences (ARIES), Nainital
(India), from 2020-04-10 UT 21:34:29 to 2020-04-10 UT 23:31:07
(corresponding to
19.15 to 21.09 hours from the GRB trigger time). We observed 12 frames
each of 300 seconds in Bessel R filter and a series of 11x300 seconds
exposures in
Bessel I filter. As mentioned by Jelinek et al., 27520, at the position of
the optical afterglow of GRB 200410A there are two nearby stars, so to do
the photometry we observed 300 seconds frame in Bessel R and I filter on
2020-04-15 UT 21:26:22 (5.79 days since burst) to do the template
subtraction. Template subtraction was done using the IRAF (
http://iraf.noao.edu/).

After the template subtraction, we do not find any new optical source
within the Swift XRT enhanced error circle in any individual as well as the
stacked frame.


The 3-sigma upper limits are as follows:

T_start-T0 (days)    Start Date (UTC)             End Date (UTC)
 Filter        3-sigma upper limit (mag)
---------------------------------------------------------------------------------------------------------------
19.15                2020-04-10 21:34:29          2020-04-10 22:30:06
 R               >22.2
20.18                2020-04-10 22:35:46          2020-04-10 23:31:07
 I               >22.4



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