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GCN Circular 27564

GRB 200412B: Optical afterglow detection with 1.3m DFOT
2020-04-13T09:14:18Z (4 years ago)
Amit Kumar at ARIES, India <>
NUMBER:  27563
SUBJECT: GRB 200412B: Optical afterglow detection with 1.3m DFOT
DATE:    20/04/13 09:05:41 GMT
FROM:    Amit Kumar at ARIES, India  <,>

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

We observed the optical afterglow of the Fermi GBM detected GRB 200412B
(GCN 27547, Lipunov et al., GCN 27555, GCN 27561)
with the 1.3m Devsthal Fast Optical Telescope (DFOT) at Aryabhatta Research
Institute of Observational Sciences (ARIES), Nainital
from 2020-04-12 UT 22:03:14 to 2020-04-12 UT 23:29:44 (corresponding to
12.90 to 14.46 hours from the GRB trigger time). We observed a series of
9x300s exposures in Bessel R filter and a series of 7x360s exposures in
Bessel I filter. We stacked the images and detected the optical afterglow
of GRB 200412B in both Bessel R and I filters which is consistent with
optical detections by Lipunov et al., GCN 27555, 27556.

The observed magnitudes are as follows:

T_start-T0 (hours)   Start Date (UTC)             End Date
(UTC)                  Filter            Magnitudes
12.90               2020-04-12 UT 22:03:14          2020-04-12 UT
22:46:11          R               18.90 +- 0.03
13.72               2020-04-12 UT 22:52:02          2020-04-12 UT
23:29:44          I               17.54 +- 0.02

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