[vsnet-grb-info 27985] GRB 210527A: GIT optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30088
SUBJECT: GRB 210527A: GIT optical upper limit
DATE:    21/05/28 07:33:04 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13 at gmail.com>

H. Kumar(IITB), U. Stanzin (IAO), G. C. Anupama(IIA), V. Bhalerao(IITB), S.
Barway(IIA) report on behalf of the GIT team:

We observed GRB 210527A detected by Swift-BAT (S. Laha et al., GCN #30081)
with the 0.7m GROWTH-India Telescope (GIT). We obtained 10 exposures, each
of 300 sec, in the r' filter starting at ~467 mins after the trigger. We
did not detect any new source in our stacked image within a 3 arcmin circle
around R.A. = 11h 29m 25s Dec(J2000) = +31d 37' 06" (GCN #30081). The
obtained upper limit follows as:

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 JD (mid) | T_mid-T0(hrs) | Exposure(sec) | Filter | Lim_mag (5-sigma) |

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 2459362.1416 | ~8.27 | 3000 (stacked) | r' | > 21.98 |

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Our upper limit is consistent with Nat Butler et al., GCN #30084; V.
Lipunov et al., GCN #30086; Y. Imai et al., GCN #30087. The magnitude is
calibrated against PanSTARRS (Flewelling et al., 2018) and not corrected
for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree
field of view, set up by the Indian Institute of Astrophysics and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).