[vsnet-grb-info 19925] GRB 171010A : Optical observations from HCT

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22012
SUBJECT: GRB 171010A : Optical observations from HCT
DATE:    17/10/13 18:11:40 GMT
FROM:    D.K. Sahu at Indian Inst of Astrophysics,Bangalore  <dks at iiap.res.in>

GRB 171010A : Optical observations from HCT

Brajesh Kumar,  D.K. Sahu, G.C. Anupama  and Avinash Singh (Indian
Institute of Astrophysics, Bangalore, India) communicate on behalf
of a larger Indian collaboration.

We observed the Fermi LAT GRB 171010A (Omodei et al., GCN 21985)
field with the 2-m Himalayan Chandra Telescope (HCT) located at
Indian Astronomical Observatory, Hanle, India.
Multiple frames in Bessell's R and I bands were obtained starting
from 18:43 UT on October 11, 2017. The optical afterglow candidate
(Thorstensen and Halpern, GCN 21987; Izzo and  Malesani, GCN 21988;
Guidorzi et al., GCN 21991; Malesani et al., GCN 22000; Harita et al.,
GCN 22001; Breeveld and Siegel, GCN 22004) was detected in our
individual frames.

The preliminary magnitudes of the OT, calibrated using nearby USNO
stars are as follows:
-------------------------------------------------------------------
  Date          Mid UT      Exp (sec)  Filter   Magnitude
  (YYYY-MM-DD)              time
-------------------------------------------------------------------
  2017-10-11    18:46       300          R      18.31 +/- 0.05
  2017-10-11    18:54       300          R      18.38 +/- 0.05
  2017-10-11    20:12       450          R      18.42 +/- 0.04
  2017-10-11    21:32       300          R      18.48 +/- 0.05
  2017-10-11    21:46       300          R      18.51 +/- 0.05
-------------------------------------------------------------------
  2017-10-11    20:21       300          I      18.06 +/- 0.05
  2017-10-11    20:28       300          I      18.09 +/- 0.05
  2017-10-11    21:53       300          I      18.22 +/- 0.05
  2017-10-11    22:00       300          I      18.24 +/- 0.05
--------------------------------------------------------------------

Contamination due to the host galaxy has not been removed.