[vsnet-grb-info 21699] GRB 190114C: Optical follow-up from HCT

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23798
SUBJECT: GRB 190114C: Optical follow-up from HCT
DATE:    19/01/27 11:12:34 GMT
FROM:    Brajesh Kumar at Indian Inst. of Astrophysics  <brajesh.kumar at iiap.res.in>

Avinash Singh (IIA), Brajesh Kumar (IIA), D. K. Sahu (IIA), G. C. 
Anupama (IIA), S. B. Pandey (ARIES) and Varun Bhalerao (IITB)

We followed-up the optical afterglow of GRB 190114C (Gropp et al., GCN 
23688) with the 2-m Himalayan Chandra Telescope (HCT)
located at the Indian Astronomical Observatory, Hanle, India. The 
observations were carried out in the Bessell R-band on
2019-01-24 15:02:44.59 UT (MJD 58507.627). The OT candidate (Lipunov et 
al., GCN 23693; Selsing et al., GCN 23695; Bolmer
et al., GCN 23702; D'Avanzo et al., GCN 23729; Kim et al., GCN 23732, 
23734; Kumar et al., GCN 23733, Kumar et al., GCN 23742,
Mazaeva et al., GCN 23746, Ragosta et al., GCN 23748, Watson et al., GCN 
23749, 23751) is detected in a stacked R-band image
comprising of 4 images, each with an exposure of 300s. The magnitude, 
calibrated using the magnitudes of field stars from the
USNO-B1.0 catalogue is estimated as 21.38+/-0.16 including host 
contamination.

We corrected the host contamination using the magnitudes reported for 
the source and source + galaxy by Mazaeva et al., GCN 23787.
The GRB OT magnitude after correction for the host galaxy is:

         UT-mid             Delta T(d)         JD          Exposure       
     Mag(AB)
  ----------------------   ------------    -----------    -------------   
  ---------------
  2019-01-24 15:02:44.59      9.754        2458508.127    1200s (4X300)   
  21.68 +/- 0.16

Using the reported magnitudes of GRB 190114C spanning almost 10 days in 
the SDSS-r and Bessell-R band filters, we estimated that
the source flux (F_lambda) is declining with a power law exponent of 
0.77+/-0.05, in agreement with the values inferred earlier
(Kumar et al. GCN 23733, Dado S. & Dar A. GCN 23735).

We thank the observing staff at IAO and CREST for their support during 
the observations.