[vsnet-grb-info 21797] GRB190211: GROWTH-India detection of optical afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23896
SUBJECT: GRB190211: GROWTH-India detection of optical afterglow
DATE:    19/02/15 01:45:15 GMT
FROM:    Varun Bhalerao at Indian Inst of Tech  <varunb at iitb.ac.in>

Harsh Kumar (IITB), Viraj karambelkar (IITB), Gaurav Waratkar(IITB), Shubham Srivastav (IITB), Tsewang Stanzin (IAO, IIAP), Varun Bhalerao (IITB), G.C. Anupama (IIAP) report on behalf of the GROWTH-India collaboration:

We observed the optical afterglow of GRB190211 (Marshall et al., GCN 23883; Xu et al. GCN 23884; Hu et al., GCN 23886; Stamatikos et al., GCN 23887; Evans et al., GCN 23888; K.E. Heintz et al., GCN 23890;  M. Oeda et al.,GCN 23891; Gregory S.H.P. et al., GCN 23893) with the 0.7m robotic GROWTH-India telescope at the Indian Astronomical Observatory. We obtained 600 s exposures in two bands, starting at UT 2019-02-11 18:16:55.961 for r filter and at UT 2019-02-11 18:28:07.536 in i filter. The afterglow is clearly detected in both images. Magnitudes were calibrated using PanSTARRs reference stars in the same field. The measured magnitude in r filter image is 21.37+/- 0.2 and in i filter is 20.28+/- 0.3.  

Based on our data combined with other r band measurements (Xu et al. GCN 23884; Hu et al., GCN 23886; M. Oeda et al.,GCN 23891; Heintz et al., GCN 23890), we see that the source flux is fading approximately as a power law t^-alpha, with alpha = 0.69 +/- 0.08.

GROWTH India telescope 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).