[vsnet-grb-info 23461] GRB 190829A: GROWTH India detection of afterglow

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  25560
SUBJECT: GRB 190829A: GROWTH India detection of afterglow
DATE:    19/08/29 22:55:45 GMT
FROM:    Varun Bhalerao at Indian Inst of Tech  <varunb at iitb.ac.in>

H. Kumar, V. Bhalerao (IITB), Jigmat Stanzin, G C Anupama, S. Barwe (IIAP) report on behalf of the GROWTH-India collaboration:

We observed the field of 190829A (Fermi GBM Team, GCN 2555; Dichiara et al., GCN 25552) with the GROWTH-India telescope. We obtained multiple 500 second exposures in g and r, starting 51 minutes after the event. We clearly detect an optical afterglow in all filters. Preliminary photometry values in g band are quoted below.

     JD           dt_minutes   ap_mag   Mag_err
2458725.366  51.16  16.93   0.01
2458725.372  59.80  17.21   0.02
2458725.394  91.48  18.00   0.12
2458725.400 100.12  18.08   0.04

The data are consistent with a power-law decline with a slope of 1.6. In addition, we also obtained an r band data point at JD 2458725.385, detecting the afterglow clearly with m_r = 16.475 +- 0.013, broadly consistent with Xu et al. (GCN 25555)

We caution that these photometry values are contaminated by flux from the host galaxy, and the afterglow brightness has been overestimated. 

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).






















H. Kumar, V. Karambelkar, K. Deshmukh, G. Waratkar, V. Bhalerao(IITB), G. C. Anupama, T. Stanzin (IIA) report on behalf of the GROWTH collaboration:

We observed GRB190701A reported by T. N. Ukwatta et al, (GCN 24934) with 0.7m GROWTH-India telescope. The field was observed in g, r and i filters. We didn’t detect any new source within an uncertainty region of 1.9 arcseconds (radius, 90% containment) around RA(J2000) = 01h 52m 19.54s,  Dec(J2000) = +58d 54' 33.9" (J.P. Osborne et al, GCN 24934).

We obtained the following upper limits:
------------------------------------------------------------------
 JD(Start)| Exposure(sec) | Filter | lim_Mag |
------------------------------------------------------------------
 2458666.351 | 600 | g | 19.18|
 2458666.373 | 600 | r | 20.57|
 2458666.382 | 600 | i | 19.52|
------------------------------------------------------------------


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).