TITLE:   GCN CIRCULAR
NUMBER:  24201
SUBJECT: LIGO/Virgo S190425z - GROWTH-India follow-up of two ZTF candidates
DATE:    19/04/26 00:20:56 GMT
FROM:    Varun Bhalerao at Indian Inst of Tech  <varunb@iitb.ac.in>

V. Bhalerao, H. Kumar, V. Karambelkar, G. Waratkar, Y. Sharma (IITB), G. C. Anupama (IIA) report on behalf of the GROWTH collaboration:

We observed the two most promising candidates reported by the Zwicky Transient Facility (Kasliwal et al., GCN 24191) for the follow up the GW candidate S190425z (GCN 24168) with the GROWTH-India telescope. We obtained multiple images in g, r, and i bands, with exposures ranging from 300 sec - 600 sec. Source photometry for ZTF19aarykkb is given below.

Date-Time	MJD	exptime	Filter	Magnitude	Magerr
2019-04-25 18:25:39	2458599.268	600	r	17.78	0.06
2019-04-25 18:06:40	2458599.255	600	r	17.82	0.08
2019-04-25 21:54:37	2458599.413	300	g	18.49	0.05
2019-04-25 22:01:34	2458599.418	300	g	18.46	0.05
2019-04-25 22:08:50	2458599.423	300	r	17.48	0.05
2019-04-25 22:40:29	2458599.445	600	i	16.99	0.04
2019-04-25 22:54:42	2458599.455	600	g	18.62	0.04
2019-04-25 23:06:41	2458599.463	600	g	18.36	0.17

We also observed ZTF19aarzaod multiple times with 3 exposures in g band, 4 r and 2 i band exposures respectively, each with an exposure time of 600 seconds. We see a weak source in the r and i band images, further analysis is underway. The source appears to be fading rapidly in all bands.

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).