GCN Circular 45841
Subject
GRB 261007A: GROWTH-India Telescope optical observations
Event
Date
2026-10-07T17:21:43Z (7 hours ago)
From
Aditya Pawan Saikia at IIT Bombay <adityaps@iitb.ac.in>
Via
Web form
R. Arya (IITB), A. Sarkar (IITB), V. Vijaykumar (IITB), S. Patil (IITB), A.P. Saikia (IITB), V. Swain (IITB), T. Mohan (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:
We observed the field of GRB 261007A detected by SVOM (SVOM mission Team, GCN 45824), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2026-10-07 15:05:35, i.e., 9.34 hours after the trigger, and obtained multiple exposures in the SDSS r' and g' filters. We detect the optical counterpart in our images at the position reported by Zheng et al., GCN 45825. The photometric results are as follows:
| MJD (mid) | Filter | tmid-t0 (hours) | Exposure Time (sec) | Magnitude (AB) |
| -------------- | ------ | --------------- | ------------------- | ---------------- |
| 61320.688 | r' | 9.603 | 4x300 | 20.11 +/- 0.06 |
| 61320.686 | g' | 10.389 | 3x300 | 20.56 +/- 0.08 |
The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
Our results are consistent with other optical observations (An et al., GCN 45840, Saccardi et al., GCN 45829 and GCN 45837, Shi. et all, GCN 45838, and Mohan.et al. GCN 45832)
The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.