GCN Circular 41858
T. Mohan, V. Swain, A.P. Saikia, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team:
We observed the field of Fermi GRB 250916A (Fermi GBM team, GCN 41839) with 0.7m GROWTH-India Telescope (GIT) in r' filter. We started the observation at 2025-09-17 17:34:08 UT, i.e., 28.08 hours after the Fermi GBM trigger. The source is detected at the position reported by GOTO (Belkin et al., GCN 41847) and photometry result follows as:
| MJD (mid) | tmid-t0 (hours) | Filter | Exposure (s) | Mag (AB) |
|---|---|---|---|---|
| 60935.73411 | 28.13 | r' | 360 | 19.73 +- 0.06 |
The source is fading and photometric result is consistent with Belkin et al., GCN 41847.
More broadband observations are under way. The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.
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/.