GCN Circular 45907

Subject

GRB 261011A: GROWTH-India Telescope optical observations

Event

GRB 261011A

Date

2026-10-11T19:15:24Z (16 hours ago)

Edited On

2026-10-11T19:32:31Z (16 hours ago)

From

Aditya Pawan Saikia at IIT Bombay <adityaps@iitb.ac.in>

Edited By

Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Aditya Pawan Saikia at IIT Bombay <adityaps@iitb.ac.in>

Via

Web form

R. Arya (IITB), Harshita (IITB), V. Vijaykumar (IITB), S. Patil (IITB), A.P. Saikia (IITB), V. Swain (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 261011A detected by SWIFT (Cenko et al., GCN 45896

), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2026-10-11 17:11:43 UT, i.e., 3.329 hours after the trigger, and obtained multiple exposures in the SDSS r' filter. We detect the optical counterpart in our images at the position reported by SWIFT-UVOT. The photometric results are as follows:

MJD (mid)	Filter	tmid-t0 (hours)	Exposure Time (sec)	Magnitude (AB)	Limiting Magnitude (5-sigma)
61324.720	r'	3.565	3x300	20.93 +/- 0.10	21.15

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 (O'Neill et al., GCN 45897

, Fu et al., GCN , Izzo et al., GCN , Wu et al., GCN , Yin et al., GCN , Shi et al., GCN , and Aryan et al., GCN )

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/.