GCN Circular 44342

Subject

EP260417b: GROWTH-India Telescope optical upper limit

Event

EP260417b

Date

2026-04-18T22:00:13Z (a day ago)

Edited On

2026-04-20T03:23:52Z (3 minutes ago)

From

V. Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

Edited By

Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov> on behalf of V. Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

Via

Web form

V. Vijaykumar (IITB), T. Mohan (IITB), V. Swain (IITB), D. Eappachen (IIA), S. Patil (IITB), A.P. Saikia (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and R. Norbu (IAO) report on behalf of the GIT team:

We observed the field of EP260417b detected by Einstein Probe (Ni et al., GCN 44323

), with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2026-04-18 19:04:51 (UTC), i.e., 1.74 days after the trigger, and obtained a single exposure in the r' filter. We did not detect any transient in our image within the uncertainty region of source position reported by EP. The photometric upper limit is as follows:

MJD (mid)	Filter	tmid-t0 (hours)	Exposure Time (sec)	Upper limit (AB)
61148.797	r'	41.78	420	19.3

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/.