TITLE: GCN CIRCULAR NUMBER: 39575 SUBJECT: EP250302a : GIT optical follow-up DATE: 25/03/03 16:09:43 GMT FROM: V. Swain at IIT Bombay vishwajeet.s@iitb.ac.in

D. Eappachen (IIA), V. Swain (IITB), A.P. Saikia (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 EP250302a (Dai et al., GCN 39556) with 0.7m GROWTH-India Telescope (GIT). We started the observation at 2025-03-02 20:51:47 UT, i.e., 5.26 hours after the EP trigger. We obtained two exposures of 360 seconds each in both r' and g' filters. We clearly detected the optical counterpart in our stacked images at the position given by HMT-0.5m telescope (Zhu et al., GCN 39550). The photometry results are as follow:

| JD (mid) | t-t0 (hours) | Filter | Exposure (s) | Mag (AB) | | ----------------- | ----------- |------- | ------------------ | -------------- | | 2460737.373565 | 5.36 | r' | 2x360s | 20.40+/- 0.11 | | 2460737.390706 | 5.78 | g' | 2x360s | 20.66+/- 0.10 |

Our results are consistent with Zhu et al., (GCN 39550); Busmann et al., (GCN 39551); Leonini et al., (GCN 39553); WU et al., (GCN 39555); Xin et al., (GCN 39558); Adami et al., (GCN 39560); Pankov et al., (GCN 39565); Reguitti et al., (GCN 39568); Komesh et al., (GCN 39569); Shilling et al., (GCN 39570).

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/.

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