GCN Circular 41554
Subject
EP250827a: Gemini-South optical counterpart detection
Event
Date
2025-08-27T08:44:22Z (a month ago)
From
Andrew Levan at Radboud University <a.levan@astro.ru.nl>
Via
Web form
A. J. Levan (Radboud and Warwick), J. A. Quirola-Vasquez (Radboud), R. A. J. Eyles-Ferris (Leicester), P. G. Jonker (Radboud), D. B. Malesani (DAWN/NBI and Radboud), report on behalf of a larger collaboration:
We observed the location of EP250827a (Hua et al. GCN 41553) with Gemini-South and the GMOS instrument. Observations began at 08:14 UT approximately 34 minutes after the EP trigger time. Within the WXT and FXT error circles we locate a new source in our first r-band exposure with a location of
RA(J2000): 00:13:52.32
DEC(J2000) -56:29:52.9
The error is about 0.3" in each coordinate. The source is not visible in the Legacy Survey and has a magnitude of r = 18.70 +- 0.02 (calibrated against nearby stars from the SkyMapper catalog and not corrected for Galactic extinction). This is very likely the optical counterpart of EP250827a.
We thank the staff of Gemini for their outstanding work in rapidly obtaining these observations.