TITLE: GCN CIRCULAR NUMBER: 42948 SUBJECT: EP251202a / GRB 251202A: LCO r- and i-band optical detection DATE: 25/12/02 14:00:22 GMT FROM: Jonathan Quirola at Radboud University jaquirola1990@gmail.com

J. Quirola-Vasquez (Radboud), J. Sanchez-Sierras (Radboud), D. B. Malesani (DAWN/NBI and Radboud), G. Corcoran (UCD), A. Martin-Carrillo (UCD), P. G. Jonker (Radboud), A. J. Levan (Radboud and Warwick), J. A. Chacón (PUC), F. E. Bauer (SSI and UTA), J. N. D. van Dalen (Radboud), A. P. C. van Hoof (Radboud) report on behalf of a larger collaboration:

We observed the optical counterpart (Li et al., GCN 42934) of EP251202a (Zhang et al., GCN 42937, Liang et al., GCN 42946) and Fermi GRB 251202A (Fermi GBM team, GCN 42933) with a spectroscopic redshift of z = 2.785 (Zhu et al., GCN 42939) using the Las Cumbres Observatory (LCO) network at the McDonald Observatory, equipped with the SINISTRO camera. Observations were obtained in the r (6x200 s) and i (6x200 s) bands, starting on 2025-12-02 at 09:00:43 UTC (i.e., a mid-time observation of 7.35 and 7.75 hr after the EP/WXT trigger, respectively).

Calibrated to nearby stars from the Pan-STARRS catalog, we measure AB magnitudes r = 19.22 +/- 0.06 and i = 19.12 +/- 0.06, not corrected for Galactic extinction.

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