TITLE: GCN CIRCULAR NUMBER: 39812 SUBJECT: EP250321a: LCO optical counterpart detection DATE: 25/03/21 12:58:42 GMT FROM: Ismael Perez-Fournon at Instituto de Astrofisica de Canarias ipf@iac.es
I. Pérez-Fournon, F. Poidevin (IAC and ULL), D. Cano-Morales, I. Correa-Plasencia, A.E. Hernández-Díaz (ULL), D. Aguado, A. López-Oramas, D. Nespral (IAC and ULL), N.C. Sun (UCAS), W. Li, Y. Wang, and Z. Niu (NAOC)
We report Las Cumbres Observatory Global Telescope network (LCOGT) observations of EP250321a detected by EP/WXT (Hu et al., GCN circ. 39800), and Swift-XRT (Page et al., GCN circ. 39811).
We observed the field of EP250321a with one of the two LCOGT 1-m telescopes, equipped with Sinistro cameras, located at the LCOGT node at McDonald Observatory (Texas). We obtained a 200-sec exposure in the SDSS i' filter starting at 2025-03-21 09:38:42 UT, about 3.48 hr after the EP trigger.
An uncatalogued source is detected at the position of the optical and near-IR counterpart reported by Fu et al. (GCN circ. 39804), Perez-Garcia et al. (GCN circ. 39805), Brivio et al. (GCN circ. 39807), Zhu et al. (GCN circ. 39809), and Becerra et al. (GCN circ. 39810). Zhu et al. (GCN circ. 39809) have reported a redshift of z = 4.368.
We measure the following magnitude, calibrated against Pan-STARRS DR2 stars and not corrected for Galactic extinction:
Date | UT start | mag | error | filter | ---------------------------------------------- 2025-03-21 09:38:42 19.3 0.15 i'
This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF).
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