TITLE: GCN CIRCULAR NUMBER: 40330 SUBJECT: GRB 250502A: LCO optical counterpart detection DATE: 25/05/03 08:01:13 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, A.E. Hernández-Díaz, I. Correa-Plasencia (ULL), and A. López-Oramas (IAC and ULL)
Following the detection of the SVOM/ECLAIRs gamma-ray burst GRB 250502A (SVOM burst-id sb25050205, Wang et al., GCN circ. 40313), we observed the GRB field with the two Las Cumbres Observatory Global Telescope network (LCOGT) 1-m telescopes, equipped with Sinistro cameras, located at the LCOGT node at Teide Obervatory (Tenerife, Spain) in the SDSS r, i, and g filters. The observations started at 2025-05-02 22:13:16 UTC, about 13.45 hours after the SVOM trigger. An uncatalogued source is clearly detected at the optical counterpart position first reported by Rakotondrainibe et al. (GCN circ. 40315) and with other optical detections reported by An et al. (GCN circ. 40319), Li et al. (GCN circ. 40320), Ghosh et al. (GCN circ. 40322), and de Ugarte Postigo et al. (redshift of z = 2.163, GCN circ. 40328).
We measure the following magnitudes, calibrated against Pan-STARRS DR2 stars, that are not corrected for Galactic extinction:
Date | UT start | mag | error | filter | exposure time (sec) | ------------------------------------------------------------------------ 2025-05-02 22:13:16 20.66 0.13 r 300 2025-05-02 22:20:27 20.68 0.17 i 300 2025-05-02 22:48:15 21.39 0.16 g 300
This work makes use of observations from the Las Cumbres Observatory global telescope network (LCOGT observing programme IAC2025A-009, SGLF).
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