TITLE:   GCN CIRCULAR
NUMBER:  38810
SUBJECT: GRB 250101A: further LCOGT optical afterglow observations
DATE:    25/01/04 01:15:20 GMT
FROM:    Ismael Perez-Fournon at Instituto de Astrofisica de Canarias <ipf@iac.es>

C. Méndez-Lapido, B. Armas-Chinea, F. Dobrindt, P. Escudero-Coca, G. Fernández-Rodríguez, Á. García Lozano, A. Huertas Ferrer, I. Ortega-Casas, M. Torreiro Martínez, G. Villa (ULL), S.R. Berlanas, F. Poidevin, and I. Pérez-Fournon (IAC and ULL)


We report on further optical imaging of the field of GRB 250101A, discovered by Swift BAT (Page et al., GCN #38752), with one of the two Las Cumbres Observatory global telescope network (LCOGT) 40-cm telescopes located at the LCOGT node at the Cerro Tololo Inter-American Observatory (CTIO, Chile).
The observation, a single 600-sec exposure in the SDSS r' filter, started on 2025-01-02 01:24:03 UT, i.e. ~ 12.02 hr after the Swift BAT trigger. We detect the optical afterglow at a position consistent with the Swift UVOT position reported by Page et al. (GCN #38752). We measure a magnitude of r' = 20.12 +/- 0.18 calibrated against PanSTARRS DR1 stars and not corrected for Galactic extinction.

This result is consistent with other reports: Li et al. (GCN 38753), Mohan et al. (GCN 38754), Zhu et al. (GCN 38755); Budnev et al. (GCN 38756), Wu et al. (GCN 38758), Moskvitin and Spiridonova (GCN 38762), Odeh and Guessoum (GCN 38763), Hu et al. (GCN 38764), Moskvitin et al. (GCN 38765), D'Avino and Izzo (GCN 38768), Escudero-Coca et al (GCN 38769), Leonini et al. (GCN 38771), Zhang et al. (GCN 38774), Siegel and Page (GCN 38775), Komesh et al. (GCN 38777), Ghosh et al. (GCN 38779), Moskvitin et al. (GCN 38780), Komesh et al. (GCN 38790), and Bochenek and Perley (GCN 38798). 

The spectroscopic redshift has been measured by Zhu et al., z = 2.49 (GCN 38759) and Li et al., z ~ 2.481 (GCN 38776).

These results are based on observations made with the Las Cumbres Observatory’s education network 
telescopes that were upgraded through generous support from the Gordon and Betty Moore Foundation 
and are part of a course on Astrophysical Techniques of the Master in Astrophysics of the Universidad 
de La Laguna, Tenerife, Spain (LCOGT observing programme IAC2024B-010, ULL-ASTRO-MASTER).