TITLE: GCN CIRCULAR NUMBER: 38779 SUBJECT: GRB 250101A: LCO optical counterpart detection DATE: 25/01/02 16:56:31 GMT FROM: ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994@gmail.com> Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Rahul Gupta (NASA GSFC), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES) on behalf of a larger collaboration. We observed the field of the GRB 250101A triggered by Swift (Page et. al., GCN 38752) in B, V filter of the 1-meter Sinistro telescope at the Las Cumbres Observatory Global Telescope (LCOGT) node located at McDonald Observatory. The 1-m Sinistro telescope is equipped with a 4K x 4K CCD (FOV: 26 x 26 arcmin, scale: 0.39 arcsec/pixel). Observations began on January 02, 2025, starting from 14.48 hours after the GRB trigger. We clearly detect the optical transient (OT) reported by GCNs (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 et al., GCN 38762; Odeh et al., GCN 38763, Hu et al., GCN 38764; D'Avino et al., GCN 38768; Escudero-Coca et al., GCN 38769, Coca et al., Zhang wt al., GCN 38774, Komesh et al., GCN 38777) in our B, V band image. |Date| |UTstart| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| --------------------------------------------------------------------------------------------------- 2025-01-02 03:51:30.528 14.48 1 x 900 V V = 20.61 +/- 0.04 2025-01-02 06:19:33.312 16.95 2 x 1200 B B = 21.82 +/- 0.03 The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction. View this GCN Circular online at https://gcn.nasa.gov/circulars/38779. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...