GCN Circular 42545
Subject
GRB 251103A: LCO optical observation
Event
Date
2025-11-03T11:02:49Z (2 days ago)
From
ankur ghosh at CAPP, University of Johannesburg <ghosh.ankur1994@gmail.com>
Via
Web form
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 251103A triggered by SVOM/ECLAIRs (Hu et al., GCN 42534) in V and r filters 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 November 03, 2025, starting from 4.22 hours after the GRB trigger.
We clearly detect the optical transient (OT) reported by GCNs (Schneider et al., GCN 42535; Turpin et al., GCN 42538; Gritsevich et al., GCN 42539; Izzo et al., GCN 42540, O'Neill et al., GCN 42543) in our V and r band images.
|Date| |JD start| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude|
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2025-11-03 2460982.90068 4.226 1 x 500 V V = 19.38 +/- 0.08
2025-11-03 2460982.90060 4.221 1 x 500 r r = 19.26 +/- 0.05
The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction.