TITLE: GCN CIRCULAR NUMBER: 39594 SUBJECT: EP 250304A: Optical counterpart detection by LCO DATE: 25/03/05 09:43:20 GMT FROM: ankur ghosh at CAPP, University of Johannesburg ghosh.ankur1994@gmail.com
Ankur Ghosh, Soebur Razzaque (CAPP, University of Johannesburg), Alexander Moskvitin, Yulia Sotnikova (SAO RAS), Naveen Dukiya (ARIES), Rahul Gupta (NASA GSFC) on behalf of a larger collaboration.
We observed the field of the EP 250304A triggered by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Chen et al., GCN 39580) in r filter of the 1-meter Sinistro telescope at the Las Cumbres Observatory Global Telescope (LCOGT) node located at South African Astronomical Observatory (SAAO), South Africa. 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 March 04, 2025, starting 19.80 hours after the GRB trigger.
We clearly detect the optical transient (OT) reported by GCNs (Xu et al, GCN 39583, Page et al., GCN 39584, Saccardi et al., GCN 39585, Shilling et al., 39587) in our r band image.
|Date| |UTstart| |t-T0 (hours)| |Exp (sec)| |Filter| |Magnitude| -------------------------------------------------------------------------------------------------- 2025-03-04 21:20:52.80 19.80 1 x 1000 r r = 20.00 +/- 0.08
The field was calibrated against nearby APASS stars, with magnitudes converted using Lupton (2005) equations, and has not been corrected for Galactic extinction.
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