TITLE: GCN CIRCULAR NUMBER: 38995 SUBJECT: EP 250108A: Late-time optical observation by LCO DATE: 25/01/20 06:12:24 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 EP 250108A triggered by Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) (Li et al., GCN 38861) in V filter of the 1-meter Sinistro telescope at the Las Cumbres Observatory Global Telescope (LCOGT) node located at South African Astronomical Observatory (SAAO). 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 19, 2025, starting 11.4 days after the GRB trigger.
We clearly detect the optical transient (OT) reported by GCNs ( Zhu et al., GCN 38885; Malesani et al., GCN 38902; Kumar et al., GCN 38907; Zhu et al, GCN 38908; Levan et al., GCN 38909; Izzo, GCN 38912; Zou et al., GCN 38914; Moskvitin & Spiridonova, GCN 38925; Song et al., GCN 38972, Eyles-Ferris et al., GCN 38983) in our V, r band image. There is a confirmation of the Ic-BL supernova connection with EP 250108A (Xu et al., GCN 38984, Levan et al., GCN 38987). Observations are still ongoing in other filters.
|Date| |UTstart| |t-T0 (days)| |Exp (sec)| |Filter| |Magnitude| 2025-01-19 21:59:26.59 11.4 1 x 1200 V V = 20.37 +/- 0.04
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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