GCN Circular 37875
Subject
EP241021a: optical follow-up observations with the Liverpool Telescope
Event
Date
2024-10-25T13:51:07Z (9 months ago)
From
Amit Kundu at Royal Holloway - U. of London, UK <amitkundu515@gmail.com>
Via
Web form
A. Kumar, J. R. Maund (RHUL), N. C. Sun (UCAS), W. X. Li, Y. N. Wang (NAOC), and K. Wiersema (Herts) report:
We conducted further optical follow-up observations of the EP-detected X-ray transient EP241021a (Hu et al., GCN 37834; Wang et al., GCN 37848) using the IO:O Imager at the 2m Liverpool telescope in SDSS-g (300s x 3 frames) and SDSS-i (300s x 3 frames) bands. Our second observation epoch (for the first epoch, see Li et al., GCN 37846) was taken on 2024-10-24 from 22:28:08.2 to 22:54:55.6 UT (around 3.722 to 3.740 days post-trigger).
In the stack images of both bands, we detected the optical counterpart of EP241021a, at a position matching the optical counterpart identified by Fu et al., GCN 37840 (see also Gompertz et al., GCN 37835; Lipunov et al., GCN 37839; Fu et al., GCN 37842; Yang et al., GCN 37843; Li et al., GCN 37844; Li et al., GCN 37846; Zheng et al., GCN 37849; Moskvitin et al., GCN 37850; Pugliese et al., GCN 37852; Pérez-Fournon et al., GCN 37858; Bochenek et al., GCN 37869).
We performed aperture photometry on the stacked g and i-band images and calibrated them against the nearby SDSS stars. The observed magnitudes are as follows:
Date_obs | Start UT | Exp. Time | T-T0 (d) | Filter | Mag | Mag_err
----------------------------------------------------------------------------------------
2024-10-24 | 22:28:08.2 | 3x300s | 3.722 | SDSS-g | 22.85 | 0.18
2024-10-24 | 22:44:16.8 | 3x300s | 3.734 | SDSS-i | 21.93 | 0.15
The quoted magnitudes are not corrected for Galactic extinction in the direction of the EP-transient.
Further observations are planned. This circular may be cited.