TITLE:   GCN CIRCULAR
NUMBER:  40999
SUBJECT: EP250704A: NOWT Detection
DATE:    25/07/07 03:57:17 GMT
FROM:    Abdusamatjan Iskandar at XAO,CAS <abudu@xao.ac.cn>

Letian Wang, Abdusamtjan Iskandar, Ali Esamdin, Yu Zhang, Jinzhong Liu, report on behalf of optical group of the XAO:

We observed the filed of EP250704a (Li et al., GCNs 40941, 40956; Schneider et al., GCN 40942; Malesani et al., GCN 40945; Brivio et al., GCN 40947; Evans et al., GCN 40951; Perez-Garcia et al., GCN 4957; Gillanders et al., GCN 40958; Xin et al., GCN 40960; Mohan et al., GCN 40962; Moskvin et al., GCN 40963; Liu et al., GCN 40965; An et al., GCN 40966; Yang et al., GCN 4970; Martin-Carillo et al., GCN 40971; Frederiks et al., GCN 40972,Malte Busmann et al., GCN 40974, Li et al., GCN40975, Li et al., GCN 40986) with the Nanshan One-meter Wide-field Telescope (NOWT) at Nanshan Station of Xinjiang Astronomical Observatory (XAO). The observations were started at 2025-07-04T18:33:06.0 (UTC, 0.43 days after the trigger), and obtained a series of V band images.

The optical afterglow was clearly detected at the position reported by Schneider et al.(GCN 40942) in the our stacked image, the preliminary photometric magnitudes is V=19.98 +- 0.16 mag (MJD 60860.7729, 6X300s).

The photometric calibration was performed using nearby stars from the GAIA synthesis catalog and the magnitude is not corrected for Galactic extinction.