TITLE:   GCN CIRCULAR
NUMBER:  38035
SUBJECT: GRB 241030A/EP241030a: TNOT observations of the optical counterpart
DATE:    24/11/01 15:11:50 GMT
FROM:    Xiaofeng Wang at Tsinghua University <wang_xf@mail.tsinghua.edu.cn>

Y.S. Yan (THU), L. T. Wang (XAO), X.F. Wang(THU), A. Iskandar（XAO), J. L. Liu (THU)，J. Mo (THU), A. Esamdin (XAO), S. Antier (OCA)，and W. X. Li (NAOC) report the detection of the optical transient associated with GRB 241026A/EP241026a with a redshift of 1.41 (Klingler et al.,GCN 37956; Beardmore et al., GCN 37962; Wang et al., GCN 37972; Pillera et al., GCN 37979; Ridnaia et al., GCN 37982; Ambrosi et al., GCN 37988; Wu et al., GCN 37997; Liang et al., GCN 38026; Watson et al., GCN 37957; Fernández-Rodríguez et al., GCN 37958; Zheng et al., GCN 37959; An et al., GCN 37960; Higuchi et al., GCN 37963; Qiu et al.,GCN 37965; Lin et al., GCN 37966; Wu et al., GCN 37970; Breeveld & Klingler, GCN 37974; Méndez-Lapido et al., GCN 37993; Moskvitin & Goranskij, GCN 38016; Busmann et al., GCN 38019; Schneider et al., GCN 38021; Li et al., GCN 38027; Masi, GCN 38031; Moskvitin et al., GCN 38032).

We obtained the CCD photometric observations on October 31 14:35--15:53 UT, with 100sx20 (~33.1 hrs from T0) exposure in the r band and 100sx20 (~33.7 hrs from T0) exposure in the i band, using the 0.8~m Tsinghua-Nanshan Optical Telescope (TNOT) located at Nanshan Station of Xinjiang Astronomy Observatory. The optical counterpart is clearly detected on the stacked images, with the following magnitudes:
 
r = 20.74 +- 0.14 mag (MJD = 60614.618)
i = 20.24 +- 0.20 mag (MJD = 60614.647)

The above photometric results are calibrated using the field stars from the Pan-STARRS1 catalog and are not corrected for the Galactic extinction.