TITLE:   GCN CIRCULAR
NUMBER:  34453
SUBJECT: GRB 230816A: Nanshan/HMT optical afterglow detection
DATE:    23/08/16 18:15:50 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

S.Q. Jiang, S.Y. Fu, X. Liu, T.H. Lu, Z.P. Zhu, D. Xu (NAOC), X. Gao (Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 230816A detected by Swift (Siegel et al., GCN 34450) using the HMT-0.5m telescope located at Nanshan, Xinjiang, China. Observations started at 16:10:20 UT on 2023-08-16, i.e., 92 s after the Swift/BAT trigger, we obtained a serise of 3x20, 3x40, 4x60, 12x90 s frames without any filter.

An uncatalogued optical source is detected in our stacked image at coordinates

R.A. (J2000) = 21:53:46.9
Dec. (J2000) = +37:51:15.9

2.23 arcsec away from the center of the XRT error circle (radius: 1.9 arcsec, 90% containment; Siegel et al., GCN 34450) with m(r) = 19.6 +/- 0.18 mag(AB) at 24.6 min post-burst, calibrated with the nearby PanSTAR field in the Sloan r-filter and the magnitude is not corrected for Galactic extinction. We thus think this OT is the optical afterglow of the burst.