TITLE: GCN CIRCULAR NUMBER: 23948 SUBJECT: GRB 190311A: NEXT-0.6m optical afterglow detection DATE: 19/03/11 15:50:36 GMT FROM: Dong Xu at NAOC/CAS Z.P. Zhu, D. Xu, B.Y. Yu (NAOC) report on behalf of larger collaboration: We observed the field of GRB 190311A (Troja et al., GCN 23946) using the robotic NEXT-0.6m telescope located at Nanshan, Xinjiang, China. Observations started at 14:25:14 UT on 2019-03-11, i.e., 101 sec after the BAT trigger. A series of 40 s, 60 s , 90 s, 300 s R-band frames were obtained, and photometry is still ongoing. An uncatalogued optical source is detected at coordinates R.A. (J2000) = 14:08:15.71 Dec. (J2000) = +53:30:01.7 with an uncertainty radius ~0.3 arcsec, being consistent with Swift/UVOT position (Troja et al., GCN 23946). The source has m(R) ~ 19.7 mag at 413 s post-burst, and is fading. We conclude that the source is the optical afterglow of the burst.