TITLE: GCN CIRCULAR NUMBER: 30268 SUBJECT: GRB 210619B: SARA-KP 0.9m Optical Afterglow Detection DATE: 21/06/20 08:18:35 GMT FROM: Kyle Pellegrin at Clemson University K. Pellegrin, S. Anandagoda, and D. Hartmann report: We observed the field of GRB 210619B detected by Swift BAT (D’Avanzo et al., GCN #30261), Global MASTER-Net (Lipunov et al., GCN #30262), GECAM (Zhao et al., GCN #30264), iTelescope (Kong, GCN #30265), and Ondrejov D50 (M. Jelinek et al., GCN #30263) using the SARA 0.9m optical telescope located at Kitt Peak, AZ, USA, equipped with the Alta-E6-1105 camera. Observation started at 05:19:14 UTC on 2021-06-20 and ended at 06:13:23 UTC on 2021-06-20. We obtained a series of 60s exposure frames in the Johnson-Cousins R filter. We detect the optical afterglow of GRB 210619B at the enhanced Swift-XRT position (Beardmore, et al., GCN #30267). The estimated magnitude of the GRB afterglow was found by stacking 20 images of 60s each in the Johnson-Cousins R band filter. The GRB was visible in each of the stacked images. T_start-T0 (hrs) T_end-T0 (hrs) Start Date (UTC) Filter Magnitude (mag) ---------------------------------------------------------------------------------------------------------------- ---------------------------------------------------------------------------------------------------------------- 5.32 5.70 2021-06-20T05:19:14 R 18.51 5.73 6.22 2021-06-20T05:43:59 R 18.77 Photometry is done based on the PanSTARRS catalog. The Southeastern Association for Research in Astronomy (SARA) consortium operates three telescopes: the 0.9-m SARA-KP at Kitt Peak in Arizona, and the 0.6-m SARA-CT at Cerro Tololo in Chile, and the 1.0-m SARA-RM (formerly the JKT) telescope at Roque de los Muchachos Observatory in the Canary Islands. For more information see: Keel et al. (2016): https://iopscience.iop.org/article/10.1088/1538-3873/129/971/015002 ---------------------------------------------------------------------------------------