[vsnet-grb-info 28152] GRB 210618A: BOOTES-2/TELMA optical upper limit

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  30255
SUBJECT: GRB 210618A: BOOTES-2/TELMA optical upper limit
DATE:    21/06/18 21:24:06 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072 at hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:

The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to the Swift and Fermi trigger of GRB 210618A (Fermi GBM team GCNC 30248, Bernardini et al. GCNC 30250). Images were taken starting at 01:54 UT, but due to poor weather conditions, only images taken after 02:17 UT (~34 min after trigger) could be used. In the co-added 10 x 60 s exposure image (clear filter), no optical afterglow is neither detected within the BAT/Swift error box (Bernardini et al. GCNC 30250) nor associated with the reported XRT/Swift sources (Osborne et al. GCNC 30252) down to 19.6 mag. This non-detection is consistent with the report from Lipunov et al. (GCNC 30249) and Lopez et al. (GCNC 30251).

We thank the staff at La Mayora for its excellent support.