TITLE:   GCN CIRCULAR
NUMBER:  32219
SUBJECT: GRB 220618A: BOOTES-5/JGT early optical upper limit
DATE:    22/06/18 17:16:46 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, I. Perez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, R. Sanchez-Ramirez (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:

Following the detection of GRB 220618A by Swift (Troja et al. GCNC 32214), the BOOTES-5/JGT 0.6m robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) observed the GRB location starting on Jun 18, 09:10:39 UT (~10 s after trigger). In the early co-added image (20 x 10 s exposures in the clear filter), no optical afterglow is detected within the Swift/XRT error region (Osborne et al. GCNC 32216) down to 19.5 mag. This non-detection is consistent with the UVOT results (Kuin et al. GCNC 32218) and MASTER results (Lipunov et al. GCNC 32213).

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for their excellent support.