GCN Circular 31859

Y.-D. Hu, E. Fernandez-Garcia, T.-R. Sun, A. J. Castro-Tirado, R. Sanchez-Ramirez and M.D. Caballero-Garcia (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 220408A by both Swift (Caputo et al. GCNC 31848) and Fermi (Fermi GBM team, GCNC 31847), the 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded to the burst on Apr 8 at 06:14 UT (i.e. ~ 28 min after trigger). In the co-added image (5 frames x 60 s exposure, clear filter), the optical afterglow is weakly detected with R = 21.1 +/- 0.3 mag at the position reported by UVOT (Caputo et al. GCNC 31848) and within the XRT error box (Beardmore et al. GCNC 31852). This is consistent with other optical detections previously reported by UVOT (Caputo et al. GCNC 31848, Oates et al. GCNC 31855) and KAIT (Zheng et al. GCNC 31850) and the upper limits provided by MASTER (Lipunov et al. GCNC 31849), Xinglong-2.16m (Jiang et al. GCNC 21853) and GIT (Kumar et al. GCNC 31857). Further observations are ongoing.

We thank the staff at San Pedro Martir Observatory for their excellent support.