TITLE:   GCN CIRCULAR
NUMBER:  30339
SUBJECT: GRB 210626A: CAHA 2.2m telescope optical limit
DATE:    21/06/28 10:43:38 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), A. Fernandez and I. Hermelo (CAHA) on behalf of a larger collaboration, report:

Following the detection of GRB 210626A by both Swift (Tohuvavohu et al. GCNC 30325) and Fermi (Fermi/GBM team GCNC 30323), we triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain), gathering images starting on June 27, 20:37 UT (i.e. 1.5 day post trigger). On the co-added image (i-band, 3x180s), no optical transient down to 22.4 mag is detected at the X-ray afterglow candidate position reported by Swift/XRT (Evans et al. GCNC 30326, Perri et al. GCNC 30329).

We thank the staff at Calar Alto observatory for their excellent support.