{
  "bibcode": "2021GCN.30525....1H",
  "body": "Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado  M. D. Caballero-Garcia, M. A. Castro Tirado (IAA-CSIC), A. Gardini and I. Hermelo (CAHA) on behalf of a larger collaboration, report:\r\n\r\nFollowing the detection of GRB210726A by Swift (Bernardini et al. GCNC 30523), we triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain). A series of i-band images were gathered starting on July 26, 20:23 UT (i.e. 1.07 h post trigger). On the co-added image (15 x 60s), no optical object is detected down to 21.9 mag at the X-ray afterglow position reported by Swift/XRT (Osborne et al. GCNC 30524).\r\n\r\nWe thank the staff at Calar Alto observatory for their excellent support.",
  "circularId": 30525,
  "createdOn": 1627338314000,
  "email": "huyoudong072@hotmail.com",
  "subject": "GRB 210726A: CAHA 2.2m telescope optical limit",
  "submitter": "Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>",
  "eventId": "GRB 210726A"
}