TITLE:   GCN CIRCULAR
NUMBER:  30545
SUBJECT: GRB 210726A: OSIRIS/GTC observations
DATE:    21/07/29 12:54:52 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all 
HETH/IAA-CSIC), J. P. U. Fynbo (DAWN/NBI), L. Izzo (DARK/NBI), N. R. 
Tanvir (U. Leicester), and G. Gomez Velarde (GRANTECAN) report:

We observed the XRT afterglow position (Osborne et al., GCN #30524) of 
GRB 210726A (Bernardini et al., GCN #30523), classified as a short GRB 
(Tohuvavohu, GCN #30535; Palmer et al., GCN #30536; Veres, GCN #30540) 
with OSIRIS mounted on the 10.4m Gran Telescopio Canarias (Observatorio 
Astrof��isco Roque de Los Muchachos, La Palma, Canary Islands, Spain), 
under mediocre conditions and at high airmass, starting July 26, 
21:21:31 UT, 2.041 h after the GRB. We obtained a sequence of 30, 30, 
60, 30 s images in r' for a total integration time of 150 s.

Within the XRT error circle, we do not detect any source down to r' > 
24.4 mag (AB magnitude), measured against a nearby PanSTARRS fiel star, 
at 0.088533 d (2.125 h) after the burst, in agreement with Kann et al., 
GCN #30543.

The possible host galaxy (Watson et al., GCN #30534, Kann et al., GCN 
#30543) is found at r' = 22.04 +/- 0.05 mag, again in agreement with 
detections from the PanSTARRS and SDSS surveys.