TITLE:   GCN CIRCULAR
NUMBER:  45340
SUBJECT: GRB 260809A: NOT optical observations
DATE:    26/08/10 08:11:19 GMT
FROM:    Andrea Saccardi at CEA/Irfu <andrea.saccardi@cea.fr>

L. Izzo (INAF/OACN and DARK/NBI), A. Saccardi (CEA/Irfu), G. Corcoran (UCD), report on behalf of a larger collaboration:

We observed the field of GRB 260809A detected by SVOM/ECLAIRs (Brunet et al., GCN  45331), using the ALFOSC camera mounted on the Nordic Optical Telescope (NOT). We obtained 3x300 s exposures in the SDSS r-band and 5x200s in the SDSS z-band.

In the stacked images, we detect the optical afterglow (Li et al., GCN 45336; Adami et al., GCN 45338; Rajabov et al., GCN 45339). We measure the following magnitudes calibrated against the Pan-STARRS catalog, and not corrected for Galactic extinction:

r = 23.78+/-0.18, midtime: 2026-08-10 at 04:29:51 UT (13.54 hr post trigger)
z = 22.25+/-0.13, midtime: 2026-08-10 at 04:47:47 UT (13.84 hr post trigger).