TITLE:   GCN CIRCULAR
NUMBER:  44920
SUBJECT: GRB 260610B / AT2026owq: OASDG optical observations
DATE:    26/06/12 07:54:38 GMT
FROM:    luca.izzo@inaf.it

L. Izzo (INAF-OACn, DARK/NBI, OASDG) reports:

We observed the counterpart of GRB 260610B (Fermi GBM team, GCN #44901) using the 0.5-m T1 telescope of the Osservatorio Astronomico S. Di Giacomo (OASDG), located in Agerola, Italy. Our observations started on 2026 June 11 at 21:44 UT, 0.917 days after the GRB trigger. We acquired a series of 8 × 300 s images in the Rc and Ic filters.

The optical counterpart, also reported as AT2026owq (O'Neill et al., GCN #44903; Watson et al., GCN #44905; Zhu et al., GCN #44909; Gillanders et al., GCN #44910; Akl et al., GCN #44911; O'Neill et al., GCN #44914; Moskvitin et al., GCN #44918; Perley et al., GCN #44919), is clearly detected in both stacked images.

We measure the following preliminary magnitudes (AB), which have been calibrated against nearby stars from the Pan-STARRS catalog and appropriately transformed to Rc and Ic magnitudes. 

Rc = 19.44 +/- 0.16 mag
Ic = 19.28 +/- 0.16 mag