TITLE:   GCN CIRCULAR
NUMBER:  34413
SUBJECT: GRB 230812B: OASDG optical observations
DATE:    23/08/14 10:47:40 GMT
FROM:    luca.izzo@inaf.it

N. Ruocco, A. Catapano (OASDG) and L. Izzo (INAF-OACN & DARK/NBI) report:  

We observed the field of GRB 230812B (Lesage et al. GCN 34387, Roberts et al. GCN 34391, Scotton et al. GCN 34392, Beardmore et al. GCN 34400, Xiong et al. GCN 34401, Casentini et al. GCN 34402, Frederiks et al. GCN 34403) with the 0.5m telescope of the Osservatorio Astronomico S. Di Giacomo located in Agerola, Italy ( https://osservatorio.astrocampania.it/ - MPC L07). We obtained multiple 300s images in the Rc filter under good weather conditions, with the first observation starting at MJD 60169.818 (1.027 days after the GRB detection). 

In the final stacked image, we detect a faint source at the enhanced position reported by Swift-XRT (Beardmore et al. GCN 34400) and by optical telescopes (Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409 & 34410, Belkin et al., GCN 34412). We measure a magnitude for the GRB afterglow of Rc(AB) = 20.51 +/- 0.16 mag. The calibration was performed using nearby stars in the Pan-STARRS PS1 catalog, and using transformation equations to Rc magnitudes. Further analyses are ongoing.