TITLE:   GCN CIRCULAR
NUMBER:  34408
SUBJECT: GRB 230812B: Montarrenti Observatory optical observations
DATE:    23/08/14 00:58:33 GMT
FROM:    Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini@iol.it>

S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:

We observed the field of GRB 230812B (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page, GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396; Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al., GCN 34401; Casentini et al., GCN 34002; Frederiks et al., GCN 34403; Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin et al., GCN 34406) with the automatic 0.53m Ritchey-Chretien telescope at Montarrenti Observatory (Siena, Italy, IAU code C88).

The observations were started under good weather conditions at 2023-08-13 19:20:53 UT (approximately 24 hours after burst) stacking 50x30s R and I-band CCD images.

The OT was clearly detected at the following position:

RA      (J2000.0)  16h 36m 31.47s +/-0.11 
Decl. (J2000.0) +47° 51' 32.7"      +/-0.14

Preliminary photometry is obtained using nearby PanSTARRS stars as follows: 

MJD                  Filter   Mag.      Err.
60170.32784    R       20.48  +/-0.07
60170.32827    I        19.78  +/-0.10

Magnitudes are converted using Lupton (2005) equations and are not corrected for galactic dust extinction.