GRB 230812B: GAD Observatory optical observations (upper limit)

I imaged 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) detected by FERMI(trigger 713559497.049606 / 230812790) with the GAD Observatory, La Spezia, Italy Italy. Member of: UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section GAD - Gruppo Astronomia Digitale The observations started 48.02 hour after the FERMI trigger, At the end of twilight with a Maksutov-Newton telescope D=180 mm F/D=4 Weather conditions were good. We co-added series of 8 exposures of 60 sec each. Start T0+ End T0+ R lim 3168 min 3178 min 19.6 I did not detect any optical afterglow in the Swift/XRT (Page, GCN Circ. 34387) position. The magnitude limit is about 19.5 mag, compared to the magnitudes of nearby stars from the Gaia EDR3 Catalog Magnitudes were estimated with the Gaia EDR3 cat. and are not corrected for galactic dust extinction. Reference: https://www.parcodellestelle.com/ The message may be cited.