TITLE:   GCN CIRCULAR
NUMBER:  34463
SUBJECT: GRB 230812B: optical photometry from Konkoly
DATE:    23/08/17 10:23:01 GMT
FROM:    Jozsef Vinko at Konkoly Observator <vinko@konkoly.hu>

J. Vinko, L. Kriskovics, A. Pal,  R. Szakats
(Konkoly Observatory, Hungary).

We report detection and photometry of the optical afterglow of GRB230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,GCN 34399; Casentini et al., GCN 34402)
with the RC80 robotic telescope at Piszkesteto Station of Konkoly
Observatory taken on 2023-08-13 to 2023-08-15. A series of 300 sec
frames were collected through Sloan r'- and i' bands. The optical afterglow
(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 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCN 34442, GCN 34461)
was detected on the stacked frames with the following magnitudes, calibrated
via nearby PS1 stars:

Date        UT-middle   t-T0(hr)  Exp(s)   r'(AB-mag)       i'(AB-mag)
2023-08-13  19:41:01    24.71     1500     20.47 (0.10)     19.75 (0.12)
2023-08-14  19:40:32    48.71     1500     21.33 (0.20)     20.51 (0.19)
2023-08-15  21:50:01    74.86     900      >21.89           >21.45

The magnitudes above are not corrected for galactic extinction.