TITLE:   GCN CIRCULAR
NUMBER:  34417
SUBJECT: GRB 230812B: Bassano Bresciano Observatory optical observations
DATE:    23/08/14 14:26:48 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>

U.Quadri and  L.Strabla (Bassano Bresciano Astronomical Observatory),
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We 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 robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili-GRB.
GAC - Gruppo Astrofili Cremonesi.

The observations started 24.57 hour after the FERMI trigger, At the end of twilight 
with our Newton telescope D=250 mm F/D=4.8

Weather conditions were good.

We co-added 2 series of 70 exposures of 60 sec each.

Start T0+      End T0+     
24.57 hour     27.09 hour

We detected a (fading) afterglow in the error box of the XRTcandidate.
at the following position (+/- 2 arcsec):

RA (J2000.0) =  16h 36m 31.51s
DEC(J2000.0) = +47d 51p 32.2s

The results of our photometry are:

-----------------------------------
      JD         Mag    Err    Flt   
-----------------------------------
2460170.36459   19.9 +/- 0.2    CR    
2460170.38708   20.1 +/- 0.2    CR    

CR is unfiltered with R zero point.

Magnitudes were estimated with the PanSTARRS cat. and 
are not corrected for galactic dust extinction.

Reference:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.