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GCN Circular 34415

GRB 230812B: Osservatorio Astronomico "Nastro Verde" optical observation
2023-08-14T13:45:40Z (9 months ago)
Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <>
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Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
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)

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 telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione

The observations started at 19:40 UT of 2023/08/13, after about 24 hours after the GRB trigger, at the end of twilight with clear skies, with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 22 image of 240 sec each. All images are unfiltered, calibrated with masterdark and masterflat, stacked with Tycho Tracker and Astrometrica software
We have detected a clearly visible 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, Ruocco et al. GCN 34413)
at following position

RA      (J2000.0)  16h 36m 31.47s 
Decl.   (J2000.0) +47° 51' 32.2"      

Preliminary photometry summing three sets of 7 images of 240 sec each, using Astrometrica and the UCAC4 catalog is as follows

2023 08 13.83014 16 36 31.46 +47 51 32.7          19.8 R      
2023 08 13.85209 16 36 31.52 +47 51 32.1          19.8 R      
2023 08 13.87403 16 36 31.47 +47 51 32.3          20.2 R      

Magnitudes were estimated with the UCAC4 cat. and 
are not corrected for galactic dust extinction.

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