TITLE:   GCN CIRCULAR
NUMBER:  34490
SUBJECT: GRB 230818A: Leavitt Observatory upper limit
DATE:    23/08/19 15:48:22 GMT
FROM:    leavittob@gmail.com

E. Pavoni and L. Moretti (Leavitt 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 observed the field of GRB 230818A (Fermi: GBM team, GCN 34478; Swift: Tohuvavohu et al., GCN 34479; Gompertz et al., GCN  34480; Moskvitin et al., GCN 34483; Malesani  et al., GCN 34485; Siegel et al., GCN 34486; Pankov et al., GCN 34487; Quadri et al., GCN 34488) with the telescope of Leavitt Observatory, Italy. Member of: 

UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.

The observations began at 00:57 UT on 2023/08/18, 90 min after the GRB trigger, with our RC telescope D=250 mm F/D=8.

Weather conditions were good.

We took 32 images of 120 sec each. All images are V filtered, calibrated with master dark and master flat, stacked with ASTAP software.

We have not detected any clearly visible sources, up to 19.60 magnitude with clear sky at 
RA (J2000): 19h 03m 33.08s
Dec (J2000): +40d 53' 48.0"

on a field of view 31.1 x 26.8 arcmin.

Start		End		Vlim
90 min		154 min	19.60

The magnitude limit was estimated with nearby stars from the Gaia EDR3 Catalog and is not corrected for galactic dust extinction.

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