TITLE:   GCN CIRCULAR
NUMBER:  34562
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
DATE:    23/08/26 08:05:10 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>

U.Quadri, P.Madurini and L.Strabla (Bassano Bresciano Astronomical Observatory),

Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
GAC - Gruppo Astrofili Cremonesi.

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 Swift J1727.8-1613(GRB 230824A) 
(Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543)
with the following telescopes:

0.25-m f/4.8 Newton reflector at Bassano Bresciano Observatory, Italy - MPC Code 565. 
0.32-m f/8.0 (iTelescope) reflector at AstroCamp at Nerpio, Spain - MPC Code I89.
0.51-m f/6.8 (iTelescope) Dall-Kirkham at Rio Hurtado Valley, Chile - MPC Code X07. 
 

We clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within 
the uncertainty radius of the Swift localization, at:

R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:18.8


The results of our photometry are:

------------------------------------------------------    
    Date UT       Exp Time   R-mag    Err  IAU STATION
------------------------------------------------------
  
2023-08-24.7967    18x20s    13.25   0.057    565
2023-08-24.8018    18x20s    13.25   0.049    565  
2023-08-24.8071    12x30s    13.24   0.048    565 
2023-08-24.8124    12x30s    13.24   0.043    565 
2023-08-24.8185    12x30s    13.24   0.042    565 
2023-08-24.9030    10x60s    13.05     -      I89
2023-08-25.1470    10x60s    12.80     -      X07
------------------------------------------------------

Magnitudes were estimated with the pan-STARRS cat. 
and are converted using Lupton (2005) equations.

Not corrected for galactic dust extinction.

Further observations are planned.

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

The message may be cited.