GCN Circular 35823

TITOLO: Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up

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)
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione.
report:

Following the Swift trigger no. 1186959 (GCN 34537
Not found
 
 
), using the 24 Inch RC Optical Ritchey-Chretien Reflector telescope and the Apogee Aspen CG16M camera of the Madrona Peak Observatory connected to the AAVSONet network,
we obtained a series of B,V,R images of the transient approximately 6 months after the first detection. 
The images were measured with the VPhot AAVSO software, using the APASS catalogue. The photometry obtained on 19/23/25 February 2024 are as follows:

with the following photometry:

    JD	           Mag	        Filter
2460363.97895	15.830            V
2460363.97781	15.987            V
2460359.99249	15.864            V
2460359.99139	15.837            V

	


JD	          Mag	       Filter
2460365.97083	15.713            R
2460363.98126	15.552            R
2460363.98014	15.535            R
2460359.99473	15.530            R
2460359.99362	15.512            R



JD	          Mag	       Filter
2460363.97611	15.230            B
2460363.97427	16.275            B
2460359.98979	16.096            B
2460359.98799	16.131            B




The magnitudes are calibrated with stars of the APASS catalog are not corrected for the expected Galactic extinction.

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