TITLE: GCN CIRCULAR NUMBER: 35823 SUBJECT: Swift J1727.8-1613 (GRB 230824A): Madrona Peak Observatory - optical follow-up DATE: 24/02/27 19:08:13 GMT FROM: Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com> 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), 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. The message may be cited. View this GCN Circular online at https://gcn.nasa.gov/circulars/35823. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...