Rapid optical fading of S4 0954+65 following recent flaring activity
ATel #17899; E. Zaharieva, B. Aleksandrov, V. Efremov, M. Petrova, A. Todorov, E. Ovcharov (Sofia University, Bulgaria)
on 16 Jul 2026; 13:01 UT
Credential Certification: Evgeni Ovcharov (evgeni@phys.uni-sofia.bg)
Subjects: Optical, Blazar
Following the recent activity of the blazar S4 0954+65 reported in ATel #17880, we performed R-band optical photometric observations of the source. The images were obtained with a 35 cm Schmidt-Cassegrain telescope + CCD SBIG STX-16803 at the student Space and Earth Sciences Summer School "Prof. Marin Bachvarov", Dren, Bulgaria, during the nights of July 13/14 and 14/15, 2026.
The preliminary nightly R-band magnitudes are:
JD mag ± err
2461235.43295 14.576 ± 0.011
2461235.43545 14.579 ± 0.008
2461235.43771 14.582 ± 0.008
2461235.43995 14.573 ± 0.008
2461235.44221 14.598 ± 0.008
2461235.44446 14.592 ± 0.008
2461235.44671 14.616 ± 0.011
2461235.44896 14.591 ± 0.008
2461235.45120 14.566 ± 0.011
2461236.39002 15.273 ± 0.015
2461236.39227 15.261 ± 0.012
2461236.39453 15.265 ± 0.012
2461236.39677 15.279 ± 0.014
2461236.39902 15.270 ± 0.012
2461236.40127 15.241 ± 0.012
2461236.40352 15.283 ± 0.011
2461236.38778 15.284 ± 0.014
The source faded by about 0.7 mag in R within 24 hours. The photometric calibration is based on the comparison stars of Raiteri C.M. et al., 1999, A&A 352, 19.
The study was supported by the National Program 'Education with Science' D01-172/18.09.2024 and the National RI Roadmap Project D01-109/30.06.2025 with the Ministry of Education and Science of the Republic of Bulgaria.
