A Large amplitude flickering from the cataclysmic varaible V425 Cas in low state descriptive title

ATel #17313; S. Boeva, S. Tsvetkova, R. Zamanov (IA s NAO, Bulgarian Academy of Sciences)
on 30 Jul 2025; 10:55 UT
Credential Certification: R. K. Zamanov (rkz@astro.bas.bg)

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V425 Cas is a nova like cataclysmic variable (CV) with orbital period of 3.6 hours (Wenzel, W., 1987, IBVS 3086, Kato et al. 2001, PASJ, 53, 1185). V425 Cas usually has V band magnitude in the range 14.5-15.5 mag. As as a member of VY Scl subclass of CVs, V425 Cas shows rare low states with fades to V=18 mag. AAVSO data show that its brightness began to decrease at the end of May 2025.
We observed V425 Cas with the 2.0 m telescope of the Rozhen National Astronomical Observatory, Bulgaria equipped with Andor-CCD in V band during two nights - 27/28 July (35 exposures of 180 sec) and 28/29 July 2025 (137 exposures of 120 sec). The typical observational errors are 0.05 mag. The results are:
2025-07-28, UT 00:20-02:01, V=18.52-17.98,
2025-07-28, UT 21:20-02:06, V=18.32-17.36.
Our observations indicate that V425 Cas is now in low state (fainter than 17.5 mag in V band) and strong flickering presents. The amplitude of the flickering was 0.52 mag and 0.92 mag for the first and second night, respectively. Large amplitude flickering in low state is also reported for another VY Scl variables like MV Lyr, TT Ari and KR Aur (e.g. Boeva et al., 2021, PoS, 368, 28).

Fig.1 V425 Cas - 4:45 hours light curve in V band on 28/29 July 2025.