Eclipsing nova-like cataclysmic variable BH Lyn enters a rare low state
ATel #16072; David Boyd (BAA Variable Star Section), Christopher Lloyd (University of Sussex)
on 4 Jun 2023; 08:16 UT
Credential Certification: Christopher Lloyd (c.lloyd@sussex.ac.uk)
Subjects: Optical, Cataclysmic Variable
We report an observation of the eclipsing nova-like cataclysmic variable BH Lyn at an out-of-eclipse magnitude 17.05±0.15 (CV)
on 2023 May 24 using a 0.35-m SCT, which confirms time-series observations at a similar magnitude on 2023 January 11 by S. Dvorak,
as reported in the AAVSO International Database.
The only other occasion when BH Lyn has been seen this faint is during the spectroscopic observations made in early 1990 when the
system was at an estimated magnitude of V=17.0±0.2. By April 1991 it had brightened by two magnitudes
(see Dhillon et al., 1992 bibcode:1992MNRAS.258..225D)
and since then the out-of-eclipse
magnitude has remained relatively constant at V=15.0-15.5.
Additional data from the synoptic surveys, ASAS-SN, ATLAS and ZTF confirm a recent fade of ≅ 2 magnitudes in the Sloan g and r bands, and the
ATLAS c and o bands, in the out-of-eclipse magnitude. The data further suggest that this occurred quickly, during a 14-day interval, between
JD 2459937 and 2459951, centred close to 2023 January 1.
The current low state of BH Lyn should provide an opportunity to observe the donor star without the interference of the bright accretion disc,
however, the current observing season is closing rapidly. Based on the one previous event, the system may be expected to remain in the low state for
at least one year. A recent linear ephemeris for the eclipses of BH Lyn is
HJD Min = 2447180.3343(2) + 0.155875642(3) x E
and the full eclipse width is 0.2 phase.
