[vsnet-alert 23381] Mode change in CRTS J162322.2+121334

[Denis Denisenko d.v.denisenko@gmail.com via vsnet-alert]

I have checked ZTF light curve of the large-amplitude variable CRTS
J162322.2+121334 aka SDSS J162322.23+121334.0, see
https://www.aavso.org/vsx/index.php?view=detail.top&oid=230817

It is listed in Outburst catalogue of cataclysmic variables by
Coppejans et al., 2016 (MNRAS, Vol. 456, p. 4441) as a non-DN. Kato et
al., 2012 (PASJ, Vol. 64, No. 3, p. 63) noticed that this object
(=CSS080606:162322+121334, not included in tables) showed multiple
deep fadings similar to VY Scl-type CVs. Variability range in SDSS
data is g=17.0-21.9.

The light curve by Zwicky Transient Facility at irsa.ipac.caltech.edu
in March-September 2018 is completely different from CRTS observations
in July 2005 - April 2016:

http://scan.sai.msu.ru/~denis/J162322+121333-ZTF-LC.gif

The variable shows three-week long outbursts every 51 days with the
profile strikingly similar to superoutbursts of SU UMa-type variables,
yet with incredibly stable cycle not normally seen in CVs that are
known to be chaotic by nature. Here is the phased light curve of ZTF
data from 2018.

http://scan.sai.msu.ru/~denis/J162322+121333-ZTF-phased_LC.gif

If the 51-day cycle has survived until 2019, the last outburst should
have started on June 26-27, and the next one should occur around
August 16-17.

Last moment addition: ASAS-SN Sky Patrol light curve (Shappee et al.,
2014, Kochanek et al., 2017) for the last 200 days confirms the
supercycle still stands stable in 2019:
https://asas-sn.osu.edu/light_curves/7f53231a-f07f-4fa9-a035-9f6e65c9ec68

Spectrum obtained in a faint state (V~20.2) is characterized by very
wide double-peaked emission lines. Oliveira et al., 2017 (AJ, Vol.
153, p. 144) provide the following FWHM values for Balmer series
lines:
H_beta 2670 km/s, H_alpha 2370 km/s indicating a possible high orbital
inclination.

Denis Denisenko