# Photometry of the SW Sex-type nova-like BH Lyncis in high state

## TL;DR

This study provides detailed photometric observations of BH Lyn, a SW Sex-type nova-like star, revealing eclipse characteristics, variability, and potential negative superhumps, contributing to understanding accretion disc behavior in such systems.

## Contribution

It offers new eclipse timings, refines the orbital period, and discusses the possible link between negative superhumps and disc tilt in SW Sex stars.

## Key findings

- Refined orbital period of 0.155875577 days.
- Detected negative superhumps with a period of ~0.145 days.
- Observed highly variable eclipse shapes and flickering effects.

## Abstract

Aims: We present a photometric study of the deeply eclipsing SW Sex-type nova-like cataclysmic variable star BH Lyn Methods: Time-resolved V-band CCD photometry was obtained for seven nights between 1999 and 2004. Results: We determined 11 new eclipse timings of BH Lyn and derived a refined orbital ephemeris with an orbital period of 0.155875577(14) day. During the observations, BH Lyn was in high-state with V~15.5 mag. The star presents ~1.5 mag deep eclipses with mean full-width at half-flux of 0.0683(+/-0.0054)P_orb. The eclipse shape is highly variable, even changing form cycle to cycle. This is most likely due to accretion disc surface brightness distribution variations, most probably caused by strong flickering. Time-dependent accretion disc self-occultation or variations of the hot spot(s) intensity are also possible explanations. Negative superhumps with period of ~0.145 day are detected in two long runs in 2000. A possible connection between SW Sex and negative superhump phenomena through the presence of tilted accretion disc is discussed, and a way to observationally test this is suggested.