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As part of a project to better characterize comparatively bright but so farlittle studied cataclysmic variables in the southern hemisphere, we haveobtained spectroscopic and photometric data of the nova-like variables LS IV-08$^{\rm o}$ 3 and HQ Mon, and of the Z Cam type dwarf nova ST Cha. Thespectra of all systems are as expected for their respective types. We deriveimproved orbital ephemeris of LS IV -08$^{\rm o}$ 3 and map its accretion diskin the light of the H$\alpha$ emission using Doppler tomography. We find thatthe emission has a two component origin, arising in the outer parts of theaccretion disk and possibly on the illuminated face of the secondary star. Thelight curve of LS IV -08$^{\rm o}$ 3 exhibits a low level of flickering andindications for a modulation on the orbital period. Spectroscopy of HQ Monsuggests an orbital period of $\approx$5.15 hours which is incompatible withprevious (uncertain) estimates. The light curves show the typical low scaleflickering of UX UMa type nova-like systems, superposed upon variations onlonger time scales. During one night a modulation with a period of $\approx$41min is observed, visible for at least 4 hours. However, it does not repeatitself in other nights. A spectroscopic orbital period of $\approx$5.5 hours isderived for ST Cha. A previously suspected period of 6.8 hours (oralternatively 9.6 hours), based on historical photographic photometry isincompatible with the spectroscopic period. Moreover, we show that our new aswell as previous photometry does not contain evidence for the quotedphotometric period.

new astronomy

Time resolved spectroscopy and photometry of three little known bright  cataclysmic variables: LS IV -08$^{\rm o}$ 3, HQ Monocerotis and ST  Chamaeleontis