# Photometry of the three eclipsing novalike variables EC 21178-5417, GS Pav and V345 Pav

## TL;DR

This study presents detailed photometric observations of three eclipsing novalike variables, improving orbital period measurements, analyzing eclipse profile variations, and detecting quasi-periodic oscillations and flickering behaviors.

## Contribution

It provides the first comprehensive long-term photometric analysis of these three systems, including refined orbital periods and evidence of QPOs and flickering patterns.

## Key findings

- Improved orbital periods for all three variables.
- Detected QPOs with periods between 200-500 seconds in GS Pav.
- Observed eclipse profile variations and short-term brightness oscillations.

## Abstract

As part of a project to better characterize comparatively bright, yet little studied cataclysmic variables time resolved photometry of the three eclipsing novalike variables EC 21178-5417, GS Pav und V345 Pav is presented. Previously known orbital periods are significantly improved and long-term ephemeris are derived. Variations of eclipse profiles, occurring on time scales of days to weeks, are analyzed. Out of eclipse the light curves are characterized by low scale flickering superposed on more gradual variations with amplitudes limited to a few tenths of a magnitude and profiles which at least in EC 21178-5417 and GS Pav roughly follow the same pattern in all observed cycles. Additionally, signs for variations on the time scale of some tens of minutes are seen in GS Pav, most clearly in two subsequent nights when in the first of these a signal with a period of 15.7 min was observed over several hours. In the second night variations with twice this period were seen. While no additional insight could be gained on quasi periodic oscillations (QPOs) and dwarf nova oscillations in EC 21178-5417, previously detected by Warner et al. (2003), and while such oscillations could not be found in V345 Pav, stacked power spectra of GS Pav clearly reveal the presence of QPOs over time intervals of several hours with periods varying between 200 sec and 500 sec in that system.