The most important event for variable stars observers in Slovakia is Variable astrocamp. Usually held in Astronomical Observatory in Kolonica Saddle. The participants are more or less advanced observers from Slovakia, Poland and Ukraine. I’m responsible for the scienific content of the activity. The format of the astrocamp is the game. The majority of the participants plays the role of the researcher who is trying to solve a task guided by the supervisor. The example of the tasks from 2019 edition is below.
1. Binary star model
To construct the binary star model. Determine the basic parameters of the binary star system. Use your own CCD observations of selected eclipsing binary with four photometric filters (B V Rc Ic) and precise photometry from Kepler database. It is necessary to observe at least one complete light curve (all phases). The corresponding model can be constructed using available program, for example “PHOEBE”.
2. Superhumps in cataclysmic variables
To determine the period of superhumps of SU UMa type cataclysmic variable and its evolution during superoutburst. Use your own CCD observations of the object in superoutburst during the astrocamp. SU UMa type cataclysmic variables shows typical “humps” on the light curve. The period is usually slightly longer than orbital period of binary system. The typical value of the period is 80 – 120 minutes. It is easy to determine the period of superhumps using all night time series observation. The period evolves during the superoutburst. This tell us something about precession movement of the accretion disc. Therefore we have to observe as long as possible every night during the superoutburst. It is not necessary to observe with photometric filters. The accretion disc light is white.
3. Intermediate Polars
To construct the O-C diagram of pulse maxima connected with white dwarf rotation in the intermediate polar system. Use the data from literature and at least one personal CCD observation. Intermediate polars has asynchronous rotation. On the light curve we can see the orbital motion and spin of the primary component as well. The spin period value is typically 10 – 20 minutes. So we need long observing run lasting several hours with good time resolution (max. ¼ of the spin period). One filter is sufficient. We have to subtract the orbital wave mathematically. The corresponding point in the O-C diagram you get after fitting the measured points with sinusoidal fit. All necessary mathematical operations can be done with the program “MCV”.
4. O-C diagrams
To construct O-C diagrams of times of minima of several eclipsing binaries or times of maxima of short period pulsating stars. Use the data from available databases and at least one personal measurement. Use both visual observations and CCD measurements. Determine time of minima using different methods. Software MAVKA is recommended. Compare the obtained values and errors. Explain the obtained graphics.
5. Semiregular and Symbiotic variables
To acquire several points on light curves of Semiregular and Symbiotic variable stars from the “MEDÚZA” list. Use both visual observations and CCD measurements. Construct the light curves using your own and archival data.