Mac.Period & Mac Chart

A robotic telescope observes starfields looking for stars whose brightness varies. It takes pictures of the fields when the weather is good and the field is in a good position in the nighttime sky. It has discovered 81 eclipsing binary stars. Congratulations! You get STAR100. Your first job is to use the Mac Chart tool to discover which of the stars in the field is actually the eclipsing binary - it's a puzzling problem. Your next job is to use the Mac.Period tool to measure the orbital period of the eclipsing binary to 6-digits accuracy. Once you learn how to deal with STAR100, there are 80 others you can try if you want to.

Dates of Minima

A robotic telescope measures the times of eclipse of a group of eclipsing binary stars. Congratulations! You get var200. Your job is to determine the orbital period to 6-digits accuracy from the dates of minima. Sounds easy, but it's a tricky business! Once you learn to deal with var200, there are 24 others you can try if you want to.

Binary Star

You have been granted the powers of a god -- complete control of your own personal binary star. Six panels display everything you ever wanted to know about a binary star: overhead view, view from the Earth with a super-gigantic telescope, light curve, radial-velocity curve, Hertzsprung-Russel diagram, and mass-radius plot. Animate the figures. Change the values of the parameters and immediately see the effects on every aspect of your binary star. Try fitting the parameters to simple practice data sets, then when you're ready, try out some real eclipsing binaries (10 real binaries are provided).


Transiting extrasolar planets have recently been discovered, adding to the total of more than 80 discovered mainly by the Doppler technique. Much can be learned by analyzing the light and radial velocity curves of the exoplanets, and now you can do it for yourself. You have control of the physical and orbital parameters of the exoplanetary system and can manipulate them to match the observations and break the code! 15 sets of observational data are provided, including the first discovered transiting exoplanet, HD 209458.

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