Friday, March 1, 2013


After a little over 2 years of deep sky photography my interests have turned to Variable Stars and Extra-Solar Planets.  Since November I've been working on creating a light curve for an Eclipsing Binary Star with my DSLR.  My original plan was Algol since its nice and bright and could probably be captured with a simple tripod mounted DSLR. In addition Sky and Telescope has a nice calculator for the minimum ( As I soon found out the nearly 3 day period made it difficult for me to arrange to photograph. Because of work I could only do imaging on the weekends so I was looking for a minimum on the weekend, obviously in the evening and with good weather.  As it turned out, this winter has been terrible in terms of cloud cover.  And the weekends that were clear also tended to be devoid on Algol minimums. 

My alternative was to focus on faster period stars so I settled on the moderately faint W Ursae Majoris.  Not only did this star meet the faster period requirements I wanted (8 hours) but during the winter it was also high in the sky and would be up all night. 
It took about a month to finally get some clear skies but after I found some decent skies the actual data gathering was quite quick. After two consecutive Saturday evenings I was able to gather enough data to produce this light curve:

This was made before I thought to put the orbital phase on the x-axis so the two different nights are represented in different colours.  Its a pretty straightforward light curve that easily shows the minimum of W UMa. The magnitude of W UMa is nearly 8 and varies by just over half a magnitude.  Considering the tools I'm using (an uncooled Canon DSLR) I'm fairly happy with the results.  Over the past few weeks I've gotten much more interested in extra-solar planets and I'm going to see if I can apply the same methods to detecting exoplanet transits; I can across and interesting group that is doing almost that very thing:

However before I get to into this next project I need to see if my camera is up to the task.  For W UMa binary stars the change in brightness is around 0.50 - 0.75 magnitudes.  For extra-solar planets the most I can expect is around 0.0030 magnitudes.  I'm not convinced that change in brightness will actually be above the noise level of the camera's sensor.  So next up will be the test of the noise levels of the Canon T3i.

Stay tuned!

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