Serendipity: Finding an Asteroid

The research group that I am a part of (Pat, Paola, Laura, and myself), proposed to the Canada-France-Hawaii Telescope (or CFHT) earlier this year to get some photometry covering a rather large section of sky. We wanted this data so that we can look for variability in the colours of quasars. Our proposal was accepted, and we have been getting data starting August 2012 through to now; you can see my blog posts on the data releases here, and here, and here, and here. The point of the project is to take images of a large section of sky in three different filters. Therefore the entire area we asked for will be imaged 3 times: once in g, once in r, and once in i.

I’ve spent my time with this data measuring magnitudes of quasars in these pass bands to look for changes in colours (compared to colours measured years ago). In order to properly measure a magnitude you need to use comparison stars (this relates to how you correct for your aperture, a post on that stuff in the future). As I was looking for a good comparison star in this particular section of sky, I noticed one ‘star’ was moving! After showing my colleagues (Lianne and George) we realized quickly we were looking at an asteroid. You can see it moving across the sky here:

This is exactly how you hunt for things in our solar system (asteroids, comets, etc.): by taking multiple images of the same section of sky and seeing if anything moves. The 3 images here are separated by about 25 min each. So in about an hour’s time the asteroid moved the distance you see there, which is a few arcminutes. Thanks to Lianne’s (@liannemanzer) investigations, we found out that, sadly, this asteroid has already been discovered (so we can’t name it after ourselves!). But it was fun to find something like this in my data!

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