Finding Asteroids in Exoplanet Data By Eric J. Roebuck

STEPUP Survey of Transiting Extrasolar Planets at the University of Pittsburgh The type of observable transiting planets tend to be constrained to 'Hot Jupiters' for ground based observations. Our picture of exobiology suggests we probably won't find anything living there. http://www.cosmosmagazine.com/files/imagecache/news/files/news/20100414_hotJupiter.jpg

Transit Timing Variation If we measure transit timing very precisely we could potentially imply the existence of other bodies in the system.

Ground-based multisite observations of two transits of HD 80606b A Ground-based multisite observations of two transits of HD 80606b A. Shporer et al., ApJ 2010 We collaborated with 9 other groups to help capture a very lengthy transit.

Difficulties with Collaboration Telescopes and observatories have unique ways of time- stamping images. Therefore images taken from different places may have inconsistencies in timing.

Wouldn't it be nice...? It appears that precise timing would be useful for both: Finding perturbations in transit timing. Collaborating with other groups.

ASTEROIDS!

Asteroids! If our images are within ecliptic latitudes of -50 and 70 degrees we would expect to have asteroids hanging out in our images. The problem is that asteroids are dim. Asteroids are well documented. Therefore if we can find an asteroid we can get a very accurate time for which the picture was taken.

Shifting and Stacking Professor Wood-Vasey proposed that if we shift our images to mimic the motion of asteroids in that field, then stack images, we can see asteroids down to 22 magnitude.

Simulated Asteroid using STEPUP data. Precise timing of Heterogeneous Exoplanet Transit Observations Using Unseen Asteroids M. Wood-Vasey

My Project My goal was to attempt to verify this method using actual data. This required the following things: First find data we currently have that happens to be close enough to the ecliptic. Find asteroids that ought to be found in that data. Shift and stack the images based on asteroid data found and check for asteroids.

Obstacle 1 Our images shift throughout the night. The Meade RCX telescope drifts as it follows a guide star throughout the night. This is usually unpredictable. I therefore, using the astrometry already done during analysis, I calculated the motion in reference to the first image taken to include when shifting.

Obstacle 2 Orbital Motion is very difficult to calculate. The goal was to verify the method, and there were time constraints, so to save time: I first found an asteroid that lived in the field of view of one of our targets, courtesy of the NASA Jet Propulsion Laboratory, and then found its position at several points in time. Using the astrometry calculated in the exoplanet analysis I converted those positions to x & y pixel values, then computed a rate of change. By simply taking the recorded date from the headers of our images I could calculate how much the asteroid would shift from image to image.

Let the Shifting Begin As you can see, no asteroids can be seen. BUMMER DUDE!

What Went Wrong The data chosen only appeared to contain 1 asteroid with our given constraints of position and magnitude. Weather toward the end of the semester didn't leave very many opportunities to obtain better data. Sky reduction would certainly have made the image nicer to look at. This stack is only comprised of 34 images. A more precise method of calculating shifts would reduce error.