Abstract
I report photometric measurements of HD 209458, an extra-solar planetary system known to have an orbiting Jupiter mass planet from radial velocity measurements. The star has been observed with a 10'' Meade Schmidt-Newtonian LXD 55 telescope and a thermo-electrically cooled Nikon Coolpix 995 CCD. I detect two full transits at projected transit times defined by radial velocity measurements. An accuracy of +/- 0.01 stellar magnitudes has been achieved using the equipment described. The primary data analysis procedure used in the determination of stellar magnitude is differential aperture photometry. Also presented are derived values for the diameter of the extra-solar planetary disk. The photometric dimming observed, attributed to the transit of a planet across the stellar disk, is consistent with past photometric measurements made by considerably large observatories (Hubble, Keck I) and provides one of the first small aperture extra-solar planetary detections to date. Sponsored in part by a grant from the Southern California Academy of Sciences and cooperation from Meade Instruments Inc.