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HD 189733, also known as V452 Vulpecula (the Fox), has a Jupiter sized planet (HD 189733 b) whose orbital plane is aligned with us. This means that it "transits" or crosses in front of the parent star causing a light reduction from the star of somewhere between 2% and 3%. This reduction can be measured from here on earth and the planet is "detected". (Actually taking a picture of this planet is not possible). HD 189733 is 63 light years away and is a magnitude 7.7 star. It is just 20 arc minutes East of M27 the Dumbbell Nebula.
The plot below is relative intensity from a blizzard of individual images over a three hour period on the night of 20/21 August at the 2009 Oregon Star Party. The plot shows the light dip for the two hour transit event centered around 12:28 am. The data drop out (gap) on the left was a pier flip problem and a mad scramble to untangle and re-point the scope.
The images were taken with the ST-8E camera at f/5 on the FSQ 106N . They are full spectrum / clear filter images (as detailed below). Calibration and photometry (intensity analytics) were done in MaxIm DL. Each data point in the chart above is also a moving average of 13 points. This smoothed the data some. A composite of all the images is below. The brighter looking star in the middle is HD 1897330. M27 can also be seen.
Image details are below. The center 1/4 subframe was chosen to speed up downloads and cram more images into the session. Also, the auto-guider was not used. I did not want to have small image shifts during the exposures. Instead, I plate solved each image for its sky location and fed that back to the scope in-between images. Basically, the individual images each "guided" the session.
Filter |
Exposure | Count | Binning | Subframe |
Clear | 10 sec | 376 | 1x1 | center 1/4 |