I was really having some fun last night.  Two nights ago I took 4 photos each with 2min exposures spaced by a 3 min separation period.  If you look at the photo you will see that I did take a picture of the planet Pluto at 3 Billion miles away, even though among all of the stars Pluto only has the reflected light from our sun.


Am I sure that I have the right dot?  Yes, and that was what the excitement was all about.  I have discovered some new sophisticated astrometric measuring tools within my growing suite of astronomy software.  I was intentionally taking multiple photos to use a blinking comparator.  The idea was… with autoguiding, the stars do not move but the planets do move, so that I could pick out Pluto by using a Blinking Comparator.  I later read, however, that while this technique works great for finding minor planets and asteroids, each picture needs about 45min of separation.  So mine were too close and showed no movement for Pluto.


So I used an alternative method last night.  Each photograph carries a great deal of information in the header of the .FIT file which is produced by the CCD camera.  This not only includes the exact date, time, exposure information but it also includes the camera’s celestial coordinates (Right Ascension and Declination) and much more.  I have software which produces a virtual image of the sky for any time and date (past or future).  This virtual image of the sky is zoom-able to almost any distance that is necessary for measurements.  The really cool trick that the software was able to do is to overlay the actual photograph (given the date, time and coordinates) onto the virtual sky and exactly fit the two images.  It takes about a 6 star match to call it a successful overlay, I had 403 matches.  So for sure my photo was in the exact right place on the virtual (and fully known) night sky.  Once this matching was complete I had 403 known star locations on my photograph,.  Also the cursor position now revealed precise celestial coordinates as I moved my mouse over the photograph.  By looking at the exact position of Pluto on the virtual sky at the moment of the photo I could see the expected RA and DEC coordinates of Pluto.  By moving the mouse over the photo and reading the coordinates within the photo I located Pluto.  I was then able to double-check and verify it by verifying the coordinates of the neighboring star images.  As a final (third) confirmation I was also able to verify the expected and actual magnitude of brightness for both the neighboring stars as well as for Pluto itself.  So without much doubt, the line in the picture points to Pluto.  Pretty cool?


Now if I had a few hundred hours to spend under clear skies, maybe I could find some new Asteroid or Minor Planet which I could name as… “Joanna.”

May, 2005