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View Full Version : Discussion: Astrophoto: Pluto by Charles Bell



Fraser
2005-Jul-08, 05:14 PM
SUMMARY: Charles Bell demonstrates that amateur astronomers can photograph Pluto with their backyard telescopes. Charles used a 12" Meade 200LX-GPS with a 120 second exposure.

Do you have photos you'd like to share? Post them to the Universe Today astrophotography forum or email them to me directly, and I might feature one in Universe Today.

What do you think about this story? Post your comments below.

damienpaul
2005-Jul-08, 05:52 PM
Hey, nice work Charles!!!

Greg
2005-Jul-09, 04:26 AM
I had no idea pluto would be visible to an amateur scope. It must not have been easy to spot it.

CharlesBell
2005-Jul-09, 04:07 PM
Thanks for the comments and interest.

Imaging Pluto has been a goal I have been purusing for many months. Pluto is low in the sky from my setup location and trees are always a problem when I want to go after a particular target. Just getting it into the field of view of the scope and then centering it is complicated. There are always lots of other uncontrollables like clouds and haze. The humidityy is very high in the early morning. I resorted to a hair dryer to keep the front end corrector plate free of dew so I would not have to fight dew heater cables in the dark.

To get a precise slew to a dim target, I center a brighter star dead in the center of the camera field. Then I do an object synch with the scope's autostar hand controller. In this case I used the star Sabik, or Eta Orphiucus. Then I slew to Pluto and do 30 second unguided shots in focusing mode with the CCD camera.
I compare the pattern of stars in the focusiing images to what I have showing in the field of view indicator of TheSky6.

I use the Rotate tool in TheSky6 to turn the display upside down and select "mirror view" so The Sky screen is oriented just like the camera (North down, and east to the left).

TheSky6 shows stars down to magnitude 16, 17, or 18. With all the practice I have had locating faint comets in recent months, this has become a little easier. I have lots of imaging attempts at Pluto that turned out to be off by a field width or more.

Sunday night I moved my scope so I could get a better longer view when Pluto came around and I stayed up all night to make sure I got it right this time. I had a sodium vapor streetlight to my back which relfected light off of my garage and into the scope. This got worse after I started my imaging. The first image was a 120 second exposure and was the best one. I had to back down to 90 second shots because of the neighbor's street light. Normally I am on my back porch shielded by surrounding trees and my house. Its very dark there.

The rest was just normal image processing. The noise in these images was very high.

But Pluto was very obvious and was in the exact location TheSky6 showed. I also used Astrometica to do an astrometry calculation of Pluto's position. Astrometrica uses the USNO-B1.0 catalog.

Detailed Description of the USNO-B1.0 Catalog (http://vizier.u-strasbg.fr/viz-bin/Cat?I/284)

It generated the following report line:

Pluto C2005 07 04.24860 17 29 35.32 -14 59 59.2 14.1 V

showing perfect agreement with the location calculated by TheSky6.
Astrometrica showed a magnitude (14.1) very close to TheSky6.

I also put vertical and horizontal tick marks on two images shot an hour apart using different colors, then stacked them with Registax, aligning on a prominent near by star. The stacked image showed a small westward retrograde movement of the planet just as it should.

http://www.quantumhyperspace.com/imagefiles/Pluto-Comparison-0557-0707.JPG

Deep Sky Survey images did not show anything at the location I had a small dot on. I use the Aladin Previewer for image comparisons.

Aladin Previewer of location 17 29 35.32 -14 59 59.2 (http://aladin.u-strasbg.fr/AladinPreview?17%2029%2035.32%20-14%2059%2059.2)


I was sure then that it was the real thing.

Greg
2005-Jul-10, 04:19 AM
Thanks for the tips, I am sure to put some of them to good use. Since I moved to northern NH from Philadelphia I have been intrigued by astronomy ever since I realized that I actually could see stars in the night sky that is fairly free of light pollution and particulate pollution.

Nick4
2005-Jul-27, 03:01 AM
Good job. I want to get a camera for mine so i can make some pics.