On Thursday night, 9/10/09, Mike Paquette and Randy Buchwald tried some webcam imaging of Jupiter using the Harken 12” scope.
A webcam is the same thing that you might have attached to your PC for Skype video contacts. While it is not as sensitive to light as the other cameras at the observatory but it is capable of continuously streaming frames to an AVI file on the computer. At 30 fps, those 2700 images may be grabbed in just a minute and a half. Jupiter is plenty bright to show up well using a webcam.
By using special software called Registax4 (freeware!!! Read about it at http://www.skyandtelescope.com/equipment/news/RegiStax_4.html ), one is able to select only the best frames when seeing is best, align and stack them into a better combined image. Registax4 also includes some image filtering and adjustment capabilities.
We collected two AVI files. One was set to expose the planet. Another used a longer exposure to visualize the moons Callisto and Io. The two images were then combined into the image below. We are happy to share the results! Too bad the great red spot was not on the visible side. Maybe the next time!
Comments Welcome!
At what focal length was the image taken? Did you use any barlow lenses? Did you spend a lot of time focusing? I think you did a great job capturing details in the cloud bands!
The webcam was mounted at the prime focus of the Meade LX200GPS scope. It has a focal length of 3048mm. No barlow lens was used. (Actually, we first tried to use a barlow, but it caused the focus to be more critical and produced an image of Jupiter that was so large that we could not avoid some dust defects on the CCD device.) The webcam used was a Creative Live! Ultra (model number VF-0060) that was modified by removal of the stock lens which was replaced with a 1.25” T-adapter. It has a 640 x 480 pixel CCD sensor. There are about 110 pixels across the equator of Jupiter (about 48 arc-sec) in this image.
Focus was a little time consuming but the Meade micro focuser in slow mode was helpful. We focused for best sharpness on the cloud bands and smallest appearance of the moons. Registax selected the best 700 frames from over 3000 frames. Very little wavelet filtering was applied.