Saturn So Far

by Matt Allard and Philip Steffey

 

The ringed planet, ideally located in our cool-season skies for several years, has been a more difficult than expected subject for video imaging since our first observations with B-CC's 14-inch telescope and an Orion "electronic eyepiece" (camera) in early 2003. Bad luck has been a major reason. Fair streaming images from the first session were improperly recorded and could not be cleanly "paused" for stills. The second session occured during a developing cold night, causing poor "seeing" that was compounded by upwelling Science Building heat, and the resulting images were too blurry to be rescued by digital computer processing. In early 2004 a newer model of the Orion camera (i.e. the Observatory's own), with better sensitivity control, produced weak and overly red images, due we believe to use of internal 9V battery power rather than AC-to-12V in the first Orion camera. (See earlier article on this Webpage.) Poor late-season weather and distractions prevented our pursuing this problem, and acquisition of the much more sensitive and versatile Polaris camera relegated the Orions to secondary usage status -- still capable, however, of yielding superb lunar and solar images.


Just before Christmas, 2004, we imaged Saturn with the Polaris for the first time. The planet's altitude was low, the "seeing" lousy, and the camera probably did not get full electric power due to a wiring defect. The images obtained were blurry but at enhanced camera sensitivity (12 times minimum) satellites were recorded, which is impossible for the Orion camera. Two raw Flash-It-captured images and corresponding processed ones are shown in the first picture following this text. On January 7, 2005 (local date, PM) the planet was higher and the "seeing" better, but after capturing a few fair images the camera power wire broke due to a soldering flaw. The best image with some details indicated is reproduced in the second picture set below. Seeking more raw images than can be captured from the computer screen with Flash-It, on February 11 we videotaped Saturn at 154 inches focal length for 21 minutes, getting several single-frame images better than any to date, despite mediocre "seeing". Computer processing didn't improve the images much. Five satellites including Enceladus were recorded at enhanced camera sensitivity, though the single-frame images are blurry. See the third picture set below. (Titan was outside the frame field in the satellites picture.)


On March 4 we finally got Saturn high in a clear, dark, steady sky for about an hour. In an eyepiece giving 100X the image was razor-sharp; Enceladus, near inferior conjunction, was easily seen. The camera's VHS output went to the computer, and video images were run on the Apple Video Player. For the first time we recorded two short movies, which haven't yet been fully examined, as well as Flash-It stills. The fourth picture set below reproduces one of the planet made at 154 inches telescope focal length plus an image of the overexposed planet with five satellites. Clearly both are superior than any of our previous images. We also imaged and recorded the planet enlarged 2X with a Barlow lens. The best Flash-It captured image is somewhat out of focus and may or may not sharpen well with computer processing, but its brightness is impressive and there may be sharper images in the movie we made. (Incidentally, this enlargement exercise exposed a nagging deficiency of the C-14: lack of fine-focusing capability.) Finally, we replaced the camera's VHS output with S-video, which the computer accepts but our TV monitor doesn't. The normal-scale (154-in.f.l.) video images on the computer's screen did not appear better than VHS images, but the "seeing" was deteriorating and in any case a careful comparison of playback quality is needed.

This last observing session brought us to a stage in our videography where the quality of our display and recording software is a major issue. The Apple Video Player's moviemaking feature records only sample frames, averaging about 15% of the total. Still-frame captures with Flash-It, at 1/10 second (?), must in many cases blend two or three video frames (1/30 sec. effective exposure time), degrading image sharpness in one way or another. Such captures from Quicktime or SimpleText playbacks are similarly suspect but the degradation effect is uncertain at present. Videotaping gets all the frames but presently limits us to VHS recording quality, notably spatial resolution about half what camera-to-computer can provide. We can rerecord a videotape on a CD but only with assistance of experienced B-CC personnel, who are not regularly available. Also, CD copying apparently reduces image quality. To get around at least the bulk of these limitations, we are contemplating installing a full video moviemaking and editing program on our computer to take real-time camera output, e.g. Avid Videoshop which one of us already has. But this will be a slow development as we don't yet have the skill and experience to use such rather complex programs.

 

 

 


 

Written March 10, 2005

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