From: Milton Aupperle <milton@outcastsoft.com>

Date: July 2, 2010 10:19:54 AM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Re: [Astro_IIDC] Jupiter on July 2

On 2-Jul-10, at 6:55 AM, jimchung2338 wrote:

Now that the days are getting shorter I was able to image Jupiter at 5 AM just before full sunrise and at about 40 degree elevation.

http://dl.dropbox.com/u/4852049/JupiterJuly2.jpg

Seeing was fair to good.  However AstroIIDC seems to have a hard time accurately ranking the sharpest frames.  Since there was the convenient shadow of Europa I was easily able to hand select the best frames but it is a very tedious operation.  Often there will be completely blurred images ranked much sharper than ones appearing a hundred images below??!!

Without your movie capture logs, the stacking logs and a sample frame, I have no point of reference for specific suggestions, I also have no idea which version of AStro IIDC your talking about either.

1) Do you have a single frame unprocessed image showing how noisy the image is (preferably a uncompressed image where jpeg hasn't DCT block mangled the image)? With a soft gasbag like Jupiter that has no edges and low contrast features, high noise levels will be seen as the dominant "sharp" element. You can turn on the noise reduction features when estimating sharpness which may helps.

2) You can try using a wider spacing for the sharpness (only in the latest 4.06.00 Alpha) estimate with the the  "Use xxx spacing when estimating sharpness". It may or may not help and is also subject to noise too.

3) If you have a big enough planetary disk, you may want to try using "Lunar - Solar" gross alignment method rather than the "Planetary" method. That also affect the algorithm used for sharpness measuring too and likely will make a difference.

I wonder if accuracy would be better if one were able to specify only a small area with a sharply defined feature rather than the entire planet?

The issue there is tracking and being able to find this feature that you think is unique. Many people have exceedingly poor tracking and then expect Astro IIDC to "magically" find the block of pixels that can be anywhere (or maybe not even in the frame) and use that. In many cases your pixel block isn't "unique" and can be matched against many other similar blocks, especially when they have cranked the gains up or have very poor periods of seeing.

HTH..

Milton J. Aupperle