From: "Alan Friedman" <alan@greatarrow.com>

Date: March 25, 2007 12:43:57 PM MDT

To: Astro_IIDC@yahoogroups.com

Subject: Saturn from the first hours of spring

Hi all -

Here's a first processing of Saturn captured with the 10" mak on March 20th in a nice little 

pocket of steady air that arrived just after the vernal equinox. (Follow the thumbnail link to 

the picture from the "Latest Images" section of my website) -

http://www.avertedimagination.com/latest_1.htm

I found (with help from Milton!) four moons lurking nearby, so I stretched the image 

enough to bring them out and included them in this picture.

This image was prepared using the image processing component of Astro IIDC. The data 

used was captured through RGB filters - 3 streams each of R and G, 2 streams of B. About 

350 frames of 1200 were stacked from each stream. Each stack was aligned four times, 

two for the ring ansae and two covering the edge of saturn's disk. Final assembly of the 

picture is done in Adobe Photoshop CS2. This was my first real effort at developing a post 

processing workflow in Astro IIDC - it worked beautifully on this data and saved a BIG pile 

of time over my usual hand selection routine.

Usually I glean my luminance (detail) information for Saturn from video streams shot 

without a filter. At the focal length I prefer (8-11 meters) the RGB filters absorb so much 

light that a slow shutter (66ms or even longer) is needed. These streams tend to be either 

grainy and dim, or very soft if given an adequate exposure. This night the seeing was 

good enough that the data was sharp even with exposures above 1/10 of a second. I was 

able to stack a third of the RGB frames for an image that was quite smooth and didn't 

require heavy processing. I sharpened the final image by making a luminance layer from 

just the red and green data and added this to the color composite - a technique I have 

used for a couple of years on (much brighter) Jupiter. I would guess the seeing approached 

8/10 at times - a hint of the Encke division was visible in the blue filtered data - quite 

unusual from my location.

I still have a pile of unfiltered data to go through and perhaps add. I don't think it will 

show any additional detail (there were no spots or storms that I could detect) but it will 

probably make the final picture a little smoother and prettier. 

Hope you enjoy this first working version -

Alan