From: "Duane" <macastronomer@mac.com>

Date: February 11, 2006 1:48:29 PM MST

To: Astro_IIDC@yahoogroups.com

Subject: Re: Saturn at Opposition

Alan, your lunar shots on nasa's site are spectacular. David Illig just posted links to it in 

macastronomer group.

Is that an older shot or a recent one?

Duane

--- In Astro_IIDC@yahoogroups.com, Alan Friedman <alan@...> wrote:

Hi Duane -

I believe Milton posted a link to Wes' web index in an earlier post. He 

is an active participant in the Astromart Planetary Imaging forum 

(which is a great forum for this topic, BTW). His lunar work with an 

18" Starmaster is the best I've seen from this planet.

I thought I would copy a post I made earlier today on the Astro-Physics 

forum. Seeing is huge, no doubt - but be sure to have a look at 

Damian's mars images from the UK in average - good seeing. There is 

hope short of lugging all your stuff down south!

I hope to have a website live by the end of this month - thanks for 

asking.

cheers-

Alan

ps - the whiner I refer to in my post below is me, not you!  8^)

-----------------------------

Hi Milt -

I think your comments are a good summary. In planetary imaging, seeing 

is still a

critical factor - but it factors differently than in visual because you 

can pick the

image apart into 33ms bits, choose the good ones and eliminate the bad 

ones. In

this way, the seeing is not a monolithic experience. In virtually every 

stream there

are images typical of 6/10 seeing and 3/10 seeing - the question is how 

many are

of the 6/10 variety in a period of time before features move and can no 

longer be

averaged to reduce noise. The Pickering scale as we use it for visual 

observing

does not really work well to describe limits for planetary imaging (I 

wonder how

many imagers begin and end their sessions with a star test - poor, 

fair, good, very

good might be just as useful).

While we often talk (and whine) about the seeing conditions it is 

important to

remember that very good imaging results can be obtained in fair-good 

seeing (5

-6/10). You need enough aperture for adequate light to record with a 

long focal

length. Assuming good processing skills, in conditions where 600 frames 

at 6/10

quality can be gleaned and averaged, the postion of the Encke division 

will be

recorded over a good section of the ansae of saturn's rings.

These conditions can drift in and out many times over a 30 minute 

observing

session and can be found during some part of the night in almost any 

location. A

big part of the challenge is getting out frequently enough to catch 

them. Damian's

images are truly spectacular - also remember that he has been out to 

image mars

more than 100 times during this apparition.

steady skies!

Alan

 ---------- Original Message ----------------------------------

From: "wilcoxmilton" <wilcoxmilton@...>

I guess the difference must be that in imaging you get to stack so

many frames (hand picked?) that it effectively neutralizes the effects

of mediocre seeing?  At the eyepiece, I find it extremely difficult to

mentally register the detail available in brief moments of clarity (I

know I am not in the skill class of many of the visual planetary

observers here).