A Crab from polluted waters

All,

I ran some tests with the 253mm f/4 on the AP1200 mount and used the
ST-7 from my backyard. This really started out as guiding tests, trying
some different techniques that enabled the system to calibrate and track.

http://www.celestial-images.com/Imag...0s-LHaRGB.html

As I said this started out as an experiment but the tracking was
excellent considering the 25mph wind gusts. Since I was using the
internal guide chip the Ha filter presented some extinction so the
guider integration was 10 seconds.LHaRGB image 4x600 seconds with 2
extra Ha subs added in. originally took 23 subs and one was lost due to
the gusty conditions. The Ha data was combined with both the luminance
and red data before the final color stack. Pretty severe gradients but
GradientXterminator really did a great job in lessening the impact from
my mag 3.5 backyard.skies. Basically just levels and very slight curve
stretch and a very mild unsharp mask on the Crab itself. I was quite
surprised to find that I easily caught the Mag 16 Pulsar progenator of
the Crab itself. Surprised me.

No Coma Corrector used in this example so the corners suffer a bit but
the small chip helped that. This was a fun target in that it really
benefited from the Ha Data.

Oh yes .... since the image scale is 1.84 arc sec/pixel and the maximum
guider error was .2 pixel as reported from Maxim this was sub arc second
guiding.... Assuming I did the math right.

Regards

Bill

William R. Mattil a écrit :
All,

I ran some tests with the 253mm f/4 on the AP1200 mount and used the
ST-7 from my backyard. This really started out as guiding tests, trying
some different techniques that enabled the system to calibrate and track.

http://www.celestial-images.com/Imag...0s-LHaRGB.html

As I said this started out as an experiment but the tracking was
excellent considering the 25mph wind gusts. Since I was using the
internal guide chip the Ha filter presented some extinction so the
guider integration was 10 seconds.LHaRGB image 4x600 seconds with 2
extra Ha subs added in. originally took 23 subs and one was lost due to
the gusty conditions. The Ha data was combined with both the luminance
and red data before the final color stack. Pretty severe gradients but
GradientXterminator really did a great job in lessening the impact from
my mag 3.5 backyard.skies. Basically just levels and very slight curve
stretch and a very mild unsharp mask on the Crab itself. I was quite
surprised to find that I easily caught the Mag 16 Pulsar progenator of
the Crab itself. Surprised me.


Nice picture for a test

--
Norbert. (no X for the answer)
======================================
knowing the universe - stellar and galaxies evolution
http://nrumiano.free.fr
images of the sky http://images.ciel.free.fr
======================================

On 2006-11-04 23:33:56 -0500, "William R. Mattil"
said:

All,

I ran some tests with the 253mm f/4 on the AP1200 mount and used the
ST-7 from my backyard. This really started out as guiding tests, trying
some different techniques that enabled the system to calibrate and
track.

http://www.celestial-images.com/Imag...0s-LHaRGB.html


Pretty darn good IMHO!