[APML] M51 & M97

["Brian Lula" <brianl@polytecpi.com>]

Hi,

Tony's M51 was an inspiration to all imagers to go deeper than usual to extract as much 
info as possible in the image field. I was intrigued to see how deep I could go in my 
moderately light polluted area near Worcester MA. Limiting magnitude is 4.9 - 5.0 at my 
site in the area of M51 reducing to about 3rd mag  25 degrees above the horizon in the 
south. Seeing was about 6 the night I took these images with transparency about 8. I took 
the images just after Tony posted his luminance image I but it took me a long time to get 
my M51 image to a half decent point and post today. 

M51 and M97 are both (L)LRGB's with 90:24:24:30 minute respective total exposures using 
10 minute individual exposures for the L frame in 1x1 bin mode and 5 minute individual 
exposures in the RGB frames in 2x2 bin mode. The L and RGB's were combined in MAXIM 
using average and bicubic resampling for each set.The luminance for M51 was also slightly 
DDP'ed ( custom setting of 20) and 0.8 gamma stretched before importing into PS6for 
further curve work. Both images were (L)LRGB' in Photoshop using the double layering 
techniques that Rob Gendler prepared on his website with considerable lassoing, 
feathering, curve adjustment and star shaping ( thanks Matt!) techniques used to enhance 
local features. 

M51 is almost a full field image using a Finger Lakes IMG6303E CCD (2K x 3K x 9 micron 
pixels) camera on my 20" homemade F/4 Newt while M97 is a subframe. 

I tried the "Mike Cook" technique on both images today to reduce the "fat" stars using the 
radius at 1 and adjusting the fade to somepoint between 40% and 70% but noted it also 
eroded finer detail in the spiral arms and eliminated faint stars. Bloated stars are one of my 
biggest challenges in imaging and I was hoping for a silver bullet fix. Are these effects 
expected or did I do something wrong in the execution?

You will note some astigmatic effects in the stars images on M51 from the cooldown 
problems with the 20" pyrex Galaxy primary as it chased thermal equilibrium all through 
that particular night. 

The new images are at:

http://www.heavensgloryobservatory.com/Color_Jpegs/m51FRGB04-6303Eweb.jpg

and 

http://www.heavensgloryobservatory.com/Color_Jpegs/m97FRGB01-6303Eweb.jpg

M97 shows additional faint galaxies through the nebula in addition to the 6 stars that form 2 
distinct triangles.

I had considerable problems to remove the magenta from the HII regions in M51's arms. 
Any ideas how to accentuate these with more "accurate" color?

Thanks, Brian Lula





Brian Lula
Polytec PI, Inc.
(508) 832-3456

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