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Contains:  NGC 5195, Whirlpool galaxy, M 51, NGC 5194
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M51 Whirlpool Galaxy, 





    
        

            Michael Southam
M51 Whirlpool Galaxy

M51 Whirlpool Galaxy

Technical card

Resolution: 3119x2261

Dates:Feb. 20, 2015

Frames: 115x45"

Integration: 1.4 hours

Avg. Moon age: 1.75 days

Avg. Moon phase: 3.41%

Astrometry.net job: 564379

RA center: 202.469 degrees

DEC center: 47.196 degrees

Orientation: 86.708 degrees

Field radius: 0.229 degrees

Locations: Rolnick Observatory, Westport, Connecticut, United States

Description

This image sums up how much I’ve learnt about astro imaging and processing in the last year.

M51 was one of my first targets last year and the result was less than pleasing. I made the background far too dark and had great difficulty highlighting the bridge. The problem essentially was that I hadn’t heard of PixInsight. I also took far too few subs. Both issues have been rectified here.

I took 100 x 45 second subs and 15 darks. I did have significant difficulty stacking though. On the first attempt I got the old ‘cannot integrate less than 3 frames’ In short what that means is that PI couldn’t register the frames on account of not finding stars. The reason for this took me 3 more attempts to resolve which when each stack takes many hours, means 3 more days. I did search the PI forums for the answer which led me to adjust the Image Registration Clamping Threshold for the second attempt at stacking to no avail. For attempt 3 I remembered that noise had been the issue last time this happened so I tried upping the Noise Reduction setting from 0 to 1. I thought this had worked but when I looked at the script closely, I noticed that only 17 of the 100 frames had been successfully integrated after 7 hours of processing. I upped the Noise Reduction to 4 and managed 80 integrated frames after 10 hours of processing. I settled for that and the result was close to the final image you see here. A few minutes removing the gradient and adjusting the histogram in PI and I moved the image over to PhotoShop. There I adjusted Levels, Curves, Color and Contrast and that was all it need.

This is my favorite image to date for a few reasons. One reason being the improvement from my last attempt at M51 and the second because I ended up with a very natural looking image with very little manual adjustment.

Comments

Author

msoutham
Michael Southam
License: Attribution-NonCommercial-ShareAlike Creative Commons
5442
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Revisions

  • M51 Whirlpool Galaxy, 





    
        

            Michael Southam
    Original
  • Final
    M51 Whirlpool Galaxy, 





    
        

            Michael Southam
    B

Sky plot

Sky plot

Histogram

M51 Whirlpool Galaxy, 





    
        

            Michael Southam

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