Celestial hemisphere:  Northern  ·  Constellation: Canes Venatici (CVn)  ·  Contains:  M 51  ·  NGC 5194  ·  NGC 5195  ·  Whirlpool galaxy
M51 Whirlpool galaxy, Artūras Medvedevas
M51 Whirlpool galaxy
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M51 Whirlpool galaxy, Artūras Medvedevas
M51 Whirlpool galaxy
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Equipment

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Acquisition details

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Description

Disclaimer first- this was imaged from the middle of a city surounded by streetlights and I no longer have astrodark, so it was only nautical dark. SQM reading was ~18.9 at best.

Alright, this one was not planned and was not expected, just decided to go out and test my 10" 1200mm FL skywatcher newtonian scope with CCD and how mount will handle it. I used to image with it with DSLR, but now I'm way less tolerant to mount hiccups and collimation, so this was quite the test.

Overall, I'm immensely pleased with the result, it's way beyond expectations. 2.5hours of guiding was 0.77" RMS which is even with shorter FL very nice indeed, so this suggests that I can plan to image small stuff in the future with this scope as mount will handle it

This test wasn't without issues though. First one was that the steel tube is bending near the focuser which results in miscollimation. I managed it a bit by hanging similar weight to CCD on the focuser drawtube and collimating only then, but lower left of the image still exhibits some weirdly shaped stars.

Another issue was that I planned to get some Ha frames (still do), but focus point was way off, then SGP autofocus got confused, tried to refocus it, find where is the focus point, but with Ha filter stars are quite dimm, so fiddled with it for 30-40mins and ran out of what little dark sky I had.

One more thing I tried doing this time was to see how 2x2bin RGB frames work with 1x1bin L frames. Overall- I think it worked just fine, I might continue this path for a bit in the future, or maybe just test some more and get same amount of RGB frames with 2x2bin and 1x1bin and then process both to see how they compare.

Processing created some unique challenges too. My flats were burned out for R and G frames (no idea why, probably somehow flats calibration wizard failed), so used B flats, which did not correct well, so had to use DBE extensively. Another issue was R frames showed severe reflections of some kind (probably from all the streetlights and inside of the tube not baffled/flocked) http://i.imgur.com/iiwWyqQ.jpg it is surreal. I managed to work around it by lots of manipulations with stretching, blurring and clone stamping with variety of masks.

More details on my website

Comments

Revisions

  • M51 Whirlpool galaxy, Artūras Medvedevas
    Original
  • Final
    M51 Whirlpool galaxy, Artūras Medvedevas
    B

B

Description: Added H-alpha to the galaxy, which changed color overall, also I saturated everything a bit less. Overall I really love those Ha regions in M51, they are so so strong.

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Sky plot

Sky plot

Histogram

M51 Whirlpool galaxy, Artūras Medvedevas