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M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah

M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO

Getting plate-solving status, please wait...
M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah

M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO

Acquisition details

Dates:
March 17, 2019 ·  March 18, 2019 ·  March 19, 2019 ·  March 20, 2019
Frames:
Astrodon Gen2E B: 40×180(2h) -25°C bin 2×2
Astrodon Gen2E G: 40×180(2h) -25°C bin 2×2
Astrodon Gen2E L: 23×180(1h 9′) -25°C bin 1×1
Astrodon Gen2E R: 40×180(2h) -25°C bin 2×2
Integration:
7h 9′
Avg. Moon age:
12.39 days
Avg. Moon phase:
92.16%

Basic astrometry details

Astrometry.net job: 2594170

Resolution: 2352x1600

File size: 1.6 MB

Locations: Ben's Backyard, Federal Way, WA, United States

Data source: Backyard

Description

This is M51, the Whirlpool Galaxy, maybe one of the most iconic and famous grand design spiral galaxies of the northern skies. I chose this one as my inaugural image for my new Astro-Physics 1100GTO mount!

Physical Description

I highly recommend Annals of the Deep Sky by Jeff Kanipe and Dennis Webb. Volume 3 has a lengthy section on M51, and I repeat just a few of the facts here that I find the most interesting. M51 is interacting with peculiar galaxy NGC 5195. Charles Messier discovered it on October 13, 1773. The book goes on to tell the tale of William Herschel's observations over the coming years as well as interruption of good seeing due to a volcanic eruption in Iceland. I'll not get into all that here, so go read the book for yourself!

M51 is described mostly as a Sbc-type galaxy. The beautiful spiral pattern shows arms of young, blue stars, interwoven with dust lanes. The center has an oval ring of blue knots, somewhat resolved in my image. Perhaps the most iconic feature is its interaction with nearby companion NGC 5195. Computer models, the first as early as 1972, have determined M51's shape is due to a series of interaction passages and collisions of this companion. It is placed now at 20 kpc behind M51. There is debate as to how many interactions there have been and exactly when.

Acquisition & Processing Description

As stated above, this was my first use of my new Astro-Physics 1100GTO. There is nothing really to be said about the experience other than to confirm what many others have said before me. Once I got everything set up and configured for imaging, the mount ran so flawlessly that I ended up forgetting it was there. I am going to enjoy this mount even more than my Mach1GTO.

There is a grand disappointment with this image in that I failed to anticipate the poor seeing conditions during three of the four nights during which I shot the frames. The first night was only a half night in that I had to wait for clouds to part. I then assumed that I would be getting several completely clear nights ahead, which was true, and that I could devote time to not only aligning and focusing the gear but also taking flat frames in preparation. I then set up to shoot LRGB the rest of the night and went to bed for much needed rest.

Having failed to read the seeing forecast properly, or perhaps getting suckered in with overly optimistic predictions, I then set up LRGB the next several nights and was disappointed to discover that the first night was good seeing, followed by poor seeing the next several nights. Had I been paying better attention, I would have devoted as much time as possible to getting L frames that first night, and then just taken RGB the following nights.

As a consequence, I have just over an hour of L data, which is devoted to detail resolution, and then lots of time, much more than probably needed for this image, to the color, 2 hours each channel. I tried to use the L data from the subsequent nights, but those nights were just so much poorer. The stars the first night averaged about 1.6" FWHM, whereas they were upwards of 3 - 4" the next nights. Ugh!

Perhaps in the future I'll come back to the lousy data and see if I can recover something from it, but so far any attempts to mix with the first night simply degrades it. A grand disappointment that I will strive never to repeat again! My lesson is to get those L frames using the best conditions Mother Nature chooses to give me, and then I can devote time to color another time, and always remember that those calibration frames can be taken during the day or twilight or maybe even indoors later if needed!

I hope you enjoy, and your comments and suggestions are always welcome!

Comments

Revisions

  • M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah
    Original
  • M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah
    B
  • M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah
    C
  • M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah
    D
  • Final
    M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah
    E

B

Description: Luminance Image

Uploaded: ...

C

Description: Inverted Luminance Image

Uploaded: ...

D

Description: Annotated LRGB Image

Uploaded: ...

E

Description: Cropped and Rotated LRGB Image

Uploaded: ...

Histogram

M51 Whirlpool Galaxy in LRGB - First Light of AP 1100GTO, 



    
        

            Ben Koltenbah