Hemisphere:  Northern  ·  Constellation: Ursa Major (UMa)  ·  Contains:  M 101  ·  NGC 5447  ·  NGC 5449  ·  NGC 5450  ·  NGC 5451  ·  NGC 5453  ·  NGC 5455  ·  NGC 5457  ·  NGC 5461  ·  NGC 5462  ·  NGC 5471  ·  NGC 5477  ·  Pinwheel galaxy
Getting plate-solving status, please wait...
The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz
Powered byPixInsight

The Pinwheel Galaxy, M101 in HaLRGB

Getting plate-solving status, please wait...
The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz
Powered byPixInsight

The Pinwheel Galaxy, M101 in HaLRGB

Acquisition details

Dates:
Jan. 16, 2022 ·  April 25, 2022 ·  April 26, 2022 ·  April 29, 2022
Frames:
Astrodon Ha 3nm 36mm: 42×300(3h 30′) (gain: 100.00) -20°C bin 1×1
Baader Planetarium B 36mm Unmounted: 31×180(1h 33′) (gain: 0.00) -20°C bin 1×1
Baader Planetarium G 36mm Unmounted: 32×180(1h 36′) (gain: 0.00) -20°C bin 1×1
Baader Planetarium L 36mm Unmounted: 81×180(4h 3′) (gain: 0.00) -20°C bin 1×1
Baader Planetarium R 36mm Unmounted: 31×180(1h 33′) (gain: 0.00) -20°C bin 1×1
Integration:
12h 15′
Darks:
30
Flats:
25
Flat darks:
50
Avg. Moon age:
22.79 days
Avg. Moon phase:
36.85%
Bortle Dark-Sky Scale:
4.00

RA center: 14h03m11s.755

DEC center: +54°2224.80

Pixel scale: 0.807 arcsec/pixel

Orientation: 130.017 degrees

Field radius: 0.477 degrees

WCS transformation: thin plate spline

More info:Open 

Resolution: 3424x2517

File size: 9.0 MB

Data source: Traveller

Description

M101, The Pinwheel Galaxy, needs no introduction. It is an enormous galaxy, twice the size of the Milky Way, situated in Ursa Major at around 25 million l.y. away.  (source: APOD).

This was a very long and complicated project, that I started in January 2022... Each year in my light polluted area I have to struggle with the light reflections present in my Newtonian, during galaxy season when shooting LRGB. I have central circle on my images that I could not get rid of, in spite of numerous improvements of my system. Thanks to a kind advice from @Anthony Husson , I changed my coma corrector for a TS Maxfield that is shorter, has 3 elements instead of 4 and makes the system even faster at 3.8. Things got better, but the field still had some gradients, that could be solved this time with DBE.

During my vacations in a fantastic area of preserved dark sky in southern France (Bortle 3), I had decided to take the Newtonian with me. On the passenger's seat, since it's too big to fit in the trunk. He remained silent the whole trip. Initially the forecast was cloudy, but things finally changed. I was able to collect data during 3 nights. The signal was absolutely fantastic, compared to what I have to endure in my backyard. Seeing was exceptional for 2 nights. Finally I decided to drop all the broad band data I had collected during 3 months and keep only the best frames from my voyage. The Ha is from my backyard.

 I performed several tests for Luminance stretching. GHS seems more adapted for nebulae and I was not able to improve the result compared to a classic Masked stretch. I wanted to keep the colour as faithful as possible during processing. I did a Photometric Colour Calibration with a good correlation of the coefficients. All saturation manipulation was global. I was careful not to break the colour balance when introducing the Ha signal.

This is the final image. I am still not decided bewteen the Widefield and the Close-up version. The Widefield has plenty of galaxies especially on the lower right and the star field puts things into perspective, best seen in full resolution. Clear skies !

Comments

Revisions

  • The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz
    Original
  • The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz
    B
  • The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz
    D
  • Final
    The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz
    E

B

Title: Widefield

Uploaded: ...

E

Description: Widefield final version

Uploaded: ...

Sky plot

Sky plot

Histogram

The Pinwheel Galaxy, M101 in HaLRGB, 



    
        

            Bogdan Borz