Hemisphere:  Northern  ·  Constellation: Ursa Major (UMa)  ·  Contains:  M 101  ·  M101  ·  NGC 5457  ·  NGC 5461  ·  NGC 5473  ·  NGC 5474  ·  NGC 5485  ·  NGC5447  ·  NGC5449  ·  NGC5450  ·  NGC5451  ·  NGC5453  ·  NGC5455  ·  NGC5461  ·  NGC5462  ·  NGC5471  ·  NGC5473  ·  NGC5474  ·  NGC5477  ·  NGC5484  ·  NGC5485  ·  NGC5486  ·  Pinwheel galaxy
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M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

            Ben Koltenbah

M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter

Imaging telescopes or lenses: Teleskop Service 130/910

Imaging cameras: FLI ML16200

Guiding telescopes or lenses: Teleskop Service 130/910

Guiding cameras: Starlight Xpress Ultrastar M

Software: PixInsight  ·  PHD 2  ·  Astro-Physics AAPC  ·  Sequence Generator Pro

Filters: Astrodon Gen2E L

Accessory: Astrodon MMOAG  ·  FLI CW2-7  ·  Moonlite CFL Focuser


Frames:Astrodon Gen2E L: 73x240" -30C bin 1x1

Integration: 4.9 hours


Astrometry.net job: 4269302

RA center: 14h 4' 1"

DEC center: +53° 38' 36"

Pixel scale: 1.364 arcsec/pixel

Orientation: -89.705 degrees

Field radius: 1.638 degrees


Resolution: 7910x3500

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

Data source: Backyard

Description

It has been a long, stark and starless winter in the Pacific Northwest. I have only had one night of imaging thus far in 2021, and this is the result of it. This is M101 and its vicinity, a luminance only image made into a mosaic showcasing M101 and its satellite neighbor NGC 5477. At the time I knew I was only going to get one night under a clear sky, and so I devoted the whole night to the L filter with the hope of coming back later with RGB. (I'm still waiting for that opportunity.)

It was, however, a nice opportunity to try out PHD2's new multistar imaging capability. I upgraded to the latest version of PHD2 but did not turn it on at first. After about 30 - 45 minutes of imaging I then switched it on for the rest of the frames, and I was pleased to see an immediate guiding improvement. As I recall, the guiding curves' RMS values decreased by about 25%. I later calculated FWHM values from the calibrated frames, and I saw about a 20% reduction in star size after switching it on. This capability is a welcome addition to guiding.

M101 (Ursa Major) is my favorite galaxy to image. Not as close to us as the galaxies of our Local Group, it is still a relatively close neighbor at 20.9 Mly (6.4 Mpc) with diameter 170 kly and apparent size 28.8' x 26.9'. This apparent size is large enough that it defies usual longer focal length images. Here I have used my TS 130/910 refractor with my FLI ML16200 CCD resulting in a resolution of 1.36 "/px.

I found this resolution to be small enough for the image to benefit from a modest touch of deconvolution. With less than 5 hours of integration time, I needed to apply noise reduction, however I did not wish to overdo it. This can be seen in the background. Hopefully, more imaging time in the near future will allow me to add more signal and reduction of noise.

The mosaic highlights M101 and I also wished to zoom in on NGC 5474. In this image, N is to the left, S right, E down, W up. Below M101 is NGC 5477, one possible candidate satellite galaxy responsible for distorting that outer arm as if unwinding it.

Hopefully, I'll get more opportunity to image again soon. I do have quite a bit of data left from last summer and fall that I haven't had time to process or upload, although much of it suffered from mediocre seeing conditions.

Comments

Revisions

  • M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

            Ben Koltenbah
    Original
  • M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

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  • M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

            Ben Koltenbah
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  • Final
    M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

            Ben Koltenbah
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  • M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

            Ben Koltenbah
    E

B

Description: Annotation of Wide FOV Luminance Image

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C

Description: Inverted Wide FOV Luminance Image

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D

Description: Mosaic Image Showing M101 and NGC 5474

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E

Description: Inverted Mosaic Image

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Sky plot

Sky plot

Histogram

M101 and Vicinity - PHD2 Multistar Guiding Test During an Otherwise Stark, Starless Winter, 



    
        

            Ben Koltenbah