Hemisphere:  Northern  ·  Constellation: Ursa Major (UMa)  ·  Contains:  M 101  ·  NGC 5457  ·  NGC 5461  ·  NGC 5471  ·  NGC 5477
Getting plate-solving status, please wait...
M101 - in a spin, 



    
        

            Tom Gray
M101 - in a spin
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M101 - in a spin

Getting plate-solving status, please wait...
M101 - in a spin, 



    
        

            Tom Gray
M101 - in a spin
Powered byPixInsight

M101 - in a spin

Technical card

Imaging telescopes or lenses: Meade 2080 SCT 8" LX5

Imaging cameras: Meade DSI 3 Pro

Mounts: Meade Fork mount w/wedge Meade

Guiding telescopes or lenses: Meade 8x50mm Finder/Guider

Guiding cameras: Orion Starshoot autoguider

Focal reducers: Meade f3.3 focal reducer/field flattener Meade Focal reducer

Software: SiliconFields / Ivo Jager Startools v1.7  ·  Stark Labs Nebulosity v3  ·  PHD2 Guiding V 2.6  ·  Meade Envisage V4.10

Filters: Meade RGB-IR Cut 1.25"  ·  Meade LRGB 1.25"

Accessory: Bahtinov Mask  ·  Homemade ST4 autoguider


Dates:April 12, 2021

Frames:
Meade Blue Filter for CCD: 12x120" bin 1x1
Meade RGB-IR Cut 1.25": 26x120" bin 1x1
Meade Red Filter for CCD: 11x120" bin 1x1
NONE at all: 10x120" bin 1x1

Integration: 2.0 hours

Avg. Moon age: 0.35 days

Avg. Moon phase: 0.14%


Basic astrometry details

Astrometry.net job: 4419486

RA center: 14h 3' 17"

DEC center: +54° 20' 16"

Pixel scale: 1.991 arcsec/pixel

Orientation: 356.279 degrees

Field radius: 0.462 degrees


Resolution: 1342x996

Locations: Home 'observatory' (Bortle 5), Derbyshire, United Kingdom

Data source: Backyard

Description

M101 is a lovely face-on spiral, perfectly placed for imaging at the zenith. With a long clear night ahead, I was excited; the live stacked image looked great coming off the camera.

After that things went rapidly downhill - my flats failed to deal with the significant vignetting from my f3.3 focal reducer, resulting in unsightly artefacts and gradients. This image has taken me by far the longest to process.

Initially stacked in ASTAP, I could not get my filter stacks aligned, despite using astrometric solving, and half my frames were dropped due to quality. ASTAP also muddled up my data, backing up and replacing files.

I resorted to manual alignment and stacking the remaining frames in Nebulosity, expecting a straightforward workflow in Startools. Not so, this image is the result of the most convoluted workflow, I have ever undertaken, and has left my head in a spin!

Suffice it to say, this is a poor representation of M101. What is so frustrating is that the raw data appeared good. So, what have I learned? Don’t make assumptions, back up the raw data before processing, and work the problem. I will try again one cloudy night, but now I’m going to lie down!

Comments

Revisions

  • M101 - in a spin, 



    
        

            Tom Gray
    Original
  • Final
    M101 - in a spin, 



    
        

            Tom Gray
    B

B

Description: WHAT a difference some proper pre-processing makes in ASTAP (thanks again @rich-sky). Exactly the same data taken from ASTAP, processed in Startools, using the defaults. A little removal of a few dust bunnies and artifacts from poor quality flats. Voila! Given the relatively short 120s exposures and 118m integration (Lx24, Rx14, Gx8, Bx13) I'm pleased with the overall depth, detail and colour. I'll keep the other, just to remind me how aweful it was!

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M101 - in a spin, 



    
        

            Tom Gray