Hemisphere:  Northern  ·  Contains:  Great Nebula in Andromeda  ·  M 110  ·  M 31  ·  M 32  ·  NGC 205  ·  NGC 221  ·  NGC 224  ·  The star 32And
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M31, the Andromeda Galaxy, 


            Wei-Hao Wang
M31, the Andromeda Galaxy
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M31, the Andromeda Galaxy

Technical card

Imaging telescopes or lenses: Takahashi TOA 150

Imaging cameras: Pentax 645z Mod

Mounts: Takahashi EM-400 Temma2

Guiding telescopes or lenses: SharpStar 50 ED

Guiding cameras: ZWO ASI290MM Mini  ·  Fishcamp Starfish

Focal reducers: Takahashi TOA 67 Flattener

Software: PixInsight  ·  RegiStar  ·  Photoshop CC

Filters: H alpha

Dates:Nov. 5, 2016Jan. 3, 2017July 19, 2018Sept. 3, 2018

338x480" ISO800
40x60" ISO800
H alpha: 40x300" ISO12800
H alpha: 23x720" ISO800

Integration: 53.7 hours

Avg. Moon age: 9.95 days

Avg. Moon phase: 36.40%

Bortle Dark-Sky Scale: 2.00

Basic astrometry details

Astrometry.net job: 2275710

RA center: 0h 42' 43"

DEC center: +41° 16' 4"

Pixel scale: 1.348 arcsec/pixel

Orientation: 270.183 degrees

Field radius: 2.342 degrees

Resolution: 10962x6027

Locations: Mt. Shiao-Shuei (Taiwan), Taichung, Taiwan; Mt. Ho-Huan (Taiwan), Taichung, Taiwan

Data source: Traveller


This is a three-frame mosaic. The mosaic panels have large overlaps. The exposures were taken over 16 different nights over three years (July 2016 to Sep 2018). Most of them were taken under good seeing. Those taken under poor seeing were discarded or given low weights in the mosaic.

The exposures were Bayer-drizzed plus 2x-drizzle stacked in PixInsight. As a result, the final mosaic has a dimension of 31320 x 17220 (539 mega pixels). The version uploaded here is reduced by 0.35x (equivalent to 0.7x the camera's native pixel size) to avoid overloading some browsers. To see a pan/zoomable higher-resolution version (0.6x reduction), you can visit this page:

Rev A (final) is the regular RGB image.

Rev E is a starless version, just for fun. Obviously the many background galaxies, and star clusters and compact HII regions in M31 are also removed.

Rev F is an inverted black and white image with strong stretch, to show the faint outer halo and stellar streams around M31.



Wei-Hao Wang
License: None (All rights reserved)


  • Final
    M31, the Andromeda Galaxy, 


            Wei-Hao Wang
  • M31, the Andromeda Galaxy, 


            Wei-Hao Wang
  • M31, the Andromeda Galaxy, 


            Wei-Hao Wang

Sky plot

Sky plot


M31, the Andromeda Galaxy, 


            Wei-Hao Wang

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Deep Sky Mosaics
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