M74

Spiral Galaxy in the Constellation Pisces

Discovered 1780 by Pierre Méchain.  Messier 74 (M74, NGC 628) is one of the nicest examples of so-called "grand-design" spiral galaxies seen face-on, so that its spiral structure stands out conspicuously. With its comparatively low surface brightness, it is one of the more difficult objects in Messier's catalog visually, situated in constellation Pisces.  This conspicuous spiral is a prototype of a grand-design Sc galaxy.  Its distance may be about 30 to 40 million light years.  It is receding from us at a speed of 793 km/sec.  Its spiral arms are about 10,000 light years broad. They are traced with clusters of blue young stars and pinkish colored diffuse gaseous nebulae (H II regions) in color photos, and reach out to cover a region of more than 10 minutes of arc in diameter, corresponding to roughly 95,000 light years, or about the same size as our Milky Way galaxy.

Image Details:

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  • Instrument:  Planewave Instruments CDK 12.5 with Astro-Physics AP27TVPH focal reducer @ f/6.2 (1971mm)
  • Mount:  AP1200GTOCP3
  • Image Scale:  1.2 arc-seconds per pixel after processing
    Camera: SBIG ST-2000XM with AO8 Adaptive Optics and CFW10 Color Filter Wheel using Custom Scientific LRGB filters 
    Filters & Exposure Times:
    • L:  18 x 5 minutes binned 1 x 1
    • R:  24 x 5 minutes binned 1 x 1
      G:  12 x 5 minutes binned 1 x 1
      B:  18 x 5 minutes binned 1 x 1
    • Super-Luminance Layer used for L-[LRGB]-RGB Stacking
    • Multiple Luminance Layering in Photoshop (technique as described by Rob Gendler)
    • Total equivalent unbinned exposure time of 10.5 hours
    Software: Maxim DL/CCD, CCDStack, Adobe Photoshop CS2, RC Astro Gradient X-Terminator
    Location:  C.A.A.S. East Observatory, Little Rock, AR., El. 650ft
    Date: January 29th, 2011

Wade Van Arsdale
Little Rock, AR., USA
February 5th, 2011