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Object Type:  Spiral Galaxy (Sc)
Constellation:  Triangulum
Magnitude:  5.7
Size:  62' x 39'

The third largest member of our Local Group of galaxies after M31 and the Milky Way, M33 is located at a distance of 3 million light-years, and is generally considered the most distant object visible to the naked eye. Despite its large apparent size, its low surface brightness makes it a challenging naked-eye object, requiring very transparent skies to be seen. M33 contains numerous H-II regions (emission nebulae), many of which are visible on this image. NGC 604, one of the largest H-II regions in the known universe at 1500 light-years in diameter (50 times the diameter of the Orion Nebula), is the bright red nebulosity to the upper right of the galactic nucleus. The next-largest H-II region is NGC 595, located below and slightly to the right of the galactic nucleus.

Equipment: ST-10XME/Vixen 102-ED/Losmandy G-11/Gemini/Astrodon RGB filters
F-ratio: f/6.5
Exposure: LRGB: L 8 x 5 minutes: R 8 x 20 minutes: G 8 x 5 minutes: B 8 x 5 minutes: GB binned 2x2
Date: December 3, 2005 and October 20, 2006
Location: Landers, California, USA
Technical Notes: Individual expsoures were dithered using CCDAutoPilot2 and then sigma combined. The RGB images were combined in Registar 1.0. The luminance image was sharpened with a High Pass Filter using a Radius of 8 pixels, and selectively applied using a Layer Mask. The RGB image was duplicated and the resulting layer combined using Soft Light to enhance color.