Cancer is a Zodiacal constellation otherwise known as the Crab. It is one of the 48 Greek constellations originally described by the 2nd century astronomer Claudius Ptolemy (Wikipedia). Cancer remains one of the 88 modern constellations defined by the International Astronomical Union (Wikipedia).
Cancer (abbrev. = Cnc; genitive = Cancri) covers 506 square degrees or 1.23% of the celestial sphere making it the 31st largest constellation. It contains 104 stars brighter than apparent magnitude 6.5, the brightest star being Tarf. See the Cancer Star Chart for a figure illustrating this constellation including the identification of its brighter stars.
- Object: Cancer
- Date/Time: 2012 Feb 23 at 04:15 UTC
- Location: Bifrost Astronomical Observatory, Portal, AZ
- Mount: Losmandy G-11 German Equatorial Mount
- Lens: Nikkor AI 35mm f/2
- Camera: Canon EOS 550D (Rebel T2i)
- Field of View: 35.3° x 24.0° at 24.5 arc-sec/pixel (web version: 138 arc-sec/pixel)
- Exposure: 240s, f/4, ISO 800 and 120s, f/4, ISO 800 with Cokin A840 Diffusion Filter
- File Name: Cnc-01w.jpg
- Processing (Adobe Camera Raw): Color Balance, Vignetting, Noise Reduction
- Processing (Photoshop CS5): Curves, Layers
- Original Image Size: 3454 × 5179 pixels (17.9 MP); 11.5" x 17.3" @ 300 dpi
- Rights: Copyright 2012 by Fred Espenak. All Rights Reserved. See: Image Licensing.