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Designations: M51, NGC 5194
Visual
Magnitude: 8.4
Size: 11.2 min X 6.9 min
Distance: 15 million light
years
Discoverer: Messier, 1773
Visual Description: About 3 ˝ degrees SW from the Great Dipper, This is the famous “Whirlpool Galaxy”, the first galaxy found to show a spiral form. It was discovered by Charles Messier in October 1773, and the intriguing spiral pattern was first detected by Lord Rosse with his giant 6-foot reflector at Parsonstown, Ireland, in 1845. Rosse published his drawing of the object in 1850; it seems that he had observed the galaxy previously with a 3-foot telescope and had missed the spiral pattern. Sir John Herschel, with his 18-inch reflector, had described a “very bright round nucleus surrounded at a distance by a luminous ring”. The discover of the spiral pattern aroused much interest, and was regarded by some 19th century students of cosmology as a confirmation of Laplace’s Nebular Hypothesis. Thus the “spiral nebulae” were at first thought to be new solar systems in the process of formation, and it was not until 1923 that the question was settled with finality. The spirals were now recognized as external galaxies, and the modern picture of the Universe began to emerge.
A near
neighbor of our own galaxy, just 15 million light years away, this graceful
pinwheel of stars, dust and gas measures about 50,000 light years across and
shines with the luminosity of about 10 billion suns.
Seeing Conditions: Clear with
better than average seeing
Telescope: TMB
152 F8 APO refractor
Focal Length: 1208mm
Mount: Mountain
Instruments MI-250
Camera: SBIG
ST10XME
Exposure:
17 12-minute exposures luminace (204 minutes) and 4 12-minute exposures
for each color (144 Minutes). Total time 5-hour and 48 minutes
Other:
SBIG ST402ME
Autoguider
The Visual description of the M51 Whirlpool Galaxy was written by Robert Burnham Jr. in Burnham’s Celestial Handbook Page. 369.
Copyright(c) 2007 Doug Sanqunetti. All rights reserved
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