M96 - Spiral Galaxy in Leo

M96 AP155 ST10XME

M96 - Spiral Galaxy in Leo
Mag 9.2 RA 10:46.8 Dec +11 49 6x4 arcminutes


Discovered by Pierre Méchain in 1781.

Messier 96 (M96, NGC 3368) is a conspicuous spiral galaxy in constellation Leo.

M96 is the brightest member of the Leo I group of galaxies, which is therefore also called the M96 group, and also includes M95, M105 as well as a number of fainter galaxies.

Pierre Méchain discovered M96, together with M95, on March 20, 1781. Consequently, Charles Messier included it in his catalog on March 24, 1781. It was among the first spirals that have been discovered, and listed by Lord Rosse as one of 14 "spiral nebulae" discovered to 1850.

Its distance was determined to be about 41 million light years (after corrections for the distance scale which are implied by the results of ESA's Hipparcos satellite) by Nial R. Tanvir with the Hubble Space Telescope by observing Cepheid variables. Interpolated with the HST result of 35.5 million light years for its neighbor M95, we adopt a value of 38 million light years here for the whole group.

At this distance, the apparent diameter of its brighter central region, 6 arc minutes, corresponds to a linear dimension of 66,000 light years. However, as can be seen, this galaxy has faint extensions, an outer ring of filaments (spiral arm fragments), which are connected to the bright visible part near the northwest end of the major axis. This ring has a diameter of at least 100,000 light years.

ST-10XME and CFW8a Astrodon LRGB
AP155EDF on AP900GTO
Luminance 23 x 5 min
RGB 3 x 10 min
Images acquired w CCDSoft5
Darks and Flats in CCDSoft5
Alignment and combines in Maxim
Colour combines, Levels and Curves in PS CS4
Some High Pass Filtering applied in PS CS4 to Luminance

Click on the image to see a larger version.
Flesherton, Ontario, Canada
April 12th, 2009
Ambient temp -1C; camera temp -25C; Moon was just past full.