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Messier 66

Spiral Galaxy M66 (NGC 3627), type Sb, in Leo

in the Leo Triplett

Right Ascension 11 : 20.2 (h:m)

Declination +12 : 59 (deg:m)

Distance 35000 (kly)

Visual Brightness 8.9 (mag)

Apparent Dimension 8x2.5 (arc min)

Right Ascension	11 : 20.2 (h:m)
Declination	+12 : 59 (deg:m)
Distance	35000 (kly)
Visual Brightness	8.9 (mag)
Apparent Dimension	8x2.5 (arc min)

Discovered 1780 by Charles Messier.

Messier 66 (M66, NGC 3627), together with its neighbors M65 and NGC 3628, forms a most conspicuous triplet of galaxies, the Leo Triplett or M66 group, located at a distance of about 35 million light years.

M66 is considerably larger than its neighbor, M65, and has a well developed but not well defined central bulge, and is therefore classified Sb. Obviously its spiral arms are deformed, probably because of the encounters with its neighbors. They seem to be distorted and displaced above the plane of the galaxy. Note how one of the spiral arms seems to pass over the left side of the central bulge. Much dust is visible here, as well as a few pink nebulae, signs of star formation, near the end of one of the arms.

This image was obtained by David Malin with the 3.9-meter Anglo-Australian Telescope of the Australian Astronomical Observatory; interested readers may obtain more detailed information on this image.

Together with its neighbor M65, M66 has been discovered by Charles Messier, who cataloged it on March 1, 1780, remarks that he missed these two objects in 1773, when a comet passed between them on November 1 to 2, 1773, probably because of the light of the comet. Because of a dubious error, Admiral Smyth has assigned this discovery of M65 and M66 (and M68) to Pierre Méchain, a view which was adopted by Kenneth Glyn Jones somewhen in the 1960s, and consequently, in many modern sources, despite the fact that Messier doesn't acknowledge such a prior sighting, which he did in all other cases.

Five supernovae have appeared in this galaxy:

1973R which was of type II and reached mag 15 was found on December 12, 1973.
1989B was discovered on January 31, 1989 and became as bright as mag 12.2 on Feb 1, 1989.
1997bs was discovered by the Lick Observatory Supernova Search Team as it occurred on April 15, 1997 at 13" west, 67" south of the galaxy's center and reached mag 17.0; this was of peculiar type IIn.
2009hd was discovered on July 2, 2009 by Berto Monard of South Africa at mag 15.8, located 28" east and 42" south of the nucleus of M66.
2016cok (also known as ASASSN-16fq) was found on May 28, 2016 by the All Sky Automated Survey for SuperNovae (ASAS-SN) when still rising at mag 16.6 to 16.7, and reached its maximum of 16.1 on June 1, 2016. It is located 61".4 east and 34".0 south of the center of M66, and was classified as of type IIP.

Halton Arp has included M66 in his Catalogue of Peculiar Galaxies as entry No. 16. Moreover, he assigned the number 317 to the Leo Triplett (M66 together with M65 and NGC 3628).

Historical Observations and Descriptions of M66

More images of M66

Amateur images of M66

More images of M65 and M66, sometimes including NGC 3628 (the whole Leo Triplett)

SIMBAD Data of M66

NED Data of M66

Publications on M66 (NASA ADS)

Observing Reports for M66 (IAAC Netastrocatalog)

NGC Online data for M66

Hartmut Frommert
Christine Kronberg
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