M100 – Spiral Galaxy in Coma Berenices

Also designated NGC 4321, M100 is a so-called grand design spiral. It lies in the southern part of Coma Berenices, near the border with Virgo and is a member of the Coma galaxy cluster.

The galaxy is 55 million light years from us, and is 170,000 light years in diameter.

A number of other galaxies appear in the image and these are annotated below.  NGC4312 lies at about the same distance as M100 and appears magnitude 12.5.

The small galaxy labelled NGC4322 below seems to have an identity crisis as it is identified as NGC4323 by some sources. For example, The Sky X software calls it 4323 and says 4322 is a star, but the Uranometria 2000 Field Guide calls it 4322 and has no entry for 4323. The PixInsight Annotate script which was used to produce the image below clearly comes dowon on the side of 4322, but several online sources prefer 4323. In any event it is a little fainter than NGC4312 at mag 13.8 and is a dwarf companion to M100.

Equipment: Planewave CDK 14″ reflector on 10Micron GM2000 mount. FLI Proline P09000 CCD camera with Astrodon LRGB filters.

Exposure times: Lum 11 hrs, Red 12 hrs, G 12 hrs, B 13 hrs.

Data acquired with ACP Expert/Maxim DL and processed in PixInsight.