The inner part of the Andromeda Galaxy, Messier 31 (NGC 224), shown from a 10-second red-light exposure (during twilight) with a Tektronix 2048x2048 CCD at the prime focus of the 4-meter Mayall telescope of Kitt Peak National Observatory. North is at the top and east to the left, for direct comparison with a chart or eyepiece view. The image has been block-averaged to 512x512 for this presentation, which uses a logarithmic intensity transformation to preserve information across a wide dynamic range. The field is 14.3 arcminutes square (about 3200 parsecs = 10,300 light-years at the 780-kiloparsec distance of M31). The bright nucleus is readily apparent, recently shown to be in fact double (see the HST image and caption ) as well as the possible site of a supermassive black hole.
Paul Hodge's Atlas of the Andromeda Galaxy from 1981 lists 27 catalogued globular clusters in this area, all of which can be identified on this image. I list them below with their (x,y) coordinates on the 512x512 picture, in which each pixel subtends 1.68 arcseconds on the sky. These coordinates take (0,0) at the lower left corner, a convention which is common in scientific and mathematical application, although some image-processing routines like to count the y-axis down from the top. (Thanks for Jorma Koski for pointing this out, along with a missing cluster). You may want to consult for comparison the beautiful HST image of the brightest globular cluster in M31, Mayall I; this cluster lies well beyond the area shown in my image. Note as well the intricate detail in the dust clouds of the innermost spiral pattern.
This BVR color composite with the 1-meter SARA telescope on Kitt Peak covers a comparable field, and captures the red tint of the central bulge common in many spiral galaxies (and visible with a large enough telescope in dark skies).
About half a degree to the southwest is the giant star cloud NGC 206, with associations of young stars making it the brightest piece of M31's spiral arms. It was in this region that Edwin Hubble first found Cepheid variable stars. This BR composite image was taken with the 1-meter Jacobus Kapteyn Telescope (JKT) on La Palma, now operated by the SARA consortium.
For additional context, here's a view of M31 and its companions M32 and M110 taken with the 20-inch astrographic refractor at Lick Observatory. This shows an area over a degree across.
Last changes: 9/2018 © 2001-2018