M31 Andromeda – revisited

So I’ve imaged Andromeda with a 105mm focal length lens and Andromeda’s core with an SCT & reducer at 945mm, but now it’s time to keep my promise to myself and return with the 100 – 400 L lens, seeking a detailed full frame image. No piggybacking this time just the camera & lens attached to the  AS-GT mount, 2.5 minute subs & a over 1.5 hours of exposure:

 M31 Andromeda Galaxy   Click on image for a larger view

The expanded image (click above) is still significantly reduced & compressed to make it web suitable but I hope it conveys what a fascinating object Andromeda is.

At 2.9 million light years distant & 250,000 light years in diameter, Andromeda is the largest galaxy in our local group of galaxies, though some recent research suggests that our own Milky Way probably has more mass.  This image also shows her 2 main companion galaxies, the oval M110 below and the apparently more rounded M32 above. Both companions are in fact dwarf elliptical galaxies. Andromeda is another deep sky object that has been known since ancient times with definite observations having been noted by Persian astronomers prior to 1000 AD. For a few details have a look at my Messier Info board below:

M31 Sept07 Click on image for a larger view

Andromeda contains billions of stars and many structures that we observe in our own galaxy (e.g. Clusters, Nebulas, Planetary Nebs, etc.), they have also been studied in M31. One such structure is NGC 206 the ‘Star cloud in Andromeda’ which The Sky describes as Cluster+Nebulosity. Looking at my main picture above it is located as a lighter patch amongst the dust lanes, towards bottom left of the galaxy. Here is a close crop of the region:

M31 Andromeda Galaxy

The lighter patch in the centre is NGC206, it is thought to lie at the intersection of 2 spiral arms and is probably the greatest region of star formation within our local galaxy group. M24 the Sagittarius Star cloud is a similar but smaller structure in our own galaxy. You can also see many globular clusters in my main image of Andromeda, they appear as lighter ‘specks’ embedded within the galactic structure.

As for companion galaxies in excess of M32 & M110 there are also NGC 147 & NGC 185 (further out and not in the image frame) and probably also the extremely feint systems named And I to XIV. Tracking down some of these other companions and the galaxies of the local group as a whole, well it looks like a substantial project & definitely one for another post.

 I must add that Tamsin helped find & frame this image before going to bed and allowing me to capture the subs. Andromeda is one of her favourite night sky objects – along with Regulus & the Big Dipper.



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