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M33 - pinwheel galaxy


This spiral galaxy is in the small constellation of Triangulum, not far south of M31. It is the third largest member of our local group (after M31 and the Milky Way). It is about 3 million light years away.

 2010 Dec 11 - 254mm Newtonian, dark site

Photo of M33 Triangulum galaxy

Canon EOS5DMkII 254mm Newtonian @ 1200mm 33 x 30s f/4.8 ISO6400 2010-12-11 22:46:47-23:09:05 UT
From Rookhope 54.8N 2.1W 330m asl. Rural, almost no light pollution (3 Bortles)

 2009 Dec 10 - 254mm Newtonian, suburban site

This photo is not great but I am not too dissatisfied, given that I could not see any hint of the galaxy at all through my 254mm Newtonian, owing to light pollution. I positioned the telescope by using a star chart generated by GRIP. I then just set the camera and crossed my fingers.

I have combined 99 10-second exposures to build up enough signal to show the galaxy after considerable enhancement in GRIP. The horizontal reddish striations are due to camera noise banding. I could not get rid of that with the extreme enhancement I have done. (One of the 100 exposures I made contained an unidentified moving object and so was not included in the processing.)

Image of M33 pinwheel galaxy

Canon EOS5DMkII 254mm Newtonian @ 1200mm 99 x 10s f/4.8 ISO6400 2009-12-10 19:06:26-19:32:36 UT
From Whitley Bay 55.1N 1.5W 10m asl. Suburban, significant light pollution (6.5 Bortles)

Several star associations and nebulae in M33 can be seen in this photo. One quite bright nebula is NGC 604, a cloud of ionised hydrogen. The following annotated version of the photo points out this and some other things.

Annotated image of M33

The star marked 162 has magnitude 16.2. That is the faintest star in this image for which I have any data.

The annotations are derived from the book "Observing handbook and catalogue of deep-sky objects" by Luginbuhl and Skiff, Cambridge University Press, paperback edition 1998. I find this a very useful reference book. It describes a large number of objects and it is good at indicating what size of instrument is needed to see each one.

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