M33, in the constellation of Triangulum, was first mentioned by Giovanni Batista Hodierna in 1654 but discovered independently by Charles Messier in 1764.
M33 is a spiral galaxy and a member of the local group, but it is much closer to the Andromeda Galaxy (about 400,000 light years) than to our Milky Way Galaxy (2,800,000 light years). With a diameter of 50,000 light years, it is the third largest galaxy of the group.
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M33 captured with a 135 mm SLR lens. The galaxy is about 69 × 42 minutes of arc. The visual magnitude is 5.7 but the surface brightness is only 14.2, so it is quite a faint object. This is not a good picture for reasons that are quite instructive. Because it is a rather faint object and because of my local light pollution, I used an Orion Skyglow filter forgetting that this does not have good rejection of the infra-red. Unfortunately the optical train I used does not have room for two filters and I was unable to add an infra-red-blocking filter. Undoubtedly the lens is optimised for the visible wavelengths and does not focus the infra-red in the same plane. Consequently this picture includes a significant out-of-focus infra-red component. Date and Time: 17th January 2010 20.34 to 21:10 UT Camera: Starlight Xpress MX716 Telescope: 135 mm SLR lens at f/4 Capture: Star_mx7. Exposure 300 sec. Processing: Star_mx7, background, non-linear stretch power 25, background Irfanview, conversion to png format. Registax5, 8 frames stacked PhotoImpact: focus magic 3,100 |
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