M86, M84, Markarian's Chain

Date: 18/04/10    Time: 0048hrs   Location: Sunningwell   Temperature: 7.6ēC  Relative Humidity: 56%

Camera: Nikon D80    Scope: William Optics Z66 Apo Doublet at prime focus   Mount: piggy-backed on Meade LX90 in equatorial mode  Filter: Astronomik CLS (LPF broadband filter)  Exposures: 6x10min,   ISO: 1600   F ratio: 5.9   Guidance: Autoguided

This is the second target of the same observing evening when I took the photograph of some of the Leo galaxies M96, M95, etc, seeing remained good the whole evening although transparency was much less than the clear moisture-free frosty winter nights until I finished at 3am.  The region between Virgo and Coma Berenices is crammed full of galaxies.  To give you an idea of what direction you are looking - instead of staring into the same plane as that of our own spiral galaxy, in this direction, you are staring almost 90° out of the plane of the Milky Way, into deep space.   From this direction, an observer looking back at us would have a view of our own galaxy 'en-face'.  M86 and 84 were first observed by Messier in March 1781 but with his quality of optics, one wonders whether he could truly appreciate the number of galaxies which are visible in the same field of vision as these two.  In 1961, Benjamin Markarian published an article in the Astronomical Journal postulating that it was probable for the apparent 'arc' of galaxies formed by M86 and M84 at the western end were linked interactively by gravitation, rather than just being a random alignment.  The galaxies are approximately 55 million light years away.  For an identity parade of all the galaxies visible in this field of view, see this graphic below which I 'borrowed' from the internet (made by Jared Wilson).

Image by Jared Wilson 

The total exposure time of the photograph was an hour - made up of 6 x 10 minute exposures, stacked and summed in Maxim DL.  The light pollution was subtracted with a 'Dust and Scratches' mask made from the original in Photoshop.  The dynamic range of the image was then stretched with the usual white and black point setting in the Levels command of Photoshop and the midtones enhanced with the Curves command.  Finally the image was cleaned up with noise removal and unsharp masking using one pass of Noise Ninja at its nominal settings.


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