NGC 6928 - Galaxy Group
In the southern part of the constellation Dolphin there is a nice galaxy group, whose brightest members NGC 6928 and NGC 6930 can be observed even
in smaller telescopes with 12" aperture thanks to their apparent visual magnitudes of 12.5 and 12.9mag. NGC 6927 and NGC 6927A also belong to this
group, as well as the small galaxy "2MFGC 15598".
All galaxies have a redshift in the range of z=0.014...0.016 and are about 220 million lightyears away from earth. With every second that passes, the group
moves away from us by another 4,700 kilometers, i.e. in one and a half minutes by the distance Earth-Moon.
With a true diameter of 130,000 light-years, NGC 6928 is the largest and brightest galaxy in the group, even slightly larger than our Milky Way. It has
tightly wound spiral arms as well as a bar, which is why it is classified as "SBab". In 2003 a supernova could be observed in this galaxy. NGC 6930 is much
smaller with a diameter of 70,000 light years and even smaller is its companion "2MFGC 15598" with a size of about 30,000 light years. NGC 6927/6927A
are also in this range of size.
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In my 20" telescope NGC 6928 and NGC 6930 show up first. At 120x they can be seen as bright, highly elongated objects. Both show a brighter central region
and a stellar core directly in the center.
Of course, the extreme close pair of NGC 6928 and "2MFGC 15598" is especially exciting. Both galaxies appear clearly separated from each other at 270x.
While NGC 6927A is easily visible with indirect vision and shows a brighter center, all other galaxies are quite faint. Especially the two galaxies at the left side
of the drawing are not easy to see even with indirect vision and appear as homogeneous blobs without structure. But at least I saw them ;)
In total I could see 9 galaxies, of which at least 5 definitely belong to the group. Great thing! :)
