NGC 6742 - Planetary Nebula
The planetary nebula NGC 6742 (also known as Abell 50) is located in the constellation Draco and was discovered by F.W. Herschel in July 1788.
With a brightness of 13.4 mag and an apparent size of 30x30“, it can even be seen in medium-sized telescopes with a 10-12”
aperture, although an UHC or OIII filter should be used.
The distance to NGC 6742 is given as approximately 16,800 light-years, but with an uncertainty of +- 3,000 light-years.
The true diameter of the nebula shell is approximately 2.7 light-years, which shines with approximately 100 times the
luminosity of the Sun. This corresponds to an absolute magnitude of M= -0.2mag. The central star has not yet been 100%
confirmed – however, the star directly in the center of the nebula appears to have spectral class O(H)III, which indicates
a very hot surface, typical of a central star.
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In my 20" f/3 telescope, NGC 6742 appeared quite bright and was easily visible at a magnification of 210x in combination
with am UHC filter using averted vision. The edge appeared slightly brighter, while the center was slightly darker. At 270x,
I could also see a very faint star in the halo, but not in the center, rather in the western part. So unfortunately, it was not the
central star.
