NGC 3918 The Blue Planetary Nebula or
The Southerner Planetary Nebula
Imaged by Martin S. Ferlito copyright
Gstar-EX Integrating Video Camera
8" SCmidt-Cassegrain on Vixen GP Mount, Stepper Driven.
NGC 3918 is a bright planetary nebula in the constellation Centaurus,
that is called the "Blue Planetary" or "The Southerner". It
is the brightest of the far southern planetary nebula NGC 3918 was discovered
by Sir John Herschel in March 1834, and in easily visible in a small telescope.
The round or even slightly oval diameter is telescopically between 8 to 10
arcsec, though deep images extends this to about 19 or 20 arcsec. More
surprising is the beautiful rich blue colour that looks much like the coloured
images of Neptune taken by Voyager 2 in 1989.
Spectroscopy reveals NGC 3918 is approaching us at 17±3.0 kilometers per
second, while the nebulosity is expanding at around 24 kilometers per second.
The central star is 15.7B magnitude, and remains invisible to optical observers
