California Nebula (NGC 1499) -- Emission Nebula in Perseus
Visual Hunt for the California Nebula under Suburban Skies
The star Menkib (xi Persei) is a massive Super Blue Giant star (Spectral Type O7) that, if
you include the ultraviolet, shines with the luminosity of 263,000 suns. Some of the star’s
prodigious radiation is absorbed by a 100-light-year across gas-cloud that ionizes (strips
electrons) from its hydrogen atoms. When the electrons later combine back to the
hydrogen, photons are emitted in the form of blue-green light at 486 nm.
Menkib is a bright, easy to find star, in the constellation Perseus. It is at the bottom-center
of the drawing. The huge nebula which Menkib feeds is known as the California Nebula
(NGC 1499). It is a show piece for astrophotographers. Although it covers the sky equal
to 5 full moons long and a full moon wide, it is notoriously difficult to see directly through a
telescope or binoculars without the aid of a Hydrogen-Beta (H-B) filter. The H-B filter
removes all incoming light except that which is emitted by the nebula. Even with the
specialized filter the nebula is difficult to see unless one is under a dark sky. Binoculars
and wide-field telescopes are needed to see the full extent of the nebula.
From my suburban backyard, with the 155mm Refractor, a 41mm Panoptic eyepiece
(2.4-degree field-of-view) and a Hydrogen-Beta filter the California Nebula can be seen.
But it is never easy. The draft drawings were done under an exceptionally transparent sky
while the nebula was near the Zenith. I made three separate drawings at the telescope of
different sections of the nebula and combined them into the single final drawing. The
famous California-like shape of the nebula could not be made out visually. The nebula
appeared fractured into four-separate pieces. The exact edges of the pieces blended into
the surrounding space, making it impossible to know-for-sure where the nebula’s edges
ended, and the blackness-of-space started. The brightest strips of the nebula were along
the northern and southern edges while the center of the nebula was difficult to make out.
After two-hours of drawing at the telescope, I realized that for the most part I was never
going to capture the exact shape of the nebula on paper -- it was just too fleeting, and I was
never sure if something was there or not. Visually the California Nebula is just too ghost-like
for me to capture perfectly on paper, but that is hardly a reason not to try.