IC 5067-70 - Pelican Nebula

IC 5067-70, the Pelican Nebula, is a large but low-surface-brightness emission nebula in Cygnus. It is part of a nebula complex which also includes the famous North American Nebula, which is situated just a small move east of IC 5067-70, as well as other smaller patches of nebulosity to the south. The Pelican nebula was named for its resemblance to that animal, the body being the brightest part and the beak stretching away towards the lower left. The true distance of the whole nebula complex is not well known, but it is thought to be within our Galaxy's next spiral arm, called the Cygnus arm, at a distance of about 1.500 light years.

The nebulosity emits all of its light in isolated emission lines. The most prominent of those are the Hα, [OIII] and [SII] lines, which were exclusively recorded to obtain the image shown above. This is a "natural color" composition mixed so that the resulting colors are close to the visible spectrum of the human eye. The following mixture was used:

Red = Hα + 24% [SII]
Green = [OIII]
Blue = [OIII] + 15% Hα to compensate for missing Hβ

IC 5067-70 - Pelican Nebula, Wright-Newtonian narrow-band natural-color CCD-image.
IC 5067-70 - Pelican Nebula in Hα, which is part of this image.

Exposure Data

Instrument: 9.5" f/4.9 Newtonian
F/stop: 5.6
Exposure: Hα: 25 x 10 min, [OIII]: 17 x 10 min, [SII]: 15 x 10 min
Camera: QHY8 Pro
Offset/Gain/Temp: 111 / 51% / -20°C to -30°C
Date: October 21 - 31, 2010
Location: Floridsdorf, Vienna
Conditions: Visual limiting magnitude 4-5 mag, SQM-L sky brightness 18.1-18.9 mag/arcsec² (decreasing), seeing 1.7" FWHM, slight wind, low humidity, 1-3°C (decreasing), various moon phases
Autoguider: Meade Pictor 216 XT, max. error: 1" (RA) / 1" (Dec)
Enhancement: Basic data reduction, combine, logarithmic curves, background flattening, local contrast enhancement, color synthesis using tone mapping, color correction, noise filtering
Notes: For color synthesis, I used a tone-mapping technique.

Immediately west of NGC 7000, in mid-Atlantic, so to speak, the Pelican Nebula, IC 5067-70, is located. It is smaller and less bright than the North America Nebula. A magnification of about 40x is a good choice, and an UHC or OIII filter is recommended (in small scopes only an UHC can be used, with an OIII the image becomes to dark) although in nights of superb transparency the nebula is also visible without filter in a 6" scope. Under dark skies an astonishing amount of structure can be found in the Pelican, including the beak, the dark intrusion between beak and body of the animal, the bonnet and the irregular outline of the nebula to the south. Small telescopes (smaller than 4") might not show the nebula at all and big ones (greater than 8") offer only a small field of view, making it possible to get lost in this area. But the views of both nebulae in big telescopes closely resemble photographs of the region.

The dark nebula separating the North America and Pelican Nebulae is LDN 935. It is responsible for the sharp nebula edges and good contrast in the Florida/Gulf of Mexico regions of NGC 7000.

The successful observation of nebulae is a skill to be learned. A beginner will not be able to see the faint structure which is readily visible to the experienced observer, as the eye has to be trained and you have to learn what to look for.