Hemisphere:  Northern  ·  Constellation: Cygnus (Cyg)  ·  Contains:  Crescent nebula  ·  IC 4996  ·  NGC 6888  ·  NGC6888  ·  PK076+01.2  ·  Sh2-105  ·  The star 34Cyg
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NGC 6888 - The Crescent Nebula, 


            Kurt Zeppetello
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NGC 6888 - The Crescent Nebula

Getting plate-solving status, please wait...
NGC 6888 - The Crescent Nebula, 


            Kurt Zeppetello
Powered byPixInsight

NGC 6888 - The Crescent Nebula

Imaging telescopes or lenses: Orion ED80 80mm f/7.5 Apochromatic Refractor Telescope

Imaging cameras: Canon T3i Full Spectrum 600D

Mounts: Orion Sirius EQ-G (HEQ5)

Guiding telescopes or lenses: Agena 50mm Guide Scope with Helical Focuser

Guiding cameras: QHY-5-L-II-M Planatary & Autoguider

Focal reducers: Orion .8X Focal Reducer

Software: Adobe photoshop  ·  Lightroom  ·  StarTools  ·  Gradient Exterminator  ·  Astronomy Tools - PS  ·  BackyardEOS  ·  PHD Guiding

Filters: Astronomik UHC Clip-Filter  ·  Astrodon UV/IR

Dates:Aug. 24, 2017Aug. 26, 2017

Frames: 44x180" (2h 12') ISO1600

Integration: 2h 12'

Darks: ~8

Bias: ~9

Avg. Moon age: 3.82 days

Avg. Moon phase: 16.36%

Bortle Dark-Sky Scale: 5.00

Temperature: 17.50

Astrometry.net job: 1711669

RA center: 20h 12' 12"

DEC center: +38° 21' 15"

Pixel scale: 1.833 arcsec/pixel

Orientation: -1.278 degrees

Field radius: 1.543 degrees

Resolution: 4080x2688

Locations: Happy Frog Observatory, Monroe, Connecticut, United States

Data source: Backyard


The Crescent Nebula (a.k.a. NGC 6888, Caldwell 27, Sharpless 105) is an emission nebula in the constellation Cygnus, about 5000 light-years away from Earth. It has an interesting history as it formed by fast stellar wind from a star catching up and colliding with slower moving wind ejected by the star when it became a red giant around 250,000 years ago source: wikipedia).

The sky was pretty clear both nights I went out to collect images and I managed to get over two hours on an object. I used my Astronomik UHC Clip filter which is very good for emission nebula with lots of ionized hydrogen especially in light polluted areas. However, this really would have benefited with some 12nm H-alpha filter luminosity frames. Trevor Jones from Astrobackyard did great job recently with this nebula using an H-alpha filter and has commented on this on his website. As I write this tonight, it is clear outside but the moon out making it not a great night for nebula imaging unless, that is, you are using an H-alpha filter as they only let H-alpha light in and block everything else including moonlight. I see one of these filters in the future.

Last thing, I have seen many other images of this and other nebulae where the star fields are quite reduced. I did some reduction in Astronomy Tools with this nebula and could have done more but I actually like the stars so did remove as many as I could have. Hope you enjoy...



Sky plot

Sky plot


NGC 6888 - The Crescent Nebula, 


            Kurt Zeppetello