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Abell 39 Planetary Nebula in OIIIRGB, 


            Douglas J Struble
Abell 39 Planetary Nebula in OIIIRGB
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Abell 39 Planetary Nebula in OIIIRGB

Technical card

Dates:May 28, 2020June 6, 2020June 7, 2020June 8, 2020

Astrodon Blue Tru-Balance E-Series Gen 2: 60x60" (gain: 0.00) -20C bin 1x1
Astrodon Green Tru-Balance E-Series Gen 2: 60x60" (gain: 0.00) -20C bin 1x1
Astrodon OIII 3nm: 427x120" (gain: 200.00) -20C bin 1x1
Astrodon Red Tru-Balance E-Series Gen 2: 60x60" (gain: 0.00) -20C bin 1x1

Integration: 17.2 hours

Darks: ~50

Flats: ~50

Bias: ~250

Avg. Moon age: 13.85 days

Avg. Moon phase: 79.70%

Bortle Dark-Sky Scale: 8.00

Basic astrometry details job: 3593912

RA center: 16h 27' 34"

DEC center: +27° 54' 32"

Pixel scale: 1.105 arcsec/pixel

Orientation: 124.222 degrees

Field radius: 0.233 degrees

Resolution: 1186x950

Locations: Backyard White Zone Observatory, Taylor, MI, Michigan, United States

Data source: Backyard


I noticed I got some magenta stars just like I did with my newer ES 165, so I am thinking it is more of a matter of my skies or my Hotech Self Leveling Field Flattener. I think I may swap out my Astrodon E-Series RGB filters with the Astronomik Deep-Sky RGB filters on this rig as well. I had to color shift several stars to correct them.

Abell 39 is a low surface brightness planetary nebula in the constellation of Hercules. It is the 39th entry in George Abell's 1966 Abell Catalog of Planetary Nebulae (and 27th in his 1955 catalog) of 86 old planetary nebulae which either Abell or Albert George Wilson discovered before August 1955 as part of the National Geographic Society - Palomar Observatory Sky Survey. It is estimated to be about 6,800 light-years from earth and 4,600 light-years above the Galactic plane. It is almost perfectly spherical and also one of the largest known spheres with a radius of about 2.5 light-years.

Its central star is slightly west of center by about 2″ or 0.1 light-years. This offset does not appear to be due to interaction with the interstellar medium, but instead, it is hypothesized that a small asymmetric mass ejection has accelerated the central star. The mass of the central star is estimated to be about 0.61 M☉ with the material in the planetary nebula comprising an additional 0.6 M☉.

This planetary nebula has a nearly uniform spherical shell. However, the eastern limb of the nebula is 50% more luminous than the western limb. Additionally, irregularities in the surface brightness are seen across the face of the shell. The source of the east–west asymmetry is not known but it could be related to the offset of the central star. The central star is classified as a subdwarf O star.



Douglas J Struble
License: None (All rights reserved)

Sky plot

Sky plot


Abell 39 Planetary Nebula in OIIIRGB, 


            Douglas J Struble