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HFG1 (Heckathorn-Fesen-Gull 1) in Ha & OIII, 


            Douglas J Struble
HFG1 (Heckathorn-Fesen-Gull 1) in Ha & OIII

HFG1 (Heckathorn-Fesen-Gull 1) in Ha & OIII

Technical card

Resolution: 4300x3236

Dates:Sept. 22, 2018Oct. 9, 2018

Astrodon Ha 5nm: 784x120" (gain: 201.00) -20C bin 1x1
Astrodon OIII 3nm: 616x120" (gain: 201.00) -20C bin 1x1

Integration: 46.7 hours

Darks: ~50

Flats: ~50

Bias: ~250

Avg. Moon age: 6.36 days

Avg. Moon phase: 46.81%

Bortle Dark-Sky Scale: 6.00 job: 2477408

RA center: 45.805 degrees

DEC center: 64.913 degrees

Pixel scale: 0.649 arcsec/pixel

Orientation: 178.270 degrees

Field radius: 0.485 degrees

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

Data source: Backyard


HFG1 was discovered in the Milky Way Emission Line Study in 1982 by Heckathorn, Fesen and Gull (A&A, 114, 414, 1982). It is defined as a type F planetary nebula by Tweedy and Kitter (Astrophys. J Supp Series 107, 255-262, 1996) meaning that is appears to be uniformly filled. Its mag. 14.5 central star is a close, precataclysmic binary, V664 Cas. One report suggests that V664 left a trail at least 20′ long of ~10,000 year old shocked material as it ejected matter and moved through the interstellar medium (ISM).

HFG1 has an interesting structure. It has a narrow rim approx. 14.5′ in diameter surrounding a 9′ diameter central region with an intervening gap. The rim is brightest in the south, suggesting that it interacted with the ISM. The rim is not complete and becomes too faint for our system to detect in the northeast. The core has three bright lobes toward the south and a central opening nearly devoid of emission. As shown in POSS II plates, blue (from OIII) shows more strongly that red (H-a), but still, both are described as faint. There appears to be a gradation from stronger OIII in the southern lobes of the core to stronger Ha toward the north.



Douglas J Struble
License: None (All rights reserved)

Sky plot

Sky plot


HFG1 (Heckathorn-Fesen-Gull 1) in Ha & OIII, 


            Douglas J Struble