HFG1 Ancient Planetary Nebula

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). North is toward the upper left.
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 H-a toward the north. The detail was brought out with 3 nm OIII and H-a filters and RGB data were added for star colors, but this object is extremely faint, even for our 16" RC and 14 hours of total exposure.