Uwe Glahn
August 16th, 2023, 09:02 AM
OC NGC 6846
R.A.: 19h56m28s
Dec.: +32°20'56"
Size: 0.8'; Magnitude: 14.2v; Type: (IV1p) II2m
PN K 4-41 (PNG 068.7+01.9, PK 068+01.1)
R.A.: 19h56m34s
Dec.: +32°22'13"
Size: 3"x2"; Magnitude: 15.9v
In the southern part of Cygnus we find a close pair of an Open Cluster and a Planetary Nebula. Both objects are not stunning for their own but their rare near positions (1.8') are the remarkable quality of both.
The small OC was discovered by Edouard Stephan in 1873 with his modern silvered 31-inch glass mirror. Modern scientific paper [JKAS 2011, 44 (1), pgs. 1-11] gives a distance of 1445pc and an age of 0,55 Gyr. This OC suffers from a incorrect position (in the RNGC) that Steve Gottlieb found out. This seems also be the reason of the wrong Trumpler classification. The Archinal/Hynes estimated a more precise II2m. Deep images shows an interesting small and faint clump of around 50 stars.
Only 1.8' NE we find a tiny PN as a faint and stellar object. Even PanSTARRS shows a very small, somewhat elongated object with a very faint central star. It has been suggested that this object is not a true PN, but rather a symbiotic system, or possibly even a supernova remnant [2002MNRAS.336...66R]. The HST pictures a true PN [2016ApJ...830...33S] and shows/suggested, that the large opening angle of the ring segment could be a bow-shock, which would indicate a low velocity interaction through a low density ISM.
With the 16-inch and 360x, the OC shows four stars within a small and unresolved, mottled spot. The PN was barely seen without a filter as a very small, stellar spot. It shows good [OIII] reaction.
picture: Rick J, 14" (cloudynights)
5199
sketch: 16", 360x, NELM 6m0+, no filter, Seeing III
5200
As always, give it a go and let us know.
R.A.: 19h56m28s
Dec.: +32°20'56"
Size: 0.8'; Magnitude: 14.2v; Type: (IV1p) II2m
PN K 4-41 (PNG 068.7+01.9, PK 068+01.1)
R.A.: 19h56m34s
Dec.: +32°22'13"
Size: 3"x2"; Magnitude: 15.9v
In the southern part of Cygnus we find a close pair of an Open Cluster and a Planetary Nebula. Both objects are not stunning for their own but their rare near positions (1.8') are the remarkable quality of both.
The small OC was discovered by Edouard Stephan in 1873 with his modern silvered 31-inch glass mirror. Modern scientific paper [JKAS 2011, 44 (1), pgs. 1-11] gives a distance of 1445pc and an age of 0,55 Gyr. This OC suffers from a incorrect position (in the RNGC) that Steve Gottlieb found out. This seems also be the reason of the wrong Trumpler classification. The Archinal/Hynes estimated a more precise II2m. Deep images shows an interesting small and faint clump of around 50 stars.
Only 1.8' NE we find a tiny PN as a faint and stellar object. Even PanSTARRS shows a very small, somewhat elongated object with a very faint central star. It has been suggested that this object is not a true PN, but rather a symbiotic system, or possibly even a supernova remnant [2002MNRAS.336...66R]. The HST pictures a true PN [2016ApJ...830...33S] and shows/suggested, that the large opening angle of the ring segment could be a bow-shock, which would indicate a low velocity interaction through a low density ISM.
With the 16-inch and 360x, the OC shows four stars within a small and unresolved, mottled spot. The PN was barely seen without a filter as a very small, stellar spot. It shows good [OIII] reaction.
picture: Rick J, 14" (cloudynights)
5199
sketch: 16", 360x, NELM 6m0+, no filter, Seeing III
5200
As always, give it a go and let us know.