Wow Howard, NGC 2392 trough a 90-inch must be an incredible experience.
The "mouth" you refer to is called "bridge" here in Germany. I chase this detail over years until I had success.
My notes about the "mouth" were as follows:
16", 515x, NELM 7m0+, Seeing I
after several failed attempts finally visible as a black hole within the pointy N end of the inner shell.
18", 740x, NELM 7m0+, Seeing I
very difficult detail, bridge is visible as a second peak within the shell; gap only little darker
27", 837x, NELM 7m0+, Seeing I
spectacular view under best seeing conditions; bridge directly and easy to see; gap between bridge and northern shell relative large
27", 586x, NELM 6m5+, Seeing III
under modest seeing bridge difficult to see despite the large aperture; no steady visible as a hole within the pointy and filled northern shell
48", 814x, NELM 7m0+, Seeing III
even under no perfect seeing conditions the bridge itself and the dark hole easy to see
>I’ve always had difficulty star hopping to the Inuit Nebula, and it usually takes me more >than one attempt to get in the eyepiece – anyone else have that experience?
Reply With Quote