Here's my sketch and observing report of NGC 2420 in Gemini, an open cluster in the neighbourhood of the Eskimo Nebula.
Date / Time : 27/12/08 / 00:34
Observing Location : Landgraaf, Netherlands
Seeing / Transparency : 3 / 5
Telescope : Orion Optics UK 300mm
Eye-piece :: 12mm Nagler Type 4
Magnification / Field of View ': 133 / 37
With the 300mm Dobson and the 35mm Panoptic I see NGC 2420 as a smudge, so it's not an easy object, but on the other hand it isn't too difficult. Giving the tube a little nudge, makes the smudge stand out more clearly from the dark background. Increasing the magnification with the 12mm Nagler T4 to 133x, helps to resolve this small and compact cluster partially. With the 7mm Pentax it's resolved even more, but I like the view in the 12mm better, so that will be my optimum magnification for producing the sketch.
With direct vision I count about 20 stars, a relatively poor cluster. However with averted vision the number of stars increases rapidly, and becomes about 40 to 50 stars, so this would make it a moderately rich cluster. According to Hynes (Star clusters) there are about 300 stars in this cluster, but visually I don't see more than 50, whatever I try. There are no dark lanes visible and there is no central star or a star with a specific colour in NGC 2420. I do not detect any significant double or multiple stars.
To the south of the cluster, is a bright yellow-orange star visible. I don't know if it belongs to the cluster but I will put it in the sketch anyway. With averted vision I not only see more stars popping in and out of the field of view, but I also notice a glow of unresolved stars. I do not see any asterisms in the cluster, except for a group of 4 stars on the southern edge of the cluster that seem to form a kind if hook. NGC 2420 looks a little irregular with no real centre.
If you want a little more info on the discovery of this cluster, where you can find it, and it's position in our galaxy, please follow this link to :NGC 2420 at Starobserver.eu