A Ring in the Bouquet

M46 (NGC 2437) and NGC 2438
By Kiminori Ikebe

From Mr. Ikebe’s observing notes:

M46 (NGC 2437) Pup open cluster Difficulty level 1

NGC 2438 Pup planetary nebula Difficulty level 3

Date of observation: 1998/11/21 03:29
Observing site: Hoshinomura
Transparency/seeing/sky darkness: 1/4/3
Instruments: 32cm Dobsonian with Er32 at 50x
Width of field: 1 degree

This is a large and bright open cluster. Even at 50x it is almost completely resolved. This fine cluster is filled with numerous pin-points of faint stars and very difficult to draw. This sketch shows it as nebulosity. There are also many bright stars embedded in this cluster. The neighboring M47 makes a good contrast with M46. M47 has fewer stars with unequal brightness. M46 presents itself as a dainty cluster while M47 shows its coarseness. Another similarly contrasting pair is NGC 2451 and NGC 2477 in Puppis. They are more contrasting than the M46 and M47 pair.

At this magnification the planetary nebula NGC 2438 is clearly seen. Its image overlapping with the open cluster is mysterious and unreal. It is rather large as planetary nebulae go. Switching to high powers a ring structure becomes clearer. This nebula is interesting by itself but it is usually viewed in association with M46 playing second fiddle to it.

(Mr. Ikebe’s sketch gallery can be found here: Visual Observation of Deep Sky Objects)

NOTE TO OUR VISITORS: Please accept my apologies for the lapse in updates for the last three days. I returned from a trip out of town to hear that Rich Handy has come down with pneumonia. He is getting some much needed rest and antibiotics and sounds like he is slowly getting better. I’ll work on keeping the posts going until he is feeling well again. Your submissions are always appreciated!

Jeremy Perez