This planetary nebula apparently is embedded in the open Cluster M46. However is is not physically related to the cluster but 1500 light years closer. Faint outer shells are visible in the images below.
Checkout a miniature PN (Rotten Egg Nebula) at 4 h near the corner;
Find a wider view centering on M46 here
Ha-O3-LRGB (Ha 24x40m, OIII 22x40m, L 6x10m, R 7x100s, G 7x100s, B 7x100s), total exposure 32h, deep NB for visualizing the very faint outer shells,
seeing 0.7-1 arc-sec,
80cm f/7 Astrooptik Keller corrected cassegrain, FLI Proline 16803, Astrodon Gen-2 Filters, Prompt 7 CTIO Chile,
Processing: Johannes Schedler
Find a wider image below in 60/80% size and a close-up in 150% size and a Ha / O-III comparison at bottom