Messier 46 or M46, also known as NGC 2437, is an open cluster of stars in the slightly southern constellation of Puppis.

[3] It has a greater spatial extent in infrared than in visible light, suggesting it is undergoing some mass segregation with the fainter (redder) stars migrating to a coma (tail) region.

The fainter stars that extend out to the south and west may form a tidal tail due to a past interaction.

[5] The planetary nebula NGC 2438 appears to lie within the cluster near its northern edge (the faint almost rainbow array of colored smudge at the top-center of the image), but it is most likely unrelated since it does not share the cluster's radial velocity.

[6][8] On the other hand, the illuminating star of the bipolar Calabash Nebula shares the radial velocity and proper motion of Messier 46, and is at the same distance, so is a bona fide member of the open cluster.