Messier 38 (center cluster), a.k.a. M38 or NGC 1912, is an open cluster in the Auriga constellation. It was discovered by Giovanni Batista Hodierna before 1654 and independently found by Le Gentil in 1749. The cluster's brightest stars form a pattern resembling the Greek letter Pi or an "oblique cross." At its distance of 4,200 light years, its angular diameter of about 20' corresponds to about 25 light years. It is of intermediate age (about 220 million years, according to Sky Catalog 2000) and features a yellow giant of apparent magnitude +7.9. This corresponds to an absolute magnitude of -1.5, or a luminosity of 900 Suns. For comparison, our Sun would appear as a faint magnitude +15.3 star from the distance of M38. Located in the disk of our Milkyway galaxy, M38 is still young enough to contain many hot blue stars.

Walter Scott Houston described its appearance as follows: "Photographs usually show a departure from circularity, a feature quite evident to visual observers. Older reports almost always mention a cross shape, which seems more pronounced with small instruments. A view with a 24-inch reflector on a fine Arizona night showed the cluster as irregular, and the host of stars made fruitless any effort to find a geometrical figure."

NGC 1907 (smaller cluster towards bottom center) is an open star cluster around 4,500 light years from Earth. It contains around 30 stars and is over 500 million years old. With a magnitude of 8.2 it is visible as part of the constellation Auriga. [Source: Wikipedia]

The image was captured with my TMB80ss refractor, mounted on the venerable Meade 12"LX200. The imaging camera was the Canon 450DXsi, at F6.3 (i.e. 504mm FL). Imaging subs were taken around 18C, and 3 minutes each.

Image -- 155 subs at 180sec (7.75 hr) on Dec 16th and 17th.

Processing was done with PixInsight, following reasonably good practice. North is up, and this is a medium crop due to star distortion in the corners. While there is the usual gradient across the image from left to right , there is for real a faint red nebula column to the right of the clusters.

To exaggerate the two clusters, I created a star mask, and cloned out the two clusters. Then used that mask to diminish surrounding stars with PI's morphological transformation tool. It's a bit of a cheat, but I think worked pretty well.

Meanwhile, my ATIK 383L+mono is on its way back from the U.K. after being reconditioned. This is good news.