M38 - Open Cluster in Auriga; small cluster at 8 o'clock is NGC1907
Discovered by Giovanni Batista Hodierna before 1654. This cluster was silently discovered by Hodierna before 1654, and independently found by Le Gentil in 1749. Charles Messier included it in his catalog on September 25, 1764.
At its distance of 4,200 light years, its angular diameter of about
20' corresponds to about 25 light years, similar to that of its more
distant neighbor M37. It is of intermediate age (about 220 million
years according to the Sky Catalog 2000) and contains a yellow giant of
mag 7.9 and spectral type G0 as its brightest member - this corresponds
to an absolute magnitude of -1.5, or a luminosity of 900 suns.