| NGC 3938 | |
| Epoch: | J2000 |
| Type: | SA(s)c[1] |
| Ra: | [2] |
| Dist Ly: | 43 Mly |
| Appmag V: | 10.9 |
| Size V: | 5.4 × 4.9 |
| Constellation Name: | Ursa Major |
NGC 3938 is an unbarred spiral galaxy in the Ursa Major constellation. It was discovered on 6 February 1788 by William Herschel. It is one of the brightest spiral galaxies in the Ursa Major South galaxy group and is roughly 67,000 light years in diameter.[3] It is approximately 43 million light years away from Earth.[2] NGC 3938 is classified as type Sc under the Hubble sequence, a loosely wound spiral galaxy with a smaller and dimmer bulge.[4] The spiral arms of the galaxy contain many areas of ionized atomic hydrogen gas, more so towards the center.[5]
Five supernovae have been identified within NGC 3938. SN 1961U (mag. 13.7) was discovered on 2 January 1962.[6] SN 1964L (mag. 13.3) was discovered on 11 December 1964.[7] SN 2005ay is a type II supernova that was discovered on 27 March 2005 and had a magnitude of 15.6.[8] SN 2017ein is a type Ic supernova that was discovered on 25 May 2017 and peaked at magnitude 14.9.[9] Images taken before the explosion point to a progenitor mass between ~47-48, if it was in a single star system, and ~60-80, if it was in a binary star system. SN 2022xlp is a type Ia supernova that was discovered on 13 October 2022 by Kōichi Itagaki.