h191. NGC 3938 -- Spiral Galaxy in Ursa Major

18 Mar 2025, 04:46 UT; Spotsylvania, Virginia USA. Bortle 4.5 zone.

 

Celestron C8 SCT at f/7. Orion Atlas AZ/EQ-G mount. QHY294M Pro mono camera, bin 1, exposure 10s, gain 1750, stack of 173 frames, no filter, no guiding, no calibration frames, sensor -10°C. Captured in Sharpcap Pro. Processed in PixInsight.

 

Clouds: partly cloudy

Transparency (AL): 6

Seeing (AL): Good

 

Description: beautiful small, dim, face-on spiral galaxy with starlike center, disk is entirely composed of 5-6 arching spiral arms with bright knots, like a tight rose bud

 

AZ 190°

ALT 65°

 

Image scale: 0.5 "/px

 

Apparent magnitude 10.9

Apparent size 5x5'

 

from Wikipedia

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. It is approximately 43 million light years away from Earth. NGC 3938 is classified as type Sc under the Hubble sequence, a loosely wound spiral galaxy with a smaller and dimmer bulge. The spiral arms of the galaxy contain many areas of ionized atomic hydrogen gas, more so towards the center.

 

Five supernovae have been identified within NGC 3938.

-SN 1961U (type II, mag. 13.7) was discovered by Paul Wild on 28 December 1961.

-SN 1964L (type Ic, mag. 13.3) was discovered by Paul Wild on 11 December 1964.

-SN 2005ay (type II, mag. 15.6) was discovered by Doug Rich on 27 March 2005.

-SN 2017ein (type Ic, mag. 17.6) was discovered by Ron Arbour on 25 May 2017 and peaked at magnitude 14.9. Images taken before the explosion point to a progenitor mass between ~47-48M☉, if it was in a single star system, and ~60-80M☉, if it was in a binary star system.

-SN 2022xlp (type Ia, mag. 17) was discovered by Kōichi Itagaki on 13 October 2022.

Done