NGC 38 — space

NGC 38

NGC 38 (also known by the designations MCG-1-1-47 or PGC 818) is a spiral galaxy in the constellation Pisces. It was discovered in 1881.

Discovered (Sep 30, 1867) by Édouard Stephan (but not published)
Re-observed (Oct 25, 1881) by Édouard Stephan (and later listed as NGC 38)
A magnitude 13.3 spiral galaxy (type (R)SA(s)a?) in Pisces (RA 00 11 47.0, Dec -05 35 11)

Historical Identification

Per Dreyer, NGC 38 (Stephan list XII (#3), 1860 RA 00 04 38, NPD 96 22.0) is "faint, small, round, much brighter middle". The position precesses to RA 00 11 47.6, Dec -05 35 15, only 0.2 arcmin from the center of the galaxy listed above and well within its outline, so the identification is certain.

Discovery Note

Stephan's date of discovery based on his published data is Oct 25, 1881, which represents the date when he made what he considered an adequate micrometric measurement; but based on Stephan's original notes, Yann Pothier has shown that he actually made his first observation of what became NGC 38 on Sep 30, 1867, as shown above.

Physical Information

Based on a recessional velocity of 8035 km/sec (and H0 = 70 km/sec/Mpc), a straightforward calculation indicates that NGC 38 is about 375 million light-years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 360 to 365 million light-years away at the time the light by which we see it was emitted, about 365 to 370 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 1.1 by 1.1 arcmin (from the images below), the galaxy is about 115 to 120 thousand light-years across.