Celestial Atlas: NGC 24 Link for sharing this page on Facebook
IC 5350 - 5386 ← NGC Objects: NGC 1 - 49 → NGC 50 - 99
Click here for Introductory Material
Click on Direct Links for page about a single NGC object
Click on IC 5350 - 5386, NGC 1 - 49 or NGC 50 - 99 for pages about all those objects
Click on NGC Objects for tables for all NGC entries

Direct Links:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69

Page last updated Aug 12, 2017

NGC 24 (= PGC 701)
Discovered (Oct 27, 1785) by William Herschel
Also observed (Sep 12, 1836) by John Herschel
A magnitude 11.6 spiral galaxy (type SA(s)c?) in Sculptor (RA 00 09 56.4, Dec -24 57 49)
Historical Identification: Per Dreyer, NGC 24 (= GC 10 = JH 2308 = WH III 461, 1860 RA 00 02 47, NPD 115 45.0) is "very faint, considerably large, much extended, gradually brighter middle". The position precesses to RA 00 09 54.8, Dec -24 58 14, only 0.5 arcmin southwest of the center of the galaxy listed above and well within its outline, so the identification is certain.
Physical Information: Based on a recessional velocity of 555 km/sec (and H0 = 70 km/sec/Mpc), NGC 24 is about 25 to 30 million light years away, but for such distances peculiar (non-Hubble-redshift) velocities can significantly affect the accuracy of the distance estimate. Unfortunately, redshift-independent estimates range from as little as 3 million to as much as 35 million light years, inspiring far less confidence. However, the galaxy's apparent size of about 6.9 by 1.5 arcmin (from the images below) makes most sense if its distance is in the 25 million light year range, in which case it would be about 50 to 55 thousand light years across. It has been suggested that NGC 24 and 45 are a pair, as they have similar recessional velocities and if at similar distances their two degree separation corresponds to less than a million light years. The latter galaxy is more certainly about 25 million light years away, so if they really are a pair it would confirm the estimate made in this entry; but both galaxies' distances are sufficiently uncertain that the suggestion that they are a pair cannot inspire much confidence. Update: The discussion of the 2.7 arcmin wide HST image below (released on Sep 26, 2016) states that the distance of the galaxy is about 25 million light years, it is about 40 thousand light years across, and about 80% of the mass of its halo is so-called "dark matter"; so the distance and size estimates in this entry appear to be more or less in agreement with most current thinking.
DSS image of region near spiral galaxy NGC 24
Above, a 12 arcmin wide DSS image centered on NGC 24
Below, a 6 arcmin wide image of the galaxy (Image Credit & © Carnegie-Irvine Survey; used by permission)
Carnegie-Irvine Survey image of spiral galaxy NGC 24
Below, a 2.7 arcmin wide HST image of the inner half of the galaxy (Image Credit ESA/Hubble & NASA)
HST image of the inner half of spiral galaxy NGC 24
Below, a 1.6 arcmin wide image of the central part of the galaxy (Image Credit Hubble Legacy Archive)
HST false-color image of the central part of spiral galaxy NGC 24
Below, a 12 arcmin wide DSS image centered on NGC 24, also showing PGC 783199, 783608 and 785296
DSS image of region near spiral galaxy NGC 24, also showing various PGC objects
Below, a 2 degree wide DSS image centered between possible companions NGC 24 and 45
(The image is centered at RA 00 00 12.0, Dec -24 06 00)
DSS image of region between NGC 24 and NGC 45

Direct Links:
1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49,
50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69
Celestial Atlas: NGC 24 Link for sharing this page on Facebook
IC 5350 - 5386 ← NGC Objects: NGC 1 - 49 → NGC 50 - 99