Celestial Atlas
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Page completed Mar 11, 2015

IC 1
Recorded (Nov 18, 1886) by
Guillaume Bigourdan
A magnitude 15.6 star in Pegasus (RA 00 08 26.8, Dec +27 43 04)
Historical Identification: Per Dreyer, IC 1 (Bigourdan 103, 1860 RA 00 01 15, NPD 63 04) is a "double star, magnitudes 13 and 13, one with nebulosity". The position precesses to RA 00 08 27.3, Dec +27 42 46, only 0.4 arcmin below the pair of stars listed above, so the identification is certain, despite the lack of any nebulosity.
Discovery Notes: Given Dreyer's entry it would seem obvious that the pair of stars should be IC 1, but per Corwin, Bigourdan notes the northeastern member of the pair merely as a reference, and suspects the southwestern star of being nebulous. That is wrong, as is true for most of Bigourdan's "stellar" objects, but if we presume the IC entry is based on the suggestion of nebulosity, then only the southwestern star should be considered to be IC 1. As a result of Corwin's argument I have changed this entry to reflect that suggestion.
DSS image of region near the star listed as IC 1
Above, a 12 arcmin wide DSS image centered on IC 1

IC 2 (= PGC 778)
Discovered (Mar 3, 1891) by
Stephane Javelle
A magnitude 14.7 spiral galaxy (type Sb?) in Cetus (RA 00 11 00.9, Dec -12 49 22)
Historical Identification: Per Dreyer, IC 2 (Javelle 1, 1860 RA 00 03 52, NPD 103 36.2) is "faint, small, brighter middle". The position precesses to RA 00 11 00.9, Dec -12 49 27, right on the galaxy listed above, so the identification is certain.
Physical Information: Based on a recessional velocity of 6775 km/sec, IC 2 is about 315 million light years away. Given that and its apparent size of 0.75 by 0.25 arcmin, it is about 70 thousand light years across.
DSS image of region near spiral galaxy IC 2
Above, a 12 arcmin wide DSS image centered on IC 2
Below, a 1 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 2
IC 3 (= PGC 836)
Discovered (Aug 27, 1892) by
Stephane Javelle
A magnitude 13.8 elliptical galaxy (type E/S0?) in Pisces (RA 00 12 06.1, Dec -00 24 55)
Historical Identification: Per Dreyer, IC 3 (Javelle 2, 1860 RA 00 04 56, NPD 91 12.1) is "faint, very small, irregular figure, mottled but not resolved". The position precesses to RA 00 12 06.2, Dec -00 25 22, less than half an arcmin south of the galaxy listed above, so the identification is certain.
Physical Information: Based on a recessional velocity of 5435 km/sec, IC 3 is about 255 million light years away. Given that and its apparent size of 0.9 by 0.5 arcmin, it is about 65 thousand light years across.
SDSS image of region near lenticular galaxy IC 3
Above, a 12 arcmin wide SDSS image centered on IC 3
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 3

IC 4 (= PGC 897)
Discovered (Sep 12, 1893) by
Frederick Pechüle
A magnitude 13.1 spiral galaxy (type SABc?) in Pegasus (RA 00 13 26.9, Dec +17 29 11)
Historical Identification: Per Dreyer, IC 4 (Pechüle ((M.N.) 3259), 1860 RA 00 06 15, NPD 73 20.6) is "very faint, very small, round". The position precesses to RA 00 13 27.8, Dec +17 26 08, about 3 arcmin south of the galaxy listed above, but there is nothing else nearby and no one has voiced any doubt about the identification, so it appears to be certain.
Physical Information: Based on a recessional velocity of 5005 km/sec, IC 4 is about 235 million light years away. Given that and its apparent size of 1.0 by 0.7 arcmin, it is about 65 thousand light years across.
SDSS image of region near spiral galaxy IC 4
Above, a 12 arcmin wide SDSS image centered on IC 4
Below, a 1.4 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4

IC 5 (= PGC 1145)
Discovered (Sep 27, 1892) by
Stephane Javelle
A magnitude 13.8 elliptical galaxy (type E3?) in Cetus (RA 00 17 34.9, Dec -09 32 36)
Historical Identification: Per Dreyer, IC 5 (Javelle 3, 1860 RA 00 10 27, NPD 100 19.1) is "faint, nebulous 13th magnitude star". The position precesses to RA 00 17 35.3, Dec -09 32 25, on the northeastern rim of the galaxy listed above and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 6720 km/sec, IC5 is about 310 million light years away. Given that and its apparent size of 0.8 by 0.55 arcmin, it is about 75 thousand light years across.
SDSS image of region near elliptical galaxy IC 5
Above, a 12 arcmin wide SDSS image centered on IC 5
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy IC 5

IC 6 (= PGC 1228)
Discovered (Sep 23, 1867) by
Truman Safford
Discovered (Sep 19, 1892) by Stephane Javelle
A magnitude 13.5 elliptical galaxy (type E0?) in Pisces (RA 00 18 55.0, Dec -03 16 34)
Historical Identification: Per Dreyer, IC 6 (Javelle 4, (Safford 89), 1860 RA 00 11 46, NPD 94 03.2) is "faint, very small, round, much brighter middle equal to 14th magnitude star". The position precesses to RA 00 18 55.5, Dec -03 16 32, right on the galaxy listed above, the description fits and the only nearby object is accounted for by IC 8, so the identification is certain.
Discovery Notes: See the entry for Truman Safford for a discussion of why Javelle had no idea that Safford had observed this object nearly 25 years earlier, making Javelle's discovery completely independent. (Even Dreyer thought Javelle's discovery was completely new, as he misidentified Safford's #89 as IC 8; but Safford's position is only 0.7 arcmin southeast of IC 6, considerably further from IC 8, and IC 6 is a magnitude brighter than IC 8, so it is essentially certain that what Safford observed was IC 6.)
Physical Information: Based on a recessional velocity of 6185 km/sec, IC 6 is about 290 million light years away. Given that and its apparent size of 0.7 by 0.7 arcmin, it is about 60 thousand light years across.
SDSS image of region near elliptical galaxy IC 6, also showing IC 8
Above, a 12 arcmin wide SDSS image centered on IC 6, also showing IC 8
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy IC 6

IC 7 (= PGC 1216)
A magnitude 13.8 lenticular galaxy (type E/S0?) in
Pisces (RA 00 18 53.2, Dec +10 35 41)
Historical Identification: Per Dreyer, IC 7 (Javelle 506, 1860 RA 00 11 51, NPD 80 13.8) is "faint, very small, round, 12.5 magnitude star close". The position precesses to RA 00 19 03.5, Dec +10 32 52, which is 10 seconds of time to the east and almost 3 arcmin south of the galaxy listed above, but there is nothing else nearby, and the star immediately southwest of the galaxy's nucleus (and actually superimposed on its modern images) appears to make the identification certain. (Odds are that Javelle misidentified his comparison star, but no one seems to have looked into that possibility, and no one has voiced any objection to the identification, so it probably is correct.)
Physical Information: Based on a recessional velocity of 5365 km/sec, IC 7 is about 250 million light years away. Given that and its apparent size of 0.9 by 0.65 arcmin, it is about 65 thousand light years across.
SDSS image of region near lenticular galaxy IC 7
Above, a 12 arcmin wide SDSS image centered on IC 7
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 7

IC 8 (= PGC 1234)
Almost certainly not observed (Sep 23, 1867) by
Truman Safford
Discovered (Sep 19, 1892) by Stephane Javelle
A magnitude 14.4 spiral galaxy (type Sbc?) in Pisces (RA 00 19 02.7, Dec -03 13 19)
Historical Identification: Per Dreyer, IC 8 (Safford 89, Javelle 5, 1860 RA 00 11 54, NPD 93 59.9), is "very faint, very small, irregularly extended, a little brighter middle". The position precesses to RA 00 19 03.5, Dec -03 13 14, right on the galaxy listed above and the description fits, so the identification is certain.
Discovery Notes: Although Dreyer listed Safford as a co-discoverer of IC 8, that is almost certainly incorrect. Safford's position is much closer to IC 6, and that galaxy is nearly a magnitude brighter than IC 8, so it is virtually certain that Safford observed IC 6 instead of IC 8.
Physical Information: Based on a recessional velocity of 6000 km/sec, IC 8 is about 280 million light years away. Given that and its apparent size of 0.6 by 0.25 arcmin, it is about 50 thousand light years across.
SDSS image of region near spiral galaxy IC 8, also showing IC 6
Above, a 12 arcmin wide SDSS image centered on IC 8, also showing IC 6
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 8

IC 9 (= PGC 1271)
Discovered (Aug 23, 1892) by
Stephane Javelle
A magnitude 14.4 peculiar galaxy (type (R)S0(r)a? pec) in Cetus (RA 00 19 44.0, Dec -14 07 19)
Historical Identification: Per Dreyer, IC 9 (Javelle 6, 1860 RA 00 12 37, NPD 104 54.1) is "very faint, pretty large, round". The position precesses to RA 00 19 43.9, Dec -14 07 27, on the southern rim of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 12555 km/sec, a straightforward calculation indicates that IC 9 is about 585 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 555 million light years away at the time the light by which we see it was emitted, just under 570 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 0.5 by 0.35 arcmin, the galaxy is about 80 thousand light years across. Because of its unusually bright center, the galaxy is listed as a Seyfert galaxy (type Sy 2).
SDSS image of region near peculiar galaxy IC 9
Above, a 12 arcmin wide SDSS image centered on IC 9
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of peculiar galaxy IC 9

IC 10 (= PGC 1305)
Discovered (Oct 8, 1887) by
Lewis Swift
A magnitude 10.4 irregular galaxy (type IBm?) in Cassiopeia (RA 00 20 23,1, Dec +59 17 35)
Historical Identification: Per Dreyer, IC 10 (Swift list VII (#1), 1860 RA 00 12 44, NPD 31 28) is a "faint star involved in extremely faint, very large nebula". The position precesses to RA 00 20 16.6, Dec +59 18 39, northwest of the modern position for the galaxy listed above, but well within its very large outline, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Dwarf galaxy IC10 is a member of the Local Group. It is considerably reddened and dimmed by clouds of gas and dust in the plane of our Milky Way Galaxy. Given its proximity its recessional velocity should be a poor indicator of its distance, and in fact it has a negative radial velocity (-350 km/sec), meaning that it is getting closer to us, not further away, so its distance can only be determined by redshift-independent methods. NED lists 28 measurements, ranging from 1.65 to 5.85 million light years, with average and median distances in the range of 2.5 to 3 million light years, indicating that IC 10 is probably a little further away than the Andromeda Galaxy. Given the galaxy's apparent size of about 9 by 8 arcmin, it is about 7 thousand light years across, hence its designation as a dwarf galaxy. IC10 is the closest example of a "starburst" galaxy, in which numerous hot, bright, massive stars have recently formed (the false-color reddish glow in the NOAO image represents radiation emitted by clouds of hydrogen heated by nearby stars). One such star raced through its life and after dying in a supernova explosion, became the most massive stellar black hole currently known: between 24 and 33 times the mass of the Sun. The black hole was detected by X-radiation emitted when mass ejected by its companion, a Wolf-Rayet star destined to become a future supernova, was pulled into the black hole's accretion disk.
DSS image of dwarf irregular galaxy IC 10
Above, a 12 arcmin DSS image centered on IC 10
Below, a 9 arcmin wide image of the galaxy
(Credit Wikimedia Commons, P. Massey/Lowell Observatory & K. Olsen/NOAO/AURA/NSF)
Lowell Observatory/NOAO image of dwarf irregular galaxy IC 10

IC 11 (probably =
NGC 281)
Probably discovered (Nov 16, 1881) by Edward Barnard (and later listed as NGC 281)
Recorded (1892) by Edward Barnard (and later listed as IC 11)
Probably an emission nebula in Cassiopeia (RA 00 52 53.8, Dec +56 37 30)
Historical Identification: Per Dreyer, IC 11 (Barnard, 1860 RA 00 13 00±, NPD 34 11) is "very faint, large, triple star on northwest corner". The position precesses to RA 00 20 30.7, Dec +56 35 39, but as shown in the image below, there is nothing near that position, either nebular or that fits the description. However, per Corwin the description is essentially identical to the one Barnard recorded for his observation of the nebula that was later listed as NGC 281, and if we assume that Barnard made a half-hour error in transcribing the right ascension (in other words, replace 00 13 00 by 00 43 00), the position precesses to RA 00 51 07.3, Dec +56 34 47, within the western outline of NGC 281, and east and southeast of a line of three stars that would fit the triple star noted in Barnard's descriptions. So although absolute certainty cannot be given to the identification, it seems most likely that IC 11 is a misrecorded reobservation of NGC 281.
Physical Information: Given the duplicate entry, see NGC 281 for anything else.
DSS image of Barnard's position for IC 11
Above, a 12 arcmin wide region centered on the position recorded for IC 11
Below, a 15 arcmin wide region centered on the "corrected" position within NGC 281
DSS image of the adjusted position for IC 11, assuming that it was a misrecorded observation of NGC 281

IC 12 (= PGC 1299)
Discovered (Nov 7, 1891) by
Stephane Javelle
A magnitude 14.9 spiral galaxy (type Sab?) in Pisces (RA 00 20 15.1, Dec -02 39 11)
Historical Identification: Per Dreyer, IC 12 (Javelle 7, 1860 RA 00 13 06, NPD 93 26.2) is "pretty faint, small, extended north and south". The position precesses to RA 00 20 15.6, Dec -02 39 33, just east of the southern end of the galaxy listed above and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 6045 km/sec, IC 12 is about 280 million light years away, in good agreement with redshift-independent distance estimates of 280 to 305 million light years. Given that and its apparent size of 0.8 by 0.2 arcmin, it is about 65 thousand light years across.
SDSS image of region near spiral galaxy IC 12
Above, a 12 arcmin wide SDSS image centered on IC 12
Below, a 1 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 12

IC 13 (= PGC 1301)
Discovered (Nov 10, 1892) by
Stephane Javelle
A magnitude 14.0 spiral galaxy (type Sbc?) in Pisces (RA 00 20 20.1, Dec +07 42 02)
Historical Identification: Per Dreyer, IC 13 (Javelle 507, 1860 RA 00 13 08, NPD 83 04.9) is "very faint, pretty large, extended north and south, diffuse". The position precesses to RA 00 20 20.0, Dec +07 41 45, on the southwestern rim of the galaxy listed above and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 5710 km/sec, IC 13 is about 265 million light years away, in reasonable agreement with redshift-independent distance estimates of 195 to 245 million light years. Given that and its apparent size of 1.2 by 0.4 arcmin, it is about 95 thousand light years across.
SDSS image of region near spiral galaxy IC 13
Above, a 12 arcmin wide SDSS image centered on IC 13
Below, a 1.5 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 13

IC 14
Recorded (Oct 30, 1889) by
Guillaume Bigourdan
Probably a 15th magnitude double star in Pisces (RA 00 22 31.3, Dec +10 29 24)
Historical Identification: Per Dreyer, IC 14 (Bigourdan 104, 1860 RA 00 15 22, NPD 80 18) is a "suspected nebula". The position precesses to RA 00 22 35.0, Dec +10 28 37, which is an empty area to the southeast of the position noted above, but given Bigourdan's tendency to see faint stars as nebulous under poor sky conditions, the fact that since he was not able to find the object on two other nights, and his description of the object as merely being "suspected", odds are that what he saw was simply a faint star. To check the possibility, I examined Bigourdan's original papers. They indicate that Bigourdan's comparison star must have been the 12th magnitude star to the northeast of NGC 95. Precessing its position to the equinox of 1900 and adding Bigourdan's offsets yields a position that precesses to RA 00 22 31.6, Dec +10 28 49, only half an arcmin nearly due south of the double star listed above; given that, I agree with Corwin's suggestion that the pair of stars is almost certainly what Bigourdan recorded, as indicated by the description above.
Physical Information: The brighter western member of the pair is about magnitude 15.2, while the fainter eastern member is about 16th magnitude.
SDSS image of the pair of stars that is probably listed as IC 14
Above, a 12 arcmin wide SDSS image centered on the probable IC 14, also showing NGC 95

IC 15 (= PGC 165498)
Discovered (Aug 27, 1892) by
Stephane Javelle
A magnitude 15.0 spiral galaxy (type (R)SABb?) in Cetus (RA 00 27 57.6, Dec -00 03 41)
Historical Identification: Per Dreyer, IC 15 (Javelle 8, 1860 RA 00 20 48, NPD 90 50.7) is "very faint, very small, irregular figure, suddenly brighter middle". The position precesses to RA 00 27 58.1, Dec -00 04 12, just half an arcmin south southeast of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 13805 km/sec, a straightforward calculation indicates that IC 15 is about 645 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 610 million light years away at the time the light by which we see it was emitted, just under 625 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 0.4 by 0.3 arcmin, the galaxy is about 70 thousand light years across.
SDSS image of region near spiral galaxy IC 15
Above, a 12 arcmin wide SDSS image centered on IC 15
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 15

IC 16 (= PGC 1730)
Discovered (Nov 3, 1891) by
Stephane Javelle
A magnitude 14.6 lenticular galaxy (type S0/a?) in Cetus (RA 00 28 07.7, Dec -13 05 37)
Historical Identification: Per Dreyer, IC 16 (= Javelle 9, 1860 RA 00 21 02, NPD 103 52.6) is "pretty bright, round, brighter middle". The position precesses to RA 00 28 07.5, Dec -13 06 06, about half an arcmin south of the galaxy listed above and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 4845 km/sec, IC 16 is about 225 million light years away. Given that and its apparent size of 0.55 by 0.35 arcmin, it is about 35 thousand light years across.
DSS image of region near lenticular galaxy IC 16
Above, a 12 arcmin wide DSS image centered on IC 16
Below, a 0.8 arcmin wide DSS image of the galaxy
DSS image of lenticular galaxy IC 16

IC 17 (= PGC 1753)
Discovered (Aug 19, 1892) by
Stephane Javelle
A magnitude 15.1 elliptical galaxy (type E1?) in Cetus (RA 00 28 29.8, Dec +02 38 55)
Historical Identification: Per Dreyer, IC 17 (Javelle 10, 1860 RA 00 21 18, NPD 88 07.8) is "pretty bright, very small, round, stellar". The position precesses to RA 00 28 29.1, Dec +02 38 42, barely outside the southwestern rim of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 4315 km/sec, IC 17 is about 200 million light years away. Given that and its apparent size of 0.6 by 0.55 arcmin, it is about 35 thousand light years across.
SDSS image of region near elliptical galaxy IC 17
Above, a 12 arcmin wide SDSS image centered on IC 17
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy IC 17

IC 18 (= PGC 1759, and with
IC 19 = Arp 100)
Discovered (Aug 31, 1892) by Stephane Javelle
A magnitude 14.6 spiral galaxy (type SBb? pec) in Cetus (RA 00 28 34.8, Dec -11 35 14)
Historical Identification: Per Dreyer, IC 18 (Javelle 11, 1860 RA 00 21 29, NPD 102 21.6) is "pretty faint, small, irregular figure, gradually brighter middle". The position precesses to RA 00 28 35.0, Dec -11 35 06, right on the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain. Used in the Arp Atlas as an example of a spiral galaxy with an elliptical companion IC 19.
Physical Information: Based on a recessional velocity of 6070 km/sec, IC 18 is about 280 million light years away. Given that and its apparent size of 0.65 by 0.25 arcmin, the central part of the galaxy is about 55 thousand light years across. However, with its northern tail and southern antitail the galaxy spans about 2.85 arcmin, corresponding to about 235 thousand light years total extent (an additional 180 thousand light years).
DSS image of region near peculiar spiral galaxy IC 18, also showing IC 19, with which it comprises Arp 100
Above, a 12 arcmin wide DSS image centered on IC 18, also showing IC 19
Below, a 3.6 arcmin wide DSS image of the galaxy
DSS image of peculiar spiral galaxy IC 18, part of Arp 100

IC 19 (= PGC 1762, and with
IC 18 = Arp 100)
Discovered (Aug 31, 1892) by Stephane Javelle
A magnitude 14.1 elliptical galaxy (type E2?) in Cetus (RA 00 28 39.5, Dec -11 38 27)
Historical Identification: Per Dreyer, IC 19 (Javelle 12, 1860 RA 00 21 33, NPD 102 24.9) is "round, small, stellar appearance equal to 14th magnitude star". The position precesses to RA 00 28 38.9, Dec -11 38 24, on the western rim of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain. Used in the Arp Atlas as an example of a spiral galaxy (IC 18) with an elliptical companion.
Physical Information: Based on a recessional velocity of 6195 km/sec, IC 19 is about 290 million light years away, or essentially the same distance as IC 18, with which it is presumably gravitationally interacting, causing the distorted appearance of the spiral galaxy. Given that and its apparent size of 0.45 by 0.35 arcmin, it is about 40 thousand light years across.
DSS image of region near elliptical galaxy IC 19, also showingn IC 18, with which it comprises Arp 100
Above, a 12 arcmin wide DSS image centered on IC 19, also showing IC 18
Below, a 1 arcmin wide DSS image of the galaxy
DSS image of elliptical galaxy IC 19, part of Arp 100

IC 20 (= PGC 1755)
Discovered (Nov 3, 1891) by
Stephane Javelle
A magnitude 13.8 lenticular galaxy (type E/S0?) in Cetus (RA 00 28 39.6, Dec -13 00 37)
Historical Identification: Per Dreyer, IC 20 (Javelle 13, 1860 RA 00 21 35, NPD 103 47.5) is "pretty bright, round". The position precesses to RA 00 28 40.4, Dec -13 01 00, only 0.4 arcmin south southeast of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 7780 km/sec, a straightforward calculation indicates that IC 20 is about 360 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 350 million light years away at the time the light by which we see it was emitted, 355 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 0.65 by 0.6 arcmin, the galaxy is about 65 thousand light years across.
DSS image of region near lenticular galaxy IC 20
Above, a 12 arcmin wide DSS image centered on IC 20
Below, a 1 arcmin wide DSS image of the galaxy
DSS image of lenticular galaxy IC 20

IC 21 (= PGC 1785)
Discovered (Nov 7, 1891) by
Stephane Javelle
A magnitude 15.2 spiral galaxy (type SB(rs)b?) in Cetus (RA 00 29 10.4, Dec -00 09 50)
Historical Identification: Per Dreyer, IC 21 (Javelle 14, 1860 RA 00 22 01, NPD 90 56.3) is "pretty bright, very small, irregular figure". The position precesses to RA 00 29 11.1, Dec -00 09 49, right on the galaxy listed above and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 18180 km/sec, a straightforward calculation indicates that IC 21 is about 845 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 790 million light years away at the time the light by which we see it was emitted, 810 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 0.4 by 0.4 arcmin, the galaxy is about 90 thousand light years across. IC 21 is probably a physical companion of its apparent neighbor, PGC 3112047, as they have nearly identical recessional velocities.
SDSS image of region near spiral galaxy IC 21
Above, a 12 arcmin wide SDSS image centered on IC 21
Below, a 0.8 arcmin wide SDSS image of the galaxy, also showing PGC 3112047
SDSS image of spiral galaxy IC 21, also showing its probable companion, PGC 3112047

PGC 3112047
Not an IC object but listed here because of its probable association with
IC 21
A magnitude 16.7 lenticular galaxy (type S0?) in Cetus (RA 00 29 09.6, Dec -00 10 07)
Physical Information: Based on its recessional velocity of 18150 km/sec, PGC 3112047 is probably a physical companion of IC 21 (which see for images), and at the same distance of about 790 million light years. Given that and its apparent size of 0.13 by 0.11 arcmin, it is about 30 thousand light years across. (Listed as SDSSJ002909.57-001007.2 in NED.)

IC 22 (= PGC 1815)
Discovered (Sep 14, 1892) by
Stephane Javelle
A magnitude 13.9 lenticular galaxy (type S0(rs)a?) in Cetus (RA 00 29 33.2, Dec -09 04 51)
Historical Identification: Per Dreyer, IC 22 (Javelle 15, 1860 RA 00 22 27, NPD 99 51.5) is "faint, small, a little brighter middle, mottled but not resolved". The position precesses to RA 00 29 33.8, Dec -09 05 02, just off the southeastern rim of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 6075 km/sec, IC 22 is about 280 million light years away. Given that and its apparent size of 0.6 by 0.3 arcmin, it is about 50 thousand light years across.
SDSS image of region near lenticular galaxy IC 22
Above, a 12 arcmin wide SDSS image centered on IC 22
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 22

IC 23 (= PGC 1872 = PGC 948601)
Discovered (Nov 2, 1891) by
Stephane Javelle
A magnitude 14.0 elliptical galaxy (type E0?) in Cetus (RA 00 30 50.8, Dec -12 43 13)
Historical Identification: Per Dreyer, IC 23 (Javelle 16, 1860 RA 00 23 47, NPD 103 30.4) is "pretty bright, small, round, brighter middle". The position precesses to RA 00 30 52.1, Dec -12 43 57, about 0.8 arcmin south southeast of the galaxy listed above, but there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 6135 km/sec, IC 23 is about 285 million light years away. Given that and its apparent size of 0.45 by 0.45 arcmin, it is about 35 thousand light years across.
DSS image of region near elliptical galaxy IC 23
Above, a 12 arcmin wide DSS image centered on IC 23
Below, a 0.8 arcmin wide DSS image of the galaxy
DSS image of elliptical galaxy IC 23

IC 24
Recorded (Oct 10, 1890) by
Guillaume Bigourdan
A magnitude 15 double star in Andromeda (RA 00 31 16.8, Dec +30 50 19)
Historical Identification: Per Dreyer, IC 24 (Bigourdan 105, 1860 RA 00 23 51, NPD 59 56) is "small, cluster, 30 to 40 seconds of arc, possible nebulosity" (the NGC entry actually reads 30" - 40', but the arcmin symbol after the 40 must be a typographical error). The position precesses to RA 00 31 14.5, Dec +30 50 26, but there is nothing obvious at that location. However, following Thomson's lead, we can precess the present position of Bigourdan's comparison star (BD 69) to his 1900 coordinates, add his offsets to find the equinox of 1900 position of Bigourdan's #105, then precess that to the equinox of 2000 for "current" coordinates. The position available to Bigourdan for BD 69 precesses to about 3 seconds of time to the west of the star's actual position (J2000 RA 00 31 27.4, Dec +30 51 21), so the correct modern position for his #105 is about 3 seconds to the east of the NGC coordinates, at RA 00 31 17.1, Dec +30 50 14, dead-center on the brighter member of the pair of stars listed above, and since Bigourdan often mistook individual stars or small groups as nebulous objects, the identification (as suggested by Thomson and accepted by virtually everyone else) is certain. (The position shown above is in-between the two stars in the pair.)
Physical Information: The pair consists of a magnitude 14.9 star with a magnitude 15.9 star 19 arcsec to the northwest (at position angle 310°).
SDSS image of region near the pair of stars listed as IC 24, also showing NGC 140
Above, a 12 arcmin wide SDSS image centered on IC 24, also showing NGC 140

IC 25 (= PGC 1905)
Discovered (Aug 27, 1892) by
Stephane Javelle
A magnitude 14.3 lenticular galaxy (type S0/a?) in Cetus (RA 00 31 12.1, Dec -00 24 27)
Historical Identification: Per Dreyer, IC 25 (Javelle 17, 1860 RA 00 24 03, NPD 91 10.1) is "faint, very small, irregularly round, very little brighter middle, mottled but not resolved". The position precesses to RA 00 31 13.0, Dec -00 23 40, about 0.85 arcmin north northeast of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 5825 km/sec, IC 25 is about 270 million light years away. Given that and its apparent size of about 0.7 by 0.35 arcmin, it is about 55 thousand light years across.
SDSS image of region near lenticular galaxy IC 25
Above, a 12 arcmin wide SDSS image centered on IC 25
Below, a 1 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 25

IC 26 (=
NGC 135 = PGC 2010 = PGC 138192)
Discovered (Oct 2, 1886) by Francis Leavenworth (and later listed as NGC 135)
Rediscovered (Nov 4, 1891) by Stephane Javelle (and later listed as IC 26)
Also observed (about 1900) by Herbert Howe (as NGC 135)
A magnitude 15.1 lenticular galaxy (type E/S0?) in Cetus (RA 00 31 45.9, Dec -13 20 14)
Historical Identification: Per Dreyer, IC 26 (Javelle 18, 1860 RA 00 24 41, NPD 104 06.8) is "faint, small, round, gradually brighter middle". Javelle's position precesses to RA 00 31 45.7, Dec -13 20 23, on the southern rim of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain. The duplicate entry is due to Leavenworth's right ascension being off by more than a minute of time, and Howe's correction to Leavenworth's position being made after the publication of the Index Catalog, so there was no way for Dreyer to know that the two observations were of the same object.
Physical Information: Given the duplicate entry, see NGC 135 for anything else.

IC 27 (= PGC 143572)
Discovered (Nov 4, 1891) by
Stephane Javelle
A magnitude 14.8 spiral galaxy (type S?) in Cetus (RA 00 33 06.2, Dec -13 22 17)
Historical Identification: Per Dreyer, IC 27 (Javelle 19, 1860 RA 00 26 02, NPD 104 08.8) is "faint, very small, a little extended east and west, brighter middle". The position precesses to RA 00 33 06.4, Dec -13 22 25, on the southern rim of the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 7030 km/sec, a straightforward calculation indicates that IC 27 is about 325 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 a little less than 320 million light years away at the time the light by which we see it was emitted, just over 320 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 0.55 by 0.5 arcmin, the galaxy is about 50 thousand light years across.
DSS image of region near spiral galaxy IC 27, also showing IC 28
Above, a 12 arcmin wide DSS image centered on IC 27, also showing IC 28
Below, a 1 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 27

IC 28 (= PGC 169992)
Discovered (Nov 4, 1891) by
Stephane Javelle
A magnitude 14.9 spiral galaxy (type SB?) in Cetus (RA 00 33 08.7, Dec -13 27 22)
Historical Identification: Per Dreyer, IC 28 (Javelle 20, 1860 RA 00 26 04, NPD 104 13.7) is "very faint, diffuse, very little brighter middle". The position precesses to RA 00 33 08.4, Dec -13 27 19, right on the galaxy listed above, there is nothing else nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 6380 km/sec, IC 28 is about 295 million light years away. Given that and its apparent size of 0.4 by 0.3 arcmin, it is about 35 thousand light years across.
DSS image of region near spiral galaxy IC 28
Above, a 12 arcmin wide DSS image centered on IC 28, also showing IC 27
Below, a 0.6 arcmin wide DSS image of the galaxy
DSS image of region near spiral galaxy IC 28

IC 29 (= PGC 2042)
Discovered (Nov 6, 1891) by
Stephane Javelle
A magnitude 15.1 elliptical galaxy (type E1?) in Cetus (RA 00 34 10.8, Dec -02 10 39)
Historical Identification: Per Dreyer, IC 29 (Javelle 21, 1860 RA 00 27 01, NPD 92 57.2) is "very faint, small, round, a little brighter middle". The position precesses to RA 00 34 10.2, Dec -02 10 51, just off the southwestern rim of the galaxy listed above, there is nothing similar nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 17380 km/sec, a straightforward calculation indicates that IC 29 is about 810 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 755 million light years away at the time the light by which we see it was emitted, almost 780 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 0.55 by 0.5 arcmin, the galaxy is about 120 thousand light years across.
SDSS image of region near elliptical galaxy IC 29, also showing IC 30
Above, a 12 arcmin wide SDSS image centered on IC 29, also showing IC 30
Below, a 1 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy IC 29

IC 30 (= PGC 2050 = PGC 1102147)
Discovered (Nov 6, 1891) by
Stephane Javelle
A magnitude 15.9 lenticular galaxy (type E/S0?) in Cetus (RA 00 34 14.7, Dec -02 05 05)
Historical Identification: Per Dreyer, IC 30 (Javelle 22, 1860 RA 00 27 05, NPD 92 51.5) is "very faint, small, round, a little brighter middle". The position precesses to RA 00 34 14.2, Dec -02 50 09, right on the galaxy listed above and there is nothing similar nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 24600 km/sec, a straightforward calculation indicates that IC 30 is about 1145 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 1040 million light years away at the time the light by which we see it was emitted, about 1085 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 0.7 by 0.35 arcmin, the brighter inner part of the galaxy is about 210 thousand light years across, but there is a fainter outer extension about 1.4 by 0.6 arcmin in size which corresponds to about 425 thousand light years, and would make this one of the largest galaxies known.
SDSS image of region near lenticular galaxy IC 30
Above, a 12 arcmin wide SDSS image centered on IC 30, also showing IC 29
Below, a 2 arcmin wide SDSS image of the galaxy and its fainter outer extension
SDSS image of lenticular galaxy IC 30

IC 31 (= PGC 2062)
Discovered (Nov 28, 1893) by
Stephane Javelle
A magnitude 14.3 spiral galaxy (type Sab?) in Pisces (RA 00 34 24.6, Dec +12 16 07)
Historical Identification: Per Dreyer, IC 31 (Javelle 508, 1860 RA 00 27 09, NPD 78 30.1) is "faint, extended east and west, diffuse". The position precesses to RA 00 34 24.6, Dec +12 16 15, just north of the nucleus of the galaxy listed above, there is nothing similar nearby and the description fits, so the identification is certain.
Physical Information: Based on a recessional velocity of 9520 km/sec, a straightforward calculation indicates that IC 31 is about 445 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 a little over 425 million light years away at the time the light by which we see it was emitted, about 435 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 1.4 by 0.2 arcmin, the galaxy is about 175 thousand light years across.
SDSS image of region near spiral galaxy IC 31
Above, a 12 arcmin wide SDSS image centered on IC 31
Below, a 1.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 31

IC 32 (= PGC 2096)
Discovered (Nov 6, 1891) by
Stephane Javelle
A magnitude 14.9 lenticular galaxy (type S0/a?) in Cetus (RA 00 35 01.7, Dec -02 08 30)
Historical Identification: Per Dreyer, IC 32 (Javelle 23, RA 00 27 52, NPD 92 55.2) is "very faint, very small, round, a little brighter middle". The position precesses to RA 00 35 01.2, Dec -02 08 52, less than 0.4 arcmin south southwest of the galaxy listed above, the description fits and the only other nearby galaxy is accounted for by IC 33, so the identification is certain.
Physical Information: Based on a recessional velocity of 16495 km/sec, a straightforward calculation indicates that IC 32 is about 770 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 720 million light years away at the time the light by which we see it was emitted, about 740 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 0.5 by 0.25 arcmin, the galaxy is about 105 thousand light years across. Note: Given their nearly identical direction and distance, IC 32 and IC 33 may be a gravitationally bound pair.
SDSS image of region near lenticular galaxy IC 32, also showing IC 33, with which it may be a gravitationally bound pair
Above, a 12 arcmin wide SDSS image centered on IC 32, also showing IC 33
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of galaxy lenticular galaxy IC 32

IC 33 (= PGC 2101)
Discovered (Nov 6, 1891) by
Stephane Javelle
A magnitude 14.5 lenticular galaxy (type S0?) in Cetus (RA 00 35 05.2, Dec -02 08 16)
Historical Identification: Per Dreyer, IC 33 (Javelle 24, 1860 RA 00 27 56, NPD 92 54.8) is "very faint, very small, round, a little brighter middle". The position precesses to RA 00 35 05.2, Dec -02 08 28, just south of the galaxy listed above, the description fits and the only other nearby galaxy is accounted for by IC 32, so the identification is certain.
Physical Information: Based on a recessional velocity of 16680 km/sec, a straightforward calculation indicates that IC 33 is about 785 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 just over 725 million light years away at the time the light by which we see it was emitted, almost 770 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 0.55 by 0.4 arcmin, it is about 115 thousand light years across. Note: Given their nearly identical direction and distance, IC 32 and IC 33 may be a gravitationally bound pair.
SDSS image of lenticular galaxy IC 33
Above, a 0.8 arcmin wide SDSS image of IC 33; see IC 32 for a wide-field view

IC 34 (= PGC 2134)
Discovered (Oct 22, 1867) by
Truman Safford
Discovered (Sep 18, 1889) by Lewis Swift
A magnitude 12.6 spiral galaxy (type SB(r)a? pec?) in Pisces (RA 00 35 36.4, Dec +09 07 27)
Historical Identification: Per Dreyer, IC 34 (Safford 97, Swift list IX (#1), 1860 RA 00 28 22, NPD 81 38.2) is "very faint, pretty small, a little extended". The position precesses to RA 00 35 36.3, Dec +09 08 07, just north of the nucleus of the galaxy listed above and within the galaxy's outline, the description fits and there is nothing else nearby, so the identification is certain.
Discovery Notes: See the entry for Truman Safford for a discussion of why most observers had no idea his earlier observations existed when they independently discovered the same objects years or decades later, leading to the listing of Safford and Swift as co-discoverers, despite the nearly 22 years between their observations.
Physical Information: Based on a recessional velocity of 5340 km/sec, IC 34 is about 250 million light years away, in good agreement with redshift-independent distance estimates of 230 to 265 million light years. Given that and its apparent size of 3.0 by 0.8 arcmin, it is about 220 thousand light years across.
SDSS image of region near spiral galaxy IC 34
Above, a 12 arcmin wide SDSS image centered on IC 34
Below, a 3 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 34

IC 35 (= PGC 2246)
Discovered (Jan 6, 1894) by
Stephane Javelle
A magnitude 14.0 spiral galaxy (type Scd?) in Pisces (RA 00 37 39.9, Dec +10 21 28)
Historical Identification: Per Dreyer, IC 35 (Javelle 509, 1860 RA 00 30 26, NPD 80 24.8) is "very faint, small, diffuse, 9.5 magnitude star to northeast". The position precesses to RA 00 37 41.2, Dec +10 21 27, on the eastern rim of the galaxy listed above, there is nothing else nearby, and the star to the northeast makes the identification certain.
Physical Information: Based on a recessional velocity of 4585 km/sec, IC 35 is about 215 million light years away. Given that and its apparent size of 0.9 by 0.6 arcmin, it is about 55 thousand light years across.
SDSS image of region near spiral galaxy IC 35
Above, a 12 arcmin wide SDSS image centered on IC 35
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 35

IC 36 (= PGC 138202)
Discovered (Aug 25, 1892) by
Stephane Javelle
A magnitude 14.5 spiral galaxy (type S?) in Cetus (RA 00 37 49.6, Dec -15 26 29)
Historical Identification: Per Dreyer, IC 36 (Javelle 25, 1860 RA 00 30 47, NPD 106 12.6) is "faint, very small, round, diffuse". The position precesses to RA 00 37 49.4, Dec -15 26 21, within the northern outline of the galaxy listed above, the description fits and there is nothing else near, so the identification is certain.
Physical Information: Based on a recessional velocity of 6960 km/sec, IC 36 is about 325 million light years away. Given that and its apparent size of 0.4 by 0.35 arcmin, it is about 35 thousand light years across.
DSS image of region near spiral galaxy IC 36
Above, a 12 arcmin wide DSS image centered on IC 36
Below, a 0.6 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 36

IC 37 (= PGC 2299)
Discovered (Aug 25, 1892) by
Stephane Javelle
A magnitude 14.9 spiral galaxy (type SBb?) in Cetus (RA 00 38 34.2, Dec -15 21 31)
Historical Identification: Per Dreyer, IC 37 (Javelle 26, 1860 RA 00 31 32, NPD 106 08.1) is "extremely faint, very small, round, diffuse". The position precesses to RA 00 38 34.3, Dec -15 21 52, just off the southern rim of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 16160 km/sec, a straightforward calculation indicates that IC 37 is over 750 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 705 million light years away at the time the light by which we see it was emitted, about 725 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 0.6 by 0.35 arcmin, the galaxy is about 125 thousand light years across. Note: Since IC 37 has nearly the same direction and distance as IC 38, they may be a gravitationally bound pair.
DSS image of region near spiral galaxy IC 37, also showing IC 38
Above, a 12 arcmin wide DSS image centered on IC 37, also showing IC 38
Below, a 0.8 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 37

IC 38 (= PGC 2311)
Discovered (Aug 25, 1892) by
Stephane Javelle
A magnitude 14.0 spiral galaxy (type SBb? pec) in Cetus (RA 00 38 38.8, Dec -15 25 10)
Historical Identification: Per Dreyer, IC 38 (Javelle 27, 1860 RA 00 31 37, NPD 106 11.8) is "faint, small, round". The position precesses to RA 00 38 39.2, Dec -15 25 34, only 0.4 south southeast of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 16355 km/sec, a straightforward calculation indicates that IC 38 is about 760 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 715 million light years away at the time the light by which we see it was emitted, about 735 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 0.8 by 0.5 arcmin, the galaxy is about 165 thousand light years across. Note: Since IC 38 has nearly the same direction and distance as IC 37, they may be a gravitationally bound pair.
DSS image of region near spiral galaxy IC 38, also showing IC 37
Above, a 12 arcmin wide DSS image centered on IC 38, also showing IC 37
Below, a 1.2 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 38

IC 39 (=
NGC 178 = PGC 2349 = PGC 928022)
Discovered (Nov 3, 1885) by Ormond Stone (and later listed as NGC 178)
Rediscovered (Aug 26, 1892) by Stephane Javelle (and later listed as IC 39)
Also observed (1898/99) by Herbert Howe (while looking for NGC 178)
A magnitude 12.6 spiral galaxy (type SB(s)m?) in Cetus (RA 00 39 08.6, Dec -14 10 16)
Historical Identification: Per Dreyer, IC 39 (Javelle 28, 1860 RA 00 32 05, NPD 104 56.4) is "pretty bright, pretty large, extended north and south, gradually brighter middle". The position precesses to RA 00 39 07.8, Dec -14 10 11, on the western rim of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain. The cause of the duplicate entry was an error in Stone's position, so see NGC 178 for a discussion of how the matter was resolved.
Physical Information: Given the duplicate entry, see NGC 178 for anything else.

IC 40 (= PGC 2376)
Discovered (Jan 8, 1894) by
Stephane Javelle
A magnitude 14.4 lenticular galaxy (type S0(r)a?) in Cetus (RA 00 39 21.4, Dec +02 27 22)
Historical Identification: Per Dreyer, IC 40 (Javelle 510, 1860 RA 00 32 12, NPD 88 18.6) is "faint, small, round, gradually brighter middle with nucleus equal to 13.5 magnitude star". The position precesses to RA 00 39 23.3, Dec +02 27 36, only 0.5 arcmin east northeast of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 5415 km/sec, IC 40 is about 250 million light years away. Given that and its apparent size of 1.0 by 0.4 arcmin, it is about 75 thousand light years across.
SDSS image of region near lenticular galaxy IC 40
Above, a 12 arcmin wide SDSS image centered on IC 40
Below, a 1.5 arcmin wide image of the galaxy
SDSS image of lenticular galaxy IC 40

IC 41 (= PGC 138206)
Discovered (Aug 26, 1892) by
Stephane Javelle
A magnitude 14.7 spiral galaxy (type S? pec) in Cetus (RA 00 39 40.4, Dec -14 10 28)
Historical Identification: Per Dreyer, IC 41 (Javelle 29, 1860 RA 00 32 38, NPD 104 56.6) is "very faint, small, diffuse". The position precesses to RA 00 39 40.7, Dec -14 10 24, well within the outline of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain. Despite that, per Thomson several references misidentify IC 41 as NGC 207, but they are separate galaxies, as can be seen in the wide-field image below.
Physical Information: Based on a recessional velocity of 3960 km/sec, IC 41 is about 185 million light years away. Given that and its apparent size of 0.4 by 0.3 arcmin, it is about 20 thousand light years across.
DSS image of region near spiral galaxy IC 41, also showing NGC 207
Above, a 12 arcmin wide image centered on IC 41, also showing NGC 207
Below, a 0.6 arcmin wide image of the galaxy
DSS image of spiral galaxy IC 41

IC 42 (= PGC 2463 = PGC 911417)
Discovered (Aug 25, 1892) by
Stephane Javelle
A magnitude 14.8 spiral galaxy (type SABbc?) in Cetus (RA 00 41 05.8, Dec -15 25 41)
Historical Identification: Per Dreyer, IC 42 (Javelle 30, 1860 RA 00 34 04, NPD 106 11.8) is "small, irregular, very diffuse". The position precesses to RA 00 41 05.6, Dec -15 25 39, right on the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 16410 km/sec, a straightforward calculation indicates that IC 42 is about 765 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 715 million light years away at the time the light by which we see it was emitted, about 735 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 0.7 by 0.45 arcmin, the galaxy is about 145 thousand light years across.
DSS image of region near spiral galaxy IC 42
Above, a 12 arcmin wide image centered on IC 42
Below, a 0.9 arcmin wide image of the galaxy
DSS image of spiral galaxy IC 42

IC 43 (= PGC 2536)
Discovered (Nov 15, 1889) by
Guillaume Bigourdan
A magnitude 13.2 spiral galaxy (type SAB(rs)c?) in Andromeda (RA 00 42 22.1, Dec +29 38 30)
Historical Identification: Per Dreyer, IC 43 (Bigourdan 106, 1860 RA 00 34 52, NPD 61 07) is "very faint, small, much brighter middle". The position precesses to RA 00 42 19.9, Dec +29 39 06, barely off the northwestern rim of the galaxy listed above, the description fits and there is nothing comparable nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 4855 km/sec, IC 43 is about 225 million light years away. Given that and its apparent size of 1.5 by 1.2 arcmin, it is about 100 thousand light years across.
SDSS image of region near spiral galaxy IC 43, also showing the pair of stars listed as IC 45, and PGC 2537, a galaxy often misidentified as IC 45
Above, a 12 arcmin wide SDSS image centered on IC 43, also showing IC 45 and PGC 2537
Below, a 2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 43

IC 44 (=
NGC 223 = PGC 2527)
Discovered (Jan 5, 1853) by George Bond (and later listed as NGC 223)
Also observed (Jan 1, 1862) by Heinrich d'Arrest (and later listed as NGC 223)
Also observed (in or before 1862) by Auwers (as a reobservation of Bond's nebula)
Also observed (Nov 21, 1886) by Lewis Swift (and later listed as IC 44)
A magnitude 13.2 spiral galaxy (type SA(rs)ab?) in Cetus (RA 00 42 15.9, Dec +00 50 43)
Historical Identification: Per Dreyer, IC 44 (Swift list X (#1), 1860 RA 00 35 08, NPD 89 53.5) is "extremely faint, small, round, between two stars". The position precesses to RA 00 42 18.6, Dec +00 52 36, just under 2 arcmin north northeast of the galaxy listed above, but as noted by Corwin the stars to the northwest and southeast make the identification essentially certain. However, the 2 arcmin error was large enough that Dreyer presumed it was a separate object from NGC 219 and 223, leading to the duplicate entry.
Physical Information: Given the duplicate entry, see NGC 223 for anything else.

IC 45
Recorded (Nov 15, 1889) by
Guillaume Bigourdan
A pair of 15th-magnitude stars in Andromeda (RA 00 42 36.5, Dec +29 39 15)
Historical Identification: Per Dreyer, IC 45 (Bigourdan 107, 1860 RA 00 35 12, NPD 61 06) is a "suspected nebula". The position precesses to RA 00 42 40.0, Dec +29 40 06, but there is nothing there, which is hardly surprising given Bigourdan's tendency to identify faint stars as nebular objects, and his description of this object as merely suspected. To determine which faint star or stars Bigourdan might have mistaken for a nebula, it is best to use his original observations, correcting (if necessary, as it often is) for any errors in the position of his comparison star. Bigourdan's comparison star was BD 111, for which he used the position (1900) RA 00 37 08.7, Dec +29 03 24, which precesses to J2000 RA 00 42 29.1, Dec +29 36 18. That means the comparison star must have been the 11th magnitude star at RA 00 42 31.7, Dec +29 36 18, which precesses to (1900) RA 00 37 11.3, Dec +29 03 24. Applying Bigourdan's offsets of RA +05.0s, Dec +3' 26", Bigourdan 107 should be at (1900) RA 00 37 16.3, Dec +29 06 50, which precesses to J2000 RA 00 42 36.8, Dec +29 39 44, approximately 30 arcsec north northeast of the double star listed above. That is essentially the same error made by Bigourdan on the (same) night of his observation of IC 43, so the identification seems certain.
Discovery Notes: Per Thomson, IC 45 is commonly misidentified as PGC 2537, which lies due north of IC 43, and well to the northwest of Bigourdan's position for his 107; so although that galaxy has nothing to do with IC 45, its common misidentification warrants an entry (immediately below) to warn the unsuspecting reader about the misidentification. (Since both IC 45 and PGC 2537 lie in the region near IC 43, see the wide-field image for IC 43 for an image of the objects.)
Physical Information: The southeastern member of the pair is listed as having magnitude 15.1, while the northwestern member is magnitude 15.5. Their separation is about 18 arcsec, while the position angle of the fainter, as compared to the brighter, is 280°.

PGC 2537 (not =
IC 45)
Not an IC object but listed here since often misidentified as IC 45
A magnitude 14.5(?) spiral galaxy (type SBc? pec) in Andromeda (RA 00 42 22.4, Dec +29 41 54)
Historical Misidentification: As noted in the entry for IC 45, this galaxy is often misidentified as that object, hence this warning about the error.
Physical Information: Based on a recessional velocity of 5280 km/sec, PGC 2537 is about 245 million light years away. Given that and its apparent size of 1.0 by 0.2 arcmin, it is about 70 thousand light years across.
SDSS image of spiral galaxy PGC 2537, which is often misidentified as IC 45
Above, a 1.2 arcmin wide SDSS image of PGC 2537, which is not IC 45

IC 46 (= PGC 2575 = PGC 1802380)
Discovered (Dec 5, 1893) by
Stephane Javelle
A magnitude 13.9 spiral galaxy (type Sc?) in Andromeda (RA 00 42 58.0, Dec +27 15 13)
Historical Identification: Per Dreyer, IC 46 (Javelle 511, 1860 RA 00 35 31, NPD 63 31.0) is "pretty bright, small, round, brighter middle". The position precesses to RA 00 42 57.4, Dec +27 15 05, on the southwestern rim of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 5285 km/sec, IC 46 is about 245 million light years away. Given that and its apparent size of 0.7 by 0.5 arcmin, it is about 50 thousand light years across.
SDSS image of region near spiral galaxy IC 46
Above, a 12 arcmin wide SDSS image centered on IC 46
Below, a 1 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 46
IC 47 (= PGC 3093693)
Discovered (Aug 23, 1892) by
Stephane Javelle
A magnitude 15.3 spiral galaxy (type Sa? pec) in Cetus (RA 00 42 55.0, Dec -13 44 26)
Historical Identification: Per Dreyer, IC 47 (Javelle 31, 1860 RA 00 35 53, NPD 104 30.8) is "extremely faint, extremely small, round, stellar". The position precesses to RA 00 42 55.2, Dec -13 44 43, less than 0.3 arcmin south of the galaxy listed above and there is nothing else nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 11020 km/sec, a straightforward calculation indicates that IC 47 is about 515 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 490 million light years away at the time the light by which we see it was emitted, about 500 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 0.5 by 0.3 arcmin, the galaxy is about 70 thousand light years across.
DSS image of region near spiral galaxy IC 47
Above, a 12 arcmin wide DSS image centered on IC 47
Below, a 0.8 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 47

IC 48 (=
IC 1577 = PGC 2603 = PGC 2608)
Discovered (Nov 30, 1888) by Edward Barnard (and later listed as IC 48)
Reobserved on several occasions (between 1891 and 1895) by Edward Barnard (and later listed as IC 48)
Reobserved (between 1895 and 1907) by Edward Barnard (and later listed as IC 1577)
A magnitude 13.1 lenticular galaxy (type SA(rs)0? pec?) in Cetus (RA 00 43 34.5, Dec -08 11 12)
Historical Identification: Per Dreyer, IC 48 (Barnard ((M.N.) 3097), 1860 RA 00 36 31, NPD 98 38.9) is "pretty faint, small, possibly variable brightness" (an IC2 note adds "See M.N. lv. p. 451. Up to 1895 always faint (Barnard)."). The position precesses to RA 00 43 36.6, Dec -07 52 50, but there is nothing there. The reason (as pointed out by Corwin) is that Dreyer reversed the sign of the precessional correction from Barnard's position to the Equinox of 1860. Barnard's actual position (1888 RA 00 37 55.7, Dec -08 48 07) precesses to RA 00 43 36.0, Dec -08 11 17, barely outside the eastern rim of the galaxy listed above and there is nothing else nearby, so the identification is certain.
Discovery Notes: Per Corwin, the duplicate entry was partially caused by a one minute error in the right ascension measured by Barnard sometime after he moved to Yerkes Observatory in 1895, presumably leading him to think he had found a new nebula (Barnard's later position was never published, having been directly communicated to Dreyer, but the error can be deduced from the position given by Dreyer in the IC2). Between that and Dreyer's mistake in converting the 1888 observation to the 1860 equinox, there was no reason for Dreyer to think that the later observation had anything to do with the earlier ones, making the duplicate entry inevitable.
Physical Information: Based on a recessional velocity of 5960 km/sec, IC 48 is about 275 million light years away, in good agreement with redshift-independent distance estimates of 270 to 305 million light years. Given that and its apparent size of 0.9 by 0.7 it is about 70 thousand light years across. Given Barnard's numerous observations of the object, his statement that the galaxy was always faint prior to 1895 suggests that it may be a Seyfert galaxy with a sudden recent onset of activity, or that there may have been a supernova near the nucleus at about that time. Its unusual structure certainly suggests that something interesting happened in "recent" astronomical times, though not necessarily as recently as historical times.
SDSS image of region near lenticular galaxy IC 48
Above, a 12 arcmin wide SDSS image centered on IC 48
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 48

IC 49 (= PGC 2617)
Discovered (Sep 18, 1890) by
Lewis Swift
A magnitude 13.7 spiral galaxy (type SAB(s)bc?) in Cetus (RA 00 43 56.2, Dec +01 51 01)
Historical Identification: Per Dreyer, IC 49 (Swift list X (#2), 1860 RA 00 36 43, NPD 88 54.6) is "most extremely faint, pretty small, round, extremely difficult". The position precesses to RA 00 43 54.1, Dec +01 51 27, just off the northwestern rim of the galaxy listed above, the description is apt and there is nothing comparable nearby, so the identification is certain.
Physical Information: Based on a recessional velocity of 4560 km/sec, IC 49 is about 210 million light years away. Given that and its apparent size of 1.5 by 1.1 arcmin, it is about 90 thousand light years across. IC 49 is classified as a starburst galaxy.
SDSS image of region near spiral galaxy IC 49
Above, a 12 arcmin wide SDSS image centered on IC 49
Below, a 1.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 49
Celestial Atlas
(NGC 7800 - 7840) ←     IC Objects: IC 1 - 49     → (IC 50 - 99)