Celestial Atlas
(IC 4450 - 4499) ←     IC Objects: IC 4500 - 4549 Link for sharing this page on Facebook     → (IC 4550 - 4599)
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Page last updated Feb 21, 2014
(Next step: Add distances, using cosmological principles for Vr = 7000+)

IC 4500 (= PGC 52656)
Discovered (Jul 10, 1896) by
Stephane Javelle
A magnitude 14.7 spiral galaxy (type Scd?) in Bo÷tes (RA 14 44 35.7, Dec +37 28 56)
Historical Identification: Per Dreyer, IC 4500 (= Javelle #1338, 1860 RA 14 39 00, NPD 51 56.2) is "faint, small, round, gradually brighter middle". The position precesses to RA 14 44 36.3, Dec +37 28 13, only a third of an arcmin south southeast of the galaxy listed above, and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 4220 km/sec, IC 4500 is about 195 million light years away. Given that and its apparent size of 0.5 by 0.35 arcmin, it is about 30 thousand light years across.
SDSS image of region near spiral galaxy IC 4500
Above, a 12 arcmin wide SDSS image centered on IC 4500
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4500

IC 4501 (= PGC 52810)
Discovered (1899) by
DeLisle Stewart
A magnitude 13.6 spiral galaxy (type SB(s)dm?) in Libra (RA 14 47 25.4, Dec -22 24 21)
Historical Identification: Per Dreyer, IC 4501 (= DeLisle Stewart #416, 1860 RA 14 39 25, NPD 111 48) is "very faint, small, indistinct". The position precesses to RA 14 47 25.0, Dec -22 23 23, only an arcmin north of the galaxy listed above and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 1.1 by 0.6 arcmin.
DSS image of region near spiral galaxy IC 4501
Above, a 12 arcmin wide DSS image centered on IC 4501
Below, a 1.5 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4501

IC 4502 (= PGC 2097463)
Discovered (Jul 10, 1896) by
Stephane Javelle
A magnitude 15.0 spiral galaxy (type S(rs)ab? pec) in Bo÷tes (RA 14 45 15.8, Dec +37 18 01)
Historical Identification: Per Dreyer, IC 4502 (= Javelle #1339, 1860 RA 14 39 39, NPD 52 06.8) is "faint, small, diffuse, mottled but not resolved, 14th magnitude star very near". The position precesses to RA 14 45 15.5, Dec +37 17 42, less than half an arcmin south of the galaxy listed above and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 0.8 by 0.3 arcmin. Probably an actual pair with its apparent companion, PGC 2097391.
SDSS image of region near spiral galaxy IC 4502
Above, a 12 arcmin wide SDSS image centered on IC 4502
Below, a 1.0 arcmin wide SDSS image of the galaxy, also showing PGC 2097391
SDSS image of spiral galaxy IC 4502, also showing PGC 2097391

IC 4503 (= PGC 52763)
Discovered (May 10, 1904) by
Royal Frost
A magnitude 14.0 spiral galaxy (type SB(rs)a?) in Bo÷tes (RA 14 46 39.5, Dec +16 08 47)
Historical Identification: Per Dreyer, IC 4503 (= Frost #1135, 1860 RA 14 40 08, NPD 73 17) is "faint, very small, round". The position precesses to RA 14 46 42.2, Dec +16 07 37, about 1.2 arcmin southeast of the galaxy listed above, but there is nothing else nearby so the identification seems certain.
Physical Information: Apparent size 0.7 by 0.55 arcmin.
SDSS image of region near spiral galaxy IC 4503
Above, a 12 arcmin wide SDSS image centered on IC 4503
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4503

IC 4504 (= PGC 52750)
Discovered (Jul 25, 1895) by
Stephane Javelle
A magnitude 14.4 lenticular galaxy (type S0?) in Bo÷tes (RA 14 46 37.0, Dec +31 41 57)
Historical Identification: Per Dreyer, IC 4504 (= Javelle #1340, 1860 RA 14 40 43, NPD 57 42.3) is "faint, small, round, nuclear, mottled but not resolved". The position precesses to RA 14 46 36.7, Dec +31 42 22, less than half an arcmin north of the galaxy listed above and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 0.8 by 0.4 arcmin.
SDSS image of region near lenticular galaxy IC 4504
Above, a 12 arcmin wide SDSS image centered on IC 4504
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4504

IC 4505 (= PGC 52754)
Discovered (Jul 21, 1903) by
Stephane Javelle
A magnitude 13.7 lenticular galaxy (type E/S0?) in Bo÷tes (RA 14 46 33.4, Dec +33 24 31)
Historical Identification: Per Dreyer, IC 4505 (= Javelle #1341, 1860 RA 14 40 45, NPD 56 00.3) is "faint, small, round, nuclear". The position precesses to RA 14 46 33.6, Dec +33 24 21, right on the galaxy listed above, so the identification is certain.
Physical Information: Apparent size 1.2 by 0.9 arcmin.
SDSS image of lenticular galaxy IC 4505
Above, a 12 arcmin wide SDSS image centered on IC 4505, also showing IC 4506
Below, a 1.5 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4505

IC 4506 (= PGC 52764)
Discovered (Jul 21, 1903) by
Stephane Javelle
A magnitude 14.8 lenticular galaxy (type S0?) in Bo÷tes (RA 14 46 39.9, Dec +33 24 04)
Historical Identification: Per Dreyer, IC 4506 (= Javelle #1342, 1860 RA 14 40 52, NPD 56 00.8) is "very faint, very small, nuclear". The position precesses to RA 14 46 40.6, Dec +33 23 52, on the southeastern rim of the galaxy listed above, and the consistency of Javelle's measurements for this and IC 4505 fits the pair of galaxies so well that the identification is certain.
Physical Information: Apparent size 0.5 by 0.5 arcmin.
SDSS image of lenticular galaxy IC 4506
Above, a 0.8 arcmin wide SDSS image of IC 4506; for a wider view, see IC 4505

IC 4507 (= PGC 52834)
Discovered (May 10, 1904) by
Royal Frost
A magnitude 14.8 spiral galaxy (type Sab? pec) in Bo÷tes (RA 14 47 42.2, Dec +18 27 20)
Historical Identification: Per Dreyer, IC 4507 (= Frost #1336, 1860 RA 14 41 15, NPD 70 58) is "very faint, extremely small, round" (since Frost's list is in order of right ascension, Frost #1336 is an obvious typographical error; this is actually Frost #1136). The position precesses to RA 14 47 43.6, Dec +18 26 46, about half an arcmin southeast of the galaxy listed above and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 0.75 by 0.4 arcmin.
SDSS image of region near spiral galaxy IC 4507
Above, a 12 arcmin wide SDSS image centered on IC 4507, also showing NGC 5760
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4507

IC 4508 (= PGC 52843)
Discovered (Jul 25, 1895) by
Stephane Javelle
A magnitude 14.4 lenticular galaxy (type S0/a?) in Bo÷tes (RA 14 47 50.8, Dec +31 45 53)
Historical Identification: Per Dreyer, IC 4508 (= Javelle #1343, 1860 RA 14 41 57, NPD 57 38.5) is "faint, small, round, suddenly brighter middle equivalent to 14th magnitude star". The position precesses to RA 14 47 50.1, Dec +31 46 19, half an arcmin north northwest of the galaxy listed above, and the description fits, so the identification is reasonably certain. There is a fainter, more distant galaxy (PGC 3833892) directly northeast of PGC 52843, and at first glance it might be supposed that both galaxies could be considered part of the IC entry, but Javelle could not have seen the fainter galaxy, so it is not part of IC 4508. However, as a result of the galaxies' apparent proximity it is common for data that applies to one being mistakenly applied to the other; for instance, NED has mostly correct physical information for IC 4508, but mistakenly uses the position for PGC 3833892, and a secondary z of 0.055676 attributed to IC 4508 also belongs to the other galaxy. Because of such confusion, even though not part of IC 4508, PGC 3833892 is discussed immediately below.
Physical Information: Based on a recessional velocity of 13620 km/sec, a straightforward calculation indicates that IC 4508 is about 635 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 600 million light years away at the time the light by which we see it was emitted, about 615 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 0.45 by 0.45 arcmin, the galaxy is about 80 thousand light years across.
SDSS image of region near lenticular galaxy IC 4508, also showing spiral galaxy PGC 3833892
Above, a 12 arcmin wide SDSS image centered on IC 4508
Below, a 0.8 arcmin wide SDSS image of IC 4508 and PGC 3833892
SDSS image of lenticular galaxy IC 4508, also showing spiral galaxy PGC 3833892

PGC 3833892 (not part of
IC 4508)
Not an IC object but listed here because of its apparent proximity to IC 4508
A magnitude 15.5(?) spiral galaxy (type SBbc? pec) in Bo÷tes (RA 14 47 51.4, Dec +31 46 06)
Historical Identification: See IC 4508 for a discussion of the problems caused by the apparent proximity of that galaxy and PGC 3833892.
Physical Information: Based on a recessional velocity of 16800 km/sec, a straightforward calculation indicates that PGC 3833892 is about 780 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 730 million light years away at the time the light by which we see it was emitted, about 750 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 0.15 arcmin, the galaxy is about 85 thousand light years across. Note that despite its apparent proximity to IC 4508 (which see for images), PGC 3833892 is only an "optical double", as it is over a hundred million light years further away.

IC 4509 (= PGC 52874)
Discovered (Jul 25, 1895) by
Stephane Javelle
A magnitude 14.0 spiral galaxy (type Sbc?) in Bo÷tes (RA 14 48 27.0, Dec +31 47 29)
Historical Identification: Per Dreyer, IC 4509 (= Javelle #1344, 1860 RA 14 42 33, NPD 57 37.0) is "faint, considerably small, irregular figure, mottled but not resolved". The position precesses to RA 14 48 25.8, Dec +31 47 54, less than half an arcmin northwest of the galaxy listed above, and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size of 0.9 by 0.3 arcmin.
SDSS image of region near spiral galaxy IC 4509
Above, a 12 arcmin wide SDSS image centered on IC 4509
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4509

IC 4510
Recorded (1899) by
DeLisle Stewart
Almost certainly a nonexistent object in Libra (RA 14 50 40.7, Dec -20 43 56)
Historical Identification: Per Dreyer, IC 4510 (= DeLisle Stewart #417, 1860 RA 14 42 44, NPD 110 09) is "very faint, very small, irregularly round, suspected". The position precesses to RA 14 50 40.7, Dec -20 43 56 (whence the position above), but there is nothing there nor anywhere near there so odds are it is nonexistent. Corwin notes that the plate in question had only a short exposure, so for the object to be real it would have to be fairly bright, and he suspects that given the description, it was probably a plate defect.
DSS image of region near Stewart's position for the almost certainly nonexistent IC 4510
Above, a 12 arcmin wide DSS image centered on Stewart's position for IC 4510

IC 4511
Recorded (May 15, 1904) by
Royal Frost
Almost certainly a nonexistent object in Centaurus (RA 14 52 05.9, Dec -40 29 49)
Historical Identification: Per Dreyer, IC 4511 (= Frost #1137, 1860 RA 14 43 10, NPD 129 55) is "considerably small, round, a little brighter middle, diffuse". The position precesses to RA 14 52 05.9, Dec -40 29 49 (whence the position above), but there is nothing there nor anywhere near there. Per Corwin, Frost's description reads "diffuse, round, a little brighter middle, diameter 0.6 arcmin"; since there is nothing like that anywhere nearby, Corwin suspects this was a plate defect, and the "object" is almost certainly nonexistent.
DSS image of region near Frost's position for the almost certainly nonexistent IC 4511
Above, a 12 arcmin wide DSS image centered on Frost's position for IC 4511

IC 4512 (= PGC 1815627)
Discovered (Jul 26, 1895) by
Stephane Javelle
A magnitude 15.0 spiral galaxy (type SB(r)bc?) in Bo÷tes (RA 14 49 54.3, Dec +27 42 01)
Historical Identification: Per Dreyer, IC 4512 (= Javelle #1345, 1860 RA 14 43 49, NPD 61 43.1) is "very faint, small, round". The position precesses to RA 14 49 53.1, Dec +27 41 59, less than half an arcmin west of the galaxy listed above, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size of 0.5 by 0.45 arcmin.
SDSS image of region near spiral galaxy IC 4512
Above, a 12 arcmin wide SDSS image centered on IC 4512
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4512

IC 4513
Recorded (1899) by
DeLisle Stewart
Probably a nonexistent object in Libra (RA 14 52 16.0, Dec -20 43 42)
Historical Identification: Per Dreyer, IC 4513 (= DeLisle Stewart #419, 1860 RA 14 44 20, NPD 110 09) is "faint, small, very extended 80░". The position precesses to RA 14 52 17.0, Dec -20 43 43, but there is nothing there. Per Corwin, this "object" was recorded on the same plate as IC 4510, and would have to be fairly bright for Stewart to have seen it. Since there is nothing in the region that is either reasonably bright or resembles the description, this was probably a plate defect, and not a real object.
DSS image of region near Stewart's position for the almost certainly nonexistent IC 4513
Above, a 12 arcmin wide DSS image centered on Stewart's position for IC 4513

IC 4514 (= PGC 53010)
Discovered (Jul 26, 1895) by
Stephane Javelle
A magnitude 14.1 spiral galaxy (type SB(s)ab) in Bo÷tes (RA 14 50 55.5, Dec +27 34 43)
Historical Identification: Per Dreyer, IC 4514 (= Swift list XI (#175), Javelle #1346, 1860 RA 14 44 51, NPD 61 48.5) is "faint, small, round, nuclear, 13th magnitude star very near". (Swift's #175 was observed on Jun 2, 1898, so Javelle is the discoverer, but Swift's note was presumably used by Dreyer as confirmation of the object's existence.) The position precesses to RA 14 50 55.0, Dec +27 36 44, about two arcmin north of the galaxy listed above, and there is nothing else nearby, so the identification appears reasonably certain. In addition, per Thomson, Javelle used Argelander's position for his comparison star, which (compared to modern data) was 1 arcmin 58 arcsec too far north; applying the appropriate correction for that error puts Javelle's position right on the galaxy, so the identification is absolutely certain.
Physical Information: Apparent size of 0.75 by 0.65 arcmin.
SDSS image of region near spiral galaxy IC 4514
Above, a 12 arcmin wide SDSS image centered on IC 4514
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4514

IC 4515 (= PGC 53026)
Discovered (Jul 10, 1896) by
Stephane Javelle
A magnitude 14.9 spiral galaxy (type Sa?) in Bo÷tes (RA 14 51 06.6, Dec +37 29 43)
Historical Identification: Per Dreyer, IC 4515 (= Javelle #1347, 1860 RA 14 45 34, NPD 51 48.9) is "faint, small, round, gradually brighter middle, mottled but not resolved". The position precesses to RA 14 51 06.7, Dec +37 36 23, but there is nothing there. However, per Corwin and Thomson, Javelle simply made a mistake in the sign of his offset for the star's declination, placing it 3' 20" north of his comparison star, instead of 3' 20" south; correcting for that error, Javelle's position lands right on the galaxy listed above. So despite the original mistake, the identification is virtually certain.
Physical Information: Apparent size of 0.7 by 0.45 arcmin.
SDSS image of region near spiral galaxy IC 4515
Above, a 12 arcmin wide SDSS image centered on IC 4515
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4515

IC 4516 (= PGC 53274 = PGC 95544)
Discovered (Jun 2, 1898) by
Lewis Swift
A magnitude 13.2 elliptical galaxy (type E3?) in Bo÷tes (RA 14 54 23.4, Dec +16 21 21)
Historical Identification: Per Dreyer, IC 4516 (= Swift list XI (#176), 1860 RA 14 47 23, NPD 73 02.6) is "very faint, pretty small, round". The position precesses to RA 14 53 55.3, Dec +16 23 00, but there is nothing there. Per Thomson, the problem is that Dreyer's precessional correction in right ascension (from 1900 to 1860) is considerably off. Swift's paper lists a 1900 position of RA 14 49 37, Dec +16 47.5, which precesses to 1860 14 47 45.0, NPD 73 02.6, or 22 seconds of time east of the IC2 position. Precessing Swift's actual position yields a J2000 position of RA 14 54 17.3, Dec +16 23 04, just over 2 arcmin northwest of the galaxy listed above, and there is nothing else nearby so the identification is reasonably certain. (This was Swift's last discovery, after more than half a century of astronomical observations beginning with an observation of the Great Comet of 1843, three days before its official discovery was announced.)
Physical Information: Apparent size of 1.1 by 0.8 for brighter central regions, and 1.7 by 1.0 arcmin including fainter outer regions.
SDSS image of region near elliptical galaxy IC 4516
Above, a 12 arcmin wide SDSS image centered on IC 4516
Below, a 1.5 arcmin wide SDSS image of the galaxy and some of its smaller companions
SDSS image of elliptical galaxy IC 4516

IC 4517 (= PGC 53291)
Discovered (Jul 28, 1903) by
Stephane Javelle
A magnitude 14.7 spiral galaxy (type Sb?) in Bo÷tes (RA 14 54 35.1, Dec +23 38 35)
Historical Identification: Per Dreyer, IC 4517 (= Javelle #1348, 1860 RA 14 48 22, NPD 65 46.6) is "faint, small, nuclear, diffuse". The position precesses to RA 14 54 35.8, Dec +23 39 07, less than half an arcmin north northeast of the galaxy listed above, and there is nothing else nearby so the identification is certain.
Physical Information: Apparent size of 1.2 by 0.3 arcmin.
SDSS image of region near spiral galaxy IC 4517
Above, a 12 arcmin wide SDSS image centered on IC 4517
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4517

IC 4518 (= PGC 53466 + PGC 53467)
Discovered (May 15, 1904) by
Royal Frost
A pair of galaxies in Lupus
PGC 53466 = A magnitude 14(?) spiral galaxy (type Sc? pec) at RA 14 57 41.1, Dec -43 07 55
PGC 53467 = A magnitude 16(?) spiral galaxy (type Sc? pec) at RA 14 57 44.5, Dec -43 07 53
Historical Identification: Per Dreyer, IC 4518 (= Frost #1138, 1860 RA 14 48 30, NPD 132 34) is "extremely small, round, also one pretty large, extremely extended 100░". The position precesses to RA 14 57 39.3, Dec -43 08 04, only a third of an arcmin southwest of the western member of the pair of galaxies listed above, and the description of the pair fits perfectly, so the identification is certain. Unfortunately, there are three PGC listings for the pair of galaxies, and sometimes the northwesterly plume extending from the eastern member is mistaken for one of them, so some references give the correct PGC entries (shown above and in the 2.4 arcmin wide image below), and some mix them up in one way or another. (Sometimes only the western galaxy is listed as IC 4518, and the other is considered a separate object; but it is generally thought that given Frost's description, Dreyer meant to include both nebulae in the entry.)
Physical Information: PGC 53466 is about 1.0 by 0.3; it is listed as a Seyfert galaxy (type Sy 2). PGC 53467 is about 1.3 by 0.25 arcmin for the main galaxy, 1.4 by 0.1 arcmin for the northwesterly plume, and 2.2 by 0.25 arcmin overall.
DSS image of region near peculiar spiral galaxies PGC 53466 and PGC 53467, which comprise IC 4518; the glare and diffraction spike at left are from magnitude 2.7 Beta Lupi
Above, a 12 arcmin wide DSS image centered on IC 4518
(The glare and diffraction spike in the DSS images are from magnitude 2.7 β Lupi)
Below, a 2.4 arcmin wide DSS image of the galaxies
DSS image of peculiar spiral galaxies PGC 53466 and PGC 53467, which comprise IC 4518; the diffraction spike running through the pair is from magnitude 2.7 Beta Lupi
Below, a 'raw' HST image of part of PGC 53466 (Image Credit Hubble Legacy Archive)
'Raw' HST image of part of peculiar spiral galaxy PGC 53466, the western component of IC 4518
Below, a 'raw' HST image of part of PGC 53467 (Image Credit Hubble Legacy Archive)
'Raw' HST image of part of peculiar spiral galaxy PGC 53467, the eastern component of IC 4518

IC 4519 (= PGC 53311)
Discovered (Jul 10, 1896) by
Stephane Javelle
A magnitude 14.5 lenticular galaxy (type SAB0(r)a?) in Bo÷tes (RA 14 54 44.5, Dec +37 24 46)
Historical Identification: Per Dreyer, IC 4519 (= Javelle #1349, 1860 RA 14 49 13, NPD 52 00.3) is "faint, small, diffuse, 14th magnitude star to southwest". The position precesses to RA 14 54 44.7, Dec +37 25 30, just over half an arcmin north of the galaxy listed above, so the identification seems certain save for the description of the field, as the nearest star is a 10th magnitude star to the northwest. The error in direction isn't that much of a problem, as visual observers often become confused about directions, since depending upon the observing setup the field of view could be upright, inverted or some combination of the two, but the large error in the brightness of the star seems unusual and bothersome. However, no one else seems to have expressed any doubt about the identification, so it is presumably reasonably certain.
Physical Information: Apparent size 0.9 by 0.5 arcmin.
SDSS image of region near lenticular galaxy IC 4519
Above, a 12 arcmin wide SDSS image centered on IC 4519
Below, a 1.0 arcmin wide SDSS image of the galaxy, with glare from the 10th magnitude star to its north
SDSS image of lenticular galaxy IC 4519

IC 4520 (= PGC 53328)
Discovered (Jun 23, 1903) by
Stephane Javelle
A magnitude 15.3 spiral galaxy (type S(r)c?) in Bo÷tes (RA 14 55 07.0, Dec +33 43 28)
Historical Identification: Per Dreyer, IC 4520 (= Javelle #1350, 1860 RA 14 49 22, NPD 55 42.5) is "faint, very small, round, nuclear, mottled but not resolved". The position precesses to RA 14 55 06.1, Dec +33 43 20, almost exactly on the galaxy listed above and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 0.5 by 0.4 arcmin.
SDSS image of region near spiral galaxy IC 4520
Above, a 12 arcmin wide SDSS image centered on IC 4520
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4520

IC 4521 (= PGC 53558)
Discovered (Jun 22, 1895) by
Stephane Javelle
A magnitude 14.7 spiral galaxy (type Sc? pec) in Bo÷tes (RA 14 59 27.5, Dec +25 35 02)
Historical Identification: Per Dreyer, IC 4521 (= Javelle #1351, 1860 RA 14 53 21, NPD 63 52.3) is "faint, considerably small, extended east-west, gradually brighter middle". The position precesses to RA 14 59 28.2, Dec +25 34 07, less than an arcmin south of the galaxy listed above and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 0.7 by 0.45 arcmin.
SDSS image of region near spiral galaxy IC 4521
Above, a 12 arcmin wide SDSS image centered on IC 4521
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4521

IC 4522 (= PGC 54216)
Discovered (Jul 18, 1900) by
DeLisle Stewart
A magnitude 12.3 spiral galaxy (type Sb? pec) in Apus (RA 15 11 29.2, Dec -75 51 34)
Historical Identification: Per Dreyer, IC 4522 (= DeLisle Stewart #420, 1860 RA 14 55 45, NPD 165 18) is "very faint, very small, considerably brighter middle, star involved". The position precesses to RA 15 11 37.7, Dec -75 50 33, a little over an arcmin north northeast of the galaxy listed above, and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 2.7 by 0.8 arcmin.
DSS image of region near spiral galaxy IC 4522
Above, a 12 arcmin wide DSS image centered on IC 4522
Below, a 3.0 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4522

IC 4523 (= PGC 53845)
Discovered (May 15, 1904) by
Royal Frost
A magnitude 13.2 spiral galaxy (type SAB(rs)bc?) in Lupus (RA 15 05 10.4, Dec -43 30 34)
Historical Identification: Per Dreyer, IC 4523 (= Frost #1139, 1860 RA 14 55 52, NPD 132 58) has a "brighter middle, magnitude 14". The position precesses to RA 15 05 07.0, Dec -43 31 00, on the southwestern rim of the galaxy listed above, and there is nothing else nearby so the identification is certain.
Physical Information: Apparent size 1.7 by 1.6 arcmin.
DSS image of region near spiral galaxy IC 4523
Above, a 12 arcmin wide DSS image centered on IC 4523
Below, a 2.0 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4523

IC 4524 (= PGC 1742463)
Discovered (Jul 26, 1895) by
Stephane Javelle
A magnitude 14.9 spiral galaxy (type SB(s)b? pec) in Bo÷tes (RA 15 02 06.4, Dec +25 36 05)
Historical Identification: Per Dreyer, IC 4524 (= Javelle #1352, 1860 RA 14 55 58, NPD 63 50.9) is "faint, small, irregular figure, gradually brighter middle, mottled but not resolved". The position precesses to RA 15 02 04.4, Dec +25 35 53, less than half an arcmin southwest of the galaxy listed above and there is nothing else nearby, so the identification is certain. (The error in position is essentially the same as for Javelle's #1353 = IC 4525, suggesting that most of the error probably lay in the position of his comparison star.) Unfortunately, despite the certain identification, the entry is sometimes misidentified as PGC 53684 (which see, immediately following).
Physical Information: Apparent size 0.55 by 0.45 arcmin.
SDSS image of region near spiral galaxy IC 4524, also showing IC 4524 and PGC 53684, which is sometimes misidentified as IC 4524
Above, a 12 arcmin wide SDSS image centered on IC 4524, also showing IC 4525 and PGC 53684
Below, a 0.75 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4524

PGC 53684 (= PGC 1740358, but not =
IC 4524)
Not an IC object but listed here since sometimes misidentified as IC 4524
A magnitude 16.5(?) spiral galaxy (type Scd?) in Bo÷tes (RA 15 02 16.1, Dec +25 32 32)
Physical Information: Apparent size 0.75 by 0.1 arcmin.
SDSS image of spiral galaxy PGC 53684, which is sometimes misidentified as IC 4524
Above, a 1.0 arcmin wide SDSS image of PGC 53684; see IC 4524 for a wider view

IC 4525 (= PGC 53705)
Discovered (Jul 26, 1895) by
Stephane Javelle
A magnitude 15.1 spiral galaxy (type SBd??) in Bo÷tes (RA 15 02 24.9, Dec +25 38 18)
Historical Identification: Per Dreyer, IC 4525 (= Javelle #1353, 1860 RA 14 56 16, NPD 63 48.7) is "very faint, considerably small, diffuse". The position precesses to RA 15 02 22.2, Dec +25 38 08, only about half an arcmin southwest of the galaxy listed above and there is nothing else nearby, so the identification is certain. (The error in position is essentially the same as for Javelle's #1352 = IC 4524, suggesting that most of the error probably lay in the position of his comparison star.)
Physical Information: Apparent size 0.6 by 0.5 arcmin.
SDSS image of region near spiral galaxy IC 4525, also showing IC 4524 and PGC 53684, which is sometimes misidentified as IC 4524
Above, a 12 arcmin wide SDSS image centered on IC 4525, also showing IC 4524 and PGC 53684
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4525

IC 4526 (= PGC 53707 =
HCG 73B, and with NGC 5829 = Arp 42)
Discovered (Jul 25, 1903) by Stephane Javelle
A magnitude 15.8 spiral galaxy (type Sm? pec) in Bo÷tes (RA 15 02 38.2, Dec +23 21 02)
Historical Identification: Per Dreyer, IC 4526 (= Javelle #1354, 1860 RA 14 56 26, NPD 66 05.1) is "very faint, very small, nuclear". The position precesses to RA 15 02 38.5, Dec +23 21 46, about 0.7 arcmin due north of the galaxy listed above, and save for the much brighter NGC 5829, which is 1.2 arcmin southeast of IC 4526, there is nothing else nearby, so the identification is certain. Per Thomson, the galaxy is sometimes mistakenly treated as part of NGC 5829, but as discussed below they have no relationship to each other, save for being in nearly the same direction.
Physical Information: IC 4526 and NGC 5829 are listed as Arp 42, an example of a spiral galaxy with a faint companion; however, IC 4526 is over 300 million light years farther away, so they are only an "optical double". Based on a recessional velocity of 13685 km/sec, a straightforward calculation indicates that IC 4526 is about 635 million light years away. However, for such distant objects, we need to 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 605 million light years away when the light by which we see it was emitted, about 620 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 0.55 arcmin, IC 4526 is about 115 thousand light years across.
SDSS image of region near spiral galaxy IC 4526, also showing NGC 5829, with which it comprises Arp 42; also shown are various members of Hickson Compact Group 73
Above, a 12 arcmin wide SDSS image centered on IC 4526, also showing NGC 5829
Below, a 6 arcmin wide SDSS image of the members of Hickson Compact Group 73
SDSS image of Hickson Compact Group 73, showing the members' NGC/IC/PGC designations
Below, a 2.4 arcmin wide SDSS image of IC 4526 and NGC 5829
SDSS image of spiral galaxies NGC 5829 and IC 4526, which comprise Arp 42, and are part of Hickson Compact Group 73
Below, a 1.0 arcmin wide SDSS image of IC 4526
SDSS image of spiral galaxy IC 4526, which is part of Arp 42, and of Hickson Compact Group 73

IC 4527 (= PGC 53879)
Discovered (May 15, 1904) by
Royal Frost
A magnitude 13.3 spiral galaxy (type SB(r)bc? pec) in Lupus (RA 15 05 40.9, Dec -42 26 57)
Historical Identification: Per Dreyer, IC 4527 (= Frost #1140, 1860 RA 14 56 29, NPD 131 54) is "considerably small, extended 225░, brighter middle". The position precesses to RA 15 05 39.7, Dec -42 26 55, practically on top of the galaxy listed above, and the description fits, so the identification is certain.
Physical Information: Apparent size 1.4 by 0.5 arcmin.
DSS image of region near spiral galaxy IC 4527
Above, a 12 arcmin wide DSS image centered on IC 4527
Below, a 1.5 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4527

IC 4528 (= PGC 53658)
Discovered (May 23, 1898) by
Guillaume Bigourdan
A magnitude 14.3 spiral galaxy (type SB(rs)ab? pec) in Bo÷tes (RA 15 01 33.3, Dec +49 06 44)
Historical Identification: Per Dreyer, IC 4528 (= Bigourdan #423, 1860 RA 14 56 56, NPD 40 21) is "extremely faint, pretty small, diffuse, mottled but not resolved". The position precesses to RA 15 01 32.6, Dec +49 05 49, which is an arcmin south of the galaxy listed above, close enough for a reasonably certain identification; but as it happens, Dreyer's NPD has a typographical error (it should have been 40 20), and precessing Bigourdan's original position instead of the incorrect IC2 position yields a J2000 position of RA 15 01 32.6, Dec +49 06 22, which falls right on the southwestern rim of the galaxy; in addition (per Corwin, relying on Bigourdan's "big" catalog), Bigourdan notes the presence of the 12th magnitude star 2 arcmin to the northwest, making the identification absolutely certain. Despite this, some catalogs have misidentified PGC 53607 (which lies a minute of time to the west and 2.7 arcmin to the north) as IC 4528, so that object is discussed immediately below.
Physical Information: Based on a recessional velocity of 7800 km/sec, a straightforward calculation indicates that IC 4528 is about 365 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, about 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 0.75 by 0.55 arcmin, the galaxy is about 80 thousand light years across.
SDSS image of region near spiral galaxy IC 4528
Above, a 12 arcmin wide SDSS image centered on IC 4528
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4528

PGC 53607 (not =
IC 4528)
Not an IC object but listed here since sometimes misidentified as IC 4528
A magnitude 16(?) spiral galaxy (type Sbc?) in Bo÷tes (RA 15 00 32.6, Dec +49 10 28)
Historical Identification: As noted in the discussion of IC 4528, PGC 53607 is sometimes misidentified as that IC object, despite being nowhere near Bigourdan's position for the object. So placing this entry on this page serves primarily as a warning for those who accidentally rely on the incorrect identification.
Physical Information: Based on a recessional velocity of 9265 km/sec, a straightforward calculation indicates that PGC 53607 is about 430 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 415 million light years away at the time the light by which we see it was emitted, about 425 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 0.9 by 0.2 arcmin, the galaxy is about 110 thousand light years across.
SDSS image of region near spiral galaxy PGC 53607, which is sometimes misidentified as IC 4528
Above, a 12 arcmin wide SDSS image centered on PGC 53607
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy PGC 53607, which is sometimes misidentified as IC 4528

IC 4529 (= PGC 53926)
Discovered (May 15, 1904) by
Royal Frost
A magnitude 14.2 spiral galaxy (type (R)S(r)c? pec) in Lupus (RA 15 06 25.6, Dec -43 13 57)
Historical Identification: Per Dreyer, IC 4529 (= Frost #1141, 1860 RA 14 57 04, NPD 132 41) has a "brighter middle, magnitude 14". The position precesses to RA 15 06 18.4, Dec -43 13 50, about 1.4 arcmin west of the galaxy listed above, but there is nothing else nearby and the description fits, so the identification seems reasonably certain. (Note: The closeup image below is not detailed enough to tell whether the "nucleus" is all part of the galaxy, or partly superimposed stars, so the position of the nucleus (which is used as the position of the galaxy, above) may prove slightly different when better pictures are available.)
Physical Information: Apparent size 0.75 by 0.65 arcmin.
DSS image of region near peculiar spiral galaxy IC 4529
Above, a 12 arcmin wide DSS image centered on IC 4529
Below, a 1.0 arcmin wide DSS image of the galaxy
DSS image of peculiar spiral galaxy IC 4529

IC 4530 (= PGC 53752)
Discovered (Jul 26, 1895) by
Stephane Javelle
A magnitude 14.5 spiral galaxy (type Sb? pec) in Bo÷tes (RA 15 03 45.3, Dec +26 06 03)
Historical Identification: Per Dreyer, IC 4530 (= Javelle #1355, 1860 RA 14 57 41, NPD 63 21.9) is "faint, small, diffuse, 13.5 magnitude star to northeast". The position precesses to RA 15 03 45.5, Dec +26 05 08, less than an arcmin south of the galaxy listed above, and the star to its north northeast makes the identification certain.
Physical Information: Apparent size 1.05 by 0.35 arcmin.
SDSS image of region near peculiar spiral galaxy IC 4530
Above, a 12 arcmin wide SDSS image centered on IC 4530
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of peculiar spiral galaxy IC 4530

IC 4531 (= PGC 53792)
Discovered (Jul 25, 1903) by
Stephane Javelle
A magnitude 14.9 lenticular galaxy (type E/S0?) in Bo÷tes (RA 15 04 26.5, Dec +23 24 53)
Historical Identification: Per Dreyer, IC 4531 (= Javelle #1356, 1860 RA 14 58 15, NPD 66 03.5) is "faint, very small, round, nuclear". The position precesses to RA 15 04 27.0, Dec +23 23 37, about 1.3 arcmin south of the galaxy listed above, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 0.8 by 0.5 arcmin.
SDSS image of region near lenticular galaxy IC 4531
Above, a 12 arcmin wide SDSS image centered on IC 4531
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4531

IC 4532 (= PGC 53828)
Discovered (Jul 25, 1903) by
Stephane Javelle
A magnitude 14.6 lenticular galaxy (type E/S0?) in Bo÷tes (RA 15 04 53.8, Dec +23 15 23)
Historical Identification: Per Dreyer, IC 4532 (= Javelle #1357, 1860 RA 14 58 19, NPD 66 14.4) is "very faint, nuclear, stellar". The position precesses to RA 15 04 31.5, Dec +23 12 44, but there is nothing there. However, per Corwin and Thomson, Javelle misidentified his companion star as DM 23 2764 (at J2000 15 04 18.9, Dec +23 09 57), but he must have actually used the star at RA 15 04 42.3, Dec +23 12 42; correcting for that mistake yields a position for IC 4532 of RA 15 04 54.9, Dec +23 15 29, within the northeastern outline of the galaxy listed above, and since the description fits the galaxy and there is nothing else nearby, the identification is certain.
Physical Information: Apparent size 0.75 by 0.45 arcmin.
SDSS image of region near the IC2 position for IC 4532, showing the actual IC 4532 and the wrong and correct comparison stars
Above, a 12 arcmin wide SDSS image centered on the IC2 position for IC 4532
Also shown are IC 4532, and Javelle's actual and incorrect comparison stars
Below, a 12 arcmin wide SDSS image centered on IC 4532
SDSS image of region near lenticular galaxy IC 4532
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4532

IC 4533 (= PGC 53803, but probably not =
NGC 5840)
Discovered (Jul 26, 1895) by Stephane Javelle
A magnitude 13.9 spiral galaxy (type SAB(rs)ab?) in Bo÷tes (RA 15 04 30.4, Dec +27 47 34)
Historical Identification: Per Dreyer, IC 4533 (= Javelle #1358, 1860 RA 14 58 31, NPD 61 39.8) is "faint, small, irregular figure, 10.5 magnitude star to east". The position precesses to RA 15 04 30.3, Dec +27 47 21, right on the galaxy listed above, and the star to the east northeast makes the identification certain. Per Corwin, IC 4533 may be the otherwise lost NGC 5840 (which see for a discussion of that possibility), but probably is not, hence the title for this entry.
Physical Information: Apparent size 0.95 by 0.75 arcmin.
SDSS image of region near spiral galaxy IC 4533
Above, a 12 arcmin wide SDSS image centered on IC 4533
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4533

IC 4534 (= PGC 53943)
Discovered (Jul 28, 1903) by
Stephane Javelle
A magnitude 13.2 lenticular galaxy (type SB0?) in Bo÷tes (RA 15 06 41.8, Dec +23 38 30)
Historical Identification: Per Dreyer, IC 4534 (= Javelle #1359, 1860 RA 15 01 59, NPD 65 45.4) is "pretty bright, small, extended north-south, nuclear". The position precesses to RA 15 08 09.2, Dec +23 42 16, but there is nothing there nor anywhere near there. However, as in the case of IC 4532, the problem can be solved if we assume that Javelle misidentified his comparison star. Per Corwin and Thomson, there is a perfect candidate for what Javelle saw about 20 arcmin west of the IC2 position. If we convert the modern position of that galaxy to 1860 coordinates and reverse Javelle's offsets from his comparison star (1m 11.7s east, 5' 11.5" south of the star), we find a suitable candidate for Javelle's comparison star at J2000 RA 15 05 30.1, Dec +23 43 36. Presuming that really was Javelle's comparison star, the position of his #1359 would become J2000 RA 15 06 41.7, Dec +23 38 35, right on the galaxy listed above, and it perfectly fits the description, so the identification seems reasonably certain.
Physical Information: Apparent size 1.3 by 0.7 arcmin.
SDSS image of region near lenticular galaxy IC 4534
Above, a 12 arcmin wide SDSS image centered on IC 4534
Below, a 1.5 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4534

IC 4535 (= PGC 2103997)
Discovered (Jul 10, 1896) by
Stephane Javelle
A magnitude 15.5 spiral galaxy (type Sb?) in Bo÷tes (RA 15 08 41.6, Dec +37 34 13)
Historical Identification: Per Dreyer, IC 4535 (= Javelle #1360, 1860 RA 15 03 17, NPD 51 53.6) is "faint, small, diffuse, 14th magnitude star to southwest". The position precesses to RA 15 08 41.9, Dec +37 34 12, right on the galaxy listed above, and the star an arcmin to the southwest confirms the identity. (Per Corwin, there was at least one earlier misidentification of the object, but all the databases referred to by Corwin or Thomson now show the correct object or no listing at all, so apparently any previous misidentifications have been corrected; for that reason, there is no supplementary entry for this object.)
Physical Information: Apparent size 0.6 by 0.2 arcmin.
SDSS image of region near spiral galaxy IC 4535
Above, a 12 arcmin wide SDSS image centered on IC 4535
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4535

IC 4536 (= PGC 54324)
Discovered by
Edward Barnard
A magnitude 13.0 spiral galaxy (type SB(s)dm?) in Libra (RA 15 13 17.3, Dec -18 08 12)
Historical Identification: Per Dreyer, IC 4536 (= Barnard, 1860 RA 15 05 28, NPD 107 36.3) is "very faint, large, round, faint star attached on northwest, faint star near to southeast". The position precesses to RA 15 13 22.7, Dec -18 07 59, only an arcmin east of the galaxy listed above, and the star on the nortwestern rim of the galaxy makes the identification certain.
Physical Information: Apparent size 2.1 by 1.9 arcmin.
DSS image of region near spiral galaxy IC 4536
Above, a 12 arcmin wide DSS image centered on IC 4536
Below, a 2.4 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4536

IC 4537 (= PGC 54583)
Discovered by
Edward Barnard
A magnitude 14.2 lenticular galaxy (type S0/a?) in Serpens (RA 15 17 32.5, Dec +02 02 51)
Historical Identification: Per Dreyer, IC 4537 (= Barnard, 1860 RA 15 10 22, NPD 87 26.2) is "extremely faint, very small, round, brighter middle". The position precesses to RA 15 17 26.7, Dec +02 02 48, about 1.4 arcmin west of the galaxy listed above, but there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 0.65 by 0.25 arcmin.
SDSS image of region near lenticular galaxy IC 4537
Above, a 12 arcmin wide SDSS image centered on IC 4537
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4537

IC 4538 (= PGC 54776)
Discovered (May 26, 1895) by
Lewis Swift
A magnitude 12.1 spiral galaxy (type SAB(s)c?) in Libra (RA 15 21 11.6, Dec -23 39 30)
Historical Identification: Per Dreyer, IC 4538 (= Swift list XI (#178), 1860 RA 15 12 50, NPD 113 10.9) is "most extremely faint, very large". The position precesses to RA 15 21 01.7, Dec -23 41 27, about 3 arcmin southwest of the galaxy listed above, but there is nothing else nearby and it fits the description, so the identification is certain.
Physical Information: Apparent size 2.4 by 2.0 arcmin.
DSS image of region near spiral galaxy IC 4538
Above, a 12 arcmin wide DSS image centered on IC 4538
Below, a 2.7 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4538
Below, a more detailed image of the same region (Image Credit & © Carnegie-Irvine Survey; used by permission)
Carnegie-Irvine Galaxy Survey image of spiral galaxy IC 4538

IC 4539 (= PGC 54642)
Discovered (Jun 23, 1903) by
Stephane Javelle
A magnitude 15.3 spiral galaxy (type Sbc?) in Corona Borealis (RA 15 18 31.2, Dec +32 23 34)
Historical Identification: Per Dreyer, IC 4539 (= Javelle #1361, 1860 RA 15 12 53, NPD 57 06.8) is "faint, small, round, very little brighter middle". The position precesses to RA 15 18 33.0, Dec +32 22 28, just over an arcmin south southeast of the galaxy listed above, but there is nothing else nearby, so the identification is considered certain.
Physical Information: Apparent size 0.4 by 0.4 arcmin.
SDSS image of region near spiral galaxy IC 4539
Above, a 12 arcmin wide SDSS image centered on IC 4539
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4539

IC 4540
Recorded (Jun 21, 1897) by
Lewis Swift
A lost or nonexistent object in Serpens (RA 15 20 03.3, Dec +01 47 12)
Historical Identification: Per Dreyer, IC 4540 (= Swift list XI (#177), 1860 RA 15 12 58, NPD 87 42.2) is "very faint, pretty small, much extended, bright star near" (Swift actually wrote "bright star partly obscures it"). The position precesses to RA 15 20 03.3, Dec +01 47 12 (whence the position above), but there no galaxies that Swift could have seen in what is an essentially stellar field, and although a close pair of stars might have been perceived as an extended object by Swift, no pair has been given any significant chance of being what (if anything) Swift thought he saw. Corwin gives a detailed discussion of his exhaustive examination of the field (and its lack of success in turning up any candidates for IC 4540), and a brief discussion of an earlier suggestion by Steinicke that Steinicke has long abandoned as being either wrong or unprovable. So it appears that IC 4540 is definitely lost or nonexistent.
SDSS image of region centered on Swift's position for the almost certainly nonexistent IC 4540
Above, a 12 arcmin wide SDSS image centered on the IC2 position for IC 4540

IC 4541 (= PGC 55252)
Discovered (Jul 19, 1900) by
DeLisle Stewart
A magnitude 13.3 spiral galaxy (type Sb?) in Apus (RA 15 29 55.7, Dec -70 35 02)
Historical Identification: Per Dreyer, IC 4541 (= DeLisle Stewart #421, 1860 RA 15 16 17, NPD 160 05) is "extremely faint, very small, much extended 150░, suspected". The position precesses to RA 15 30 13.0, Dec -70 34 34, about 1.5 arcmin northeast of the galaxy listed above, and the description fits, so the identification is certain.
Physical Information: Apparent size 2.3 by 0.5 arcmin.
DSS image of region near spiral galaxy IC 4541
Above, a 12 arcmin wide DSS image centered on IC 4541
Below, a 2.7 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4541

IC 4542 (= PGC 54855 + PGC 54856)
Discovered (Jun 23, 1903) by
Stephane Javelle
A pair of galaxies in Bo÷tes
PGC 54855 = A magnitude 14.1 lenticular galaxy (type SB0/a?) at RA 15 22 05.4, Dec +33 08 55
PGC 54856 = A magnitude 15.1 spiral galaxy (type Sc?) at RA 15 22 06.0, Dec +33 08 51
Historical Identification: Per Dreyer, IC 4542 (= Javelle #1362, 1860 RA 15 16 30, NPD 56 19.7) is "faint, small, round, nuclear, 12th magnitude star to southwest". The position precesses to RA 15 22 06.0, Dec +33 10 08, just over an arcmin north of the galaxies listed above, and the star to their west southwest makes the identification certain. The main question is whether to count the fainter component as part of the IC object, as Javelle almost certainly took no notice of it; but the pair are at essentially the same distance and are probably gravitationally interacting, and in such situations it is customary to include both "components" in the listing, as I have done.
Physical Information: The recessional velocity of PGC 54855 is 9480 km/sec, and of PGC 54856 is 9595 km/sec, with an uncertainty of about 50 km/sec for each object. This means that for all practical purposes they share a common recessional velocity of 9535 km/sec, with little if any radial velocity relative to each other. Given that recessional velocity a straightforward calculation indicates that the pair 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 pair was just under 430 million light years away at the time the light by which we see them 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 0.75 by 0.5 arcmin, PGC 54855 is about 95 thousand light years across, and PGC 54856's apparent size of 0.3 by 0.05 arcmin corresponds to about 35 thousand light years.
SDSS image of region near lenticular galaxy PGC 54855 and spiral galaxy PGC 54856, which comprise IC 4542
Above, a 12 arcmin wide SDSS image centered on IC 4542
Below, a 1.0 arcmin wide SDSS image of the pair of galaxies
SDSS image of lenticular galaxy PGC 54855 and spiral galaxy PGC 54856, which comprise IC 4542

IC 4543 (=
IC 1118 = PGC 55035)
Recorded (Jun 3, 1897) by Lewis Swift
A magnitude 14.3 lenticular galaxy (type E/S0?) in Serpens (RA 15 24 59.5, Dec +13 26 42)
Historical Identification: Per Dreyer, IC 4543 (= Swift list XI (#179), 1860 RA 15 17 59, NPD 76 01.2) is "extremely faint, pretty small, very faint star near to northwest". The position precesses to RA 15 24 34.1, Dec +13 28 56, about two arcmin west of PGC 3090879, but the description of the field makes it clear that the brighter IC 1118, which has the required star to its northwest, though four and a half arcmin further away, must be what Swift observed (hence the double listing). Unfortunately, PGC 3090879's closer position has led to its often being misidentified as IC 4543, so it is discussed immediately below.
Physical Information: Given the duplicate entry, see IC 1118 for anything else.

PGC 3090879 (not =
IC 4543)
Not an IC object but listed here since often misidentified as IC 4543
A magnitude 15.5(?) spiral galaxy (type SBab?) in Serpens (RA 15 24 42.3, Dec +13 28 34)
Historical Identification: As noted in the entry for IC 4543, that object is a reobservation of IC 1118, but because of PGC 3090879's greater proximity to Swift's position for IC 4543, it is often misidentified as that object. (Note: Listed in NED as 2MASXJ15244226+1328340.)
Physical Information: Based on a recessional velocity of 6930 km/sec, PGC 3090879 is about 320 million light years away. Given that and its apparent size of 0.5 by 0.25 arcmin, it is about 45 thousand light years across.
SDSS image of spiral galaxy PGC 3090879, which is sometimes misidentified as IC 4543; also shown is IC 1118, which is the same as IC 4543
Above, a 12 arcmin wide SDSS image centered on PGC 3090879, also showing IC 1118
(The box shows Swift's position for IC 4543, which is a duplicate observation of IC 1118)
Below, a 0.6 arcmin wide SDSS image of PGC 3090879
SDSS image of spiral galaxy PGC 3090879, which is sometimes misidentified as IC 4543

IC 4544 (= IL Normae = Nova Normae 1893)
Discovered (Oct 26, 1893) by
Williamina Fleming
A nova in Norma (RA 15 29 23.07, Dec -50 35 00.6)
Historical Identification: Per Dreyer, IC 4544 (= Fleming #71, 1860 RA 15 19 20, NPD 140 06) is "planetary, stellar". The position precesses to RA 15 29 26.0, Dec -50 35 23, which is in a region so full of faint stars that it is impossible to tell which might be Fleming's object. As a result, for a long time IC 4544 was listed as lost. Dreyer placed it in the IC2 because it was in a 1908 Harvard Annals list of newly discovered objects, and the reference in the HA to the "original" paper was incorrect, which would have made it impossible for Dreyer to realize that it was the 1893 nova (if he had he probably would have listed it as such, as it is not the only nova in the NGC/IC). Although the position in the 1908 HA was a bit off, (per Corwin) the variable star observers at Harvard continued to follow its variations, and when they published a precise position it was essentially the same as the modern position (as listed above to 0.1 arcsec accuracy). As shown in the images below, it required exceptionally detailed imaging of the region by Woudt and Warner to identify the particular star that must be the remnant of Nova Normae 1893, and is therefore IC 4544.
Physical Information: Per PASP 53, Fleming discovered the nova in 1893, at which time it reached magnitude 7 (it now erratically varies between magnitudes 18.5 and 19.0). The nova was not visible on a plate of the region taken on Jun 21, 1893, but was visible on the plate taken on July 10, 1893 (and examined by Fleming on Oct 26), so it must have erupted between those two dates.
DSS image of region near the nova remnant listed as IC 4544
Above, a 12 arcmin wide DSS image centered on IC 4544
Below, a 2.0 arcmin wide DSS image centered on the nova remnant
DSS image centered on the nova remnant listed as IC 4544
Below, the image above with a superimposed detail based on a finding chart by Woudt and Warner
DSS image centered on the nova remnant listed as IC 4544, with a superimposed detail based on a finding chart by Woudt and Warner

IC 4545 (= PGC 55799)
Discovered (Jun 13, 1901) by
DeLisle Stewart
A magnitude 12.9 spiral galaxy (type SAB(s)cd?) in Apus (RA 15 41 28.4, Dec -81 37 35)
Historical Identification: Per Dreyer, IC 4545 (= DeLisle Stewart #422, 1860 RA 15 19 28▒, NPD 171 11▒) is "most extremely faint, extremely small, much extended 145░, between 2 very faint stars, suspected". The position precesses to RA 15 43 06.4, Dec -81 39 17, though with a considerable uncertainty due to the uncertain positions in the IC2. Despite that, it is only 2 arcmin southeast of the galaxy listed above, and the description fits perfectly, so the identification is certain.
Physical Information: Apparent size 2.15 by 0.85 arcmin.
DSS image of region near spiral galaxy IC 4545
Above, a 12 arcmin wide DSS image centered on IC 4545
Below, a 2.4 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4545

IC 4546 (= PGC 55115)
Discovered (Jul 24, 1895) by
Stephane Javelle
A magnitude 14.5 spiral galaxy (type SB(rs)c?) in Corona Borealis (RA 15 26 58.4, Dec +28 51 09)
Historical Identification: Per Dreyer, IC 4546 (= Javelle #1363, 1860 RA 15 21 09, NPD 60 39.8) is "faint, very small, round, 13th magnitude star attached". The position precesses to RA 15 26 58.4, Dec +28 50 47, barely below the southern rim of the galaxy listed above, and the star on its northeastern rim confirms the identification. (Per Thomson, there was a typographical error in the second part of Javelle's catalog involving the sign of the offset from Javelle's comparison star, but the first part of the catalog had the correct position, so Dreyer's position was correct, and there has never been any doubt about the identification.)
Physical Information: Apparent size 0.6 by 0.55 arcmin. A starburst galaxy?
SDSS image of region near spiral galaxy IC 4546, also showing IC 4547 and IC 4548
Above, a 12 arcmin wide SDSS image centered on IC 4546, also showing IC 4547 and 4548
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4546

IC 4547 (= PGC 55130)
Discovered (Jul 22, 1895) by
Stephane Javelle
A magnitude 14.3 lenticular galaxy (type E/S0?) in Corona Borealis (RA 15 27 15.0, Dec +28 47 20)
Historical Identification: Per Dreyer, IC 4547 (= Javelle #1364, 1860 RA 15 21 25, NPD 60 43.5) is "faint, small, round, nuclear, mottled but not resolved". The position precesses to RA 15 27 14.5, Dec +28 47 07, within the southwestern outline of the galaxy listed above, so the identification is certain.
Physical Information: Apparent size 0.8 by 0.6 arcmin.
SDSS image of region near lenticular galaxy IC 4547, also showing IC 4546 and IC 4548
Above, a 12 arcmin wide SDSS image centered on IC 4547, also showing IC 4546 and 4548
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4547

IC 4548 (= PGC 55136)
Discovered (Jul 24, 1895) by
Stephane Javelle
A magnitude 15.6 lenticular galaxy (type E/S0?) in Corona Borealis (RA 15 27 24.0, Dec +28 50 59)
Historical Identification: Per Dreyer, IC 4548 (= Javelle #1365, 1860 RA 15 21 34, NPD 60 39.9) is "very faint, small, irregular figure, mottled but not resolved". The position precesses to RA 15 27 23.3, Dec +28 50 45, on the southwestern rim of the galaxy listed above, so the identification is essentially certain.
Physical Information: Apparent size 0.35 by 0.35 arcmin.
SDSS image of region near lenticular galaxy IC 4548, also showing IC 4546 and IC 4547
Above, a 12 arcmin wide SDSS image centered on IC 4548, also showing IC 4546 and 4547
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4548

IC 4549 (= PGC 55217)
Discovered (Jul 23, 1903) by
Stephane Javelle
A magnitude 14.6 spiral galaxy (type Sbc?) in Bo÷tes (RA 15 29 14.6, Dec +32 49 32)
Historical Identification: Per Dreyer, IC 4549 (= Javelle #1366, 1860 RA 15 23 39, NPD 56 42.0) is "faint, considerably small, extended east-west". The position precesses to RA 15 29 13.9, Dec +32 48 57, only half an arcmin south of the galaxy listed above, and the description fits, so the identification is certain.
Physical Information: Apparent size 0.8 by 0.3 arcmin.
SDSS image of region near spiral galaxy IC 4549
Above, a 12 arcmin wide SDSS image centered on IC 4549
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4549
Celestial Atlas
(IC 4450 - 4499) ←     IC Objects: IC 4500 - 4549     → (IC 4550 - 4599)