Celestial Atlas
(IC 4550 - 4599) ←     IC Objects: IC 4600 - 4649 Link for sharing this page on Facebook     → (IC 4650 - 4699)
Click here for Introductory Material
QuickLinks:
4600, 4601, 4602, 4603, 4604, 4605, 4606, 4607, 4608, 4609, 4610, 4611, 4612, 4613, 4614, 4615, 4616,
4617, 4618, 4619, 4620, 4621, 4622, 4623, 4624, 4625, 4626, 4627, 4628, 4629, 4630, 4631, 4632, 4633,
4634, 4635, 4636, 4637, 4638, 4639, 4640, 4641, 4642, 4643, 4644, 4645, 4646, 4647, 4648, 4649

Page last updated Feb 28, 2014
WORKING: Add distances, etc

IC 4600 (almost certainly not =
PGC 57668)
Recorded (Jul 7, 1899) by DeLisle Stewart
A lost or nonexistent object in Scorpius (RA 16 18 16.0, Dec -22 46 51)
Historical Identification: Per Dreyer, IC 4600 (= DeLisle Stewart #430, 1860 RA 16 09 56, NPD 112 26) is "extremely faint, extremely small, round". The position precesses to RA 16 18 16.0, Dec -22 46 51 (whence the position above), but there is nothing there. Corwin suggests that Stewart might have mistaken the close triple just west of the nominal position, or the curved triple a little to the north as a nebular object, and also raises the possibility that this was simply a plate defect (which could be checked if the original plate still exists). There has also been a suggestion that the faint galaxy 2m 10s west of the recorded position (PGC 57668, which see) might be IC 4600, but the only other object Stewart found on this plate was very close to his recorded position, so there is no good reason to believe that any particular suggestion represents what Stewart recorded, and IC 4600 almost certainly represents a lost or nonexistent object.
DSS image of region near Stewart's position for IC 4600, also showing the two triplets suggested by Corwin as the basis for the otherwise lost or nonexistent object
Above, a 12 arcmin wide DSS image centered on the position for IC 4600, showing Corwin's suggestions

PGC 57668 (almost certainly not =
IC 4600)
Not an IC object but listed here since sometimes misidentified as IC 4600
A magnitude 15.5 lenticular galaxy (type S0/a? pec) in Scorpius (RA 16 16 05.3, Dec -22 46 59)
Historical Identification: See IC 4600 for a discussion of the sort of thrashing about that led to this object being misidentified as that IC entry.
Physical Information: Apparent size 0.65 by 0.55 arcmin.
DSS image of region near lenticular galaxy PGC 57668, which is sometimes misidentified as IC 4600
Above, a 12 arcmin wide DSS image centered on PGC 57668
Below, a 0.8 arcmin wide DSS image of the galaxy
DSS image of lenticular galaxy PGC 57668, which is sometimes misidentified as IC 4600

IC 4601
Discovered (Jun 22, 1895) by
Edward Barnard
A pair of double stars and reflection nebula in Scorpius (RA 16 20 18.0, Dec -20 04 54)
Historical Identification: Per Dreyer, IC 4601 (= Barnard, DeLisle Stewart #431, 1860 RA 16 12 28, NPD 109 44) is "2 stars of 8th magnitude in extremely large diffuse nebula, a little extended northwest-southeast". The position precesses to RA 16 20 39.3, Dec -20 04 24, within the eastern boundary of a reflection nebula that perfectly fits the description, save that each of the "2 stars" is actually double. When such reflection nebulae are lit by a single star, the position of the star is usually taken as the position of the nebula; in this case the position is taken to be halfway between the two pairs, and the identification is considered certain.
Physical Information: Apparent size about 20 by 10 arcmin?
DSS image of region near the stars and reflection nebula representing IC 4601
Above, a 20 arcmin wide DSS image cenetered on IC 4601

IC 4602 (=
NGC 6132 = PGC 58002)
Discovered (Jul 16, 1876) by Édouard Stephan (and later listed as NGC 6132)
Discovered (Jul 22, 1897) by Lewis Swift (and later listed as IC 4602)
A magnitude 13.6 spiral galaxy (type Sab?) in Hercules (RA 16 23 38.7, Dec +11 47 12)
Historical Identification: Per Dreyer, IC 4602 (= Swift list XI (#183), 1860 RA 16 16 53, NPD 76 55.0) is "most extremely faint, a little extended, extremely difficult, faint star to east" (Swift's original notes add "small", and "2 bright stars to the south nearly point to it". The position precesses to RA 16 23 24.4, Dec +12 45 16, but there is nothing there. However, per Corwin, there is a galaxy that perfectly fits the description almost exactly one degree to the south, namely NGC 6132, and since whole-digit errors of even a degree are not uncommon in Swift's observations, the equality is believed to be reasonably certain.
Physical Information: Given the duplicate entry, see NGC 6132 for anything else.
SDSS image showing a region one degree to the south of Swift's position for IC 4602, thereby confirming its status as a duplicate of NGC 6132
     Above, a 20 arcmin wide SDSS image showing the two bright stars to the south of NGC 6132 that point at the faint star to its east, exactly matching Swift's description of IC 4602, and essentially ensuring that it is a duplicate of the NGC entry.

IC 4603 (= LBN 1109)
Discovered (1882) by
Edward Barnard
A star and reflection nebula in Ophiuchus (RA 16 25 24.3, Dec -24 27 57)
Historical Identification: Per Dreyer, IC 4603 (= Barnard, (A. N. 3301), 1860 RA 16 16 53, NPD 114 07) is "extremely faint, very large, diffuse, star involved". The position precesses to RA 16 25 20.0, Dec -24 26 34, just northeast of 8th magnitude HD 146778, which is almost certainly the "star involved", and coincidentally right on a fainter companion of the brighter star; so the identification is considered certain. (As in most such cases, the position listed for the object is that of the primary star.)
Physical Information: Apparent size 30 by 20 arcmin?
DSS image of region near HD 146778 and its associated reflection nebula, known as IC 4603
Above, a 24 arcmin wide DSS image centered on IC 4603

IC 4604 = ρ Ophiuchi Nebula (= LBN 1112)
Discovered (1882) by
Edward Barnard
A magnitude 5 star and reflection nebula in Ophiuchus (RA 16 25 35.2, Dec -23 26 50)
Historical Identification: Per Dreyer, IC 4604 (= Barnard, (A. N. 3301), 1860 RA 16 17 12, NPD 113 07.2) is "ρ Ophiuchi in extremely large nebula". The position precesses to RA 16 25 35.5, Dec -23 26 43, right on ρ Ophiuchi, and of course the description would make the identification obvious even if the position were badly mangled.
Physical Information: Apparent size 60 by 50 arcmin?
DSS image of region near Rho Ophiuchi, showing its associated reflection nebula, or IC 4604
Above, a degree wide DSS image centered on ρ Ophiuchi and IC 4604

IC 4605 (= LBN 1110)
Discovered (1882) by
Edward Barnard
A magnitude 5 star and reflection nebula in Scorpius (RA 16 30 12.4, Dec -25 06 54)
Historical Identification: Per Dreyer, IC 4605 (= Barnard, (A. N. 3301), 1860 RA 16 21 29, NPD 114 50.5) is a "7th magnitude star in extremely faint, very large nebula". The position precesses to RA 16 29 59.3, Dec -25 09 12, right on a 7th magnitude star enveloped in a large reflection nebula. However, well within the nebula and only 3 arcmin to the northeast is the 5th magnitude star 22 Scorpii, so following the tradition of using the position of the brightest star in such nebulae to determine their position, modern catalogs use the position of 22 Scorpii (as I have also done, above), rather than that of the "original" 7th magnitude star.
Physical Information: Apparent size 30 by 30 arcmin?
DSS image of region near 22 Scorpii, showing its associated reflection nebula, or IC 4605
Above, a half degree wide DSS image centered on 22 Scorpii and IC 4605

IC 4606 (possibly =
NGC 6144 = GCL 42)
If = NGC 6144, Discovered (May 22, 1784) by William Herschel (and later listed as NGC 6144)
Recorded (Sep 8, 1887) by William Finlay (and later listed as IC 4606)
Either a lost or nonexistent object in Scorpius (RA 16 31 33.8, Dec -26 03 25)
or a magnitude 9.0 globular cluster (type XI) at RA 16 27 14.1, Dec -26 01 27
Historical Identification: Per Dreyer, IC 4606 (= Finlay (#7), 1860 RA 16 23, NPD 115 45) is a "nebula; faint star 4.5 seconds of time to west, 0.5 arcmin to north". The position precesses to RA 16 31 33.8, Dec -26 03 25 (whence the first position above), but there is nothing there, and since the position was merely estimated from Finlay's setting circles and self-admittedly crude, for a long time there appeared to be no way to connect Finlay's observation with any real object, and it was presumed lost or nonexistent. However, per Corwin, an early 2000's thread on amastro suggested a possible candidate about a degree to the west, namely the globular cluster NGC 6144. If Finlay's 7-inch refractor showed the cluster as only a faint nebular object, then one of the brighter stars on the western rim of its central condensation might be the star mentioned in the description. Whether that is a reasonable possibility is anybody's guess; as a result, IC 4606 is still generally treated as lost or nonexistent, but in some cases the possibility that it might be a duplicate of NGC 6144 is briefly mentioned.
Physical Information: If lost or nonexistent, there is nothing to say. If a duplicate entry, see NGC 6144.
DSS image of region near Finlay's position for IC 4606
Above, a 12 arcmin wide region centered on Finlay's position for IC 4606
Below, a 3.6 arcmin wide HST image of NGC 6144 (Image Credits Hubble Legacy Archive, Wikisky cutout tool)
The bright star at right center is the one thought to connect the cluster to IC 4606
HST image of core of globular cluster NGC 6144, which might also be IC 4606

IC 4607 (= PGC 58366)
Discovered (Jul 20, 1903) by
Stephane Javelle
A magnitude 15.0 elliptical galaxy (type E3?) in Hercules (RA 16 30 15.9, Dec +24 34 27)
Historical Identification: Per Dreyer, IC 4607 (= Javelle #1394, 1860 RA 16 24 25, NPD 65 07.9) is "faint, considerably small, diffuse". The position precesses to RA 16 30 16.1, Dec +24 33 42, less than an arcmin south of the galaxy listed above, so the identification is reasonably certain. The several fainter galaxies nearby may have contributed to its visual appearance, so it is possible that the IC entry should include some of its companions; but in the absence of any certain knowledge, this entry assumes that only the brightest galaxy is Javelle's object.
Physical Information: Apparent size 0.8 by 0.55 arcmin
SDSS image of region near elliptical galaxy IC 4607
Above, a 12 arcmin wide SDSS image centered on IC 4607
Below, a 1.0 arcmin wide SDSS image of the galaxy and several fainter companions
SDSS image of elliptical galaxy IC 4607

IC 4608 (= PGC 58968)
Discovered (Jul 23, 1900) by
DeLisle Stewart
A magnitude 13.7 spiral galaxy (type SB(s)m pec) in Apus (RA 16 46 54.1, Dec -77 29 19)
Historical Identification: Per Dreyer, IC 4608 (= DeLisle Stewart #432, 1860 RA 16 26 37, NPD 167 13) is "very faint, very small, considerably extended 85°, brighter middle". The position precesses to RA 16 46 46.9, Dec -77 29 38, only half an arcmin southwest of the galaxy listed above, the description fits the part of the galaxy Stewart could have seen, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 0.9 by 0.8 arcmin.
DSS image of region near spiral galaxy IC 4608
Above, a 12 arcmin wide DSS image centered on IC 4608
Below, a 1.0 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4608

IC 4609 (= PGC 58489)
Discovered (Jul 28, 1903) by
Stephane Javelle
A magnitude 14.3 lenticular galaxy (type E/S0?) in Hercules (RA 16 33 01.6, Dec +22 47 50)
Historical Identification: Per Dreyer, IC 4609 (= Javelle #1395, 1860 RA 16 27 03, NPD 66 54.6) is "faint, very small, round, gradually brighter middle and nucleus". The position precesses to RA 16 33 00.1, Dec +22 47 30, on the southwestern rim of the galaxy listed above, so the identification is certain.
Physical Information: Based on a recessional velocity of 10865 km/sec, a straightforward calculation indicates that IC 4609 is about 505 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 485 million light years away at the time the light by which we see it was emitted, about 495 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 0.85 by 0.8 arcmin, the galaxy is about 120 thousand light years across.
SDSS image of region near lenticular galaxy IC 4609
Above, a 12 arcmin wide SDSS image centered on IC 4609
Below, a 1.0 arcmin SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4609

IC 4610 (= PGC 3098331)
Discovered (Jul 25, 1903) by
Stephane Javelle
A magnitude 15.2 spiral galaxy (type Sab?) in Hercules (RA 16 33 39.1, Dec +39 15 28)
Historical Identification: Per Dreyer, IC 4610 (= Javelle #1396, 1860 RA 16 28 50, NPD 50 26.6) is "faint, extremely small, round, gradually brighter middle". The position precesses to RA 16 33 38.0, Dec +39 15 44, less than an arcmin northwest of the galaxy listed above, and although there is another galaxy to the northwest of the position, it is far too faint for Javelle to have seen, so the identification is certain. Despite that, there have been several errors made in identifying this object. For instance, IC 4612 is often misidentified as IC 4610, and although Steinicke has the correct position for the object, he misidentifies it as PGC 58499, hence the entry immediately following.
Physical Information: Apparent size 0.7 by 0.2 arcmin.
SDSS image of region near spiral galaxy IC 4610, also showing IC 4611, and IC 4612 and PGC 58499, both of which are sometimes misdientified as IC 4610
Above, a 12 arcmin wide SDSS image centered on IC 4610, also showing IC 4611 and 4612 and PGC 58499
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4610

PGC 58499 (not =
IC 4610)
Not an IC object but listed here since sometimes misidentified as IC 4610
A magnitude 16? spiral galaxy (type Scd?) in Hercules (RA 16 33 46.1, Dec +39 16 19)
Physical Information: Apparent size 0.5 by 0.15 arcmin.
SDSS image of spiral galaxy PGC 58499, which is sometimes misidentified as IC 4610
Above, a 0.6 arcmin wide SDSS image of PGC 58499; for a wider view see IC 4612

IC 4611 (= PGC 58498)
Discovered (Jul 25, 1903) by
Stephane Javelle
A magnitude 15.0 lenticular galaxy (type SB0/a?) in Hercules (RA 16 33 42.3, Dec +39 11 06)
Historical Identification: Per Dreyer, IC 4611 (= Javelle #1397, 1860 RA 16 28 53, NPD 50 22.1) is "faint, very small, irregular figure". The position precesses to RA 16 33 40.6, Dec +39 20 15, but there is nothing there. However, per Corwin, Javelle apparently reversed the sign of the polar distance offset for this object, for if the sign is reversed the position falls right on the galaxy listed above; so the identification is considered reasonably certain.
Physical Information: Apparent size 0.5 by 0.45 arcmin.
SDSS image of region near lenticular galaxy IC 4611, also showing IC 4610 and IC 4612
Above, a 12 arcmin wide SDSS image centered on IC 4611, also showing IC 4610 and 4612
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4611

IC 4612 (= PGC 58505)
Discovered (Jul 25, 1903) by
Stephane Javelle
A magnitude 13.8 lenticular galaxy (type S0(r)a? pec) in Hercules (RA 16 33 49.7, Dec +39 15 48)
Historical Identification: Per Dreyer, IC 4612 (= Javelle #1398, 1860 RA 16 29 00, NPD 50 26.3) is "faint, extremely small, round, gradually brighter middle". The position precesses to RA 16 33 47.9, Dec +39 16 04, practically on the northwestern rim of the galaxy listed above, so the identification should be certain. However, per Corwin, Javelle's paper has an error in the sign of the right ascension offset. Apparently that was only a printing error, as his position for the galaxy was correct; but it somehow led to a misidentification of IC 4612 as IC 4610 (as noted in the entry for that object), and the galaxy is sometimes correctly listed as IC 4612, and sometimes mis-listed as IC 4610 (for instance, in LEDA and Wikisky).
Physical Information: Apparent size 0.85 by 0.75 arcmin.
SDSS image of region near lenticular galaxy IC 4612, which is sometimes misidentified as IC 4610, also showing the correct IC 4610 and IC 4611, and PGC 58499, which is also sometimes misidentified as IC 4610
Above, a 12 arcmin wide SDSS image centered on IC 4612, also showing IC 4610, IC 4611 and PGC 58499
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4612

IC 4613 (probably not =
NGC 6196 = IC 4615)
Recorded (Jun 28, 1895) by Guillaume Bigourdan
Probably a lost or nonexistent object in Hercules (RA 16 37 15.6, Dec +36 05 00.0)
or (unlikely but possibly) a poorly recorded reobservation of NGC 6196 = IC 4615
Historical Identification: Per Dreyer, (= Bigourdan #425, 1860 RA 16 32 13, NPD 53 38) is "extremely faint, diffuse [perhaps = (NGC) 6196]". The position precesses to RA 16 37 15.6, Dec +36 05 00.0 (whence the position above), but there is nothing there, and despite Dreyer's suggestion that IC 4613 might be NGC 6196 (which lies 8 arcmin to the east), that is probably incorrect, as Bigourdan's #325 (= IC 4615) is a duplicate of NGC 6196, which means that IC 4613, if it represents anything at all, should represent something else. And since there is no nonstellar object anywhere near Bigourdan's position, IC 4613 would normally be listed as lost or nonexistent. However, since Bigourdan's observations for IC 4613 and 4615 were separated by nine years, it is possible that IC 4613 is simply a poorly measured reobservation of the galaxy. But whether that is true or not, thanks to Dreyer's original suggestion the reader may occasionally run across an identification of IC 4613 as NGC 6196 anyway (hence the warning that such an identification is very suspect).
Physical Information: If nonexistent, there is nothing more to say. If a duplicate entry, see NGC 6196 for anything else.
SDSS image of region near Bigourdan's position for IC 4613, also showing IC 4614, NGC 6194, NGC 6197, and NGC 6196, which may or may not be the otherwise nonexistent IC 4613
Above, an 18 arcmin wide SDSS image centered on IC 4613
Also shown are NGC 6194, 6196 and 6197 and IC 4614

IC 4614 (= PGC 58641)
Recorded (Jun 28, 1895) by
Guillaume Bigourdan
A magnitude 14.3 spiral galaxy (type S(rs)c?) in Hercules (RA 16 37 47.2, Dec +36 06 53)
Historical Identification: Per Dreyer, IC 4614 (= Bigourdan #324, 1860 RA 16 32 48, NPD 53 37) is "extremely faint, stellar". The position precesses to RA 16 37 50.4, Dec +36 06 07, about an arcmin southeast of the galaxy listed above. The description fits, and Bigourdan's position for IC 4615 matches the larger, brighter galaxy to its southeast (removing it from consideration), so the identification is certain.
Physical Information: Apparent size of brighter inner galaxy is about 0.7 by 0.6 arcmin; of the fainter outer regions, about 1.0 by 0.9 arcmin.
SDSS image of region near lenticular galaxy IC 4614, also showing NGC 6196
Above, a 12 arcmin wide SDSS image centered on IC 4614, also showing NGC 6196
Below, a 1.0 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4614

IC 4615 (=
NGC 6196 = PGC 58644)
Discovered (Jul 9, 1864) by Albert Marth (and later listed as NGC 6196)
Discovered (Aug 28, 1886) by Guillaume Bigourdan (and later listed as IC 4615)
A magnitude 12.9 lenticular galaxy (type SAB0/a?) in Hercules (RA 16 37 53.8, Dc +36 04 23)
Historical Identification: Per Dreyer, IC 4615 (= Bigourdan #325, 1860 RA 16 32 51, NPD 53 38) is a "13th magnitude star in small nebula". The position precesses to RA 16 37 53.5, Dec +36 05 07, on the northern rim of the galaxy listed above, so the identification is certain. (As noted in the entry for IC 4613, it is sometimes claimed that IC 4613 = NGC 6196, but that is unlikely at best.) The double listing was caused by Marth's position being badly off, so see NGC 6196 for a discussion of that.
Physical Information: Given the duplicate entry, see NGC 6196 for anything else.

IC 4616 (=
NGC 6197 = PGC 58655)
Discovered (Jul 9, 1864) by Albert Marth (and later listed as NGC 6197)
Discovered (Aug 28, 1886) by Guillaume Bigourdan (and later listed as IC 4616)
A magnitude 14.6 lenticular galaxy (type S0/a? pec) in Hercules (RA 16 37 59.8, Dec +35 59 45)
Historical Identification: Per Dreyer, IC 4616 (= Bigourdan #426, 1860 RA 16 32 58, NPD 53 44) is "extremely faint, small, diffuse, mottled but not resolved; 12th magnitude star 2 arcmin to southeast". The position precesses to RA 16 38 00.9, Dec +35 59 09, only half an arcmin southeast of the galaxy listed above, and the star to the southeast of the galaxy makes the identification certain. The double listing was caused by Marth's position being badly off, so see NGC 6197 for a discussion of that. (Per Thomson, NGC 6197 is sometimes misidentified as NGC 6199 (e.g., in LEDA and Wikisky), and even as IC 6199, an even more egregious error, since there aren't that many IC entries.)
Physical Information: Given the duplicate entry, see NGC 6197 for anything else.

IC 4617 (= PGC 2085077)
Discovered by
Edward Barnard
A magnitude 15.2 spiral galaxy (type Sbc?) in Hercules (RA 16 42 08.1, Dec +36 41 03)
Historical Identification: Per Dreyer, (= Barnard, 1860 RA 16 36 19, NPD 53 02.8) is "small, extended 29°, brighter middle". The position precesses to RA 16 41 18.0, Dec +36 40 59, but there is nothing there (save for globular cluster M13, which is obviously not the correct object). However, almost exactly 1 minute of time to the east there is an object which perfectly fits the description, namely the galaxy listed above. So it is considered reasonably certain that Barnard or Dreyer made a simple 1-digit error in the minutes of right ascension, and the identification is considered equally certain.
Physical Information: Apparent size 0.75 by 0.25 arcmin.
SDSS image of region near spiral galaxy IC 4617
Above, a 12 arcmin wide SDSS image centered on IC 4617
The innumerable stars at lower right represent the northeastern outskirts of M13
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4617

IC 4618 (= PGC 59325)
Discovered (Jul 23, 1900) by
DeLisle Stewart
A magnitude 12.0 spiral galaxy (type SB(rs)bc pec?) in Apus (RA 16 57 50.0, Dec -76 59 33)
Historical Identification: Per Dreyer, IC 4618 (= DeLisle Stewart #433, 1860 RA 16 37 47, NPD 166 44) is a "very remarkable object, extremely faint, extremely small, 2 branch spiral". The position precesses to RA 16 57 39.0, Dec -76 58 31, less than an arcmin from the northwestern rim of the galaxy listed above, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 1.8 by 1.3 arcmin.
DSS image of region near spiral galaxy IC 4618
Above, a 12 arcmin wide DSS image centered on IC 4618
Below, a 2.0 arcmin wide image of the galaxy (Image Credit & © Carnegie-Irvine Galaxy Survey; used by permission)
Carnegie-Irvine Galaxy Survey image of spiral galaxy IC 4618

IC 4619 (= PGC 58871)
Discovered (Jul 17, 1903) by
Royal Frost
A magnitude 14.1 spiral galaxy (type Sc?) in Hercules (RA 16 44 11.1, Dec +17 45 33)
Historical Identification: Per Dreyer, IC 4619 (= Frost #1145, 1860 RA 16 38 02, NPD 71 59) is "faint, round". The position precesses to RA 16 44 15.5, Dec +17 45 13, about an arcmin east of the galaxy listed above, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 0.5 by 0.5 arcmin.
SDSS image of region near spiral galaxy IC 4619
Above, a 12 arcmin wide SDSS image centered on IC 4619
Below, a 0.6 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4619

IC 4620 (= PGC 59034)
Discovered (Jul 17, 1903) by
Royal Frost
A magnitude 15.0 spiral galaxy (type SB(rs)bc?) in Hercules (RA 16 48 30.1, Dec +19 18 19)
Historical Identification: Per Dreyer, IC 4620 (= Frost #1146, 1860 RA 16 42 21, NPD 71 28) is "very faint, round". The position precesses to RA 16 48 32.3, Dec +18 17 03, but there is nothing there. However, per Corwin, the problem was merely a careless error by Dreyer in recording the polar distance, which should be 70 28. (Those with access to a copy of the IC2 can easily see this by comparing the 1860 and 1900 coordinates, which generally differ by only a few arcmin; whereas in this case the difference is more than a degree.) The correct coordinates precess to RA 16 48 28.8, Dec +19 17 03, which is only 1.3 arcmin south of the galaxy listed above, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 0.6 by 0.35 arcmin.
SDSS image of region near spiral galaxy IC 4620
Above, a 12 arcmin wide SDSS image centered on IC 4620
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4620

IC 4621 (= PGC 59104)
Discovered (May 15, 1890) by
Hermann Kobold
A magnitude 13.8 spiral galaxy (type Sab?) in Hercules (RA 16 50 51.1, Dec +08 47 03)
Historical Identification: Per Dreyer, IC 4621 (= Kobold (#36 = K10), 1860 RA 16 44 07, NPD 80 57.6) is "very faint, very small". The position precesses to RA 16 50 49.4, Dec +08 47 51, less than an arcmin northwest of the galaxy listed above, and there is nothing else nearby, so the identification is certain.
Physical Information: Apparent size 0.85 by 0.75 arcmin.
DSS image of region near spiral galaxy IC 4621
Above, a 12 arcmin wide DSS image centered on IC 4621
Below, a 1.2 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4621

IC 4622
Recorded (July 1899) by
DeLisle Stewart
A lost or nonexistent object in Ophiuchus (RA 16 52 08.7, Dec -16 14 26)
Historical Identification: Per Dreyer, IC 4622 (= DeLisle Stewart #434, 1860 RA 16 44 07, NPD 106 00) is "considerably faint, small, irregular figure, double". The position precesses to RA 16 52 08.7, Dec -16 14 26 (whence the position above), but there is nothing there nor anywhere near there, and it is hard to see how this could be anything real. Per Corwin, another apparently nonexistent object, IC 4629, was found on the same plate, and is almost certainly a plate defect. He suspects that is probably the case with IC 4622 as well, but notes that it would require an examination of the original plate to be sure.
DSS image of region near Stewart's position for the apparently nonexistent IC 4622
Above, a 12 arcmin wide DSS image centered on Stewart's position for IC 4622

IC 4623 (= PGC 59115)
Discovered (Jul 27, 1903) by
Stephane Javelle
A magnitude 14.7 spiral galaxy (type Sc? pec) in Hercules (RA 16 51 05.4, Dec +22 31 39)
Historical Identification: Per Dreyer, IC 4623 (= Javelle #1399, 1860 RA 16 45 08, NPD 67 14.0) is "faint, small, round, gradually brighter middle". The position precesses to RA 16 51 04.1, Dec +22 31 34, on the eastern rim of the galaxy listed above, so the identification is certain.
Physical Information: Apparent size 0.7 by 0.35 arcmin.
SDSS image of region near spiral galaxy IC 4623
Above, a 12 arcmin wide SDSS image centered on IC 4623
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4623

IC 4624 (= PGC 59131)
Discovered (Jul 17, 1903) by
Royal Frost
A magnitude 14.8 spiral galaxy (type S(rs)c?) in Hercules (RA 16 51 33.5, Dec +17 26 57)
Historical Identification: Per Dreyer, IC 4624 (= Frost #1147, 1860 RA 16 45 19, NPD 72 20) is "very faint, round". The position precesses to RA 16 51 33.0, Dec +17 25 38, about 1.3 arcmin due south of the galaxy listed above, and there is nothing else nearby, so the identification seems certain.
Physical Information: Apparent size 0.6 by 0.45 arcmin.
SDSS image of region near spiral galaxy IC 4624
Above, a 12 arcmin wide SDSS image centered on IC 4624
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4624

IC 4625 (=
NGC 6240 = PGC 59186)
Discovered (Jul 12, 1871) by Édouard Stephan (and later listed as NGC 6240)
Discovered by Edward Barnard (and later listed as IC 4625)
A magnitude 12.9 irregular galaxy (type I0? pec) in Ophiuchus (RA 16 52 58.8, Dec +02 24 11)
Historical Identification: Per Dreyer, IC 4625 (= Barnard, 1860 RA 16 45 54, NPD 87 19.5) is a "nebula; 10th magnitude star close to northeast [perhaps = (NGC) 6240]". The position precesses to RA 16 52 56.3, Dec +02 26 19, about 2.4 arcmin northwest of the galaxy listed above, and the star near its northeast edge makes the identification suggested by Dreyer certain.
Physical Information: Given the duplicate entry, see NGC 6240 for anything else.

IC 4626
Recorded (Jul 2, 1886) by
Guillaume Bigourdan
A pair of stars in Ophiuchus (RA 16 53 21.5, Dec +02 20 19)
Historical Identification: Per Dreyer, IC 4626 (= Bigourdan #427, 1860 RA 16 46 18, NPD 87 27) is "extremely faint". The position precesses to RA 16 53 20.7, Dec +02 18 54, but there is nothing there. However, a comment by Corwin implies that the position of Bigourdan's comparison star was off, and correcting for that points to the pair of stars listed above. To check that I looked up the comparison star and offsets in Bigourdan's original paper. The actual position of the comparison star is north of the position used by Bigourdan, which made the IC2 position of IC 4626 too far south. To correct for that involves precessing the modern position of the star to the equinox of Bigourdan's publication, adding his offsets to find the historical position of his observation, and precessing that to modern coordinates. The result (RA 16 53 21.6, Dec +02 20 18) falls exactly between the two stars listed above, so Corwin's identification of them as IC 4626 seems certain, particularly since many of Bigourdan's "extremely faint" "novae" were actually stars or double stars.
Physical Information:
DSS image of region near pair of stars listed as IC 4626
Above, a 12 arcmin wide DSS image centered on IC 4626, also showing NGC 6240

IC 4627 (= PGC 165701)
Discovered by
Edward Barnard
A magnitude 14.7 spiral galaxy (type Sbc? pec) in Ophiuchus (RA 16 54 08.5, Dec -07 38 07)
Historical Identification: Per Dreyer, IC 4627 (= Barnard, 1860 RA 16 46 34, NPD 97 24.1) is "extremely faint, extremely small, diffuse, 12th magnitude star 12 arcsec to south". The position precesses to RA 16 54 07.9, Dec -07 38 06, on the eastern rim of the galaxy listed above, and the nearby star, though more east than south, makes the identification certain.
Physical Information: Apparent size 0.7 by 0.35 arcmin.
DSS image of region near spiral galaxy IC 4627
Above, a 12 arcmin wide DSS image centered on IC 4627
Below, a 1.0 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4627

IC 4628, the Prawn Nebula
Discovered by
Edward Barnard
An emission nebula in Scorpius (RA 16 56 58, Dec -40 27 24)25 18)
Historical Identification: Per Dreyer, IC 4628 (= Barnard, Frost #1148, 1860 RA 16 46 44, NPD 130 14) is "faint, extremely large, extended east-west, diffuse". The position precesses to RA 16 56 26, Dec -40 27 45, on the western side of the nebula listed above, but well within its overall outline, so the identification is certain. (Note: The images below are centered near the brightest part of the nebula, and are as much as 2 arcmin north of the listed position.)
Physical Information: Apparent size about 30 by 15 arcmin.
NOAO image of region near emission nebula IC 4628, also known as the Prawn Nebula
Above, a 40 arcmin wide NOAO image of IC 4628 (Image Credits Adam Block/NOAO/AURA/NSF)
Below, an ESO image of the region (Image Credit ESO, Acknowledgement Martin Pugh)
ESO image of region near emission nebula IC 4628, also known as the Prawn Nebula

IC 4629
Recorded (July 1899) by
DeLisle Stewart
A nonexistent object in Ophiuchus (RA 16 56 09.6, Dec -16 42 39)
Historical Identification: Per Dreyer, IC 4629 (= DeLisle Stewart #435, 1860 RA 16 48 06±, NPD 106 29) is "very faint, very small, extremely extended 75°, suspected". The position precesses to RA 16 56 09.6, Dec -16 42 39 (whence the position above), but there is nothing there or anywhere near there. Per Corwin, this was observed on only one short-exposure plate (the same plate as for the nonexistent IC 4622), hence Stewart's "suspected", and is probably a plate defect, though it would require an examination of the plate to be certain. What is certain is that there is nothing there that matches Stewart's description, so the object is almost certainly nonexistent.
DSS image of region near Stewart's position for the apparently nonexistent IC 4629
Above, a 12 arcmin wide DSS image centered on Stewart's position for IC 4629

IC 4630 (= PGC 59257)
Discovered (Jul 27, 1903) by
Stephane Javelle
A magnitude 13.6 lenticular galaxy (type S0(r)a? pec) in Hercules (RA 16 55 09.6, Dec +26 39 46)
Historical Identification: Per Dreyer, IC 4630 (= Javelle #1400, 1860 RA 16 49 29, NPD 63 06.8) is "faint, small, round, stellar nucleus". The position precesses to RA 16 55 09.0, Dec +26 39 35, practically on top of the galaxy listed above, so the identification is certain.
Physical Information: IC 4630 is a starburst galaxy whose distorted shape and bright core are almost certainly the result of a relatively recent interaction between or merger of two galaxies. Based on a recessional velocity of 10375 km/sec, a straightforward calculation indicates that it is about 485 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 465 million light years away at the time the light by which we see it was emitted, about 470 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 1.2 by 0.5 arcmin, the galaxy and its extended arms are about 160 thousand light years across.
SDSS image of region near lenticular galaxy IC 4630
Above, a 12 arcmin wide SDSS image centered on IC 4630
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy IC 4630

IC 4631
Recorded (Aug 17, 1900) by
DeLisle Stewart
A nonexistent object in Apus (RA 17 10 59.2, Dec -77 36 00)
Historical Identification: Per Dreyer, IC 4631 (= DeLisle Stewart #436, 1860 RA 16 50 13, NPD 167 24) is "extremely faint, most extremely small, possibly annular, suspected". The position precesses to RA 17 10 59.2, Dec -77 36 00 (whence the position above), but there is nothing there nor anywhere near there, so IC 4631 is almost certainly nonexistent. (Per Corwin, this was probably a plate defect.)
DSS image of region near Stewart's position for the apparently nonexistent IC 4631
Above, a 12 arcmin wide DSS image centered on Stewart's position for IC 4631

IC 4632
Recorded (Aug 24, 1891) by
Guillaume Bigourdan
A lost or nonexistent object in Hercules (RA 16 58 29.9, Dec +22 55 01)
Historical Identification: Per Dreyer, IC 4632 (= Bigourdan #326, 1860 RA 16 52 36, NPD 66 52) is "extremely faint, possibly nebulous". The position precesses to RA 16 58 29.9, Dec +22 55 01 (whence the position above), but there is nothing there or anywhere near there that fits the description, so the object is almost certainly nonexistent. Per Corwin, this was probably one of Bigourdan's numerous "fausses images" (cases where he thought he saw something that wasn't actually there).
SDSS image of region near Bigourdan's position for the apparently nonexistent IC 4632, also showing NGC 6267
Above, a 12 arcmin wide SDSS image centered on Dreyer's position for IC 4632, also showing NGC 6267

IC 4633 (= PGC 59884)
Discovered (Aug 17, 1900) by
DeLisle Stewart
A magnitude 13.0 spiral galaxy (type SA(r)cd?) in Apus (RA 17 13 47.1, Dec -77 32 09)
Historical Identification: Per Dreyer, IC 4633 (= DeLisle Stewart #437, 1860 RA 16 52 55, NPD 167 19) is "very faint, considerably large, considerably brighter middle, possibly spiral". The position precesses to RA 17 13 37.8, Dec -77 30 28, over an arcmin and a half north of the center of the galaxy listed above, but still within its outline, and the description fits perfectly, so the identification is certain.
Physical Information: Apparent size about 4.5 by 3.0 arcmin, but since seen through clouds of glowing gas in our own galaxy that obscure our view of the other galaxy, the numbers are uncertain.
Wikisky cutout of image submitted by Jim Riffle of region near spiral galaxy IC 4633, also showing part of IC 4635
Above, a 12 arcmin wide image centered on IC 4633, also showing part of IC 4635
Below, a 6 arcmin wide image of the galaxy (Image Credits above and below, Wikisky cutout submitted by Jim Riffle)
Wikisky cutout of image submitted by Jim Riffle of spiral galaxy IC 4633

IC 4634
Discovered (1894) by
Williamina Fleming
A magnitude 10.9 planetary nebula in Ophiuchus (RA 17 01 33.6, Dec -21 49 33)
Historical Identification: Per Dreyer, IC 4634 (= Fleming #72, 1860 RA 16 53 13, NPD 111 36) is "planetary, stellar". The position precesses to RA 17 01 35.0, Dec -21 48 37, less than an arcmin northeast of the planetary nebula listed above, and there is nothing else in the field of view that fits the description, so the identification is certain.
Physical Information: Apparent size 19 by 7 arcsec.
DSS image of region near planetary nebula IC 4634
Above, a 12 arcmin wide DSS image centered on IC 4634
Below, a 21 arcsec wide HST image of the planetary nebula (Image Credits ESA/Hubble & NASA)
HST image of planetary nebula IC 4634

IC 4635 (= PGC 59959)
Discovered (Aug 17, 1900) by
DeLisle Stewart
A magnitude 14.0 spiral galaxy (type SAB(s)b?) in Apus (RA 17 15 40.4, Dec -77 29 21)
Historical Identification: Per Dreyer, IC 4635 (= DeLisle Stewart #438, 1860 RA 16 54 49, NPD 167 16) is "very faint, extremely small, considerably brighter middle". The position precesses to RA 17 15 29.9, Dec -77 27 06, a couple of arcmin north of the galaxy listed above; but the error is about the same as for the nearby IC 4633, and although in this case the galaxy is not large enough to overlap the measured position, and its fringes are so faint that Stewart didn't notice them, there is no doubt about the identification.
Physical Information: Apparent size 3.5 by 0.6 arcmin. Like its neighbor, heavily obscured by clouds of gas and dust in our own galaxy.
Wikisky cutout of image submitted by Jim Riffle of region near spiral galaxy IC 4635, also showing part of IC 4633
Above, a 12 arcmin wide image centered on IC 4635, also showing part of IC 4633
(Image Credit above: Wikisky cutout from image submitted by Jim Riffle)
Below, a 4 arcmin wide image of the galaxy (Image credit: superposition of DSS image and Jim Riffle image)
Superposition of DSS image and Wikisky cutout of image submitted by Jim Riffle of spiral galaxy IC 4635

IC 4636
Recorded (Jul 15, 1895) by
Guillaume Bigourdan
A star in Hercules (RA 16 59 06.8, Dec +47 11 43)
Historical Identification: Per Dreyer, IC 4636 (= Bigourdan #327, 1860 RA 16 55 06, NPD 42 36) is "very faint, fainter than (NGC) 6279". The position precesses to RA 16 59 01.2, Dec +47 11 19, but there is nothing obvious there. However, per Corwin, Bigourdan's original notes make it clear that the star listed above, which lies about an arcmin northeast of the IC2 position, must be what Bigourdan recorded, as he noted the presence of a 12th magnitude star 5 seconds of time due east of his #327, and although the "following" star is actually about 7 seconds due east, it makes the identification certain. Corwin adds that IC 4636 is sometimes misidentified as NGC 6279, but it is obvious that it is not that galaxy, as NGC 6279 was what Bigourdan used for his offsets, placing the IC object 2.5 seconds of time to its east and 2.5 minutes of arc to its south. As it happens, that provides an even more accurate position for the object (for those not aware of the process, the calculation involves precessing the modern position of NGC 6279 to the 1900 coordinates used by Bigourdan, adding his offsets, then precessing back to J2000 coordinates to obtain a modern position of RA 16 59 04.0, Dec +47 11 47), less than half an arcmin due west of the star listed as IC 4636, and as already stated the presence of the following star makes the identification certain.
SDSS image of region near the star listed as IC 4636, also showing NGC 6279
Above, a 12 arcmin wide SDSS image centered on IC 4636, also showing NGC 6279

IC 4637
Discovered (1901) by
Williamina Fleming
A magnitude 12.5 planetary nebula in Scorpius (RA 17 05 10.5, Dec -40 53 08)
Historical Identification: Per Dreyer, IC 4637 (= Flaming #95, 1860 RA 16 55 19, NPD 130 40) is "planetary, stellar". The position precesses to RA 17 05 05.2, Dec -40 52 04, about 1.4 arcmin northwest of the planetary nebula listed above, and there is nothing else nearby, so the identification is certain. (Note: The position listed for the nebula is of the bright central star.)
Physical Information: Apparent size 33 by 28 arcsec.
DSS image of region near planetary nebula IC 4637
Above, a 12 arcmin wide DSS image centered on IC 4637 (semi-transparent closeup superimposed on nebula)
Below, a 40 arcsec wide image of the planetary nebula (Image Credit R. Corradi et al)
Image by Corradi et al of planetary nebula IC 4637
Below, a 25 arcsec wide HST image of the center of the planetary nebula
(Image Credit Hubble Legacy Archive, Acknowledgement Judy Schmidt)
HST image of brighter regions of planetary nebula IC 4637, processed by Judy Schmidt, reprocessed by Courtney Seligman

IC 4638 (= PGC 59446)
Discovered (Apr 15, 1899) by
Sherburne Burnham
A magnitude 14.9 elliptical galaxy (type E1?) in Hercules (RA 17 01 13.7, Dec +33 30 47)
Historical Identification: Per Dreyer, IC 4638 (= Burnham, 1860 RA 16 56 04, NPD 56 14) has "no description; 9th magnitude star 2.5 arcmin to southeast". The position precesses to RA 17 01 14.1, Dec +33 33 38, but there is nothing at that position. However, there is a suitable candidate almost exactly 3 arcmin due south, namely the galaxy listed above, and the star to its southeast makes its identification as IC 4638 certain. (Usually, I run across a discussion of this sort of problem by one of the experts in the field, but rather oddly no one seems to have mentioned it. Perhaps because the answer is so obvious, it was just taken for granted.)
Physical Information: Apparent size 0.5 by 0.45 arcmin.
SDSS image of region near elliptical galaxy IC 4638
Above, a 12 arcmin wide SDSS image centered on IC 4638 (Note to self: the spiral to its southwest is PGC 3412105)
Below, a 0.8 arcmin wide SDSS image of the galaxy (photomosaic artifacts are due to 5th magnitude 59 Herculis)
SDSS image of elliptical galaxy IC 4638

IC 4639 (= PGC 1678509)
Discovered (Jul 28, 1903) by
Stephane Javelle
A magnitude 15.5 elliptical galaxy (type E0?) in Hercules (RA 17 02 54.9, Dec +22 55 48)
Historical Identification: Per Dreyer, IC 4639 (= Javelle #1401, 1860 RA 16 57 01, NPD 66 53.5) is "very faint, very small, round". The position precesses to RA 17 02 54.6, Dec +22 54 23, almost one and a half arcmin due south of the galaxy listed above, but there is nothing else nearby and the description fits, so the identification seems certain.
Physical Information: Apparent size 0.6 by 0.6 arcmin.
SDSS image of region near elliptical galaxy IC 4639
Above, a 12 arcmin wide SDSS image centered on IC 4639
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy IC 4639

IC 4640 (= PGC 60209)
Discovered (Aug 17, 1900) by
DeLisle Stewart
A magnitude 13.6 spiral galaxy (type SAB(r)cd?) in Apus (RA 17 23 57.8, Dec -80 03 50)
Historical Identification: Per Dreyer, IC 4640 (= DeLisle Stewart #439, 1860 RA 17 00 00, NPD 169 54) is "very faint, extremely small, considerably brighter middle". The position precesses to RA 17 24 26.7, Dec -80 03 41, about 1.3 arcmin east of the galaxy listed above, and the description fits, so the identification is certain.
Physical Information: Apparent size 1.0 by 0.95 arcmin.
DSS image of region near spiral galaxy IC 4640, also showing IC 4641
Above, a 12 arcmin wide DSS image centered on IC 4640, also showing IC 4641
Below, a 1.2 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4640

IC 4641 (= PGC 60221)
Discovered (Aug 17, 1900) by
DeLisle Stewart
A magnitude 13.1 spiral galaxy (type SA(rs)c?) in Apus (RA 17 24 10.8, Dec -80 08 51)
Historical Identification: Per Dreyer, IC 4641 (= DeLisle Stewart #440, 1860 RA 17 00 03, NPD 169 59) is "extremely faint, very small, brighter middle". The position precesses to RA 17 24 38.6, Dec -80 08 40, about 1.2 arcmin east of the galaxy listed above (essentially the same error as for IC 4640) and the description fits, so the identification is certain.
Physical Information: Apparent size 1.2 by 1.2 arcmin.
DSS image of region near spiral galaxy IC 4641, also showing IC 4640 and IC 4647
Above, a 12 arcmin wide DSS image centered on IC 4641, also showing IC 4640 and 4647
Below, a 1.2 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4641

IC 4642
Discovered (1901) by
Williamina Fleming
A magnitude 13(?) planetary nebula in Ara (RA 17 11 45.3, Dec -55 24 00)
Historical Identification: Per Dreyer, IC 4642 (= Fleming #96, 1860 RA 17 00 12, NPD 145 13) is "planetary, stellar". The position precesses to RA 17 11 45.1, Dec -55 23 56, right on the planetary nebula listed above, so the identification is certain.
Physical Information: Apparent size 26 by 24 arcsec.
DSS image of region near planetary nebula IC 4642
Above, a 12 arcmin wide DSS image centered on IC 4642 (semi-transparent closeup superimposed on nebula)
Below, a 40 arcsec wide closeup of the planetary nebula (Image Credit R. Corradi et al)
Image by Corradi et al of planetary nebula IC 4642

IC 4643 (=
NGC 6301 = PGC 59681)
Discovered (Jun 11, 1788) by William Herschel (and later listed as NGC 6301)
Discovered (Oct 6, 1896) by Johann Palisa (and later listed as IC 4643)
A magnitude 13.4 spiral galaxy (type Scd?) in Hercules (RA 17 08 32.7, Dec +42 20 21)
Historical Identification: Per Dreyer, IC 4643 (= Palisa, 1860 RA 17 04 08, NPD 47 28.9) is "faint, 12th magnitude star involved". The position precesses to RA 17 08 32.0, Dec +42 20 15, right on NGC 6301, so the identification is certain. Since Herschel's position was also good, the duplicate listing appears to be a case where the observer and Dreyer simply failed to notice the prior discovery.
Physical Information: Given the duplicate entry, see NGC 6301 for anything else.

IC 4644 (= PGC 60234)
Discovered (Jul 30, 1900) by
DeLisle Stewart
A magnitude 13.9 spiral galaxy (type Sb? pec) in Apus (RA 17 24 36.9, Dec -73 56 25)
Historical Identification: Per Dreyer, IC 4644 (= DeLisle Stewart #441, 1860 RA 17 06 57, NPD 163 47) is "extremely faint, very small, much extended 135°". The position precesses to RA 17 24 41.8, Dec -73 55 58, only half an arcmin northeast of the galaxy listed above, and the description fits perfectly, so the identification is certain.
Physical Information: Apparent size 1.75 by 0.25 arcmin.
DSS image of region near spiral galaxy IC 4644
Above, a 12 arcmin wide DSS image centered on IC 4644
Below, a 1.8 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4644

IC 4645 (= PGC 59915)
Discovered by
Edward Barnard
A magnitude 15.1 spiral galaxy (type Sd?) in Hercules (RA 17 14 43.1, Dec +43 06 15)
Historical Identification: Per Dreyer, IC 4645 (= Barnard, 1860 RA 17 10 27, NPD 46 45) is "extremely faint, pretty small, 13.5 magnitude star 80 arcsec to east". The position precesses to RA 17 14 45.5, Dec +43 05 24, less than an arcmin southeast of the galaxy listed above, and the star about 80 arcsecs to the east northeast makes the identification certain.
Physical Information: Apparent size 0.6 by 0.45 arcmin.
SDSS image of region near spiral galaxy IC 4645
Above, a 12 arcmin wide SDSS image centered on IC 4645
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy IC 4645

IC 4646 (= PGC 60208)
Discovered (Jul 20, 1903) by
Royal Frost
A magnitude 11.9 spiral galaxy (type SA(rs)bc?) in Ara (RA 17 23 53.4, Dec -60 00 01)
Historical Identification: Per Dreyer, IC 4646 (= Frost #1149, 1860 RA 17 11 33, NPD 149 52) is "faint, pretty large, spiral". The position precesses to RA 17 24 01.1, Dec -60 00 34, just outside the southeastern outline of the galaxy, and the description fits perfectly, so the identification is certain.
Physical Information: Apparent size 2.9 by 1.9 arcmin.
DSS image of region near spiral galaxy IC 4646
Above, a 12 arcmin wide DSS image centered on IC 4646
Below, a 3.0 arcmin wide DSS image of the galaxy
DSS image of spiral galaxy IC 4646
Below, a newer image of the galaxy (Image Credits & © Carnegie-Irvine Galaxy Survey; used by permission)
Carnegie-Irvine Galaxy Survey image of spiral galaxy IC 4646

IC 4647 (= PGC 60280)
Discovered (Aug 17, 1900) by
DeLisle Stewart
A magnitude 13.3 lenticular galaxy (type SAB(s)0?) in Apus (RA 17 26 03.3, Dec -80 11 42)
Historical Identification: Per Dreyer, IC 4647 (= DeLisle Stewart #443, 1860 RA 17 11 40, NPD 170 02) has a "brighter middle". The position precesses to RA 17 36 28.9, Dec -80 09 19, but there is nothing there. nor anywhere near there. However, per Thomson, there is a suitable candidate about 10 minutes of time due west, namely the galaxy listed above. This suggests that perhaps Stewart made in inadvertent error of 10 minutes of time in his right ascension. Supporting this idea is the fact that all the other objects Stewart discovered on Bruce plate 4595 have right ascensions of 17 07.0 or less, so his (1900) RA of 17 18.7 was probably actually 17 08.7. Precessing Stewart's (corrected) position yields a position of RA 17 26 24.9, Dec -80 11 09, which lies only one arcmin northeast of the galaxy listed above, and it perfectly fits the description, having an exceptionally bright core, so the identification seems certain.
Physical Information: Apparent size 1.4 by 0.6 arcmin. Given the exceptional brightness of its nucleus compared to the rest of the galaxy, probably a starburst or Seyfert galaxy.
DSS image of region near lenticular galaxy IC 4647, also showing IC 4641
Above, a 12 arcmin wide DSS image centered on IC 4647, also showing IC 4641
Below, a 1.5 arcmin wide DSS image of IC 4647
DSS image of lenticular galaxy IC 4647

IC 4648
Recorded (Jun 1, 1897) by
Guillaume Bigourdan
A pair of stars in Hercules (RA 17 16 10.0, Dec +43 51 46)
Historical Identification: Per Dreyer, IC 4648 (= Bigourdan #428, 1860 RA 17 11 59, NPD 43 59) is a "cluster, very small, nebulous, very faint double star involved". The position precesses to RA 17 15 59.9, Dec +45 51 40, but there is nothing there or anywhere near there. That is just as well, because if there had been something there, it would probably have been incorrectly identified as IC 4648. Incorrectly, because (based on a note by Corwin) Bigourdan made a two degree error in the Comptes Rendus paper used by Dreyer for the IC2 position. In that paper Bigourdan gives the position of B428 as 1900 RA 17 13 08, Dec +45 58, which corresponds exactly to Dreyer's position. But in Bigourdan's "big list", the position of his comparison star (HD 156583) and his measured offsets yield a position of 1900 RA 17 13 08.5, Dec +43 57 44, which rounds off to exactly the same position as the earlier paper, save for the two degree error in the declination (suggesting a simple transcription error by Bigourdan). Precessing the correct position to modern coordinates yields RA 17 16 09.8, Dec +43 51 10, which is only 0.6 arcmin south of the pair of stars listed above, and Bigourdan's detailed notes about the double star, which place its fainter component due west of its brighter one, make the identification certain. (There is a line of extremely faint stars running east northeast from the western component, which might lead modern observers to wonder if there was more to Bigourdan's observation than just the pair of stars, but the fainter stars were almost certainly beyond his telescope's limit, and Bigourdan often mistook single or double stars for nebulous objects, so the IC designation almost certainly applies only to the double star listed above.)
SDSS image of region near the pair of stars listed as IC 4648, also showing NGC 6336
Above, a 12 arcmin wide SDSS image centered on IC 4648, also showing NGC 6336

IC 4649 (=
IC 1252 = PGC 59962)
Discovered (Sep 5, 1888) by Guillaume Bigourdan (and later listed as IC 1252)
Recorded (Sep 5, 1888) by Guillaume Bigourdan (and later listed as IC 4649)
A magnitude 14.9 spiral galaxy (type Sab?) in Draco (RA 17 15 50.0, Dec +57 22 01)
Historical Identification: Per Dreyer, IC 4649 (= Bigourdan #429, 1860 RA 17 13 28, NPD 32 28) is "extremely faint, pretty small, very diffuse, 12.5 magnitude star 0.5 arcmin to east". The position precesses to RA 17 15 50.9, Dec +57 22 48, only three quarters of an arcmin north of the galaxy listed above, and the star to its east makes the identification certain. Per Corwin, the duplicate entry is due to an oversight in Bigourdan's record-keeping. In a table that lists his observations in order of right ascension, he notes that B429 is the same as IC 1252; but in the table that lists his "novae" in numerical order, he failed to note the duplication, and apparently Dreyer made a similar oversight.
Physical Information: Given the duplicate entry, see IC 1252 for anything else.
Celestial Atlas
(IC 4550 - 4599) ←     IC Objects: IC 4600 - 4649     → (IC 4650 - 4699)