Celestial Atlas
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Page last updated Feb 10, 2013
WORKING: historical / physical data

IC 3600 (= PGC 42161)
Discovered (Mar 23, 1903) by
Max Wolf (4-250)
A 15th-magnitude irregular galaxy (type Irr?) in Coma Berenices (RA 12 37 41.0, Dec +27 07 46)
Based on a recessional velocity of 4635 km/sec, IC 3600 is about 215 million light years away. Given that and its apparent size of 0.6 by 0.4 arcmin, it about 35 thousand light years across.
SDSS image of irregular galaxy IC 3600
Above, a 2.4 arcmin wide closeup of IC 3600
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near irregular galaxy IC 3600

IC 3601
Recorded (May 7, 1904) by
Royal Frost
Probably a nonexistent object in Coma Berenices (RA 12 37 49.5, Dec +15 11 45)
Per Dreyer, IC 3601 (Frost #985, 1860 RA 12 30 47, NPD 74 02) has a "brighter middle, magnitude 15". The position precesses to RA 12 37 49.5, Dec +15 11 45 (whence the position above), but there is nothing there. Per Corwin, Adelaide Ames stated that this was a defect on Frost's plate, and if so IC 3601 represents a nonexistent object. However, he notes that PGC 165275, the brightest galaxy in a small group about 2 arcmin northeast of Frost's position is typical of the objects discovered by Frost, and feels that unless and until an examination of Frost's plate proves that his #985 is a defect, that galaxy should be considered a likely candidate for IC 3601. For that reason it is discussed immediately below, but with the caveat that it may or may not be what Frost recorded.
SDSS image of region near the position of the probably nonexistent IC 3601 (shown by a box), showing lenticular galaxy PGC 165275, which is otherwise the most likely candidate for IC 3601
Above, a 12 arcmin wide region centered on the position of IC 3601, also showing PGC 165275

PGC 165275 (perhaps =
IC 3601)
Probably not an IC object but tentatively proposed as being IC 3601
A 15th-magnitude lenticular galaxy (type S0?) in Coma Berenices (RA 12 37 53.7, Dec +15 13 29)
(See the discussion of IC 3601 for why PGC 165275 might be but probably is not that IC object.) Based on a recessional velocity of 21450 km/sec, a straightforward calculation indicates that PGC 165275 is about 1000 million light years away. However, for objects at such distances we should take into account the Universal expansion during the time it took their light to reach us. Doing that shows that the galaxy was about 920 million light years away at the time the light by which we see it was emitted, about 950 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 0.95 by 0.45 arcmin, the galaxy is about 250 thousand light years across.
SDSS image of lenticular galaxy PGC 165275, which might be but probably is not IC 3601
Above, a 2.4 arcmin wide closeup of PGC 165275; for a wide-field view see IC 3601

IC 3602 (generally thought to be = PGC 42205)
Discovered (May 10, 1904) by
Royal Frost (986)
A 14th-magnitude elliptical galaxy (type dE5?) in Virgo (RA 12 38 06.8, Dec +10 04 55)
Per Dreyer, IC 3602 (Frost #986, 1860 RA 12 31 04, NPD 79 09) is "faint, extremely small, round, a little brighter middle". The position precesses to RA 12 38 09.1, Dec +10 04 45, just east of the galaxy listed above, so the identity seems reasonably certain. However, per Corwin, Frost's original description also included "diameter = 0.1 arcmin", so he feels that PGC 3091291, a galaxy with a much brighter more nearly stellar core a bit to the east of Frost's position is a more suitable candidate for what Frost recorded. NED has followed Corwin's lead (with a caveat about the uncertainty of the identification), but PGC 42205 is otherwise universally accepted as IC 3602, so it is discussed here and PGC 3091291 is discussed immediately below. (A print of Frost's plate would be of great use in clearing up this mess, but there is no mention of one being available.) Apparent size 0.9 by 0.45 arcmin. Listed as a member (VCC 1743) of the Virgo Cluster.
SDSS image of elliptical galaxy PGC 42205, which is generally thought to be IC 3602
Above, a 2.4 arcmin wide closeup of PGC 42205
Below, a 12 arcmin wide region centered on the galaxy, also showing PGC 3091291
SDSS image of elliptical galaxy PGC 42205, which is generally thought to be IC 3602; also shown is spiral galaxy PGC 3091291, which is an equally likely candidate for the IC entry

PGC 3091291 (quite possibly =
IC 3602)
Not definitely an IC object but a likely candidate for IC 3602
A 16th-magnitude spiral galaxy (type Sa?) in Virgo (RA 12 38 18.3, Dec +10 04 22)
(See IC 3602 for a discussion of Corwin's opinion that PGC 3091291 is the correct IC object.) Based on a recessional velocity of 21205 km/sec, a straightforward calculation indicates that PGC 165275 is about 990 million light years away. However, for objects at such distances we should take into account the Universal expansion during the time it took their light to reach us. Doing that shows that the galaxy was about 910 million light years away at the time the light by which we see it was emitted, about 940 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 0.2 arcmin, the galaxy is about 170 thousand light years across.
SDSS image of spiral galaxy PGC 3091291, which is a likely but not certain candidate for IC 3602
Above, a 2.4 arcmin wide closeup of PGC 3091291; for a wider view see IC 3602

IC 3603 (= PGC 3090633)
Discovered (May 7, 1904) by
Royal Frost (987)
A 15th-magnitude lenticular galaxy (type S0?) in Coma Berenices (RA 12 38 16.1, Dec +15 34 13)
Apparent size 0.6 by 0.4 arcmin.
SDSS image of lenticular galaxy IC 3603
Above, a 2.4 arcmin wide closeup of IC 3603
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3603

IC 3604 (= PGC 1397945)
Discovered (May 10, 1904) by
Royal Frost (989)
A 15th-magnitude spiral galaxy (type SBab?) in Virgo (RA 12 38 20.7, Dec +11 43 50)
Apparent size 0.5 by 0.3 arcmin for inner brighter portion, 0.55 by 0.5 arcmin for fainter extensions.
SDSS image of spiral galaxy IC 3604
Above, a 2.4 arcmin wide closeup of IC 3604
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3604

IC 3605 (= PGC 86642)
Discovered (May 7, 1904) by
Royal Frost (988)
A 16th-magnitude spiral galaxy (type Sdm?) in Coma Berenices (RA 12 38 20.9, Dec +19 32 28)
Apparent size 0.85 by 0.55 arcmin.
SDSS image of spiral galaxy IC 3605
Above, a 2.4 arcmin wide closeup of IC 3605
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3605

IC 3606 (= PGC 1412725)
Discovered (May 10, 1904) by
Royal Frost
A 15th-magnitude lenticular galaxy (type S0/a?) in Virgo (RA 12 38 25.1, Dec +12 36 37)
Per Dreyer, IC 3606 (Frost #990, 1860 RA 12 31 23, NPD 76 38) is "faint, very little extended". The position precesses to RA 12 38 26.7, Dec +12 35 46, about an arcmin southeast of the galaxy, but there is nothing else nearby so the identification is reasonably certain. The main caveat is that (presumably due to the compact appearance and bright center of the galaxy) it was (per Corwin) previously identified as a stellar object, rather than as the galaxy it actually is. Apparent size 0.5 by 0.5 arcmin.
SDSS image of lenticular galaxy IC 3606
Above, a 2.4 arcmin wide closeup of IC 3606
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3606

IC 3607 (= PGC 42248)
Discovered (May 10, 1904) by
Royal Frost
A 15th-magnitude elliptical galaxy (type dE6?) in Virgo (RA 12 38 32.1, Dec +10 22 34)
Per Dreyer, IC 3607 (Frost #991, 1860 RA 12 31 28, NPD 78 52) is "faint, extremely small, round". The position precesses to RA 12 38 32.9, Dec +10 21 46, about an arcmin south-southeast of the galaxy, but there is nothing else nearby so the identification is reasonably certain. Corwin notes that the galaxy was incorrectly listed as a star by Carlson, but Ames listed it as a galaxy, as is clearly the case in modern images. Apparent size 0.7 by 0.3 arcmin. Listed as a member (VCC 1762) of the Virgo Cluster.
SDSS image of elliptical galaxy IC 3607
Above, a 2.4 arcmin wide closeup of IC 3607
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3608
SDSS image of region near elliptical galaxy IC 3607, also showing part of spiral galaxy IC 3608

IC 3608 (= PGC 42264)
Discovered (May 10, 1904) by
Royal Frost (993)
A 14th-magnitude spiral galaxy (type Sb?) in Virgo (RA 12 38 37.4, Dec +10 28 33)
Apparent size 3.4 by 0.5 arcmin. Listed as a member (VCC 1768) of the Virgo Cluster.
SDSS image of spiral galaxy IC 3608
Above, a 3.6 arcmin wide closeup of IC 3608
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3607
SDSS image of region near spiral galaxy IC 3608, also showing part of elliptical galaxy IC 3607

IC 3609 (= PGC 42251)
Discovered (May 10, 1904) by
Royal Frost (992)
A 15th-magnitude spiral galaxy (type Sbc pec?) in Coma Berenices (RA 12 38 34.7, Dec +14 21 11)
Per Corwin, this was misidentified in the CGCG and hence in the UZC (per Thomson, as CGCG 99-100 = PGC 42183), but all other lists have it as the correct object. Apparent size 0.5 by 0.4 arcmin. Listed as a member (VCC 1765) of the Virgo Cluster.
SDSS image of spiral galaxy IC 3609
Above, a 2.4 arcmin wide closeup of IC 3609
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3609

PGC 42183 (not =
IC 3609)
Not an IC object but listed here due to the error discussed in this entry
A 14th-magnitude elliptical galaxy (type E2?) in Coma Berenices (RA 12 37 53.2, Dec +14 16 53)
Per (Corwin and) Thomson, this galaxy was misidentified as IC 3609 in the CGCG. (The cause was almost certainly a typographical error, in which the CGCG listing for PGC 42183 (99-100) replaced the one for IC 3609 (99-101).) The error has been universally recognized, so this entry is placed here only as a precaution, in case someone runs across the incorrect CGCG identification and fails to notice the later correction. Apparent size 0.8 by 0.65 arcmin. Listed as a member (VCC 1737) of the Virgo Cluster.
SDSS image of elliptical galaxy PGC 42183, which was inadvertently misidentified as IC 3609 in the CGCG
Above, a 2.4 arcmin wide closeup of PGC 42183
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near elliptical galaxy PGC 42183, which was inadvertently misidentified as IC 3609 in the CGCG
Below, a 12 arcmin wide region centered between PGC 42183 and IC 3609
SDSS image of region between spiral galaxy IC 3609 and elliptical galaxy PGC 42183, which was inadvertently misidentified as IC 3609 in the CGCG

IC 3610 (= PGC 1790902 + a foreground star)
Discovered (Mar 23, 1903) by
Max Wolf (4-252)
A 16th-magnitude spiral galaxy (type S? pec) in Coma Berenices (RA 12 38 47.1, Dec +26 52 22)
plus a 16th-magnitude star at RA 12 38 45.0, Dec +26 52 17, and anything in between
Per Dreyer, IC 3610 (Wolf list IV #252, 1860 RA 12 31 52, NPD 62 21.4) is "extremely faint, small, very irregular figure". The position precesses to RA 12 38 47.5, Dec +26 52 23, right on the galaxy listed above, so the identification is certain. The only complication is that per Corwin, on a print of Wolf's plate the "object" is a faint irregular linear structure, so IC 3610 must be everything from PGC 1790902 to the 16th-magnitude star to its west. Using DSS images Corwin suspected that this was three faint galaxies plus the star, but in the SDSS images below it appears that only the stars to the west of PGC 1790902 are bright enough to have made any significant contribution to Wolf's image. (Data for PGC 1790902) Vr 26505 km/sec (z = 0.088412), apparent size 0.3 by 0.2 arcmin.
SDSS image of IC 3610, which consists of spiral galaxy PGC 1790902, the 16th magnitude star to its west, and as shown by the line, everything in between
Above, a 2.4 arcmin wide closeup of IC 3610
Below, a 12 arcmin wide region centered on PGC 1790902, the main component of IC 3610
SDSS image of IC 3610, which consists of spiral galaxy PGC 1790902, the 16th magnitude star to its west, and everything in between

IC 3611 (= PGC 42307)
Discovered (Nov 19, 1900) by
Arnold Schwassmann (265)
A 13th-magnitude spiral galaxy (type SBm?) in Coma Berenices (RA 12 39 04.1, Dec +13 21 51)
Apparent size 1.5 by 0.8 arcmin. Listed as a member (VCC 1778) of the Virgo Cluster.
SDSS image of spiral galaxy IC 3611
Above, a 2.4 arcmin wide closeup of IC 3611
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3611

IC 3612 (=
IC 3616 = PGC 42309)
Discovered (May 7, 1904) by Royal Frost (and later listed as IC 3616)
Discovered (May 10, 1904) by Royal Frost (and later listed as IC 3612)
A 14th-magnitude lenticular galaxy (type dS0?) in Coma Berenices (RA 12 39 04.6, Dec +14 43 54)
Per Dreyer, IC 3612 (Frost #995, 1860 RA 12 32 05, NPD 74 31) is "bright, very small, round, possibly a planetary". The position precesses to RA 12 39 07.5, Dec +14 42 47, about an arcmin southeast of the only nearby nebular object (the galaxy listed above), so the identification is reasonably certain. (See IC 3616 for a discussion of the duplicate entry.) Apparent size 1.2 by 0.5 arcmin. Listed as a member (VCC 1779) of the Virgo Cluster.
SDSS image of lenticular galaxy IC 3612
Above, a 2.4 arcmin wide closeup of IC 3612
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3612

IC 3613 (= PGC 165284)
Discovered (May 10, 1904) by
Royal Frost
A 16th-magnitude lenticular galaxy (type S0/a?) in Coma Berenices (RA 12 39 04.8, Dec +13 45 31)
Per Dreyer, IC 3613 (Frost #996, 1860 RA 12 32 05, NPD 75 30) is "faint, extremely small, round, a little brighter middle". The position precesses to RA 12 39 08.0, Dec +13 43 47. There is nothing at that location, but there are two galaxies (PGC 165284 and 1439240) a couple of arcmin to the north-northwest and west-northwest, and odds are that one of them is Frost's #996, and hence IC 3613. Per Corwin, the more compact brighter one (listed above) is more likely to be IC 3613, since the larger but fainter one probably has too low a surface brightness to be visible on Frost's plate. Corwin does not refer to having seen a print of the plate, but having had much experience with such prints he is probably correct, and in any event Frost's description seems to better fit the smaller but brighter galaxy, so I have listed it (as has most everyone else) as IC 3613, while giving PGC 1439240 an entry of its own, immediately below. Apparent size 0.6 by 0.15 arcmin.
SDSS image of lenticular galaxy PGC 165284, which is generally believed to be IC 3613, and spiral galaxy PGC 1439240, which is not
Above, a 2.4 arcmin wide closeup of PGC 165284 and 1439240
Below, a 12 arcmin wide region centered on the pair (the bright star is 9th-magnitude HD 109983)
SDSS image of region near lenticular galaxy PGC 165284, which is generally believed to be IC 3613, and spiral galaxy PGC 1439240, which is not

PGC 1439240 (probably not =
IC 3613)
Probably not an IC object but listed here since mentioned in the discussion of IC 3613
A 17th-magnitude spiral galaxy (type SABbc?) in Coma Berenices (RA 12 38 59.6, Dec +13 44 36)
(See IC 3613 for a historical discussion and images.) Apparent size 0.55 by 0.4 arcmin.

IC 3614 (= PGC 169886 + a foreground star)
Recorded (Mar 23, 1903) by
Max Wolf
A 17th-magnitude irregular galaxy (type I?) in Coma Berenices (RA 12 39 01.2, Dec +26 18 12)
plus a 17th-magnitude star at RA 12 39 01.8, Dec +26 17 49
Per Dreyer, IC 3614 (Wolf list IV #253, 1860 RA 12 32 06, NPD 62 55.7) is "extremely faint, pretty small, gradually brighter middle, spiral". The position precesses to RA 12 39 01.7, Dec +26 18 05, in between the galaxy and star listed above. Per Corwin, the star and galaxy form a single elongated image on a print of Wolf's plate, so the identification with the pair is certain. Corwin notes that another galaxy (presumably PGC 1770479, to the southeast of the star) could be mistakenly identified as IC 3614, but states that it is barely visible on the print and is therefore a far less satisfactory candidate for the IC listing; and as far as I can tell no one else has made such a suggestion, so although I have created an entry for PGC 1770479 I have placed it on the appropriate PGC page. The apparent size of PGC 169886 is 0.35 by 0.15 arcmin.
SDSS image of the star and irregular galaxy that comprise IC 3614, also showing spiral galaxy PGC 1770479
Above, a 2.4 arcmin wide closeup of IC 3614, also showing PGC 1770479
Below, a 12 arcmin wide region centered on IC 3614
SDSS image of region near the star and irregular galaxy that comprise IC 3614, also showing spiral galaxy PGC 1770479

IC 3615 (= PGC 42306)
Discovered (May 7, 1904) by
Royal Frost (994)
A 15th-magnitude spiral galaxy (type Sc?) in Coma Berenices (RA 12 39 01.6, Dec +18 12 03)
Apparent size 1.2 by 0.35 arcmin.
SDSS image of spiral galaxy IC 3615
Above, a 2.4 arcmin wide closeup of IC 3615
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3615

IC 3616 (=
IC 3612)
Discovered (May 7, 1904) by Royal Frost (and later listed as IC 3616)
Discovered (May 10, 1904) by Royal Frost (and later listed as IC 3612)
A 14th-magnitude lenticular galaxy (type dS0?) in Coma Berenices (RA 12 39 04.6, Dec +14 43 54)
Per Dreyer, IC 3616 (Frost #997, 1860 RA 12 32 11, NPD 74 30) has a "brighter middle, magnitude 14". The position precesses to RA 12 39 13.4, Dec +14 43 47, about 2 arcmin east of the only nearby nebula, IC 3612 (which see for anything else). Since the description for IC 3616 is a good fit to that galaxy's appearance, IC 3612 and 3616 are almost certainly duplicate listings of the same object. (Corwin states that Frost measured the galaxy on overlapping regions of different plates. Measurements near plate edges tend to be less accurate than those near the center, so the difference of an arcmin or so between the two positions and that of the actual galaxy is not particularly surprising.)

IC 3617 (= PGC 42348)
Discovered (Nov 22, 1899) by
Arnold Schwassmann (70)
A 14th-magnitude irregular galaxy (type Im?) in Virgo (RA 12 39 25.0, Dec +07 57 59)
Apparent size 1.5 by 0.7 arcmin. Listed as a member (VCC 1791) of the Virgo Cluster.
SDSS image of irregular galaxy IC 3617
Above, a 2.4 arcmin wide closeup of IC 3617
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near irregular galaxy IC 3617

IC 3618 (= PGC 42315)
Discovered (Mar 23, 1903) by
Max Wolf (4-254)
A 15th-magnitude lenticular galaxy (type S0?) in Coma Berenices (RA 12 39 17.1, Dec +26 40 42)
Apparent size 0.5 by 0.5 arcmin.
SDSS image of lenticular galaxy IC 3618
Above, a 2.4 arcmin wide closeup of IC 3618
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3618

IC 3619
Recorded (Mar 23, 1903) by
Max Wolf
A pair of 16th-magnitude stars in Coma Berenices (RA 12 39 18.8, Dec +24 08 31)
Per Dreyer, IC 3619 (Wolf list IV #255, 1860 RA 12 32 22, NPD 65 05.4) is "very faint, considerably small, extended 160, brighter middle". The position precesses to RA 12 39 19.0, Dec +24 08 24, between the two stars whose midpoint is given above. The stars' relative position corresponds to a position angle of about 140, and per Corwin their image is not resolved on a print of Wolf's plate, so there is no doubt that he saw the pair as the extended object listed as IC 3619.
SDSS image of region near the pair of stars listed as IC 3619
Above, a 12 arcmin wide region centered on IC 3619

IC 3620 (= PGC 42330)
Discovered (May 1, 1894) by
Isaac Roberts
A 15th-magnitude spiral galaxy (type Sbc?) in Coma Berenices (RA 12 39 17.9, Dec +27 54 30)
Apparent size 0.8 by 0.2 arcmin.
SDSS image of spiral galaxy IC 3620
Above, a 2.4 arcmin wide closeup of IC 3620
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3620

IC 3621 (= PGC 3090634)
Discovered (May 7, 1904) by
Royal Frost (998)
A 15th-magnitude lenticular galaxy (type S0?) in Coma Berenices (RA 12 39 33.5, Dec +15 30 11)
Apparent size 0.7 by 0.7 arcmin.
SDSS image of lenticular galaxy IC 3621
Above, a 2.4 arcmin wide closeup of IC 3621
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3622
SDSS image of region near lenticular galaxy IC 3621, also showing spiral galaxy IC 3622

IC 3622 (= SDSS J123932.48+152555.3)
Discovered (May 7, 1904) by
Royal Frost (999)
A 15th-magnitude spiral galaxy (type S(rs)bc?) in Coma Berenices (RA 12 39 32.4, Dec +15 25 56)
Apparent size 0.7 by 0.6 arcmin.
SDSS image of spiral galaxy IC 3622
Above, a 2.4 arcmin wide closeup of IC 3622
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3621
SDSS image of region near spiral galaxy IC 3622, also showing lenticular galaxy IC 3621

IC 3623 (= PGC 42353)
Discovered (Mar 23, 1903) by
Max Wolf (4-257)
A 14th-magnitude elliptical galaxy (type E2?) in Coma Berenices (RA 12 39 27.6, Dec +27 06 10)
Apparent size 0.9 by 0.7 arcmin.
SDSS image of elliptical galaxy IC 3623
Above, a 2.4 arcmin wide closeup of IC 3623
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near elliptical galaxy IC 3623

IC 3624 (= PGC 1401857)
Discovered (May 10, 1904) by
Royal Frost (1000)
A 15th-magnitiude spiral galaxy (type S0/a?) in Virgo (RA 12 39 34.5, Dec +11 58 55)
Apparent size 0.4 by 0.35 arcmin.
SDSS image of spiral galaxy IC 3624
Above, a 2.4 arcmin wide closeup of IC 3624
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3624

IC 3625 (= PGC 42361 = PGC 42364)
Discovered (May 10, 1904) by
Royal Frost (1001)
A 14th-magnitude spiral galaxy (type Sa(s)?) in Virgo (RA 12 39 33.2, Dec +10 58 04)
Listed as a member (VCC 1799) of the Virgo Cluster, but not really a member, since much further away. Sometimes called IC 3625A, with a slightly different position and characteristics, as if a separate galaxy; but there is only one galaxy there. Based on a recessional velocity of 22430 km/sec, a straightforward calculation indicates that IC 3625 is about 1045 million light years away. However, for objects at such distances we should take into account the Universal expansion during the time it took their light to reach us. Doing that shows that the galaxy was about 960 million light years away at the time the light by which we see it was emitted, about 990 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 200 thousand light years across.
SDSS image of spiral galaxy IC 3625 and elliptical galaxy PGC 42372, which is also known as IC 3625B
Above, a 2.4 arcmin wide closeup of IC 3625 and PGC 42372
Below, a 12 arcmin wide region centered on IC 3625, also showing PGC 42372
SDSS image of region near spiral galaxy IC 3625 and elliptical galaxy PGC 42372, which is also known as IC 3625B

PGC 42372 (= "IC 3625B")
Not an IC object but listed here since sometimes called IC 3625B
A 16th-magnitude elliptical galaxy (type dE0?) in
Virgo (RA 12 39 37.7, Dec +10 58 34)
Apparent size 0.55 by 0.55 arcmin. Listed as a member (VCC 1803) of the Virgo Cluster. Although its designation as IC 3625B might be considered reasonable due to its apparent proximity to IC 3625 (which see for images), the galaxies are otherwise unconnected, as their distances differ by more than a factor of ten.

IC 3626 (= PGC 42355)
Discovered (Mar 23, 1903) by
Max Wolf (4-258)
A 15th-magnitude spiral galaxy (type SBbc?) in Coma Berenices (RA 12 39 31.6, Dec +25 40 36)
Apparent size 0.55 by 0.4 arcmin.
SDSS image of spiral galaxy IC 3626
Above, a 2.4 arcmin wide closeup of IC 3626
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3626

IC 3627 (= PGC 139990)
Discovered (Mar 23, 1903) by
Max Wolf (4-259)
A 16th-magnitude spiral galaxy (type Sa pec?) in Coma Berenices (RA 12 39 31.9, Dec +27 29 52)
Apparent size of main galaxy 0.4 by 0.2 arcmin; with fainter extensions, about 0.55 by 0.3 arcmin.
SDSS image of spiral galaxy IC 3627
Above, a 2.4 arcmin wide closeup of IC 3627
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3627

IC 3628
Recorded (Mar 23, 1903) by
Max Wolf
A 16th-magnitude star in Coma Berenices (RA 12 39 38.8, Dec +26 14 19)
Per Dreyer, IC 3628 (Wolf list IV #260, 1860 RA 12 32 44, NPD 62 59.3) is "extremely faint, small, round". The position precesses to RA 12 39 39.5, Dec +26 14 30, just northeast of the star listed above, and there is nothing else nearby, so the identification is certain.
SDSS image of region near the star listed as IC 3628
Above, a 12 arcmin wide region centered on IC 3628

IC 3629 (= PGC 42387)
Discovered (May 10, 1904) by
Royal Frost (1002)
A 15th-magnitude spiral galaxy (type SABbc?) in Coma Berenices (RA 12 39 46.8, Dec +13 31 59)
Apparent size 1.0 by 0.35 arcmin. Listed as a member (VCC 1808) of the Virgo Cluster.
SDSS image of spiral galaxy IC 3629 and spiral galaxy PGC 42390, which is sometimes called IC 3629A
Above, a 2.4 arcmin wide closeup of IC 3629 and PGC 42390
Below, a 12 arcmin wide region centered on the galaxies, also showing PGC 42381
SDSS image of region near spiral galaxy IC 3629 and spiral galaxy PGC 42390, which is sometimes called IC 3629A; also shown is elliptical galaxy PGC 42381, which is sometimes called IC 3629B

PGC 42390 (= "IC 3629A")
Not an IC object but listed here since sometimes called IC 3629A
A 16th-magnitude spiral galaxy (type Sb?) in
Coma Berenices (RA 12 39 49.2, Dec +13 32 55)
Apparent size 0.7 by 0.15 arcmin. Although an apparent companion of IC 3629 (which see for images), it is much further away, so they are only an optical double.

PGC 42381 (= "IC 3629B")
Not an IC object but listed here since sometimes called IC 3629B
A 16th-magnitude elliptical galaxy (type dE1?) in
Coma Berenices (RA 12 39 42.9, Dec +13 36 23)
Apparent size 0.35 by 0.3 arcmin. Listed as a member (VCC 1806) of the Virgo Cluster.
SDSS image of elliptical galaxy PGC 42381, which is sometimes called IC 3629B
Above, a 2.4 arcmin wide closeup of PGC 42381; for a wider view see IC 3629

IC 3630
Recorded (Mar 23, 1903) by
Max Wolf
A 16th-magnitude star in Coma Berenices (RA 12 39 46.6, Dec +25 25 57)
Per Dreyer, IC 3630 (Wolf list IV #261, 1860 RA 12 32 51, NPD 63 47.9) is "very faint, very small, a little elongated, perhaps a double star". The position precesses to RA 12 39 47.0, Dec +25 25 55, right on the star listed above, so the identification is certain.
SDSS image of region near the star listed as IC 3630
Above, a 12 arcmin wide region centered on IC 3630

IC 3631 (= PGC 42389)
Discovered (May 10, 1904) by
Royal Frost (1003)
A 13th-magnitude lenticular galaxy (type S0/a?) in Virgo (RA 12 39 47.9, Dec +12 58 28)
Apparent size 1.1 by 0.7 arcmin. Listed as a member (VCC 1809) of the Virgo Cluster, but probably not an actual member, as distance estimates place it about twice as far away as the Cluster.
SDSS image of lenticular galaxy IC 3631
Above, a 2.4 arcmin wide closeup of IC 3631
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3631

IC 3632 (= PGC 169888)
Discovered (Mar 23, 1903) by
Max Wolf (4-262)
A 17th-magnitude spiral galaxy (type SBm?) in Coma Berenices (RA 12 39 59.9, Dec +26 40 56)
Apparent size 0.55 by 0.4 arcmin.
SDSS image of spiral galaxy IC 3632
Above, a 2.4 arcmin wide closeup of IC 3632
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3642
SDSS image of region near spiral galaxy IC 3632, also showing spiral galaxy IC 3642

IC 3633 (= PGC 42426)
Discovered (May 10, 1904) by
Royal Frost (1005)
A 14th-magnitude elliptical galaxy (type dE4?) in Virgo (RA 12 40 11.2, Dec +09 53 48)
Apparent size 0.7 by 0.45 arcmin. Listed as a member (VCC 1826) of the Virgo Cluster.
SDSS image of elliptical galaxy IC 3633
Above, a 2.4 arcmin wide closeup of IC 3633
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3634
SDSS image of region near elliptical galaxy IC 3633, also showing elliptical galaxy IC 3634

IC 3634 (= PGC 42425)
Discovered (May 10, 1904) by
Royal Frost (1006)
A 15th-magnitude elliptical galaxy (type dE1?) in Virgo (RA 12 40 11.4, Dec +09 50 50)
Apparent size 0.6 by 0.55 arcmin. Listed as a member (VCC 1825) of the Virgo Cluster.
SDSS image of elliptical galaxy IC 3634
Above, a 2.4 arcmin wide closeup of IC 3634
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3633
SDSS image of region near elliptical galaxy IC 3634, also showing elliptical galaxy IC 3633

IC 3635 (= PGC 42430)
Discovered (May 10, 1904) by
Royal Frost (1004)
A 14th-magnitude lenticular galaxy (type dS0?) in Virgo (RA 12 40 13.3, Dec +12 52 31)
Apparent size 1.2 by 0.7 arcmin. Listed as a member (VCC 1828) of the Virgo Cluster.
SDSS image of lenticular galaxy IC 3635
Above, a 2.4 arcmin wide closeup of IC 3635
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3635

IC 3636
Recorded (Jan 27, 1904) by
Max Wolf (6-1)
A pair of 16th- and 17th-magnitude stars in Coma Berenices (RA 12 40 15.4, Dec +22 04 31)
Per Dreyer, IC 3636 (Wolf list VI #1, 1860 RA 12 33 17, NPD 67 09.4) is "extremely faint, very small, extended 0, brighter middle". The position precesses to RA 12 40 14.9, Dec +22 04 25, almost exactly on the double star listed above, which is extended nearly north and south (in agreement with "extended 0"), so the identification is certain.
SDSS image of region near the pair of stars listed as IC 3636
Above, a 12 arcmin wide region centered on IC 3636

IC 3637 (= PGC 42443)
Discovered (May 10, 1904) by
Royal Frost (1007)
A 14th-magnitude lenticular galaxy (type dS0 pec?) in Coma Berenices (RA 12 40 19.4, Dec +14 42 54)
Apparent size 3.2 by 1.0 arcmin. Listed as a member (VCC 1836) of the Virgo Cluster.
SDSS image of lenticular galaxy IC 3637
Above, a 3.6 arcmin wide closeup of IC 3637
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy IC 3637

IC 3638 (= PGC 42435)
Discovered (May 10, 1904) by
Royal Frost (1008)
A 14th-magnitude spiral galaxy (type Sbc(r)?) in Virgo (RA 12 40 16.6, Dec +10 31 07)
Apparent size 0.75 by 0.7 arcmin. Listed as a member (VCC 1830) of the Virgo Cluster, but not actually a member, since much further away.
SDSS image of spiral galaxy IC 3638
Above, a 2.4 arcmin wide closeup of IC 3638
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3638

IC 3639 (= PGC 42504)
Discovered (Feb 15, 1898) by
Lewis Swift (XI-140)
A 12th-magnitude spiral galaxy (type SB(rs)bc?) in Centaurus (RA 12 40 52.9, Dec -36 45 21)
Apparent size 1.1 by 0.9 arcmin. Listed as a Seyfert galaxy (type Sy 2). NED lists two recessional velocities for IC 3639: 3275 5 km/sec and 3745 100 km/sec. Based on those values, the galaxy is perhaps 150 to 175 million light years away. Given that, its apparent size of 1.1 by 0.9 arcmin corresponds to about 50 to 55 thousand light years.
DSS image of spiral galaxy IC 3639
Above, a 2.4 arcmin wide closeup of IC 3639
Below, a detailed view of the galaxy's central regions (Image Credits: Hubble Legacy Archive)
'Raw' HST closeup of spiral galaxy IC 3639 (partial processing by Courtney Seligman)
Below, a 12 arcmin wide region centered on the galaxy
DSS image of region near spiral galaxy IC 3639

IC 3640 (= PGC 169892)
Discovered (Mar 23, 1903) by
Max Wolf
A 15th-magnitude spiral galaxy (type Sab?) in Coma Berenices (RA 12 40 25.1, Dec +26 31 28)
Per Dreyer, IC 3640 and 3641 shared the same entry: (Wolf list IV #263, 1860 RA 12 33 30, NPD 62 42.3) is "faint, small, bright middle, spiral; very faint round nebula 30 arcsec to northwest". In other words, Wolf's observation was of two nebulae, one of which (the western one) was listed as IC 3640 and the other (the eastern one) as IC 3641. The position precesses to RA 12 40 25.0, Dec +26 31 32, right on the brighter western galaxy, so the identification of the pair is certain (though Corwin points out that since the eastern galaxy is the fainter, "to northwest" must have been reversed, and should have read "to southeast"). Apparent size 0.45 by 0.2 arcmin.
SDSS image of spiral galaxies IC 3640 and 3641
Above, a 2.4 arcmin wide closeup of IC 3640 and 3641
Below, a 12 arcmin wide region centered on the pair, also showing IC 3644, IC 3645, 3646 and 3650
SDSS image of region near spiral galaxies IC 3640 and 3641, also showing spiral galaxies IC 3644 and 3646, the star listed as IC 3645, and the pair of stars listed as IC 3650

IC 3641 (= PGC 2800811)
Discovered (Mar 23, 1903) by
Max Wolf
A 17th-magnitude spiral galaxy (type Scd?) in Coma Berenices (RA 12 40 26.8, Dec +26 31 18)
Per Dreyer, IC 3640 (which see for images) and 3641 shared the same entry: (Wolf list IV #263, 1860 RA 12 33 30, NPD 62 42.3) is "faint, small, bright middle, spiral; very faint round nebula 30 arcsec to northwest". In other words, Wolf's observation was of two nebulae, one of which (the western one) was listed as IC 3640 and the other (the eastern one) as IC 3641. The position precesses to RA 12 40 25.0, Dec +26 31 32, right on the brighter western galaxy, so the identification of the pair is certain (though Corwin points out that since the eastern galaxy is the fainter, "to northwest" must have been reversed, and should have read "to southeast"). Apparent size 0.4 by 0.1 arcmin.

IC 3642 (= PGC 1786619)
Discovered (Mar 23, 1903) by
Max Wolf (4-264)
A 15th-magnitude spiral galaxy (type Sa?) in Coma Berenices (RA 12 40 25.9, Dec +26 43 54)
Apparent size 0.35 by 0.35 arcmin.
SDSS image of spiral galaxy IC 3642
Above, a 2.4 arcmin wide closeup of IC 3642
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 3632 and 3651
SDSS image of region near spiral galaxy IC 3642, also showing spiral galaxy IC 3632 and lenticular galaxy IC 3651

IC 3643 (= PGC 1408965)
Discovered (May 10, 1904) by
Royal Frost (1009)
A 15th-magnitude spiral galaxy (type SB(rs)b?) in Virgo (RA 12 40 40.9, Dec +12 24 24)
Apparent size 0.45 by 0.25 arcmin.
SDSS image of spiral galaxy IC 3643
Above, a 2.4 arcmin wide closeup of IC 3643
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3643

IC 3644 (= PGC 42479)
Discovered (Mar 23, 1903) by
Max Wolf (4-265)
A 15th-magnitude spiral galaxy (type Sb?) in Coma Berenices (RA 12 40 36.1, Dec +26 30 17)
Apparent size 0.9 by 0.2 arcmin. (Note: LEDA incorrectly lists this as IC 3645, and vice-versa.)
SDSS image of spiral galaxies IC 3644 and 3646
Above, a 2.4 arcmin wide closeup of IC 3644 and 3646
Below, a 12 arcmin wide region centered on the pair, also showing IC 3640, 3641, 3645 and 3650
SDSS image of region near spiral galaxies IC 3644 and 3646, also showing spiral galaxies IC 3640 and 3641, the star listed as IC 3645, and the pair of stars listed as IC 3650

IC 3645
Recorded (Mar 23, 1903) by
Max Wolf
A 15th-magnitude star in Coma Berenices (RA 12 40 37.6, Dec +26 32 29)
Per Dreyer, IC 3645 (Wolf list IV #266, 1860 RA 12 33 43, NPD 62 41.4) is "faint, very small, round, brighter middle". The position precesses to RA 12 40 37.9, Dec +26 32 26, right on the star listed above, so the identification is certain (despite this, LEDA incorrectly identifies IC 3644 as IC 3645, and vice-versa). In the same field of view as IC 3644, which see for an image.

IC 3646 (= PGC 42478)
Discovered (Mar 23, 1903) by
Max Wolf (4-267)
A 15th-magnitude spiral galaxy (type Sb pec?) in Coma Berenices (RA 12 40 38.6, Dec +26 31 32)
Apparent size 0.6 by 0.25 arcmin. (See IC 3644 for images.)

IC 3647 (= PGC 42503)
Discovered (May 10, 1904) by
Royal Frost (1010)
A 14th-magnitude elliptical galaxy (type dE4?) in Virgo (RA 12 40 53.0, Dec +10 28 35)
Apparent size 1.6 by 0.9 arcmin. Listed as a member (VCC 1857) of the Virgo Cluster.
SDSS image of elliptical galaxy IC 3647
Above, a 2.4 arcmin wide closeup of IC 3647
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near elliptical galaxy IC 3647

IC 3648
Recorded (Nov 18, 1900) by
Arnold Schwassmann
A 15th-magnitude star in Virgo (RA 12 40 52.2, Dc +12 59 04)
Per Dreyer, IC 3648 (Schwassmann #266, 1860 RA 12 33 50, NPD 76 14.7) is "extremely faint, small, very questionable". The position precesses to RA 12 40 53.1, Dec +12 59 09, just east of the star listed above, so the identification is certain (especially given its "very questionable" nebular nature).
SDSS image of region near the star listed as IC 3648
Above, a 12 arcmin wide region centered on IC 3648

IC 3649 (= PGC 1642864)
Discovered (Jan 27, 1904) by
Max Wolf (6-2)
A 16th-magnitude spiral galaxy (type S?) in Coma Berenices (RA 12 40 49.7, Dec +21 06 16)
Apparent size 0.3 by 0.2 arcmin.
SDSS image of spiral galaxy IC 3649
Above, a 2.4 arcmin wide closeup of IC 3649
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy IC 3649
Celestial Atlas
(IC 3550 - 3599) ←     IC Objects: IC 3600 - 3649     → (IC 3650 - 3699)