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.

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.

(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.

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.

(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.

Apparent size 0.6 by 0.4 arcmin.

Apparent size 0.5 by 0.3 arcmin for inner brighter portion, 0.55 by 0.5 arcmin for fainter extensions.

Apparent size 0.85 by 0.55 arcmin.

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.

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.

Apparent size 3.4 by 0.5 arcmin. Listed as a member (VCC 1768) of the Virgo Cluster.

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.

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.

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.

Apparent size 1.5 by 0.8 arcmin. Listed as a member (VCC 1778) of the Virgo Cluster.

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.

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.

(See IC 3613 for a historical discussion and images.) Apparent size 0.55 by 0.4 arcmin.

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.

Apparent size 1.2 by 0.35 arcmin.

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.)

Apparent size 1.5 by 0.7 arcmin. Listed as a member (VCC 1791) of the Virgo Cluster.

Apparent size 0.5 by 0.5 arcmin.

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.

Apparent size 0.8 by 0.2 arcmin.

Apparent size 0.7 by 0.7 arcmin.

Apparent size 0.7 by 0.6 arcmin.

Apparent size 0.9 by 0.7 arcmin.

Apparent size 0.4 by 0.35 arcmin.

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.

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.

Apparent size 0.55 by 0.4 arcmin.

Apparent size of main galaxy 0.4 by 0.2 arcmin; with fainter extensions, about 0.55 by 0.3 arcmin.

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.

Apparent size 1.0 by 0.35 arcmin. Listed as a member (VCC 1808) of the Virgo Cluster.

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.

Apparent size 0.35 by 0.3 arcmin. Listed as a member (VCC 1806) of the Virgo Cluster.

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.

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.

Apparent size 0.55 by 0.4 arcmin.

Apparent size 0.7 by 0.45 arcmin. Listed as a member (VCC 1826) of the Virgo Cluster.

Apparent size 0.6 by 0.55 arcmin. Listed as a member (VCC 1825) of the Virgo Cluster.

Apparent size 1.2 by 0.7 arcmin. Listed as a member (VCC 1828) of the Virgo Cluster.

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.

Apparent size 3.2 by 1.0 arcmin. Listed as a member (VCC 1836) of the Virgo Cluster.

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.

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.

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.

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.

Apparent size 0.35 by 0.35 arcmin.

Apparent size 0.45 by 0.25 arcmin.

Apparent size 0.9 by 0.2 arcmin. (Note: LEDA incorrectly lists this as IC 3645, and vice-versa.)

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.

Apparent size 0.6 by 0.25 arcmin. (See IC 3644 for images.)

Apparent size 1.6 by 0.9 arcmin. Listed as a member (VCC 1857) of the Virgo Cluster.

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).

Apparent size 0.3 by 0.2 arcmin.