New General Catalog Objects: NGC 3650 (original) (raw)

QuickLinks:
3650, 3651, 3652, 3653, 3654, 3655, 3656, 3657, 3658, 3659, 3660, 3661, 3662, 3663, 3664, 3665, 3666,
3667, 3668, 3669, 3670, 3671, 3672, 3673, 3674, 3675, 3676, 3677, 3678, 3679, 3680, 3681, 3682, 3683,
3684, 3685, 3686, 3687, 3688, 3689, 3690, 3691, 3692, 3693, 3694, 3695, 3696, 3697, 3698, 3699

Page last updated Feb 4, 2020
Updated entries for NGC 3697 and its companions
All done save where noted (but still need to take care of all PGC backlinks)
WORKING 3679, 3684, 3685, 3686, 3688, 3696, 3698: dealing with various serious problems

NGC 3650 (= PGC 34913)
Discovered (May 5, 1886) by Lewis Swift
A magnitude 13.9 spiral galaxy (type SAb?) in Leo (RA 11 22 35.4, Dec +20 42 15)

Historical Identification: Per Dreyer, NGC 3650 (Swift list III (#60), 1860 RA 11 14 56, NPD 68 31.9) is "extremely faint, small, round, between 2 stars". The position precesses to RA 11 22 19.2, Dec +20 42 05, about 3.7 arcmin due west of the galaxy listed above, but given the very wide field of view used by Swift that isn't a terribly bad position for him, the description fits (including the mention of the nearby stars), and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 4385 km/sec, NGC 3650 is about 205 million light years away. Given that and its apparent size of about 1.8 by 0.3 arcmin, is is 105 to 110 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3650
Below, a 1.8 arcmin wide SDSS image of the galaxy

NGC 3651 (= PGC 34898 = HCG 51A), a member of Hickson Compact Group 51
Discovered (Apr 10, 1785) by William Herschel
Also observed (Feb 19, 1827) by John Herschel
A magnitude 13.6 elliptical galaxy (type E1? pec) in Leo (RA 11 22 26.3, Dec +24 17 57)

Historical Identification: Per Dreyer, NGC 3651 (= GC 2392 = JH 870 = WH III 335, 1860 RA 11 15 01, NPD 64 56.1) is "considerably faint, very small, round, brighter middle, northwest of 2", the other being NGC 3653. The position precesses to RA 11 22 26.7, Dec +24 17 53, within the southeastern outline of the galaxy listed above, the description fits (including the position relative to its apparent companion) and there is nothing comparable nearby (save for the aforementioned companion), so the identification is certain.
Discovery Notes: Some references treat PGC 34899 as part of NGC 3651, but it is far too faint for Herschel to have noticed, so it is merely a companion (and in fact, one of several companions) of the NGC object.
Physical Information: Based on a recessional velocity of 7625 km/sec, a straightforward calculation indicates that NGC 3651 is about 355 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 345 million light years away at the time the light by which we see it was emitted, about 350 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 about 1.1 by 0.95 arcmin, the galaxy is about 110 thousand light years across. NGC 3651 is a member of Hickson Compact Group 51, many members of which are interacting with the others, and as a result stellar material torn from one galaxy or another fills most of the space between the southeastern and northwestern members of the Group. The portion of that material nearest NGC 3651 covers an angle of about 2.3 by 1.6 arcmin, corresponding to about 230 thousand light years.

Above, a 12 arcmin wide SDSS image centered on NGC 3651, also showing NGC 3653 and IC 2759
Below, a 1.2 arcmin wide SDSS image of the galaxy, also showing PGC 34899 and PGC 34901

Below, a 6 arcmin wide labeled SDSS image of Hickson Compact Group 51

NGC 3652 (= PGC 34917)
Discovered (Mar 23, 1789) by William Herschel
Also observed (Apr 28, 1827) by John Herschel
A magnitude 12.2 spiral galaxy (type SBbc? pec) in Ursa Major (RA 11 22 39.0, Dec +37 45 54)

Historical Identification: Per Dreyer, NGC 3652 (= GC 2394 = JH 871 = WH II 775, 1860 RA 11 15 03, NPD 51 28.2) is "pretty faint, considerably large, a little extended, very gradually brighter middle". The position precesses to RA 11 22 39.5, Dec +37 45 47, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1995 km/sec, NGC 3652 is 90 to 95 million light years away, in good agreement with redshift-independent distance estimates of 75 to 135 million light years. Given that and its apparent size of about 2.8 by 0.75 arcmin (including the fainter northern and southern extensions), it is about 75 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3652
Below, a 3.2 arcmin wide SDSS image of the galaxy

NGC 3653 (= PGC 34905 = HCG 51C), a member of Hickson Compact Group 51
Discovered (Apr 10, 1785) by William Herschel
Also observed (Feb 19, 1827) by John Herschel
A magnitude 13.7 lenticular galaxy (type S0/a?) in Leo (RA 11 22 30.1, Dec +24 16 45)

Historical Identification: Per Dreyer, NGC 3653 (= GC 2393 = JH 872 = WH III 336, 1860 RA 11 15 06, NPD 64 57.8) is "very faint, very small, southeastern of 2", the other being NGC 3651. The position precesses to RA 11 22 31.6, Dec +24 16 11, just under 0.7 arcmin southeast of the galaxy listed above, the description fits (including the position relative to its apparent companion), and there is nothing comparable nearby (save for the aforementioned companion), so the identification is certain.
Physical Information: Based on a recessional velocity of 8900 km/sec, a straightforward calculation indicates that NGC 3653 is about 415 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 400 million light years away at the time the light by which we see it was emitted, over 405 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 about 1.1 by 0.55 arcmin, the galaxy is 125 to 130 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3653, also showing NGC 3651 and IC 2759
Below, a 1.3 arcmin wide SDSS image of the galaxy

Below, a 6 arcmin wide labeled SDSS image of Hickson Compact Group 51

NGC 3654 (= PGC 35025)
Discovered (Apr 6, 1793) by William Herschel
A magnitude 12.8 spiral galaxy (type SBbc? pec) in Ursa Major (RA 11 24 10.9, Dec +69 24 48)

Historical Identification: Per Dreyer, NGC 3654 (= GC 2395 = WH II 880, 1860 RA 11 15 30, NPD 19 48.5) is "faint, small, a little extended 15��". The position precesses to RA 11 24 09.0, Dec +69 25 27, about 0.6 arcmin north northwest of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1570 km/sec, NGC 3654 is 70 to 75 million light years away, in fair agreement with redshift-independent distance estimates of 85 to 140 million light years. Given that and its apparent size of about 1.3 by 0.65 arcmin, it is 25 to 30 thousand light years across.

Above, a 12 arcmin wide DSS image centered on NGC 3654
Below, a 1.4 arcmin wide DSS image of the galaxy

NGC 3655 (= PGC 34935)
Discovered (Dec 30, 1783) by William Herschel
Also observed (Apr 21, 1832) by John Herschel
A magnitude 11.7 spiral galaxy (type SA(s)c?) in Leo (RA 11 22 54.6, Dec +16 35 24)

Historical Identification: Per Dreyer, NGC 3655 (= GC 2396 = JH 873 = WH I 5, 1860 RA 11 15 35, NPD 72 38.6) is "pretty bright, pretty small, irregularly round, brighter middle, mottled but not resolved". The position precesses to RA 11 22 55.4, Dec +16 35 22, within the eastern outline of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1475 km/sec, NGC 3655 is 65 to 70 million light years away, in good agreement with redshift-independent distance estimates of 45 to 125 million light years. Given that and its apparent size of about 1.5 by 0.95 arcmin, it is about 30 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3655
Below, a 1.8 arcmin wide SDSS image of the galaxy

NGC 3656 (= PGC 34989 = PGC 2452392 = Arp 155)
Discovered (Apr 14, 1789) by William Herschel
Also observed (Feb 10, 1831) by John Herschel
A magnitude 12.3 lenticular galaxy (type (R)I0/a? pec) in Ursa Major (RA 11 23 38.6, Dec +53 50 32)

Historical Identification: Per Dreyer, NGC 3656 (= GC 2397 = JH 874 = WH II 782, 1860 RA 11 15 41, NPD 35 23.4) is "pretty bright, small, round, very gradually brighter middle, 12th magnitude star to west". The position precesses to RA 11 23 36.8, Dec +53 50 33, within the western outline of the galaxy listed above, the description fits (including the 13th magnitude star on its western rim) and there is nothing comparable nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2890 km/sec, NGC 3656 is about 135 million light years away, in good agreement with a single redshift-independent distance estimate of 135 to 140 million light years. Given that and its apparent size of about 1.85 by 1.65 arcmin, it is 70 to 75 thousand light years across. NGC 3656 is used by the Arp Atlas as an example of disturbed galaxies with interior absorption. It is thought that the strange apparent of the galaxy is due to one or two recent mergers with other galaxies ("recent", in astronomy, meaning as much as several hundred million years ago).

Above, a 12 arcmin wide SDSS image centered on NGC 3656
Below, a 2.4 arcmin wide SDSS image of the galaxy

NGC 3657 (= PGC 35002)
Discovered (Apr 12, 1789) by William Herschel
Also observed (Feb 17, 1831) by John Herschel
A magnitude 12.4 lenticular galaxy (type (R)S0(rs)a? pec) in Ursa Major (RA 11 23 55.6, Dec +52 55 16)

Historical Identification: Per Dreyer, NGC 3657 (= GC 2398 = JH 876 = WH III 768, 1860 RA 11 15 59, NPD 36 18.7) is "considerably faint, very small, round, stellar". The position precesses to RA 11 23 52.9, Dec +52 55 15, only 0.4 arcmin west of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1215 km/sec, NGC 3657 is about 55 to 60 million light years away, in fair agreement with a single redshift-independent distance estimate of 70 to 75 million light years. Given that and its apparent size of about 0.8 by 0.65 arcmin, it is 13 to 17 thousand light years across. "Stretched" images (particularly inverted images showing the sky in white and the galaxy in black) show extremely faint vestiges of spiral arms in the outer ring, so NGC 3657 is probably the result of the merger of two galaxies which is now in the last stages of becoming a more "normal" lenticular galaxy.

Above, a 12 arcmin wide SDSS image centered on NGC 3657
Below, a 1 arcmin wide SDSS image of the galaxy

NGC 3658 (= PGC 35003)
Discovered (Mar 23, 1789) by William Herschel
Also observed (Apr 28, 1827) by John Herschel
A magnitude 12.2 lenticular galaxy (type (R)SAB0?) in Ursa Major (RA 11 23 58.3, Dec +38 33 44)

Historical Identification: Per Dreyer, NGC 3658 (= GC 2400 = JH 877 = WH IV 59, 1860 RA 11 16 22, NPD 50 41.3) is "faint, small, round, suddenly very much brighter middle and nucleus = 14th magnitude star". The position precesses to RA 11 23 58.4, Dec +38 32 38, just over 1 arcmin south of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2040 km/sec, NGC 3658 is about 95 million light years away. Given that and its apparent size of about 2.1 by 1.95 arcmin, it is 55 to 60 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3658
Below, a 2.4 arcmin wide SDSS image of the galaxy

NGC 3659 (= PGC 34995)
Discovered (Mar 14, 1784) by William Herschel
Also observed (Mar 25, 1827) by John Herschel
A magnitude 12.2 spiral galaxy (type SB(s)d?) in Leo (RA 11 23 45.3, Dec +17 49 05)

Historical Identification: Per Dreyer, NGC 3659 (= GC 2399 = JH 878 = WH II 53, 1860 RA 11 16 24, NPD 71 25.0) is "considerably faint, small, a little extended, mottled but not resolved". The position precesses to RA 11 23 44.9, Dec +17 48 56, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1285 km/sec, NGC 3659 is about 60 million light years away, in reasonable agreement with redshift-independent distance estimates of 65 to 90 million light years. Given that and its apparent size of about 2.0 by 0.7 arcmin, it is about 35 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3659
Below, a 2.1 arcmin wide SDSS image of the galaxy

NGC 3660 (= PGC 34980)
Discovered (Feb 22, 1787) by William Herschel
A magnitude 11.9 spiral galaxy (type SB(rs)bc?) in Crater (RA 11 23 32.3, Dec -08 39 31)

Historical Identification: Per Dreyer, NGC 3660 (= GC 2401 = WH II 635, 1860 RA 11 16 27, NPD 97 52.7) is "faint, pretty large, irregularly round, very gradually brighter middle". The position precesses to RA 11 23 32.6, Dec -08 38 46, within the northern outline out the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 3685 km/sec, NGC 3660 is 170 to 175 million light years away, in fair agreement with redshift-independent distance estimates of 195 to 210 million light years. Given that and its apparent size of about 3.0 by 2.1 arcmin, it is about 150 thousand light years across. NGC 3660 is listed as a starburst galaxy and as a Seyfert galaxy (type Sy 2).

Above, a 12 arcmin wide SDSS image centered on NGC 3660
Below, a 3.6 arcmin wide SDSS image of the galaxy

NGC 3661 (= PGC 34986 = IC 689)
Discovered (Mar 27, 1786) by William Herschel (and later listed as NGC 3661)
Also observed (Mar 16, 1836) by John Herschel (and later listed as NGC 3661)
Discovered (Jan 1, 1889) by Ormond Stone (and later listed as IC 689)
A magnitude 13.1 lenticular galaxy (type SA0(r)a?) in Crater (RA 11 23 38.4, Dec -13 49 52)

Historical Identification: Per Dreyer, NGC 3661 (= GC 2402 = JH 3339 = WH III 530, 1860 RA 11 16 37, NPD 103 03.5) is "faint, small, round, stellar, preceding (western) of 2", the other being NGC 3667. The position precesses to RA 11 23 39.5, Dec -13 49 34, barely outside the northeastern rim of the galaxy listed above, the description is a reasonable fit and there is nothing else nearby so the identification is certain.
Discovery Notes: See IC 689 for a discussion of the duplicate listing.
Physical Information: Based on a recessional velocity of 6690 km/sec, NGC 3661 is 310 to 315 million light years away. Given that and its apparent size of about 1.5 by 0.6 arcmin, it is 135 to 140 thousand light years across.

Above, a 12 arcmin wide DSS image centered on NGC 3661
Below, a 1.8 arcmin wide DSS image of the galaxy

NGC 3662 (= PGC 34996)
Discovered (Feb 22, 1784) by William Herschel
Also observed (Apr 13, 1828) by John Herschel
A magnitude 12.9 spiral galaxy (type SAB(r)bc? pec) in Leo (RA 11 23 46.5, Dec -01 06 18)

Historical Identification: Per Dreyer, NGC 3662 (= GC 2403 = JH 879 = WH IV 4, 1860 RA 11 16 40, NPD 90 19.9) is "very faint, small, attached to 13th magnitude star". The position precesses to RA 11 23 49.9, Dec -01 05 58, about 0.9 arcmin east northeast of the galaxy listed above, the description is a perfect fit (including the "attached" star) and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 5580 km/sec, NGC 3662 is about 260 million light years away, in reasonable agreement with redshift-independent distance estimates of 260 to 310 million light years. Given that and its apparent size of about 1.45 by 0.85 arcmin, it is about 110 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3662
Below, a 1.8 arcmin wide SDSS image of the galaxy

NGC 3663 (= PGC 35006)
Discovered (1880) by Andrew Common
A magnitude 12.3 spiral galaxy (type SA(rs)c? pec) in Crater (RA 11 24 00.0, Dec -12 17 47)

Historical Identification: Per Dreyer, NGC 3663 (Common (#16), 1860 RA 11 16 49, NPD 101 17) is "extremely faint, fan shaped, star close". The position precesses to RA 11 23 52.6, Dec -12 03 04, but there is nothing there save for a completely stellar field. However, all Common's positions were by his own admission merely approximate, and it appears that in this case he accidentally misread the setting circle for declination by 15 arcmin (those who have used manual setting circles are all too familiar with errors of 5 or 15 arcmin in pointing or reading the positions of telescopes), and the actual NPD should have been 101 32, as the only nebula that he could have seen within a very large region near his original position is close to the provisionally corrected position (which precesses to RA 11 23 52.5, Dec -12 18 04). That galaxy, listed above, lies only 1.8 arcmin nearly due east of the corrected position, the description fits and as already noted there is nothing else nearby so the identification is as certain as possible under the circumstances.
Discovery Notes: The modern identification appears to be due to the 1973 RNGC by Sulentic and Tifft, which is full of mistakes, as they merely looked for the closest object to the NGC positions, regardless of whether any other factors might have helped choose a better candidate. However, given the discussion above, in this case they almost certainly chose the correct object, if only because there is nothing else they could have chosen.
Physical Information: Based on a recessional velocity of 5020 km/sec, NGC 3663 is 230 to 235 million light years away, in good agreement with redshift-independent distance estimates of 160 to 275 million light years. Given that and its apparent size of about 1.9 by 1.7 arcmin (counting its fainter northern extension), it is about 130 thousand light years across. Given its exceptionally bright core it may be a Seyfert galaxy.

Above, a 12 arcmin wide DSS image centered on NGC 3663
Below, a 2.4 arcmin wide DSS image of the galaxy

Below, a 2.2 arcmin wide image of the galaxy (Image Credit Gil Esquerdo, SAO Arizona)

NGC 3664 (= PGC 35041 = Arp 5)
Discovered (Mar 14, 1879) by Wilhelm Tempel
A magnitude 12.8 spiral galaxy (type SB(s)m? pec) in Leo (RA 11 24 25.2, Dec +03 19 43)

Historical Identification: Per Dreyer, NGC 3664 (Tempel list II, 1860 RA 11 17 06, NPD 85 55.2) is "pretty faint, binuclear". The position precesses to RA 11 24 18.3, Dec +03 18 43, about 1.7 arcmin west southwest of the brightest part of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1380 km/sec, NGC 3664 is about 65 million light years away, in fair agreement with a redshift-independent distance estimate of 80 million light years. Given that and its apparent size of 2.0 by 1.9 arcmin, it is 35 to 40 thousand light years across. The galaxy is by the Arp Atlas as an example of spiral galaxies of low surface brightness. NGC 3664 is probably gravitationally interacting with PGC 35042.

Above, a 12 arcmin wide SDSS image centered on NGC 3664
Below, a 2.2 arcmin wide SDSS image of the galaxy

Below, a 1.8 arcmin wide image of most of the galaxy (Image Credit Hubble Legacy Archive)

Below, a 12 arcmin wide region centered between NGC 3664 and its probable companion, PGC 35042

PGC 35042 (= "NGC 3664A")
Not an NGC object, but listed here since sometimes called NGC 3664A
A magnitude 14.5 spiral galaxy (type (R)SB(s)m? pec) in Leo (RA 11 24 25.0, Dec +03 13 16)

Physical Information: Based on a recessional velocity of 1325 km/sec, PGC 35042 is 60 to 65 million light years away, or essentially the same distance as NGC 3664. That and its apparent proximity to the NGC object has led to its sometimes being called NGC 3664A. If the two galaxies really are at the same distance they could be separated by less than 120 thousand light years, in which case PGC 35042 may be a gravitationally bound companion of NGC 3664, and their peculiar appearance may be due to gravitational interaction (in fact, it is generally assumed that they are an interacting pair). Given its estimated distance and apparent size of about 1.0 by 0.9 arcmin (including its outer extensions), PGC 35042 is 15 to 20 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on PGC 35042, also showing NGC 3664 (which see)
Below, a 1.2 arcmin wide SDSS image of the galaxy

NGC 3665 (= PGC 35064)
Discovered (Mar 23, 1789) by William Herschel
Also observed (Mar 18, 1831) by John Herschel
A magnitude 10.8 lenticular galaxy (type SA0(s)a?) in Ursa Major (RA 11 24 43.7, Dec +38 45 46)

Historical Identification: Per Dreyer, NGC 3665 (= GC 2404 = JH 881 = WH I 219, 1860 RA 11 17 09, NPD 50 28.1) is "considerably bright, considerably large, irregularly round, pretty gradually much brighter middle". The position precesses to RA 11 24 45.1, Dec +38 45 49, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2070 km/sec, NGC 3665 is 95 to 100 million light years away, in good agreement with redshift-independent distance estimates of 60 to 115 million light years. Given that and its apparent size of about 4.3 by 3.1 arcmin, it is about 120 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3665
Below, a 4.8 arcmin wide SDSS image of the galaxy

NGC 3666 (= PGC 35043)
Discovered (Mar 15, 1784) by William Herschel
Also observed (Mar 23, 1830) by John Herschel
A magnitude 12.3 spiral galaxy (type SA(rs)c? pec) in Leo (RA 11 24 26.1, Dec +11 20 32)

Historical Identification: Per Dreyer, NGC 3666 (= GC 2405 = JH 882 = WH I 20, 1860 RA 11 17 10, NPD 77 53.4) is "faint, extended 90��, 6th magnitude star 34 seconds to east and 5 arcmin to north". The position precesses to RA 11 24 26.9, Dec +11 20 31, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Supposed Variability: For several decades there was a question about whether this object had variable brightness, so there are many historical notes and observations that have more to do with its supposed variability than with its identification or general appearance. There is no good reason to believe that it ever had any real variation in its brightness, but given the existence of such papers and the odds that a persistent reader will run across them, a brief summary seems appropriate here:
A note at the end of the NGC reads "NGC 3666 = JH 882 = WH I 20. This nebula would seem to have decreased in brightness. (Per) John Herschel: According to Winnecke it was again fully of the second class in 1878-79 (A.N. 2293). On May 24, 1887, I could only see it with the greatest difficulty, guided by the 6th magnitude star to the northeast". Many others examined the nebula over the years, and in August Winnecke's paper he provides a list of several observers and their comments on the brightness and appearance of the nebula (Palm Boguslawski in 1834 and 1847, Winnecke in 1856, 1878 and 1879, and Heinrich d'Arrest on Feb 19, 1863). The second IC states "Later observations at Armagh in 1889 and 1891 have not confirmed the suspected variability"; John Dreyer was the director and primary observer at Armagh during this period, so the observations in question were probably made by him. The nebula was also apparently observed in 1856 and 1857 by the 4th Lord Rosse or his assistants, but there is some kind of error in the identification of the object, so it might not have been NGC 3666, and in any event those observations do not address the question of variability in its brightness.
Physical Information: Based on a recessional velocity of 1060 km/sec, NGC 3666 is about 50 million light years away, in reasonable agreement with redshift-independent distance estimates of 50 to 75 million light years. Given that and its apparent size of about 4.4 by 1.1 arcmin, it is 60 to 65 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3666
Below, a 5 arcmin wide SDSS image of the galaxy

Below, a 1.9 by 1.4 arcmin wide image of part of the galaxy (Image Credit Hubble Legacy Archive)

NGC 3667 (= PGC 35028)
Discovered (Mar 27, 1786) by William Herschel
Also observed (Mar 16, 1836) by John Herschel
A magnitude 13.0 spiral galaxy (type (R)SA(rs)ab?) in Crater (RA 11 24 17.0, Dec -13 51 26)

Historical Identification: Per Dreyer, NGC 3667 (= GC 2406 = JH 3340 = WH III 531, 1860 RA 11 17 12, NPD 103 04.5) is "pretty faint, pretty large, irregularly round, very little brighter middle". The position precesses to RA 11 24 14.6, Dec -13 50 35, about 1 arcmin northwest of the galaxy listed above, the description fits and there is nothing comparable nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 5350 km/sec, NGC 3667 is about 250 million light years away, in fair agreement with redshift-independent distance estimates of 260 to 280 million light years. Given that and its apparent size of about 1.55 by 0.9 arcmin, it is 110 to 115 thousand light years across. Given the peculiar appearance of its apparent companion (PGC 35034) and a difference of only 270 km/sec in their recessional velocities, it is possible that they are physical companions.

Above, a 12 arcmin wide DSS image centered on NGC 3667, also showing PGC 35034
Below, a 1.75 arcmin wide DSS image of the galaxy

PGC 35034 (= "NGC 3667B")
Not an NGC object but listed here since sometimes called NGC 3667B
A magnitude 13.5 spiral galaxy (type SAB(rs)b? pec) in Crater (RA 11 24 21.5, Dec -13 51 21)

Physical Information: Based on a recessional velocity of 5080 km/sec, PGC 35034 is 235 to 240 million light years away. Given that and its apparent size of about 1.1 by 0.45 arcmin, it is about 75 thousand light years across. Given its peculiar appearance and a difference of only 270 km/sec in their recessional velocities, it is possible that it is a physical companion of NGC 3667.

Above, a 1.2 arcmin wide DSS image of PGC 34034; for a wider field image see NGC 3667

NGC 3668 (= PGC 35123)
Discovered (Mar 20, 1790) by William Herschel
Also observed (Apr 2, 1832) by John Herschel
A magnitude 12.3 spiral galaxy (type SAB(s)bc?) in Ursa Major (RA 11 25 30.5, Dec +63 26 47)

Historical Identification: Per Dreyer, NGC 3668 (= GC 2407 = JH 880 = WH II 845, 1860 RA 11 17 14, NPD 25 47.0) is "faint, pretty small, irregularly round, gradually brighter middle, 9th magnitude star to northwest". The position precesses to RA 11 25 28.2, Dec +63 26 54, well within the northwest outline of the galaxy listed above, the description fits (though the 10th magnitude star is actually to the southwest, that sort of error in direction is common) and there is nothing comparable nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 3510 km/sec, NGC 3668 is 160 to 165 million light years away, in good agreement with redshift-independent distance estimates of 120 to 215 million light years. Given that and its apparent size of about 1.55 by 1.2 arcmin, it is 70 to 75 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3668
Below, a 1.9 arcmin wide SDSS image of the galaxy

NGC 3669 (= PGC 35113)
Discovered (Mar 18, 1790) by William Herschel
Also observed (Feb 9, 1831) by John Herschel
A magnitude 12.4 spiral galaxy (type SBcd?) in Ursa Major (RA 11 25 26.8, Dec +57 43 16)

Historical Identification: Per Dreyer, NGC 3669 (= GC 2408 = JH 883 = WH II 829, 1860 RA 11 17 24, NPD 31 30.9) is "very faint, pretty large, pretty much extended 135��, extremely mottled but not resolved". The position precesses to RA 11 25 24.6, Dec +57 43 00, less than 0.4 arcmin southwest of the nucleus of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1940 km/sec, NGC 3669 is about 90 million light years away, in reasonable agreement with widely varying redshift-independent distance estimates of 75 to 245 million light years. Given that and its apparent size of about 1.95 by 0.55 arcmin, it is 50 to 55 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3669
Below, a 2.2 arcmin wide SDSS image of the galaxy

NGC 3670 (= PGC 35067)
Discovered (Apr 10, 1785) by William Herschel
Also observed (Mar 28, 1832) by John Herschel
A magnitude 13.5 lenticular galaxy (type SAB0(r)a?) in Leo (RA 11 24 49.7, Dec +23 56 43)

Historical Identification: Per Dreyer, NGC 3670 (= GC 2409 = JH 884 = WH III 337, 1860 RA 11 17 25, NPD 65 16.6) is "very faint, very small, round". The position precesses to RA 11 24 49.6, Dec +23 57 18, only 0.6 arcmin north of the nucleus of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 7050 km/sec, a straightforward calculation indicates that NGC 3670 is 325 to 330 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was just under 320 million light years away at the time the light by which we see it was emitted, 320 to 325 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 about 1.05 by 0.7 arcmin, the galaxy is 95 to 100 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3670
Below, a 1.2 arcmin wide SDSS image of the galaxy

NGC 3671 (= PGC 35149)
Discovered (Apr 9, 1793) by William Herschel
Also observed (Mar 25, 1832) by John Herschel
A magnitude 14.8 lenticular galaxy (type E/S0? pec) in Ursa Major (RA 11 25 52.6, Dec +60 28 46)

Historical Identification: Per Dreyer, NGC 3671 (= GC 2410 = JH 885 = WH III 922, 1860 RA 11 17 54, NPD 28 45.2) is "very faint, very small, 2 very small stars involved". The position precesses to RA 11 25 59.7, Dec +60 28 41, less than 0.9 arcmin east of the galaxy listed above, the description fits (though one of the "2 very small stars" is actually the nearly stellar nucleus of the galaxy) and there is nothing else nearby so the identification is certain.
Physical Information: NGC 3671 is dramatically distorted, but for no obvious reason (as there is no nearby galaxy that it could have recently interacted with), so (as suggested by Corwin) it is probably a late stage in the merger of two galaxies. Based on a recessional velocity of 18000 km/sec, a straightforward calculation indicates that NGC 3671 is 835 to 840 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was a little over 780 million light years away at the time the light by which we see it was emitted, almost 805 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 about 0.4 by 0.35 arcmin for the central galaxy and about 1.6 by 1.5 arcmin for its distended extensions, the central galaxy is 95 to 100 thousand light years across, and its outer extensions cover about 390 thousand light years.

Above, a 12 arcmin wide SDSS image centered on NGC 3671
Below, a 2 arcmin wide SDSS image of the galaxy

NGC 3672 (= PGC 35088 = PGC 986466)
Discovered (Mar 4, 1786) by William Herschel
Also observed (Mar 9, 1828) by John Herschel
A magnitude 11.4 spiral galaxy (type SAB(s)bc?) in Crater (RA 11 25 02.5, Dec -09 47 43)

Historical Identification: Per Dreyer, NGC 3672 (= GC 2411 = JH 886 = WH I 131, 1860 RA 11 17 58, NPD 99 01.5) is "pretty bright, large, extended 0��, gradually brighter middle". The position precesses to RA 11 25 03.1, Dec -09 47 37, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1860 km/sec, NGC 3672 is 85 to 90 million light years away, in good agreement with redshift-independent distance estimates of 65 to 120 million light years. Given that and its apparent size of about 4.65 by 2.1 arcmin, it is 115 to 120 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3672
Below, a 5 arcmin wide image of the galaxy (Image Credit & © Carnegie-Irvine Galaxy Survey; used by permission)

NGC 3673 (= PGC 35097)
Discovered (Mar 22, 1836) by John Herschel
A magnitude 11.5 spiral galaxy (type SB(rs)b? pec) in Hydra (RA 11 25 12.8, Dec -26 44 12)

Historical Identification: Per Dreyer, NGC 3673 (= GC 2412 = JH 3341, 1860 RA 11 18 20, NPD 115 58.5) is "faint, very large, gradually very little brighter middle, 7th magnitude star 6 arcmin south". The position precesses to RA 11 25 14.9, Dec -26 44 38, within the southeastern outline of the galaxy listed above, the description fits (including the star to the south) and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1940 km/sec, NGC 3673 is about 90 million light years away, in reasonable agreement with redshift-independent distance estimates of 55 to 90 million light years. Given that and its apparent size of about 4.2 by 2.6 arcmin, it is about 110 thousand light years across.

Above, a 12 arcmin wide DSS image centered on NGC 3673
Below, a 4.5 arcmin wide image of the galaxy (Image Credit & © Carnegie-Irvine Galaxy Survey; used by permission)

NGC 3674 (= PGC 35191)
Discovered (Apr 8, 1793) by William Herschel
Also observed (Dec 11, 1865) by Heinrich d'Arrest
A magnitude 12.3 lenticular galaxy (type S0?) in Ursa Major (RA 11 26 26.6, Dec +57 02 54)

Historical Identification: Per Dreyer, NGC 3674 (= GC 2415 = WH II 886, d'Arrest, 1860 RA 11 18 26, NPD 32 11.3) is "pretty faint, irregular figure". The position precesses to RA 11 26 24.1, Dec +57 02 34, on the southwestern rim of the galaxy listed above, the description is reasonable and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2055 km/sec, NGC 3674 is about 95 million light years away. Given that and its apparent size of about 1.7 by 0.6 arcmin, it is 45 to 50 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3674
Below, a 2 arcmin wide SDSS image of the galaxy

NGC 3675 (= PGC 35164)
Discovered (Jan 14, 1788) by William Herschel
Also observed (Apr 12, 1830) by John Herschel
A magnitude 10.2 spiral galaxy (type SA(s)b? pec) in Ursa Major (RA 11 26 08.6, Dec +43 35 10)

Historical Identification: Per Dreyer, NGC 3675 (= GC 2413 = JH 887 = WH I 194, 1860 RA 11 18 28, NPD 45 38.5) is "very bright, considerably large, very much extended 0��, very suddenly much brighter middle and nucleus, many stars to west".
Physical Information: Based on a recessional velocity of 770 km/sec, NGC 3675 is about 35 million light years away, in good agreement with widely varying redshift-independent distance estimates of 20 to 65 million light years. Given that and its apparent size of about 8.6 by 5.8 arcmin (including most of its fainter outer regions), it is about 90 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3675
Below, a 7.5 by 9 arcmin wide image of the galaxy
(Image Credit & © Adam Block/Mount Lemmon SkyCenter/University of Arizona; used by permission)

Below, a 'raw' HST image of part of the galaxy (Image Credit Hubble Legacy Archive)

All linear and most point objects in 'raw' HST images are cosmic ray tracks, and barring exhaustive comparison of multiple images, determining which are real and which are not is impossible, so I have tried to remove all linear images, and slightly blurred the resulting image to remove most point sources. Even so, a comparison of this image with a "clean" image would undoubtedly reveal a multitude of nonexistent "artifacts".

NGC 3676 (= PGC 35131)
Discovered (1886) by Frank Muller
A magnitude 13.6 lenticular galaxy (type E/S0?) in Crater (RA 11 25 37.5, Dec -11 08 23)

Historical Identification: Per Dreyer, NGC 3676 (Muller list II (#436), 1860 RA 11 18 30, NPD 99 51.2) is "extremely faint, very small, round, 2 stars of 10th magnitude to northeast and southeast". The position precesses to RA 11 25 34.7, Dec -10 37 20, in a completely stellar field. However (per Corwin), there is an object that perfectly matches Muller's description (including 11th magnitude stars just under an arcmin to the northeast and southeast) almost exactly half a degree to the south, so it is likely that Muller's original observation or Ormond Stone's paper had some kind of typographical error in the position for II-436, which was listed as (1890) RA 11 20, Dec -10 01, but probably should have been (1890) RA 11 20, Dec -10 31. That position precesses to RA 11 25 33.6, Dec -11 07 16, only 1.4 arcmin northwest of the galaxy listed above, as already noted it fits the description perfectly, and it is the only thing Muller could have seen within a very large area near the NGC position, so the identification is certain.
Physical Information: Based on a recessional velocity of 5710 km/sec, NGC 3676 is about 265 million light years away, in relatively poor agreement with a single redshift-independent distance estimate of 335 million light years. Given that and its apparent size of about 0.9 by 0.65 arcmin, it is about 70 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3676
Below, a 1.2 arcmin wide SDSS image of the galaxy

NGC 3677 (= PGC 35181)
Discovered (Mar 19, 1828) by John Herschel
A magnitude 12.6 lenticular galaxy (type (R)SA0(r)a? pec) in Ursa Major (RA 11 26 17.8, Dec +46 58 27)

Historical Identification: Per Dreyer, NGC 3677 (= GC 2414 = JH 888, 1860 RA 11 18 35, NPD 42 14.5) is "extremely faint, small, round, very suddenly brighter stellar middle, 2 stars of 11th magnitude to northeast". The position precesses to RA 11 26 18.4, Dec +46 59 22, about 0.9 arcmin nearly due north of the galaxy listed above, the description fits and the 11th magnitude stars in a line to the north northeast make the identification certain.
Physical Information: Based on a recessional velocity of 7390 km/sec, a straightforward calculation indicates that NGC 3677 is about 345 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 335 million light years away at the time the light by which we see it was emitted, about 340 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 about 1.65 by 1.2 arcmin (counting its northwestern extension), the galaxy is about 160 thousand light years across. The galaxy's considerable distortion does not appear to be related to any nearby object, so perhaps it represents a late stage in a merger of two galaxies.

Above, a 12 arcmin wide SDSS image centered on NGC 3677
Below, a 2.1 arcmin wide SDSS image of the galaxy

NGC 3678 (= PGC 35177)
Discovered (Apr 13, 1831) by John Herschel
A magnitude 13.6 spiral galaxy (type Sbc?) in Leo (RA 11 26 15.8, Dec +27 52 02)

Historical Identification: Per Dreyer, NGC 3678 (= GC 2416 = JH 889, 1860 RA 11 18 48, NPD 61 21.7) is "very faint, small, round, pretty suddenly brighter middle, 12th magnitude star to northeast".
Physical Information: Based on a recessional velocity of 7210 km/sec, a straightforward calculation indicates that NGC 3678 is about 335 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was just over 325 million light years away at the time the light by which we see it was emitted, about 330 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 about 0.8 by 0.7 arcmin, the galaxy is about 75 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3678
Below, a 1 arcmin wide SDSS image of the galaxy

WORKING HERE: Identification/discovery considerably confused; skip & come back later

NGC 3679 (= PGC 34844)
Discovered (Apr 24, 1784) by William Herschel
Supposedly but probably not observed (Mar 21, 1892) by Rudolf Spitaler
A magnitude 13.6 elliptical galaxy (type E2??) in Leo (RA 11 21 48.0, Dec -05 45 28) (uncertain ID?)

Historical Identification: Per Dreyer, NGC 3679 (= GC 2417 = WH III 112, 1860 RA 11 18 52�, NPD 95 05�) is "extremely faint, considerably large, round, mottled but not resolved (very near very bright star)". The first IC adds "The position should be RA 11 19 02, NPD 94 48.8 (1892 RA 11 20 39.47 Dec -04 59 23.7), according to Spitaler, who found nothing in Auwers' place, as well as in that given in the Catalogue".
Discovery Notes: There is a long note at the end of the NGC, and in Corwin's papers; they suggest that Spitaler's object is not NGC 3679 after all (though it is labeled as such in Wikisky, but PGC 35165).
Physical Information: At least two different identifications; one reasonably certain, the other almost certainly wrong. Still, will take considerable time and effort to sort things out.

NGC 3680 (= OCL 823 = "PGC 3518293")
Discovered (May 7, 1826) by James Dunlop
Also observed (Feb 3, 1835) by John Herschel
A magnitude 7.6 open cluster (type I2p) in Centaurus (RA 11 25 39.0, Dec -43 14 06)

Historical Identification: Per Dreyer, NGC 3680 (= GC 2418 = JH 3342, Dunlop 481, 1860 RA 11 18 57, NPD 132 27.8) is a "cluster, considerably large, pretty rich, a little compressed, stars from 10th to 14th magnitude". The position precesses to RA 11 25 38.9, Dec -43 13 57, nearly in the center of the cluster listed above, the description fits perfectly and there is nothing comparable nearby so the identification is certain.
Physical Information: NGC 3680 is thought to be about 3100 light years away. Given that and its apparent size of about 12 arcmin, its few dozen stars are scattered across about 10 light years. It is listed in LEDA as a cluster with designation PGC 3518293, but a search of the database for that designation returns no result.

Above, a 16 arcmin wide DSS image centered on NGC 3680

NGC 3681 (= PGC 35193)
Discovered (Apr 17, 1784) by William Herschel
Also observed (Apr 21, 1832) by John Herschel
A magnitude 11.2 spiral galaxy (type SB(rs)bc?) in Leo (RA 11 26 29.8, Dec +16 51 48)

Historical Identification: Per Dreyer, NGC 3681 (= GC 2419 = JH 891 = JH 3343 = WH II 159, 1860 RA 11 19 11, NPD 72 21.1) is "bright, pretty small, round, brighter middle". The position precesses to RA 11 26 30.7, Dec +16 52 45, within the northern outline of the galaxy listed above, the description fits and there is nothing comparable nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1240 km/sec, NGC 3681 is 55 to 60 million light years away, in fair agreement with redshift-independent distance estimates of 80 to 90 million light years. Given that and its apparent size of about 2.95 by 2.75 arcmin, it is about 50 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3681 (superimposed on a DSS image to fill in missing areas)
Below, a 3.4 arcmin wide SDSS image of the galaxy

NGC 3682 (= PGC 35266)
Discovered (Apr 6, 1793) by William Herschel
Also observed (Apr 3, 1832) by John Herschel
A magnitude 12.5 lenticular galaxy (type SA0(rs)a? pec) in Draco (RA 11 27 41.2, Dec +66 35 24)

Historical Identification: Per Dreyer, NGC 3682 (= GC 2420 = JH 890 = WH I 262, 1860 RA 11 19 20, NPD 22 38.6) is "considerably bright, small, irregularly round, suddenly pretty much brighter middle and nucleus". The position precesses to RA 11 27 40.1, Dec +66 35 13, within the southwestern outline of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1515 km/sec, NGC 3682 is about 70 million light years away, in fair agreement with a single redshift-independent distance estimate of 50 million light years. Given that and its apparent size of about 1.6 by 1.2 arcmin, it is 30 to 35 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3682
Below, a 2 arcmin wide SDSS image of the galaxy

NGC 3683 (= PGC 35249)
Discovered (Mar 18, 1790) by William Herschel
Also observed (Nov 19, 1829) by John Herschel
A magnitude 12.5 spiral galaxy (type SB(s)c?) in Ursa Major (RA 11 27 31.9, Dec +56 52 37)

Historical Identification: Per Dreyer, NGC 3683 (= GC 2421 = JH 892 = WH I 246, 1860 RA 11 19 36, NPD 32 21.2) is "considerably bright, pretty large, extended". The position precesses to RA 11 27 32.3, Dec +56 52 37, dead center on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based a recessional velocity of 1715 km/sec, NGC 3683 is about 80 million light years away, in reasonable agreement with redshift-independent distance estimates of 80 to 140 million light years. Given that and its apparent size of about 2.0 by 0.7 arcmin, it is 45 to 50 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3683
Below, a 2 arcmin wide SDSS image of the galaxy

PGC 35376 (= "NGC 3683A")
Not an NGC object but listed here since sometimes called NGC 3683A
A magnitude 11.9 spiral galaxy (type SAB(rs)bc?) in Ursa Major (RA 11 29 11.8, Dec +57 07 56)

Physical Information: Based on a recessional velocity of 2425 km/sec, PGC 35376 is 110 to 115 million light years away, in fair agreement with redshift-independent distance estimates of 120 to 145 million light years. Given that and its apparent size of about 2.4 by 1.4 arcmin, it is 75 to 80 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on PGC 35376
Below, a 2.5 arcmin wide SDSS image of the galaxy

WORKING HERE: Discovery history very uncertain

NGC 3684 (= PGC 35224)
Discovered (Apr 17, 1784) by William Herschel???
Discovered (Mar 17, 1831) by John Herschel
A magnitude 11.4 spiral galaxy (type Sbc??) in Leo (RA 11 27 11.2, Dec +17 01 49)

Historical Identification: Per Dreyer, NGC 3684 (= GC 2422 = JH 893, 1860 RA 11 19 51, NPD 72 12.1) is "pretty bright, pretty large, extended, very gradually brighter middle".
Discovery Notes: Per Steinicke and Corwin, William Herschel's II 160 was observed in a sweep that did not completely cover the region near NGC 3686, so John Herschel's identification of GC 2423 (= NGC 3686) as III 28 = II 160, and Dreyer's acceptance of that identification must be wrong. Instead, WH II 160 must = NGC 3684, making William Herschel the discoverer of that object, as well as NGC 3686.
Calculations for WH II 160: Herschel's first list of 1000 nebulae and clusters states that he observed II 160 on April 17, 1784, using 81 Leonis as his comparison star. Its position was 1m east and 45' north of the star, and he described it as "considerably large, round, very gradually brighter middle". The modern position of 81 Leonis is J2000 RA 11 25 36.4, Dec +16 27 24, and its proper motion is -0.142"/yr in right ascension and -0.0047"/yr in declination. That means that in the 216 years between the epochs of 1784 and 2000 it moved 2.0s west and 1" south, making its 1784 position J2000 RA 11 25 38.4, Dec +16 27 25, or (1784) RA 11 14 19.3, Dec +17 38 29. Applying Herschel's offsets, this places his II 160 at (1784) RA 11 15 19.3, Dec +18 23 29, which precesses to J2000 RA 11 26 38.7, Dec +17 12 22, about 13 arcmin northwest of the galaxy listed above, and just under 16 arcmin nearly due west of NGC 3686, and since errors in right ascension are more common in historical observations than errors in declination, it makes sense that both John Herschel and John Dreyer would have assumed that WH II 160 corresponded to a poor measurement on NGC 3686. However, as noted above, Steinicke is certain and Corwin agrees that the sweep in which Herschel observed his II 160 did not extend as far north as NGC 3686, so he could not have seen it; and WH's error must be a digit-error (most likely 10 arcmin) in the declination. Applying an extra 10 arcmin to his NPD places his II 160 at (1784) RA 11 15 19.3, Dec +18 13 29, which precesses to J2000 RA 11 26 35.4, Dec +17 02 42, about 8.5 arcmin north northwest of the galaxy listed above, making the identification acceptable, even if not as convincing as one might prefer.
Physical Information:

WORKING HERE: Need to complete Discovery Notes to confirm identification

NGC 3685 (= PGC 35305)
Discovered (Dec 11, 1877) by David Todd
A magnitude 14.1 lenticular galaxy (type E/S0?) in Leo (RA 11 28 16.2, Dec +04 19 38)

Historical Identification: Per Dreyer, NGC 3685 (Todd (#9), 1860 RA 11 19, NPD 85 06) is "extremely faint, very small". The position precesses to RA 11 26 12.7, Dec +04 07 51, in a completely stellar field, but that is not unusual for Todd's discoveries, as his nebular discoveries were merely an afterthought associated with his unsuccessful search for a trans-Neptunian planet, and he used an unorthodox method of recording the nebulae he happened to notice that makes identifying them very difficult. However (per Corwin), his sketches of the region he actually observed are very good, so the identification of NGC 3685 as the galaxy listed above is certain.
Discovery Notes: Need a detailed discussion of how the sketches show that the above statement is correct.
Physical Information: Based on a recessional velocity of 8615 km/sec, a straightforward calculation indicates that NGC 3685 is about 400 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 385 to 390 million light years away at the time the light by which we see it was emitted, almost 395 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 about 0.55 by 0.3 arcmin, the galaxy is 60 to 65 thousand light years across.
Possible Interaction With PGC 35295: The recessional velocity for PGC 35295 is only 365 km/sec smaller than that of NGC 3685, which isn't that much larger than typical random motions ("peculiar velocities") of galaxies relative to each other, so it is quite possible that the two galaxies are either a physical pair or that they had a relatively recent close passage, which could explain the peculiar structure of the supposedly slightly nearer (by about 15 to 20 million light years) PGC 35295. If the galaxies are a physical pair, they would actually be at about the same distance, or about 380 to 385 million light years away; but that would not affect the estimate of the physical size of either galaxy.

Above, a 12 arcmin wide SDSS image centered on NGC 3685, also showing PGC 35295
Below, a 0.8 arcmin wide SDSS image of the galaxy

WORKING HERE: Discovery information very uncertain

NGC 3686 (= PGC 35268)
Discovered (Mar 14, 1784) by William Herschel?
Also observed (Mar 23, 1827) by John Herschel
A magnitude 11.3 spiral galaxy (type SBbc??) in Leo (RA 11 27 44.0, Dec +17 13 27)

Historical Identification: Per Dreyer, NGC 3686 (= GC 2423 = JH 894 = WH III 28 = WH II 160, 1860 RA 11 20 24, NPD 72 00.5) is "pretty bright, large, very little extended, very gradually brighter middle, mottled but not resolved".
Discovery Notes: (See notes for 3684)
Physical Information:

NGC 3687 (= PGC 35285)
Discovered (Feb 22, 1789) by William Herschel
Also observed (Mar 26, 1827) by John Herschel
A magnitude 12.0 spiral galaxy (type (R)SB(rs)bc?) in Ursa Major (RA 11 28 00.6, Dec +29 30 40)

Historical Identification: Per Dreyer, NGC 3687 (= GC 2424 = JH 895 = WH II 770, 1860 RA 11 20 32, NPD 59 42.9) is "pretty bright, pretty small, round, a little brighter middle, mottled but not resolved". The position precesses to RA 11 27 59.0, Dec +29 30 54, within the northwestern outline of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2505 km/sec, NGC 3687 is 115 to 120 million light years away, in good agreement with redshift-independent distance estimates of 70 to 140 million light years. Given that and its apparent size of about 1.75 by 1.7 arcmin, it is about 60 thousand light years across. There is a possibility that its apparent (foreground) companion PGC 213835 has interacted with it at some time in the past, but the factors noted in the entry for that object that might lead to such a conclusion do not appear to have been given any consideration anywhere else, so barring further developments they should be treated as merely an optical double with a separation of 10 to 20 million light years.

Above, a 12 arcmin wide SDSS image centered on NGC 3687
Below, a 2.4 arcmin wide SDSS image of the galaxy and PGC 213835

WORKING HERE: Need to discuss Common's observation (check Steinicke's book?)

NGC 3688 (= PGC 35269)
Discovered (1880) by Andrew Common
Also observed (1886) by Francis Leavenworth
A magnitude 14.3 spiral galaxy (type (R)SB(rs)bc?) in Crater (RA 11 27 44.5, Dec -09 09 56)

Historical Identification: Per Dreyer, NGC 3688 (Leavenworth list II (#437), (Common #17), 1860 RA 11 20 41, NPD 98 23.1) is "extremely faint, extremely small, a little elongated 0�, gradually brighter middle". The position precesses to RA 11 27 46.8, Dec -09 09 18, about 0.8 arcmin northeast of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Discovery Notes: Common's observation was not noted by Dreyer in the original NGC entry, hence its inclusion in parentheses.
Physical Information: Based on a recessional velocity of 6630 km/sec, NGC 3688 is 305 to 310 million light years away. Given that and its apparent size of about 1.05 by 1.05 arcmin, it is about 95 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3688
Below, a 1.4 arcmin wide SDSS image of the galaxy

NGC 3689 (= PGC 35294)
Discovered (Apr 6, 1785) by William Herschel
Also observed (Feb 19, 1827) by John Herschel
A magnitude 12.3 spiral galaxy (type SAB(rs)c?) in Leo (RA 11 28 11.0, Dec +25 39 40)

Historical Identification: Per Dreyer, NGC 3689 (= GC 2426 = JH 897 = WH II 339, 1860 RA 11 20 44, NPD 63 34.2) is "pretty bright, pretty large, a little extended, brighter middle". The position precesses to RA 11 28 08.4, Dec +25 39 36, on the western rim of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2740 km/sec, NGC 3689 is 125 to 130 million light years away, in good agreement with redshift-independent distance estimates of 85 to 165 million light years. Given that and its apparent size of about 1.9 by 1.0 arcmin, it is about 70 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3689
Below, a 2 arcmin wide SDSS image of the galaxy

NGC 3690 (= PGC 35321 + PGC 35326) (and = Arp 299 with (or without?) IC 694)
Discovered (Mar 18, 1790) by William Herschel
Also observed (Nov 19, 1829) by John Herschel
A pair of interacting galaxies in Ursa Major
PGC 35321 = A magnitude 10.9 irregular galaxy (type IBm? pec) at RA 11 28 33.6, Dec +58 33 47
PGC 35326 = A magnitude 11.2 spiral galaxy (type SBm? pec) at RA 11 28 30.9, Dec +58 33 42

Historical Identification: Per Dreyer, NGC 3690 (= GC 2425 = JH 896 = WH I 247, 1860 RA 11 20 45, NPD 30 40.8) is "pretty bright, pretty small, very little extended 80��, pretty gradually brighter middle, small star near to southeast". The position precesses to RA 11 28 42.9, Dec +58 32 59, about 1.7 arcmin east southeast of the pair of galaxies listed above, the description fits (though the "small star" is more south southeast than southeast) and there is nothing comparable nearby, so the identification is certain.
Warning About Misidentification With IC 694: Depending on the reference, each of the interacting galaxies that comprise NGC 3690 has been misidentified as IC 694, but that is the elliptical galaxy to the northwest of the pair (and part of the problem with the Arp Atlas designation).
Arp Atlas Notes: The Arp Atlas of Peculiar Galaxies uses this galaxy (and perhaps IC 694) as one of its Double Galaxies, with the note "Bright internal knots". There is no doubt that there are many bright knots in the pair of colliding galaxies, but the question is whether the galaxy to the northwest (which is IC 694) was meant to be included in that description. It is clearly within the outer reaches of the mess created by the colliding pair that form NGC 3690, so Arp may have considered it part of Arp 299, but whether he was actually referring to that "knot" when he mistakenly labeled Arp 296 as NGC 3690 + IC 694 is another matter. As noted in the paragraph immediately above, NGC 3690 is often mistakenly referred to as both NGC 3690 and IC 694 by people who presume that one of the colliding galaxies is the former and the other is the latter; and odds are that Arp meant only the pair of colliding galaxies (that is, only NGC 3690) when using the pair of designations. However, since he might have thought that the actual IC 694 was also one of the bright internal knots (it is actually a completely separate object, 40 to 45 million light years more distant than NGC 3690), it is possible that he was including it in Arp 299, albeit not in the way we would now. As a result, we cannot know whether Arp 299 should only be thought of as NGC 3690, or as also including IC 694 (hence the uncertain identification in the title of this entry).
Labeling Arp 298 to Arp 310: Arp used charts to show how he subdivided the various kinds of galaxies, and from the numbers involved and the appearance of the Arp objects shown here, they must be among his Double Galaxies, but not part of any of the specified subdivisions of such galaxies. This is one of a number of mostly small errors in the charts, but has led to the unfortunately common misidentification of these Arp objects as "Unclassified Galaxies". The correct designation is "Unclassified Double Galaxies".
Physical Information: Since the pair of galaxies is obviously interacting they must be at the same distance, so their average radial velocity is the best measure of their distance. PGC 36321 has a recessional velocity of 3120 km/sec, and PGC 36326 has a recessional velocity of 3065 km/sec, so based on their average recessional velocity of 3090 to 3095 km/sec (and H0 = 70 km/sec/Mpc), the pair is about 140 to 145 million light years away. Given that and its apparent size of 0.8 by 0.6 arcmin (all apparent sizes from the images below), the brighter part of southwestern component (PGC 36326) is 30 to 35 thousand light years across, the apparent size of 1.2 by 0.55 arcmin for the brighter part of the northeastern component (PGC 36321) corresponds to about 50 thousand light years, and the overall apparent size of the pair (including their faint outer extensions) of about 3.1 by 1.8 arcmin corresponds to about 130 thousand light years.

Above, a 12 arcmin wide SDSS image centered on NGC 3690, also showing IC 694
Below, a 2.4 by 2.8 arcmin wide SDSS image of NGC 3690 and IC 694

Below, a 2.4 by 3.0 arcmin wide HST image of the group (Image Credit NASA/ESA/Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University))

Below, a 1.6 by 1.9 arcmin wide version of the image above

Below, a very wide-field composite of visual and radio images of the region
(Image Credit NRAO/AUI, Zoltan G. Levay (STScI) & Juan M. Uson (NRAO))

NGC 3691 (= PGC 35292)
Discovered (Mar 14, 1784) by William Herschel
Also observed (Apr 21, 1832) by John Herschel
A magnitude 12.4 spiral galaxy (type SB(r)cd? pec) in Leo (RA 11 28 09.4, Dec +16 55 14)

Historical Identification: Per Dreyer, NGC 3691 (= GC 2427 = JH 898 = WH II 54, 1860 RA 11 20 50, NPD 72 18.6) is "faint, pretty small, a little extended, mottled but not resolved". The position precesses to RA 11 28 09.3, Dec +16 55 11, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1085 km/sec, NGC 3691 is about 50 million light years away, in fair agreement with redshift-independent distance estimates of 70 to 100 million light years. Given that and its apparent size of about 1.0 by 0.7 arcmin, it is about 15 thousand light years across.

Above, a 12 arcmin wide DSS image centered on NGC 3691
(The SDSS field involved is severely compromised by artifacts, so the DSS wide-field image is superior)
Below, a 1.2 arcmin wide SDSS image of the galaxy

NGC 3692 (= PGC 35314)
Discovered (Apr 15, 1784) by William Herschel
Also observed (probably 1876/77) by Wilhelm Tempel
A magnitude 12.1 spiral galaxy (type S(rs)b?) in Leo (RA 11 28 24.0, Dec +09 24 28)

Historical Identification: Per Dreyer, NGC 3692 (= GC 2428 = WH II 152, Tempel (list I notes), 1860 RA 11 21 00, NPD 79 51.7) is "faint, much extended, mottled but not resolved". The position precesses to RA 11 28 15.2, Dec +09 22 05, over 3 arcmin southwest of the galaxy listed above, but the description fits and there is nothing else nearby so the identification is certain.
Discovery Notes: Tempel's list I, published in 1878, includes a discussion of a number of nebulae he observed or discovered, one of which was Herschel's II 152. Although Tempel gives no details about the observation, Dreyer's 1877 Supplement to the General Catalog stated that per (a presumably private communication from) Tempel, Herschel's NPD was 10 arcmin too small, so Tempel must have made that observation sometime prior to the date of Dreyer's publication (based on dates of other observations described in Tempel's paper, most likely between 1876 and mid 1877).
Physical Information: Based on a recessional velocity of 1725 km/sec, NGC 1892 is about 80 million light years away, in fair agreement with redshift-independent distance estimates of 100 to 140 million light years. Given that and its apparent size of about 3.2 by 0.6 arcmin, the galaxy is about 75 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on NGC 3692
Below, a 3.4 arcmin wide SDSS image of the galaxy

NGC 3693 (= PGC 35299)
Discovered (Mar 27, 1786) by William Herschel
Also observed (May 7, 1836) by John Herschel
A magnitude 12.7 spiral galaxy (type (R)SA(r)b?) in Crater (RA 11 28 11.6, Dec -13 11 40)

Historical Identification: Per Dreyer, NGC 3693 (= GC 2429 = JH 3334 = WH III 532, 1860 RA 11 21 09, NPD 102 24.9) is "considerably faint, small, extended, gradually brighter middle". The position precesses to RA 11 28 12.8, Dec -13 11 07, only 0.6 arcmin north northeast of the nucleus of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 4955 km/sec, NGC 3693 is about 230 million light years away, in reasonable agreement with redshift-independent distance estimates of 130 to 240 million light years. Given that and its apparent size of about 3.2 by 0.7 arcmin, it is about 215 thousand light years across.

Above, a 12 arcmin wide DSS image centered on NGC 3693
Below, a 3.5 arcmin wide DSS image of the galaxy

NGC 3694 (= PGC 35352)
Discovered (Mar 11, 1831) by John Herschel
A magnitude 12.7 lenticular galaxy (type S0(r)a? pec) in Ursa Major (RA 11 28 54.1, Dec +35 24 50)

Historical Identification: Per Dreyer, NGC 3694 (= GC 2430 = JH 899, 1860 RA 11 21 23, NPD 53 48.7) is "considerably faint, small, round, much brighter middle". The position precesses to RA 11 28 53.7, Dec +35 25 04, just off the northern rim of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2245 km/sec, NGC 3694 is about 105 million light years away, in reasonable agreement with a single redshift-independent distance estimate of 115 million light years. Given that and its apparent size of about 1.0 by 0.75 arcmin, it is about 30 thousand light years across. It is probably a starburst galaxy.

Above, a 12 arcmin wide SDSS image centered on NGC 3694
Below, a 1.2 arcmin wide SDSS image of the galaxy

NGC 3695 (= NGC 3698 = PGC 35389)
Discovered (Mar 31, 1867) by Robert Ball (and later listed as NGC 3695)
Also observed (Mar 18, 1876) by John Dreyer (and later listed as NGC 3698)
A magnitude 13.9 spiral galaxy (type SB(rs)bc? pec) in Ursa Major (RA 11 29 17.3, Dec +35 34 32)

Historical Identification: Per Dreyer, NGC 3695 (= GC 5564, Ball using Lord Rosse's Leviathan, 1860 RA 11 21 23, NPD 53 44.4) is "extremely faint, pretty small, h899 4 arcmin to south", h899 being NGC 3694. The position precesses to RA 11 28 53.8, Dec +35 29 22, which as might be expected from the description is about 4 arcmin north of NGC 3694, but there is nothing near the listed position save for a 15th-magnitude star which Dreyer mistook (in his 1876 observation of the region) for what Ball observed nine years earlier. However (per Corwin), Ball's original observation (recorded in the 4th Lord Rosse's compendium of observations made between 1848 and 1878 as an observation of the region near GC 2430 = NGC 3694) perfectly describes the region and the relative positions of the two objects discovered by Ball (NGC 3695 and 3700). The entry reads as follows: "1867, Mar. 31. 3 faint nebulae forming a triangle certainly seen here and one or more suspected in the neighbourhood. There being no great difference of brightness it is not easy to see which is h899 (= NGC 3694). The 2 northeastern ones, position angle 310�, distance 339 arcsec. [5564 and 5566.]", the last two numbers being the GC designations assigned by Dreyer in his 1877 Supplement to the GC. A measurement of the first image below shows that the northeastern nebulae are separated by 337 arcsec at a position angle of 310�, so there is no doubt that they are the objects observed by Ball, making the identification of NGC 3695 as PGC 35389 and NGC 3700 as PGC 35413 absolutely certain.
A Note About the Duplicate Entry: As a result of his misidentification of the 15th magnitude star north of h899 (= NGC 3694) as Ball's "GC 5564", Dreyer's 1877 Supplement to the General Catalog contained incorrect positions and descriptions for what became NGC 3695 and 3700, and he copied those incorrect positions and descriptions word for word into the NGC. One result of this is the duplicate entry for NGC 3695 listed as NGC 3698 (which see).
Additional Note: In his book about the history of early observations and catalogs of nebulae and clusters, Steinicke states that the triangle of nebulae described by Ball is 10 arcmin wide. The distance between the southwestern galaxy (NGC 3694) and the midpoint of the northeastern pair (NGC 3695 and 3700) is just over 10 arcmin, but since Ball's note (quoted above) does not state the size of the triangle, it is not clear whether Steinicke is quoting some other (unknown) source, or is just making an offhand comment that the triangle happens to be that large.
Physical Information: Based on a recessional velocity of 10355 km/sec, a straightforward calculation indicates that NGC 3695 is 480 to 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 460 to 465 million light years away at the time the light by which we see it was emitted, just over 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 about 1.05 by 0.65 arcmin, the galaxy is about 140 thousand light years across. The galaxy is binuclear and considerably distorted (even the northwestern nucleus is itself considerably distorted). It is possible that it represents two more nearly normal spirals that just happen to be superimposed (in other words an optical double), but there are two separate but otherwise essentially equal recessional velocities for different parts of the object, and the nuclear distortion of the northwestern component suggests that there is some kind of interaction taking place, so even if the object is currently (meaning as we currently see it, since we are seeing it as it was more than 470 million years ago) a separate pair of galaxies they were probably in an early stage of a spectacular interaction or even merger.

Above, a 12 arcmin wide SDSS image centered between NGC 3694, 3695 and 3700
Below, a 12 arcmin wide SDSS image centered on Dreyer's position for NGC 3695
(also shown are NGC 3694 and the actual position of NGC 3695)

Below, a 12 arcmin wide SDSS image centered on NGC 3695; also shown is NGC 3700

Below, a 1.2 arcmin wide SDSS image of the galaxy pair

WORKING HERE: Identification either wrong or very uncertain.

NGC 3696 (= PGC 35340)
Discovered (1886) by Francis Leavenworth
A magnitude 14.1 spiral galaxy (type Sc??) in Crater (RA 11 28 44.0, Dec -11 16 58) (ID uncertain?)

Historical Identification: Per Dreyer, NGC 3696 (Leavenworth list II (#438), 1860 RA 11 21 29, NPD 100 41.1) is "extremely faint, extremely small, round, brighter middle and nucleus". The position precesses to RA 11 28 33.7, Dec -11 27 20, in a completely stellar field. *Need a lot of work here*
Physical Information:

NGC 3697 (= PGC 35347 = HCG 53A), a member of Hickson Compact Group 53
Discovered (Feb 24, 1827) by John Herschel
A magnitiude 13.1 spiral galaxy (type SABb?) in Leo (RA 11 28 50.4, Dec +20 47 42)

Historical Identification: Per Dreyer, NGC 3697 (= GC 2431 = JH 900, 1860 RA 11 21 30, NPD 68 25.9) is "extremely faint, very small, extended 90�". The position precesses to RA 11 28 51.3, Dec +20 47 52, within the northern outline of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 6260 km/sec (and H0 = 70 km/sec/Mpc), NGC 3697 is 290 to 295 million light years away, in good agreement with redshift-independent distance estimates of 255 to 350 million light years. Given that and its apparent size of about 2.7 by 0.75 arcmin (from the images below), it is 230 thousand light years across. NGC 3697 is the brightest member of Hickson Compact Group 53, and the only member of the Group that is an NGC/IC object.

Above, a 12 arcmin wide SDSS image centered on NGC 3697
Below, a 2.8 arcmin wide SDSS image of the galaxy

Below, an 8 arcmin wide labeled SDSS image of Hickson Compact Group 53

PGC 35355 (= "NGC 3697B" = HCG 53C), a member of Hickson Compact Group 53
Not an NGC object but listed here since sometimes called NGC 3697B
A magnitude 14.4 spiral galaxy (type SBbc? pec) in Leo (RA 11 28 58.5, Dec +20 44 59)

Physical Information: Based on a recessional velocity of 6250 km/sec (and H0 = 70 km/sec/Mpc), PGC 35355 is about 290 to 295 million light years away (which means it is an actual part of HCG 53). Given that and its apparent size of about 0.7 by 0.45 arcmin (from the images below), it is about 60 thousand light years across.

Above, a 0.8 arcmin wide SDSS image of PGC 35355; for other images see PGC 35360 or HCG 53

PGC 35360 (= "NGC 3697C" = HCG 53B), a member of Hickson Compact Group 53
Not an NGC object but listed here since sometimes called NGC 3697C
A magnitude 14.2 lenticular galaxy (type (R)S0(r)a?) in Leo (RA 11 28 59.9, Dec +20 44 21)

Physical Information: Based on a recessional velocity of 6335 km/sec (and H0 = 70 km/sec/Mpc), PGC 35360 is about 295 million light years away (which means it is an actual part of HCG 53). Given that and its apparent size of about 0.9 by 0.6 arcmin (from the images below), it is about 75 to 80 thousand light years across.

Above, a 12 arcmin wide SDSS image centered on PGC 35360, also showing NGC 3697
Below, a 1.4 arcmin wide SDSS image of the galaxy, also showing PGC 35355

Below, an 8 arcmin wide labeled SDSS image of Hickson Compact Group 53

WORKING HERE: Cleaning up Dreyer's mess

NGC 3698 (= PGC 35389 = NGC 3695)
Discovered (Mar 31, 1867) by Robert Ball (and later listed as NGC 3695)
Also observed (Mar 18, 1876) by John Dreyer (and later listed as NGC 3698)
A magnitude 13.9 spiral galaxy (type SB(rs)bc? pec) in Ursa Major (RA 11 29 17.3, Dec +35 34 32)

Historical Identification: Per Dreyer, NGC 3698 (= GC 5565, Dreyer using Lord Rosse's 72-inch Leviathan, 1860 RA 11 21 33, NPD 53 33.5) is "extremely faint, very small". The position precesses to RA 11 29 03.8, Dec +35 40 16, in a nearly completely stellar field. Per Corwin, the problem was due to a misunderstanding of the situation by Dreyer, resulting in both NGC 3695 and 3698 being assigned incorrect positions, even though they are actually observations of the same object, correctly observed and described by Ball.
Discovery Notes: (for now see notes for NGC 3695)
Physical Information: Given the duplicate entry, see NGC 3695 for anything else.

NGC 3699 (= P-K 292+01.1 = "PGC 3517766")
Discovered (Apr 1, 1834) by John Herschel
A magnitude 11.3 planetary nebula in Centaurus (RA 11 27 57.6, Dec -59 57 29)

Historical Identification: Per Dreyer, NGC 3699 (= GC 2432 = JH 3345, 1860 RA 11 21 34, NPD 149 11.1) is "bright, pretty large, irregularly round, pretty gradually pretty much brighter middle". The position precesses to RA 11 27 55.5, Dec -59 57 19, right on the nebula listed above, the description fits and there is nothing comparable nearby so the identification is certain.
PGC Designation Note: For purposes of completeness, LEDA assigns a PGC designation to this object even though it isn't a galaxy; but a search of the database for that designation returns no result, so it is shown in quotes.
Physical Information: For a long time, NGC 3699 was thought to be an emission nebula, but in 1978 is was shown that it is actually an oddly shaped planetary nebula. The central star (now a white dwarf) is unusually hot (more than 140 thousand Kelvins, equivalent to more than 250 thousand Fahrenheit degrees), indicating a relatively young age for the planetary. It is thought that the complex structure is due to multiple stages of mass ejection in which later ejections had much faster velocities, causing compressional shock wave heating of the material when it ran into gases ejected at an earlier time. The brightest portion of the planetary nebula has an apparent size of about 1.1 by 0.9 arcmin, while the fainter regions shown in the image by Gorny et al span about 2.3 by 1.7 arcmin, and the even fainter regions shown in the image by Hua et al span about 4.4 by 3.5 arcmin, but the distance of the object appears to be unknown, so the physical sizes corresponding to these apparent sizes are also unknown.

Above, a 12 arcmin wide DSS image centered on NGC 3699
Below, a 3 arcmin wide DSS image of the planetary nebula

Below, a 2.1 arcmin wide image of the nebula (Image Credit Gorny, Corradi, Schwarz & van Winckel)

Below, a 4.2 arcmin wide image of the nebula (Image Credit Hua, Dopita and Martinis)