Historical Identification: Per Dreyer, NGC 3550 (= GC 2319 = JH 829 = WH III 351, 1860 RA 11 03 04, NPD 60 28.8) is "faint (perhaps variable?), small, round, brighter middle, 9th magnitude star 1 arcmin to east, 1st of 4", the others being NGC 3552, 3554 and 3561.
Physical Information:

Historical Identification: Per Dreyer, NGC 3551 (Swift list I (#10), 1860 RA 11 03 05, NPD 67 30.4) is "most extremely faint, very small, round, southwestern of 2", the other being NGC 3555.
Physical Information:

Historical Identification: Per Dreyer, NGC 3552 (= GC 2320 = JH 832 = WH III 352, 1860 RA 11 03 10, NPD 60 33.1) is "extremely faint, very small, 2nd of 4", the others being NGC 3550, 3554 and 3561.
Physical Information: Noted in the entry for NGC 3553 as forming a double nebula with that object.

Historical Identification: Per Dreyer, NGC 3553 (Bigourdan (list I #45), 1860 RA 11 03 10, NPD 60 32.3) is "extremely faint, very small, forms double nebula with III 352", (WH) III 52 being NGC 3552.
Physical Information:

Historical Identification: Per Dreyer, NGC 3554 (= GC 2321 = JH 833, 1860 RA 11 03 12, NPD 60 36.4) is "very faint, pretty small, round, brighter middle, 3rd of 4", the others being NGC 3550, 3552 and 3561.
Physical Information:

Historical Identification: Per Dreyer, NGC 3555 (Swift list I (#11), 1860 RA 11 03 15, NPD 67 29.9) is "very faint, round, northeastern of 2", the other being NGC 3551.
Physical Information:

Historical Identification: Per Dreyer, NGC 3556 (= GC 2318 = JH 831 = WH V 46, G. Rümker, 1860 RA 11 03 18, NPD 33 34.0) is "considerably bright, very large, very much extended 79°, pretty bright middle, mottled but not resolved". The position precesses to RA 11 11 31.5, Dec +55 40 38, right on the galaxy listed above and the description fits, so the identification is certain.
Additional Notes (about its listing as M108): Méchain observed this nebula on Feb 19, 1781 and noted its approximate position relative to M97, but as of his letter of May 6, 1783 to Bernoulli, had still not gotten around to measuring an accurate position. Messier also noted the nebula while observing M97, and apparently meant to add it to his Catalog, as he marked it as "98" in the preliminary manuscript; but he failed to measure its position before he had to send the manuscript to the publisher, so it was not included in the published Catalog. However, he did add a handwritten position to his personal copy of the published Catalog, which Owen Gingerich was able to use in 1953 to identify it as NGC 3556; and as a result of Messier's obvious original intention to add the nebula to his Catalog, Gingerich suggested adding it as M108. The failure of its original discoverers to publish their observations meant that neither Herschel nor Dreyer knew of the original observations when they compiled the General Catalog and New General Catalog, so there was no mention of Méchain or Messier in the NGC entry for the galaxy.
Physical Information: Apparent size 8.6 by 2.4 arcmin?

Historical Identification: Per Dreyer, NGC 3557 (= GC 2322 = JH 3319, 1860 RA 11 03 20, NPD 126 46.8) is "bright, small, round, pretty gradually much brighter middle, 1st of 3", the others being NGC 3564 and 3568.
Physical Information:

Historical Identification: Per Dreyer, NGC 3558 (= GC 5549, d'Arrest, 1860 RA 11 03 22, NPD 60 40.5) is "pretty faint, small".
Physical Information:

Historical Identification: Per Dreyer, NGC 3559 (= GC 2323 = WH III 79, d'Arrest, 1860 RA 11 03 26, NPD 77 13.3) is "extremely faint, pretty small, a little extended, mottled but not resolved".
Physical Information: LEDA SBc; NED S pec, RIDE 35.5 - 59.1 Mpc (median 36.5), 3K Vr 3601 km/sec; apparent size about 1.35 by 0.8 arcmin (from the images below).

Historical Identification: Per Dreyer, NGC 3560 (= GC 2324 = JH 834, 1860 RA 11 03 26, NPD 78 03.6) is "faint, small, round, gradually brighter middle".
Physical Information: Given the duplicate entry, see NGC 3559 for anything else.

Historical Identification: Per Dreyer, NGC 3561 (= GC 2326 = JH 835, 1860 RA 11 03 36, NPD 60 32.8) is "very faint, pretty large, 4th of 4", the others being NGC 3550, 3552 and 3554.
Physical Information: Apparent size about 1.1 by 0.8 arcmin. Used by the Arp Atlas as an example of an elliptical galaxy connected to a spiral galaxy (PGC 33992). A Seyfert galaxy (type Sy 3). (Note: NED muddles the galaxy types for Arp 105, listing both types for each galaxy.)

Physical Information: Apparent size of main galaxy about 1.0 by 0.6 arcmin; including the long counter-tail, about 3.8 arcmin. Used in the Arp Atlas as an example of an elliptical galaxy (NGC 3561, which see for images) connected to a spiral galaxy. (Note: NED muddles the galaxy types for Arp 105, listing both types for each galaxy.)

Historical Identification: Per Dreyer, NGC 3562 (= GC 2325 = JH 830 = WH II 337, 1860 RA 11 03 38, NPD 16 21.5) is "pretty faint, pretty small, a little extended, gradually brighter middle, 15th magnitude star 70 arcsec distant at position angle 22°".
Physical Information:

Historical Identification: Per Dreyer, NGC 3563 (= GC 5550, Otto Struve, 1860 RA 11 03 49, NPD 62 16) is "pretty faint, pretty large, 8th magnitude star 2 arcmin to north".
Physical Information:

Historical Identification: Per Dreyer, NGC 3564 (= GC 2327 = JH 3320, 1860 RA 11 03 57, NPD 126 46.7) is "pretty faint, small, round, brighter middle, 2nd of 3", the others being NGC 3557 and 3568.
Physical Information:

Historical Identification: Per Dreyer, NGC 3565 (Ormond Stone list I (#185), 1860 RA 11 03, NPD 109 17.2) is "very faint, very small, round, gradually brighter middle and nucleus, 1st of 2", the other being NGC 3566.
Physical Information:

Historical Identification: Per Dreyer, NGC 3566 (Ormond Stone list I (#186), 1860 RA 11 03, NPD 109 17.2) is "most extremely faint, extremely small, round, gradually brighter middle, 2nd of 2", the other being NGC 3565.
Physical Information:

Historical Identification: Per Dreyer, NGC 3567 (= GC 2328 = JH 836 = WH III 89, 1860 RA 11 04 02, NPD 83 25.1) is "extremely faint, round, suddenly brighter middle, mottled but not resolved".
Physical Information:

Historical Identification: Per Dreyer, NGC 3568 (= GC 2329 = JH 3321, 1860 RA 11 04 10, NPD 126 42.2) is "very faint, pretty large, round, star involved, 3 bright stars near, 3rd of 3," the others being NGC 3557 and 3564. The position precesses to RA 11 10 48.2, Dec -37 27 45, not quite 0.9 arcmin nearly due south of the center of the galaxy listed above and well within its southern outline, the description of the galaxy and its field fits and there is nothing else that could possibly be what Herschel observed, so the identification is certain.
Physical Information: Based on a recessional velocity relative to the Cosmic Microwave Background radiation of 2765 km/sec (and H₀ = 70 km/sec/Mpc), NGC 3568 is about 125 to 130 million light-years away, in reasonable agreement with redshift-independent distance estimates of about 55 to 130 million light-years and the HST press release's "roughly 57 million light-years from the Milky Way"). Given that and its apparent size of about 2.8 by 0.7 arcmin (from the images below), if the galaxy is at the lower HST distance estimate then it is about 45 thousand light-years across, but if it is at the higher distance suggested by the Hubble Flow velocity and other redshift-independent distance estimates, then it spans about 105 thousand light-years.

Historical Identification: Per Dreyer, NGC 3569 (= GC 5551, d'Arrest, 1860 RA 11 04 24, NPD 53 47.6) is "faint, very small, stellar".
Physical Information:

Historical Identification: Per Dreyer, NGC 3570 (Stephan list IX (#23), 1860 RA 11 04 31, NPD 61 39.0) is "very faint, very small, round, brighter middle".
Physical Information:

Historical Identification: Per Dreyer, NGC 3571 (= GC 2330 = WH II 819, 1860 RA 11 04 32, NPD 107 31.5) is "pretty faint, pretty large, irregular figure, brighter middle".
Physical Information:

Historical Identification: Per Dreyer, NGC 3572 (= GC 2331 = JH 3323, 1860 RA 11 04 33, NPD 149 28.9) is a "cluster, pretty rich, a little compressed".
Physical Information:

Historical Identification: Per Dreyer, NGC 3573 (= GC 2332 = JH 3322, 1860 RA 11 04 40, NPD 126 05.5) is "extremely faint, small, round, gradually a little brighter middle, 3 stars of 11th magnitude to east".
Physical Information:

Historical Identification: Per Dreyer, NGC 3574 (Stephan list IX (#24), 1860 RA 11 04 40, NPD 61 36.9) is "extremely faint".
Physical Information:

Historical Identification: Per Dreyer, NGC 3575 (= GC 5552, d'Arrest, 1860 RA 11 05 44, NPD 66 35.2) is "pretty bright, pretty large, round, 11th magnitude star to west".
Physical Information:

Historical Identification: Per Dreyer, NGC 3576 (= GC 2333 = JH 3324, 1860 RA 11 05 53, NPD 150 37.0) is "faint, a little extended, 1st of 6", the others being NGC 3579, 3581, 3582, 3584 and 3586.
Physical Information:

Historical Identification: Per Dreyer, NGC 3577 (= GC 2334 = WH III 723, 1860 RA 11 05 53, NPD 40 53.5) is "extremely faint, very small, preceding (western) of 2", the other being NGC 3583.
Physical Information:

Historical Identification: Per Dreyer, NGC 3578 (= GC 2335 = JH 837, 1860 RA 11 05 54, NPD 105 11.8) is a "doubtful object, probably a nebula".
Physical Information:

Historical Identification: Per Dreyer, NGC 3579 (= GC 2336 = JH 3325, 1860 RA 11 05 56, NPD 150 28.1) is "faint, a little extended, suddenly brighter middle, 2nd of 6", the others being NGC 3576, 3581, 3582, 3584 and 3586.
Physical Information:

Historical Identification: Per Dreyer, NGC 3580 (= GC 5553, Tempel list I (#32), 1860 RA 11 06 00, NPD 85 35.7) is "very faint, 14th magnitude star to east".
Physical Information:

Historical Identification: Per Dreyer, NGC 3581 (= GC 2337 = JH 3326, 1860 RA 11 06 03, NPD 150 33.0) is a "12th magnitude star with fan-shaped nebula attached, 3rd of 6", the others being NGC 3576, 3579, 3582, 3584 and 3586.
Physical Information:

Historical Identification: Per Dreyer, NGC 3582 (= GC 2338 = JH 3327, 1860 RA 11 06 14, NPD 150 30.6) is "bright, brighter stellar middle, 4th of 6", the others being NGC 3576, 3579, 3581, 3584 and 3586.
Physical Information:

Historical Identification: Per Dreyer, NGC 3583 (= GC 2339 = WH II 728, 1860 RA 11 06 18, NPD 40 51.5) is "pretty bright, pretty large, round, very gradually much brighter middle", implied in the entry for NGC 3577 as being the 2nd of 2. The position precesses to RA 11 14 14.2, Dec +48 22 50, about 3.8 arcmin north of the galaxy listed above, but the description fits and there is nothing else nearby save for NGC 3577, which is (as its NGC entry states) the "1st of 2" if the identification is correct; and as a result, the identification is certain.
Physical Information: Based on a recessional velocity relative to the Cosmic Microwave Background radiation of 2345 km/sec (and H₀ = 70 km/sec/Mpc), NGC 3583 is about 110 million light years away, in good agreement with redshift-independent distance estimates of about 70 to 110 million light years. Given that and its apparent size of about 2.7 by 2.1 arcmin (from the images below), the galaxy is about 85 thousand light years across, though very faint outer parts of the spiral arms extend for perhaps another 10 to 15 thousand light years.
About A Possible Companion: The elliptical galaxy on the northeastern rim of NGC 3583 (PGC 2315061) has a very similar recessional velocity, and may be a physical companion of the grand barred spiral galaxy, so it is discussed in the entry immediately following this one. However, as noted in that entry, dust lanes in the spiral lie in front of the elliptical galaxy, so even if they are physical companions the elliptical definitely lies beyond the spiral; and it might be far enough beyond it that they are merely in the same general region of space.

Designation Note: Although a search of the LEDA database returns a result for this galaxy, NED does not recognize that designation; to search the NED database, use SDSSJ111415.42+481934.3.
Physical Information: Based on a recessional velocity relative to the Cosmic Microwave Background radiation of 2320 km/sec (and H₀ = 70 km/sec/Mpc), PGC 2315061 is about 110 to 115 million light years away, about the same value as obtained for NGC 3583, and the difference in their recessional velocities is only a fraction of typical peculiar velocities (random motions of galaxies relative to each other) in a given region, so they could be at nearly the same distance, and physical companions (on the other hand, dust lanes in the spiral obviously lie in front of the elliptical, so even if they are companions, PGC 2315061 does lie behind the spiral, and it may be far enough behind it to merely be in the same general region of space). Given that and its apparent size of about 0.5 by 0.5 arcmin (from the image below), the galaxy is about 15 thousand light years across, whence its description as a "dwarf" elliptical galaxy.

Historical Identification: Per Dreyer, NGC 3584 (= GC 2340 = JH 3329, 1860 RA 11 06 21, NPD 150 26.7) is "faint, large, extended 0°, brighter middle, 5th of 6", the others being NGC 3576, 3579, 3581, 3582 and 3586.
Physical Information: about 0.25 by 0.25 arcmin

Historical Identification: Per Dreyer, NGC 3585 (= GC 2341 = JH 3328 = WH II 269, 1860 RA 11 06 28, NPD 115 59.9) is "bright, pretty large, extended, very suddenly much brighter middle and nucleus, forming a triangle with 2 bright stars".
Physical Information:

Historical Identification: Per Dreyer, NGC 3586 (= GC 2342 = JH 3330, 1860 RA 11 06 31, NPD 150 35.5) is "extremely faint, small, extended 160°±, 6th of 6", the others being NGC 3576, 3579, 3581, 3582 and 3584.
Physical Information:

Historical Identification: Per Dreyer, NGC 3587 (= GC 2343 = JH 838, Méchain, M97, 1860 RA 11 06 40, NPD 34 13.3) is "a very remarkable object, a planetary nebula, very bright, very large, round, very very gradually then very suddenly bright middle, 150 arcsec diameter".
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:

Historical Identification: Per Dreyer, NGC 3588 (Swift list I (#12), 1860 RA 11 06 45, NPD 68 50.9) is "very faint, considerably small, 4 seconds of time east and 8 arcmin south of δ Leonis".
Physical Information:

Historical Identification: Per Dreyer, NGC 3589 (= GC 2344 = JH 839 = WH III 921, 1860 RA 11 06 52, NPD 28 32.5) is "very faint, large, extended, very gradually brighter middle, in triangle of little (faint) stars".
Physical Information:

Historical Identification: Per Dreyer, NGC 3590 (= GC 2345 = JH 3332, 1860 RA 11 06 59, NPD 150 02.3) is a "cluster, pretty rich, compressed, extended".
Physical Information:

Historical Identification: Per Dreyer, NGC 3591 (= GC 2346 = JH 3331 = WH III 529, 1860 RA 11 07 05, NPD 103 19.8) is "very faint, small, irregularly round, a little brighter middle".
Physical Information:

Historical Identification: Per Dreyer, NGC 3592 (= GC 5554, Marth 216, 1860 RA 11 07 07, NPD 71 58) is "extremely faint, small, pretty much extended, position angle 60°".
Physical Information:

Historical Identification: Per Dreyer, NGC 3593 (= GC 2347 = JH 840 = WH I 29, 1860 RA 11 07 18, NPD 76 25.4) is "bright, considerably large, extended 90±, pretty suddenly much brighter middle".
Physical Information:

Historical Identification: Per Dreyer, NGC 3594 (= GC 2348 = WH III 770, 1860 RA 11 07 26, NPD 33 29.5) is "very faint, very small, stellar".
Physical Information:

Historical Identification: Per Dreyer, NGC 3595 (= GC 2349 = WH III 706, 1860 RA 11 07 30, NPD 41 45.5) is "very faint, very small, very little extended, stellar, considerably bright star to north".
Physical Information:

Historical Identification: Per Dreyer, NGC 3596 (= GC 2350 = JH 841 = WH II 102, 1860 RA 11 07 44, NPD 74 26.9) is "pretty faint, large, round, gradually a little brighter middle".
Physical Information:

Historical Identification: Per Dreyer, NGC 3597 (= GC 2351 = JH 3333, 1860 RA 11 07 49, NPD 112 57.7) is "very faint, pretty small, round, brighter middle".
Physical Information:

Historical Identification: Per Dreyer, NGC 3598 (= GC 5555, Marth 217, Tempel list I (#??), 1860 RA 11 07 50, NPD 71 58) is "faint, very small, stellar, star to north".
Physical Information:

Historical Identification: Per Dreyer, NGC 3599 (= GC 2352 = JH 843 = WH II 49, 1860 RA 11 08 04, NPD 71 07.7) is "bright, pretty small, round, pretty gradually much brighter middle".
Physical Information: