Historical Identification: Per Dreyer, NGC 3400 (= GC 2220 = JH 768 = WH II 361, 1860 RA 10 43 03, NPD 60 47.4) is "pretty faint, small, round, brighter middle".
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Historical Identification: Per Dreyer, NGC 3401 (= WH III 88, 1860 RA 10 43 04±, NPD 83 28) is "extremely faint (not verified)".
Corwin lists a possible trio of stars at RA 10 50 03.8, Dec +05 47 06
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Historical Identification: Per Dreyer, NGC 3402 (Common (#6), 1860 RA 10 43 11, NPD 101 56) is "faint, round".
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Historical Identification: Per Dreyer, NGC 3403 (= GC 2221 = JH 767 = WH II 335, 1860 RA 10 43 15, NPD 15 34.6) is "pretty faint, large, irregularly extended, very gradually brighter middle".
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Historical Identification: Per Dreyer, NGC 3404 (Common (#7), 1860 RA 10 43 17, NPD 101 08) is "pretty bright, very large, extended east-west".
The second IC lists a corrected NPD (per Howe) of 101 22.0.
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Historical Identification: Per Dreyer, NGC 3405 (= GC 5537, Marth 206, 1860 RA 10 43 18, NPD 73 01) is "faint, extremely small, almost stellar, close to small (faint) star".
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Some references mistakenly list this galaxy as part of NGC 3405. In addition, they typically use the wrong PGC designations for the two galaxies, and sometimes assign the right ascension and/or declination for one to the other. However, there is no doubt that PGC 32418 is the fainter, northeastern "member" of the apparent pair.

Historical Identification: Per Dreyer, NGC 3406 (= GC 2222 = JH 771, 1860 RA 10 43 18, NPD 38 13.9) is "pretty bright, round, pretty gradually brighter middle".
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Historical Identification: Per Dreyer, NGC 3407 (= GC 2223 = JH 769 = WH III 919, 1860 RA 10 43 20, NPD 27 53.1) is "very faint, very small, round, very small (faint) star near".
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Historical Identification: Per Dreyer, NGC 3408 (= GC 2224 = JH 770 = WH III 913, 1860 RA 10 43 21, NPD 30 49.8) is "very faint, considerably small, round, 2 pretty bright stars to south".
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Historical Identification: Per Dreyer, NGC 3409 (Leavenworth list II (#426), 1860 RA 10 43 26, NPD 106 17.5) is "extremely faint, small, extended 200°, 2 very faint stars involved".
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Historical Identification: Per Dreyer, NGC 3410 (4th Lord Rosse, 1860 RA 10 43 28, NPD 38 15) is "faint, pretty small, diffuse, 2 arcmin southeast of h771", h771 being NGC 3406.
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Historical Identification: Per Dreyer, NGC 3411 (= GC 2228 = JH 776 = WH III 522, 1860 RA 10 43 29, NPD 102 06.5) is "faint, small, round, a little brighter middle".
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Historical Identification: Per Dreyer, NGC 3412 (= GC 2229 = JH 774 = WH I 27, 1860 RA 10 43 29, NPD 75 50.9) is "bright, small, a little extended 135°±, suddenly much brighter middle and nucleus".
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Historical Identification: Per Dreyer, NGC 3413 (= GC 2232 = WH II 493, d'Arrest, 1860 RA 10 43 33, NPD 56 29.5) is "faint, small".
The second IC notes "3413 is = Javelle 1167".
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Historical Identification: Per Dreyer, NGC 3414 (= GC 2227 = JH 773 = WH II 362, 1860 RA 10 43 35, NPD 61 17.1) is "bright, pretty large, round, much brighter middle".
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Historical Identification: Per Dreyer, NGC 3415 (= GC 2225 = JH 772 = WH II 718, 1860 RA 10 43 36, NPD 45 32.8) is "pretty bright, small, very little extended, stellar, 3 small (faint) stars near".
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Historical Identification: Per Dreyer, NGC 3416 (= GC 2226, 3rd Lord Rosse, 1860 RA 10 43 37, NPD 45 29) is "extremely faint (perhaps faint star?), north of h772", h772 being NGC 3415.
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Historical Identification: Per Dreyer, NGC 3417 (= GC 5538, Marth 207, 1860 RA 10 43 41, NPD 80 48) is "extremely faint, very small, almost stellar".
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Historical Identification: Per Dreyer, NGC 3418 (= GC 2230 = JH 775 = WH II 363, 1860 RA 10 43 42, NPD 61 08.8) is "considerably faint, small, round, brighter middle".
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Historical Identification: Per Dreyer, NGC 3419 (= GC 5539, Marth 208, Tempel list I (#??), 1860 RA 10 43 54, NPD 75 18.7) is "faint, very small, round, almost stellar, small (faint) star very near".
Discovery Notes: Dreyer's failure to mention Herschel's supposed observation in the NGC means that it was identified at a later or even far later time; that also suggests that the observation is of uncertain quality, so this entry may involve considerably more information and/or speculation when it is finished. For now, the attribution to Herschel should probably be treated as tentative. Physical Information:

Historical Identification: Per Dreyer, NGC 3421 (Common (#8), 1860 RA 10 43 57, NPD 101 29) is one of "2 nebulae, faint, round", the other being NGC 3422. The second IC says of NGC 3421-22 "Only one seen by Howe, RA 10 44 00, NPD 101 42.4, two suspected north and southwest of it."
Discovery Note: See IC 652 for a discussion of the duplicate listing.
Physical Information: Apparent size 1.7 by 1.4 arcmin.

Historical Identification: Per Dreyer, NGC 3422 (Common (#8), 1860 RA 10 43 57, NPD 101 29) is one of "2 nebulae, faint, round", the other being NGC 3421.
The second IC says of NGC 3421-22 "Only one seen by Howe, RA 10 44 00, NPD 101 42.4, two suspected north and southwest of it."
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Historical Identification: Per Dreyer, NGC 3423 (= GC 2234 = JH 777 = WH IV 6 = WH II 131, 1860 RA 10 43 58, NPD 83 25.0) is "faint, very large, round, very gradually brighter middle, partially resolved (some stars seen)".
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Historical Identification: Per Dreyer, NGC 3424 (= GC 2235 = JH 778 = WH II 494, 1860 RA 10 44 00, NPD 56 21.6) is "pretty faint, pretty large, a little extended, southwestern of 3", the second being NGC 3430, but there is no "third", as discussed in the entry for NGC 3430.
Discovery Notes: As discussed in the entry for NGC 3430, d'Arrest's examination of the area near NGC 3424 and 3430 was crucial in proving the nonexistence of the "third" galaxy mentioned in the NGC entries; hence the need to list the date of his observation above.
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Historical Identification: Per Dreyer, NGC 3425 (= GC 2237 = WH III 108, Tempel list I (#??) and list V (#??), 1860 RA 10 44 00, NPD 80 43.0) is "extremely faint, extremely small, round".
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Historical Identification: Per Dreyer, NGC 3426 (Swift list VI (#37), 1860 RA 10 44 05, NPD 70 46.4) is "pretty faint, small, round, double star to north".
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Historical Identification: Per Dreyer, NGC 3427 (Tempel list I (#29) & list V (#??), 1860 RA 10 44 10, NPD 81 00.0) is a "nebula, no description".
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Historical Identification: Per Dreyer, NGC 3428 (= GC 5540, Marth 209, 1860 RA 10 44 10, NPD 79 59) is "very faint, small, a little extended, gradually a little brighter middle".
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Historical Identification: Per Dreyer, NGC 3429 (Common (#9), 1860 RA 10 44 12, NPD 80 00.0) is "pretty faint, round".
Physical Information: Given the duplicate listing, see NGC 3428 for anything else.

Historical Identification: Per Dreyer, NGC 3430 (= GC 2236 = JH 779 = GC 2239 = JH 782 = WH I 118, 1860 RA 10 44 23, NPD 56 18.5) is "pretty bright, large, irregularly extended, gradually brighter middle, 2nd of 3", the first of three being NGC 3424, but there is no "third" (see Discovery Notes).
Discovery Notes: In John Herschel's General Catalog, GC 2235, 2236 and 2239 were listed as the southwestern, 2nd and northeastern of three nebulae, but in Dreyer's 1877 Supplement to the GC he states that GC 2239 is to be struck out, as per d'Arrest's discussion of the region, it is a duplicate of GC 2236; hence the line equating the two in the NGC listing. As a result, there are only two galaxies in "the line of three" discussed in the GC, and the reference to "southwestern of 3" for NGC 3424 and "2nd of 3" for NGC 3430 is an inadvertent carry-over of the incorrect description in the GC.
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Historical Identification: Per Dreyer, NGC 3431 (Leavenworth list II (#428), 1860 RA 10 44 26, NPD 106 16.5) is "extremely faint, small, extended 130°, gradually brighter middle".
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Historical Identification: Per Dreyer, NGC 3432 (= GC 2238 = JH 780 = WH I 172, 1860 RA 10 44 36, NPD 52 38.5) is "pretty bright, pretty large, very much extended 40°, double star close to southwest". The position precesses to RA 10 52 29.5, Dec +36 36 59, 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 615 km/sec (and H₀ = 70 km/sec/Mpc), NGC 3432 is almost 30 million light-years away, in good agreement with redshift-independent distance estimates of about 25 to 55 million light-years. Given that and its apparent size of about 6.5 by 1.0 arcmin (from the images below), it is about 55 thousand light-years across. Probably due to a relatively recent encounter with another galaxy (perhaps its southwestern companion), NGC 3432 is filled with numerous regions of star formation. With that apparent companion, PGC 32617, it is listed as Arp 206, as an example of a galaxy with material ejected from the nucleus. Note: The galaxy type is reasonably certain, but since it is almost exactly edge-on to our line of sight, it might be given a slightly different classification if we could see it face-on, hence the question mark added to its stated type.

Physical Information: Based on a recessional velocity of 765 km/sec (and H₀ = 70 km/sec/Mpc), PGC 32617 is about 35 million light-years away, in reasonable agreement with the distance of its apparent companion, NGC 3432 (though their Hubble distances are a little different, they are very likely to be at nearly the same distance, and simply moving at 150 or so km/sec relative to each other). Given that and its apparent size of about 1.15 by 0.75 arcmin (from the image below), it is about 12 to 15 thousand light-years across, making it a dwarf galaxy.

Historical Identification: Per Dreyer, NGC 3433 (= GC 2240 = JH 783 = WH III 20, 1860 RA 10 44 43, NPD 79 06.0) is "very faint, very large, round, very gradually brighter middle".
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Historical Identification: Per Dreyer, NGC 3434 (= GC 2241= JH 784 = WH III 497, 1860 RA 10 44 44, NPD 85 28.0) is "faint, pretty small, round, very gradually a little brighter middle".
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Historical Identification: Per Dreyer, NGC 3435 (= GC 2242 = JH 781 = WH II 887, 1860 RA 10 44 55, NPD 27 58.4) is "considerably faint, pretty small, a little extended, very gradually brighter middle".
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Historical Identification: Per Dreyer, NGC 3436 (Todd (#6), 1860 RA 10 44, NPD 81 18) is "extremely small".
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Historical Identification: Per Dreyer, NGC 3437 (= GC 2243 = JH 786 = WH II 47, 1860 RA 10 45 01, NPD 66 19.6) is "pretty bright, pretty large, a little extended 120°, gradually brighter middle".
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Historical Identification: Per Dreyer, NGC 3438 (= GC 5541, Marth 210, 1860 RA 10 45 06, NPD 78 43) is "very faint, extremely small, almost stellar".
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Historical Identification: Per Dreyer, NGC 3439 (= GC 5542, Marth 211, 1860 RA 10 45 06, NPD 80 43) is "most extremely faint, very small, almost stellar".
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Historical Identification: Per Dreyer, NGC 3440 (= GC 2244 = JH 785 = WH III 914, 1860 RA 10 45 11, NPD 32 08.5) is "very faint, small, a little extended".
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Historical Identification: Per Dreyer, NGC 3441 (Holden (#2), 1860 RA 10 45 13, NPD 82 03) is "pretty bright".
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Historical Identification: Per Dreyer, NGC 3442 (Stephan list XIII (#59), 1860 RA 10 45 20, NPD 55 20.8) is "faint, very small, round, much brighter middle, mottled but not resolved?"
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Historical Identification: Per Dreyer, NGC 3443 (Swift list VI (#38), 1860 RA 10 45 24, NPD 71 49.3) is "most extremely faint, very small, round".
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Historical Identification: Per Dreyer, NGC 3444 (= GC 5543, Marth 212, 1860 RA 10 45 39, NPD 79 04) is "extremely faint, very small, pretty much extended".
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Historical Identification: Per Dreyer, NGC 3445 (= GC 2245 = JH 787 = WH I 267, 1860 RA 10 45 58, NPD 32 16.3) is "considerably bright, pretty large, irregularly round, very gradually a little brighter middle, 10th magnitude star 2 arcmin to northeast." The position precesses to RA 10 54 35.7, Dec +56 59 05, slightly below the southern rim of the nucleus of the galaxy listed above but well within its overall outline, the description is a perfect fit and there is nothing comparable nearby, so the identification is certain.
Discovery Note: As pointed out by Gottlieb, Mitchell observed the nebula with the 3rd Lord Rosse's 72-inch "Leviathan", and among other things noted (and sketched) a "streak south-following", which is obviously the physically interacting companion, PGC 32784. This means that though not part of NGC 3445, or (as noted in the next paragraph) of Arp 24, PGC 32784 is in Corwin's list of "notngc" objects — objects that were discovered prior to the publication of the NGC, but never became part of it or its supplements.
Usage By The Arp Atlas: NGC 3445 is used by the Arp Atlas as an example of a one-armed spiral galaxy. Though it is probably interacting with PGC 32784, that galaxy is not part of Arp 24, but merely a companion of its larger neighbor.
Physical Information: Based on a recessional velocity relative to the Cosmic Microwave Background radiation of 2210 km/sec (and H₀ = 70 km/sec/Mpc), NGC 3445 is about 100 to 105 million light-years away, in good agreement with redshift-independent distance estimates of about 55 to 105 million light-years. Given that and its apparent size of about 1.45 by 1.25 arcmin (from the images below), the galaxy is about 40 to 45 thousand light-years across. (Note: The third galaxy shown in the images below, PGC 2554198, is roughly 635 million light-years from us, and is therefore a much more distant background object.)

Discovery Note: As noted in the entry for NGC 3445, Mitchell noted (and sketched) the faint streak to the southeast of the larger galaxy, but presumably because no position was published for it, it was not included in either the GC or NGC, and wasn't cataloged until over a century later (as MCG +10-16-024). As a result, it is one of the numerous objects in Corwin's "notngc" list of objects discovered before the publication of the NGC, but not included in that catalog or its supplements.
(Non-)Usage By The Arp Atlas: Most references (e.g., LEDA and NED) list PGC 32784 as part of Arp 24 (= NGC 3445); however, although it is probably an interacting companion of that galaxy, there is absolutely nothing in Arp's catalog to justify its being considered part of the Arp object. Arp 24 is classified as a one-armed spiral galaxy (NGC 3445), but in cases where a small second galaxy was involved, Arp classified the pair as a spiral galaxy with a small high or low surface brightness companion. Since he did not classify Arp 24 as a pair of any sort, PGC 32784 cannot be part of Arp 24, hence the warning about that in the title for this entry.
Physical Information: There is some disagreement about the recessional velocity of PGC 32784. LEDA and SIMBAD list values (relative to the Cosmic Microwave Background) of about 2085 and 2045 km/sec, while NED lists a value of only 1900 km/sec, despite stating that this is a member of a pair with NGC 3445, which has a recessional velocity of 2210 km/sec. The first two values would suggest that the two galaxies are a pair, in which case they would have to be at the same distance, and any difference in their recessional velocities would be due to their "peculiar velocities" (random motions relative to their neighbors, unrelated to the Hubble Flow recessional velocity). The HST image showing both galaxies (below) shows what appears to be a filament connecting the pair, also suggesting that they are a physical pair. Given that, I have chosen to ignore the disagreement in the recessional velocities, and to just assume that PGC 32784 is at the same distance (roughly 100 to 105 million light-years away) from us as NGC 3445. Given that and its apparent size of about 0.6 by 0.2 arcmin (from the images below), PGC 32784 is about 18 thousand light-years across (give or take a thousand or so).
Classification Note: Most references list this galaxy as type Sm (with or without a question mark), but SIMBAD lists it as Sm/Im? There is nothing in the images on this page to indicate which is more likely to be correct, so I have used the double classification from SIMBAD.

Historical Identification: Per Dreyer, NGC 3446 (= GC 2246 = JH 3301, 1860 RA 10 45 59, NPD 134 24.4) is a "cluster, pretty large, poor, a little compressed, irregular figure, stars from 9th to 13th magnitude".
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Historical Identification: Per Dreyer, NGC 3447 (= GC 2247 = JH 3300, 1860 RA 10 46 00, NPD 72 29.5) is "extremely faint, very large, very gradually very little brighter middle, bright double star to southwest".
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Historical Identification: Per Dreyer, NGC 3448 (= GC 2248 = JH 788 = WH I 233, 1860 RA 10 46 10, NPD 34 57.1) is "bright, pretty large, much extended 67°.0, gradually brighter middle".
Physical Information: Based on a recessional velocity of 1350 km/sec, NGC 3448 is about 65 million light-years away, in fair agreement with a redshift-independent distance estimate of 80 million light-years. (Its apparent companion, PGC 32740, has a recessional velocity of 1495 km/sec, which corresponds to a distance of 70 million light-years.) Given that and its apparent size of 2.6 by 1.0 arcmin, the main galaxy is about 50 thousand light-years across, and the entire complex listed as Arp 205, which is 8.0 by 1.1 arcmin, is about 150 thousand light-years across. Used by the Arp Atlas as an example of a galaxy (NGC 3448) with material (PGC 32740) ejected from its nucleus.
Classification Note: Steinicke lists this as type S0/a (lenticular).

Historical Identification: Per Dreyer, NGC 3449 (= GC 2249 = JH 3302, 1860 RA 10 46 20, NPD 122 11.0) is "faint, small, round, 6.7 magnitude star to southeast".
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