Per Dreyer, NGC 2400 (= Bond (#10, HN 10), 1860 RA 07 22 46, NPD 89 55.7) is one of "two faint nebulae (Auwers 24 & 25), ? very small clusters", the other being NGC 2399. The position precesses to RA 07 29 56.0, Dec -00 12 55, within 0.2 arcmin of the triplet of stars, so the identification is certain. Note: A Wikisky search for NGC 2400 shows a region to the east of the triple star, and does not indicate any NGC label; so use the coordinates to see the correct object.

Per Dreyer, NGC 2401 (= John Herschel's GC 1539, 1860 RA 07 22 57, NPD 103 41.4) is "cluster, small, considerably rich, considerably compressed, stars very small". The position precesses to RA 07 29 24.4, Dec -13 58 35, about 0.6 arcmin south of the "standard" position, but well within the 2 or 3 arcmin diameter of the cluster, so the identification is certain. A 2006 study of the Hertzsprung-Russell Diagram of the cluster down to the 22nd magnitude yielded a distance of 20 thousand light-years and an age of 25 million years, with its Main Sequence extending to B stars, and some indication that its lower mass stars might still be approaching the Main Sequence. This would make it among the youngest clusters in its region. Given its apparent size and distance, the cluster is between 12 and 16 light-years in diameter.

Per Dreyer, NGC 2402 (= John Herschel's GC 1540, 1860 RA 07 23 06, NPD 80 03.4) is "extremely faint, small, round, slightly brighter middle, star involved". The "star involved" could be either of the two stars between the two galaxies, but is probably the brighter one. The position precesses to RA 07 30 46.3, Dec +09 39 17, which agrees with the right ascension of the southwestern galaxy, and the declination of the northeastern one, so the identification is certain. The only question is whether Herschel (and later his son John) saw the combined light of both galaxies, or only that of the brighter one. Since the brighter star is closer to the fainter galaxy, its "involvement" suggests that they saw the entire grouping as a nebula and star; but the galaxies are a gravitationally interacting pair, so it seems appropriate to include both in any discussion of the NGC object whether the Herschels observed the light of both galaxies or only that of the brighter one. Based on a recessional velocity of 5300 km/sec, PGC 21176 is about 245 million light-years away. Given that and its apparent size of 0.8 by 0.8 arcmin, it is about 55 thousand light-years across. The fainter component, PGC 200236, has a recessional velocity of 5225 km/sec, but since peculiar (non-Hubble expansion) galaxy velocities are typically a hundred or more km/sec, the small difference in the galaxies' radial velocity says nothing about their relative distance, save that they must be almost as close in space as they appear in the sky. Even though the quality of the images below is not as good as might be desired, the brighter galaxy definitely shows some signs of gravitational distortion, so the two are probably separated by no more than a few hundred thousand light-years. Given its apparent size of 0.8 by 0.5 arcmin, PGC 200236 is also about 55 thousand light-years across. (Note: NGC 2402 is listed in NED simply as a pair; to access information about the individual galaxies, search for NGC 2402 NED01 and NGC 2402 NED02.)

Per Dreyer, NGC 2403 (= John Herschel's GC 1541, 1860 RA 07 23 15, NPD 24 06.2) is "very remarkable, considerably bright, extremely large, very much extended, very gradually much brighter middle and nucleus". The position precesses to RA 07 36 48.9, Dec +65 35 54, about 0.4 arcmin southwest of the center of the galaxy, but well within its outline, so the identification is certain. NGC 2403's recessional velocity of 130 km/sec is too small in comparison to peculiar (non-Hubble-expansion) velocities to provide a reliable distance indicator. Redshift-independent distance estimates range from 9 to 21 million light-years, with 11 million light-years being the most generally accepted current value. Given that, the apparent size of 22 by 12 arcmin implies that the galaxy is about 70 thousand light-years across. It contains a number of HII (emission) regions associated with various star clusters, one of which is an NGC object in its own right (NGC 2404). Used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type SAB(s)d.

Per Dreyer, NGC 2404 (= Bigourdan (list 1, #28), 1860 RA 07 23 28, NPD 24 00.0) is "very faint, very small". The position precesses to RA 07 37 03.6, Dec +65 42 03, almost 6 arcmin north of the correct position; but per Corwin, this is due to Dreyer's copying the incorrect position in Bigourdan's original paper. When Bigourdan published a massive compilation of all his discoveries he corrected the position, and the offsets he lists from reference stars agree with the corrected position, so the identification is certain. As shown in the images below, NGC 2404 is the largest and brightest emission nebula and "association" of hot bright stars in spiral galaxy NGC 2403. Given that galaxy's roughly 11 million light-year distance, the approximately 0.3 arcmin apparent size of NGC 2404 suggests that it is about 1000 light-years across. (Note: A Wikisky search for NGC 2404 shows the original incorrect NGC position, so use the coordinates above to see the correct region.)

Per Dreyer, NGC 2405 (= Marth 105, 1860 RA 07 23 38, NPD 63 49) is "very faint, small, irregularly round". The position precesses to RA 07 32 13.0, Dec +25 53 29, about 0.9 arcmin southwest of the galaxy listed above. This is a larger than usual error for Marth, but there is nothing else nearby and no one seems to have raised any question about the identification, so it appears to be certain. Based on a recessional velocity of 5665 km/sec, NGC 2405 is about 265 million light-years away. Given that and its apparent size of 0.45 by 0.35 arcmin, the galaxy is about 35 thousand light-years across. Note: Steinicke lists the object as consisting of two components, a spiral galaxy and an elliptical galaxy, and in low resolution images there does appear to be an elliptical galaxy superimposed on the spiral; but the closeup below clearly shows that the superimposed object is a foreground star (namely, the lower star of the pair on the eastern side of the galaxy).

Historical Identification: Per Dreyer, NGC 2406 (= Stephan's list XIII (#30), 1860 RA 07 23 40, NPD 71 25.3) is extremely faint, extremely small, very small nucleus?". The position precesses to RA 07 31 48.1, Dec +18 17 14, less than 0.2 arcmin southeast of the galaxy, so the identification is certain.
Physical Information: Based on a recessional velocity of 8295 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that NGC 2406 is about 385 to 390 million light-years away; but for such distant objects we need to take into account the expansion of the Universe during the time it took the light of the object to reach us. Doing that shows that the galaxy was about 370 to 375 million light-years away when the light by which we see it was emitted, about 380 million years ago (the difference between the two numbers being due to the expansion of the intervening space during that time). Given that and its apparent size of 0.85 by 0.65 arcmin, NGC 2406 is about 90 to 95 thousand light-years across. The galaxy is a Seyfert galaxy (type Sy 2); this may be the reason Stephan thought it had a very small nucleus.

Historical Identification: Per Dreyer, NGC 2407 (= Stephan's list XIII (#31), 1860 07 23 49, NPD 71 22.5) is "extremely faint, extremely small, very small nucleus?". The position precesses to RA 07 31 57.3, Dec +18 20 00, less than 0.2 arcmin east of the center of the galaxy, so the identification is certain.
Physical Information: Based on a recessional velocity of 8405 km/sec (and H₀ = 70 km/sec/Mpc), a straightforward calculation indicates that NGC 2407 is about 390 million light-years away; but for such distant objects we need to take into account the expansion of the Universe during the time it took the light of the object to reach us. Doing that shows that the galaxy was about 375 to 380 million light-years away when the light by which we see it was emitted, about 385 million years ago (the difference between the two numbers being due to the expansion of the intervening space during that time). Given that and its apparent size of 0.95 by 0.85 arcmin, it is about 105 thousand light-years across. As in the case of NGC 2406, NGC 2407 displays a bright core which may explain Stephan's reference to a possible nucleus; but there has been no suggestion that this galaxy might be a Seyfert galaxy.

Per Dreyer, NGC 2408 (= John Herschel's GC 1542, 1860 RA 07 24 36, NPD 18 01.6) is "cluster, very slightly compressed". The position precesses to RA 07 40 30.2, Dec +71 40 01, dead center on the position listed above, so the identification is certain. Per Corwin, the group is probably an irregular fluctuation in the general star field. He states that about two dozen stars of greater than average brightness are scattered over a roughly 25 arcmin wide region centered on the bright star taken as its center by Herschel. Similarly, Gottlieb states that about 50 stars are scattered across a roughly 20 arcmin wide region. I have seen some references that list the group as being only about 10 arcmin in size, but as shown by the images below there is no sign of the group at the smaller size, so the 20+ arcmin size quoted by Corwin and Gottlieb seems a far better estimate (it also better fits the "very slightly compressed" description from the original NGC). Note: A Wikisky search for NGC 2408 shows the correct region, but at such a high magnification that it is impossible to tell what is being shown; so a search using the coordinates is recommended.

Per Dreyer, NGC 2409 (= John Herschel's GC 1543, 1860 RA 07 25 22, NPD 106 54.3) is a "cluster, small but bright, stars from 8th to 10th magnitude". The position precesses to RA 07 31 39.1, Dec -17 11 55, dead center on the group's brightest members, so the identification seems certain. The group is only 2.5 arcmin across, and makes a striking concentration; but given the small number of stars (only 8 or 9) cannot be a true cluster (such a small group would be quickly disrupted by the gravitational effects of passing stars as it orbits the galaxy). Note: A Wikisky search for NGC 2409 shows the correct region, but does not provide any label indicating what, if anything, is the NGC object.

Per Dreyer, NGC 2410 (= Stephan's list VIII, 1860 RA 07 26 00, NPD 56 52.6) is "extremely faint, very small, several very faint stars involved". The second IC adds "= Javelle 1005, faint, extended 250°, 1 arcmin long, gradually brighter middle, mottled but not resolved". There is also a note in the Appendix to the NGC, stating that an overlooked list by Truman Safford included 106 nebulae, fifty-nine of which had already been listed in the NGC with attribution to other individuals. Unfortunately, the Appendix only lists those objects that Safford discovered which had not yet been listed in the NGC; so where he had the right of prior discovery, it was not noted. However, per Steinicke, NGC 2410 is Safford #74, one of the fifty-nine objects for which Safford deserved credit for the original discovery. The position precesses to RA 07 35 02.3, Dec +32 49 24, dead center on the galaxy, so the identification is certain. Based on a recessional velocity of 4680 km/sec, NGC 2410 is about 220 million light-years away, in reasonable agreement with redshift-independent distance estimates of 205 to 210 million light-years. Given that and its 2.35 by 0.7 arcmin apparent size, it is about 150 thousand light-years across. The galaxy is listed as a Seyfert galaxy (type Sy 2).

Per Dreyer, NGC 2411 (= Stephan's list XIII (#32), 1860 RA 07 26 29, NPD 71 25.1) is "14th-magnitude star, slightly nebulous". The position precesses to RA 07 34 36.8, Dec +18 16 54, within 0.1 arcmin of the center of the galaxy, so the identification is certain. Based on a recessional velocity of 5075 km/sec, NGC 2411 is about 235 million light-years away. Given that and its apparent size of 1.1 by 0.65 arcmin, it is about 75 thousand light-years across.

Per Dreyer, NGC 2412 (= J. G. Lohse, 1860 RA 07 26 45, NPD 81 09.4) is "very faint, 8th-magnitude star 59 arcsec and 1.5 seconds of time to the southeast, 13th-magnitude star 10 arcsec away". The position precesses to RA 07 34 21.7, Dec +08 32 36, right on the southern member of the pair, so the identification is certain. As noted by Corwin, such close doubles are easily confused with nebulous objects in normal observing conditions, so it is not surprising that Lohse mistook the pair for a nebula.

Per Dreyer, NGC 2413 (= John Herschel's GC 1544, 1860 RA 07 26 50, NPD 102 47.8) is a "cluster, very large, poor, very slightly compressed". The position precesses to RA 07 33 20.5, Dec -13 05 43, about 1.5 arcmin northeast of the star (9th magnitude HD 60307) taken as the center of the group by Herschel, but well within the 12 to 15 arcmin wide region containing the "cluster". Most observers agree that this is not a true cluster, but merely an accidental concentration of the general star field consisting of two loose groups of stars lying to the north and south of the "central" star. Note: A Wikisky search for NGC 2413 centers on a region to the northeast of the cluster, and no label is shown to indicate its identity; so a search should be based on the listed coordinates.

Per Dreyer, NGC 2414 (= John Herschel's GC 1545, 1860 RA 07 26 50, NPD 105 08.8) is a "cluster, poor, slightly compressed, stars 9th-magnitude etc". The position precesses to RA 07 33 13.0, Dec -15 26 42, about 0.5 arcmin north of the center of the cluster; but given the cluster's size and the difficulty of determining the center of an open cluster, the position might as well be dead center, and the identification is certain. The group consists of several arcs of faint stars spread across a 5 to 6 arcmin wide region centered on 8th magnitude star HD 60308. Fewer than two dozen stars stand out from the general background, and how many of the fainter background stars are associated with the group is unknown.

Per Dreyer, NGC 2415 (= John Herschel's GC 1546, 1860 RA 07 27 43, NPD 54 28.4) is "pretty bright, considerably small, round, very gradually very slightly brighter middle, mottled but not resolved, almost planetary nebular". The position precesses to RA 07 36 55.5, Dec +35 13 16, over a minute of arc to the south of the galaxy, but there is nothing else nearby, and the "almost planetary nebular" appearance certainly fits the appearance of the galaxy, so the identification seems certain. Based on a recessional velocity of 3785 km/sec, NGC 2415 is about 175 million light-years away. Given that and its apparent size of 0.9 by 0.9 arcmin, it is about 45 thousand light-years across.

Per Dreyer, NGC 2416 (= Marth 106, 1860 RA 07 28 05, NPD 78 06) is "extremely faint, small". The position precesses to RA 07 35 51.1, Dec +11 35 44, about 2.6 arcmin to the southeast of the galaxy. Even for Marth, who often made errors of an arcmin or so (per Steinicke, because the 48" equatorial refractor he used was very cumbersome to handle), a 2.6 arcmin error is unusually large; but there is nothing else nearby, and no one seems to have ever expressed any concern about the identification, so it must be presumed reasonably certain. Based on a recessional velocity of 5100 km/sec, NGC 2416 is about 235 million light-years away, somewhat further than redshift-independent distance estimates of 180 to 195 million light-years. Using an intermediate distance of about 200 million light-years, its 1.0 by 0.7 arcmin apparent size would suggest that the galaxy is about 60 thousand light-years across.

Per Dreyer, NGC 2417 (= John Herschel's GC 1547, 1860 RA 07 28 25, NPD 151 57.8) is "very faint, large, round, gradually brighter middle, mottled but not resolved". The position precesses to RA 07 30 08.2, Dec -62 15 34, a little over 1 arcmin southwest of the center of the galaxy, but within its outline, so there has never been any doubt of the identification. Based on a recessional velocity of 3210 km/sec, NGC 2417 is about 150 million light-years away, in good agreement with redshift-independent distance estimates of 110 to 170 million light-years. Given that and its apparent size of 2.8 by 1.9 arcmin, the galaxy is about 120 thousand light-years across.

Per Dreyer, NGC 2418 (= Stephan's list VIII (#21), 1860 RA 07 28 31, NPD 71 48.6) is "very faint, extremely small, brighter middle". The position precesses to RA 07 36 37.3, Dec +17 53 01, dead center on the galaxy, so the identification is certain. Based on a recessional velocity of 5035 km/sec, NGC 2418 is about 235 million light-years away. Given that and its apparent size of 1.8 by 1.8 arcmin, it is about 120 thousand light-years across. The galaxy exhibits some distortion to the north, and considerable distortion to the southeast.

Historical Identification: Per Dreyer, NGC 2419 (= GC 1548 = JH 457 = WH I 218, 1860 RA 07 28 39, NPD 50 48.6) is "pretty bright, pretty large, a little extended 90°, very gradually brighter middle, 7th or 8th magnitude star 4 arcmin distant in direction 267° (nearly due west)." The position precesses to RA 07 38 08.5, Dec +38 52 52, almost dead center on the cluster, and there is a bright star just to the west, so the identification is certain.
Discovery Notes: Per Gottlieb, Lord Rosse's first observation noted that the object seemed to be clearly resolved, but mostly noted that it was more round, as WH thought, rather than elongated, as stated by JH. A note of Feb 13, 1853 adds that "Lord Rosse thought it like a cluster at a great distance," which is indeed the case. It was proven to be an extremely distant globular cluster by Shapley, based on a plate taken at Lowell Observatory in 1922.
Physical Information: NGC 2419 is one of the most distant globular clusters in our galaxy; in fact, until recently it was thought that it might not be a permanent part of our halo at all, and was referred to as "The Intergalactic Wanderer". However, it is now believed that it is orbiting the Milky Way, though in a path which takes it beyond the Magellanic Clouds (it is currently nearly twice as far away as the Large Magellanic Cloud), with an orbital period of around 3 billion years. Based on it and the Sun's relative locations, NGC 2419 is about 290 thousand light-years from the Sun and more than 320 thousand light-years from the galactic center. Given that and its apparent size of nearly 7 arcmin (based on the 12 arcmin wide image below), it is almost 600 light-years across, making it nearly four times the diameter and sixty times the volume of the next largest Milky Way globular, Omega Centauri. Omega Centauri contains ten to fifteen million Solar masses, so if NGC 2419 has a similar stellar density, it could have a mass of well over half a billion Solar masses, more than that of many "dwarf" galaxies (and in fact it is often suggested that it might well be a dwarf galaxy "captured" by our own galaxy, but a 2007 paper by Repepi et al. contradicts this, stating that its properties more accurately fit those of other distant globular clusters that clearly originated with the Milky Way itself; however, a 2013 paper by Lee et al. contradicts that conclusion, so the origin of the cluster is still up in the air, and all we can say is that it is an exceptional object of uncertain origin, though now definitely connected to our galaxy). Even if its concentration of stars is considerably lower than that of Omega Centauri, it must have the best part of a hundred million Solar masses, and far outstrip any other Milky Way globular in every respect. If it were as close as Omega Centauri, it would be a 3rd-magnitude fuzzball two degrees in diameter, and as easily visible to the unaided eye as the Magellanic Clouds; and since it lies north of the Celestial Equator, would be one of the most spectacular objects in the northern sky.
 Per Repepi's paper, most of the mass of the cluster appears to lie with a region about 9 arcmin across, but it appears that some cluster stars lie within a region nearly 20 arcmin across, though there is no distinguishable difference between the overall distribution of stars and field stars at a radius of 15 arcmin (30 arcmin diameter), so the 20 arcmin diameter is probably a more or less absolute upper limit on the extent of the cluster. As noted above, if 7 arcmin across, the cluster would be about 600 light-years in diameter, but if most cluster stars are found within a region of nearly 9 arcmin diameter, and some within a region nearly 20 arcmin in diameter, then the corresponding physical diameters are over 750 light-years for the bulk of the stars in the cluster, and nearly 1700 light-years for the maximum size of the clusters, making it a truly enormous structure, whatever its nature and origin are.
 In opposition to the numbers just listed, Corwin states that aperture photometry only yields a diameter of 4.5 arcmin, which correspons to only 380 light-years, so NGC 2419 may not be as enormous as stated above; however, any estimate of its size and mass is far greater than any other Milky Way globular cluster, so it is still a spectacular object, and would still be a magnificent sight if at a more typical distance.

Per Dreyer, NGC 2420 (= John Herschel's GC 1549, 1860 RA 07 30 06, NPD 68 07.2) is a "cluster, considerably large, rich, compressed, stars from 11th to 18th magnitude". The position precesses to RA 07 38 24.6, Dec +21 34 06, about 0.4 arcmin southeast of the center of the cluster; but in comparison to the size of the cluster and the difficulty of determining its center, the position can be considered to be dead on, and the identification is certain. NGC 2420 is a group of nearly a thousand stars located about 6500 light-years from the Sun. Its superficial appearance is of a central core about 6 arcmin in diameter, with a considerable scattering of stars to about twice that distance; but a detailed study of stars in the neighborhood of the cluster indicates that some members are nearly 20 arcmin from the center, which would correspond to an overall size of nearly 75 light-years, and since the tidal radius of the cluster is even greater than that, the actual number of cluster stars may be considerably larger than the estimate above. However, at least half the mass of the cluster is within 4.5 arcmin of its center, so the "smaller" view does show the most visible cluster members.

Per Dreyer, NGC 2421 (= John Herschel's GC 1550, 1860 RA 07 30 10, NPD 110 18.0) is a "cluster, large, considerably rich, stars from 11th to 13th magnitude". The position precesses to RA 07 36 16.1, Dec -20 36 30, about 1 arcmin north of the "center" of the cluster, but between the size of the cluster and the difficulty of saying where the center is, the position is essentially dead on, and the identification is certain. NGC 2421 is a group of several hundred stars about 7000 light-years from the Sun. The main portion of the cluster is about 6 arcmin in diameter, but the numerous field stars make it difficult to tell its true extent, or which stars are cluster members and which are not. Still, a photometric study of the cluster has been carried out which indicates that it is only about 80 million years old, making it one of the youngest clusters known.

Per Dreyer, NGC 2422 (= John Herschel's GC 1551, 1860 RA 07 30 11, NPD 104 10.5) is a "cluster, bright, very large, pretty rich, stars large and small". The position precesses to RA 07 36 37.4, Dec -14 29 03, about 0.7 arcmin southeast of the center of the cluster; but for an open cluster, between its size and the difficulty of defining a center, this is essentially dead on, and the identification is certain. As far as the obviously complex credit for discovery goes, see the note about Hodierna for an explanation of why none of his observations resulted in an NGC listing. Messier's discovery went unnoticed because he made an error in the calculation of the position which resulted in his being given credit for a nonexistent object which was not recognized as being the same as NGC 2422 until 1959 (see NGC 2478). Given that, by all rights Caroline Herschel should have received contemporary credit for the discovery; but when her brother William rediscovered the object and added it to his catalog, that record resulted in his receiving the credit for the discovery. NGC 2422 consists of about 50 fairly bright stars spread across a region about half a degree in diameter. At its estimated distance of 1600 light-years, this corresponds to a physical diameter of about 15 light-years. The hottest Main Sequence star in the cluster is of spectral type B2; this suggests an age for the cluster of about 80 million years. As shown in the wide-field image below, there are several open clusters in Puppis that are in the same general area.

Per Dreyer, NGC 2423 (= John Herschel's GC 1552, 1860 RA 07 30 38, NPD 103 32.9) is a "cluster, very large, rich, pretty compressed, stars very small". The position precesses to RA 07 37 06.4, Dec -13 51 32, within 0.8 arcmin of the center of the cluster, which as noted for other open clusters, is essentially dead on, so the identification is certain. NGC 2423 is a loose collection of 50 to 60 faint stars spread across a region nearly 20 arcmin wide, lying about 2500 light-years from the Sun. Given the distance and apparent size of the cluster, it has a diameter of about 15 light-years.

Per Dreyer, NGC 2424 (= Stephan's list XIII (#33), 1860 RA 07 31 09, NPD 50 27.0) is "very faint, pretty small, much extended, slightly brightly middle, mottled but not resolved?". The position precesses to RA 07 40 39.6, Dec +39 13 59, dead center on the galaxy, so the identification is certain. Based on a recessional velocity of 3355 km/sec, NGC 2424 is about 155 million light-years away, in good agreement with redshift-independent distance estimates of 155 to 165 million light-years. Given that and its apparent size of 3.5 by 0.55 arcmin, it is about 160 thousand light-years across. The edge-on orientation of the galaxy, even though it agrees with Dreyer's note "much extended", makes accurate classification of the galaxy difficult; hence the question mark about its type.

Per Dreyer, NGC 2425 (= John Herschel's GC 1553, 1860 RA 07 31 52, NPD 104 35.2) is a "cluster, poor, small, stars very small". The position precesses to RA 07 38 17.2, Dec -14 54 03, about 1.4 arcmin south of the "current" center of the cluster; but as for all such clusters, such an "error" is insignificant, and the identification is certain. NGC 2425 appears to consist of about three dozen stars located about 11 thousand light-years from the Sun (this estimate only represents the brighter, more obvious cluster members; there may be far more fainter ones, which do not stand out against the starry background). Given that and its apparent size of 4 arcmin, it is about 13 light-years in diameter. Studies of its Hertzsprung-Russell Diagram suggest that it is between 2 and 2.5 billion years old.

Historical Identification: Per Dreyer, NGC 2426 (= GC 1554 = JH 460 = WH II 822, 1860 RA 07 32 27, NPD 37 20.8) is "considerably faint, round, very gradually brighter middle, mottled but not resolved, 8th magnitude star to west". The position precesses to RA 07 43 19.1, Dec +52 19 49, only 0.7 arcmin north of the center of the galaxy and close to its outer glow, and 8th magnitude HD 233440 lies directly to the west, so the identification is certain.
Physical Information: Based on a recessional velocity of 5675 km/sec, NGC 2426 is about 265 million light-years away. Given that and its apparent size of 1.1 by 1.1 arcmin, it is about 85 thousand light-years across.

Per Dreyer, NGC 2427 (= John Herschel's GC 1555, 1860 RA 07 32 32, NPD 173 18.5) is "extremely faint, large, pretty much extended, gradually much brighter middle, 2 stars involved". The position precesses to RA 07 36 35.4, Dec -47 37 15, about 2 arcmin to the northeast of the center of the galaxy, but close to its very large outline, so the identification is certain. Based on a recessional velocity of 970 km/sec, NGC 2427 is about 45 million light-years away, in good agreement with redshift-independent distance estimates of 35 to 45 million light-years. Given that and its apparent size of 5.2 by 2.2 arcmin, the galaxy is about 65 thousand light-years across.

Per Dreyer, NGC 2428 (= John Herschel's GC 1556, 1860 RA 07 32 56, NPD 106 11.8) is a "cluster, very large, very slightly compressed". The position precesses to RA 07 39 16.1, Dec -16 30 51, about 1.7 arcmin northwest of the center of the cluster, but in comparison to the size of the cluster and the difficulty of determining its center, this is an insignificant error, so the identification is certain. Barely distinguishable from the background stars around it, NGC 2428 is a loose scattering of stars 6 to 12 arcmin across. The group is thought to be about 7000 light-years away, in which case its apparent size corresponds to a physical diameter of 10 to 20 light-years. Note: A Wikisky search for NGC 2428 shows the correct region, but does not display the NGC listing.

Historical Identification: Per Dreyer, NGC 2429 (= Copeland, using Lord Rosse's Leviathan, 1860 RA 07 32 56, NPD 37 18.6) is "pretty faint, pretty small, very much extended, 12th magnitude star attached". The position precesses to RA 07 43 48.2, Dec +52 21 56, only 0.5 arcmin north of the galaxy listed above and the description fits, so the identification is certain. (Note: Although a Wikisky search shows the correct object, it labels it as NGC 2429A. If used only to distinguish it from its companion, which is sometimes called NGC 2429B, using such a label is "reasonable"; but such labels are often used to refer to completely different objects, so their use should be discouraged.)
Physical Information: The galaxy and its fainter southeastern companion (PGC 21663) are obviously distorted and must be a gravitationally interacting pair. Based on a recessional velocity of 5450 km/sec, NGC 2429 is about 250 million light-years away. Given that and its apparent size of 1.7 by 0.35 arcmin, it is about 125 thousand light-years across.

Physical Information: No recessional velocity is listed for PGC 21663, but it and its brighter northwestern companion (NGC 2429, which see for images) are obviously distorted and must be a gravitationally interacting pair, so PGC 21663 must also be about 250 million light-years away. Given that and its apparent size of 0.4 by 0.2 arcmin, it is about 30 thousand light-years across.

Per Dreyer, NGC 2430 (= John Herschel's GC 1557, 1860 RA 07 33 05, NPD 106 01.8) is a "cluster, very large, very slightly compressed". The position precesses to RA 07 39 25.6, Dec -16 20 53, about 5 arcmin southwest of the position listed above. As shown in the images below, there is little to choose between the two positions. Both images show a sparse group of moderately bright stars scattered across a 12 to 15 arcmin wide region, which are probably little more than an accidental enhancement of the starry background. Neither view gives any great impression of an actual cluster of stars, and for that reason many catalogs don't bother to list NGC 2430 as a cluster. However, Corwin feels that the region 5 arcmin to the northeast of Herschel's position looks a little more like Herschel's description than the region centered on Dreyer's precessed position; and Steinicke, agreeing with Corwin, has based the position for the cluster on that opinion. My own view is that what Herschel saw was somewhere in the region shown by the images, but whether it was at the position measured by him or the one suggested by Corwin (or some completely different position) cannot be determined with any confidence, hence my decision to place a question mark after Steinicke's position. Note: Although a Wikisky search for NGC 2430 shows the more or less correct region (depending upon which region you think is the correct one), it does not indicate the NGC listing; but given the uncertainty of the identification, perhaps that is appropriate.

Per Dreyer, NGC 2431 (= John Herschel's GC 1558, 1860 RA 07 34 27, NPD 36 35.0) is "extremely faint, very small, round, brighter middle". The position precesses to RA 07 45 24.4, Dec +53 05 15, almost 3 arcmin northeast of the center of the galaxy; but there is nothing else nearby, so the identification is reasonably certain. (See NGC 2436 for a discussion of the double listing.) Based on a recessional velocity of 5680 km/sec, NGC 2431 is about 265 million light-years away. Given that and its apparent size of 0.9 by 0.9 arcmin, it is about 70 thousand light-years across.

Per Dreyer, NGC 2432 (= John Herschel's GC 1559, 1860 RA 07 34 42, NPD 108 45.6) is a "cluster, pretty large, pretty compressed, extended 0°, stars large and small". The position precesses to RA 07 40 53.8, Dec -19 04 58, about 0.4 arcmin northeast of the center of the cluster; and given the difficulty of determining the center of such objects, such a small "error" means the identification is certain. The cluster consists of a few dozen stars scattered across a 6 to 8 arcmin wide region, but the majority of the stars are in a north-south arc about 5 arcmin high and 2 arcmin wide. A color-magnitude analysis of the central region of NGC 2432 indicates that it is between 4500 and 8500 light-years away, which would make the region studied about 8 to 10 light-years in diameter, and the entire cluster about 12 to 15 light-years across. Based on the turnoff point for the Main Sequence, the age of the cluster is estimated at 200 million years. Note: A Wikisky search for NGC 2432 shows and labels a region nearly 4 arcmin to the southeast; so it is better to use the coordinates to do a search.

Per Dreyer, NGC 2433 (= John Herschel's GC 1560, 1860 RA 07 35 05, NPD 80 24.8) is "extremely faint, with a 15th-magnitude star 90 arcsec to the southwest". A note at the end of the original NGC questions whether Herschel's measurement is correct, or a different one by d'Arrest; however, the first IC adds (per Spitaler) "Herschel's RA is correct". The position precesses to RA 07 42 43.5, Dec +09 15 38, dead on the position of the triple star, and there is a 15th-magnitude (fairly wide) double star to the southwest, so the identification is certain. Despite this there is considerable confusion about the identification of NGC 2433. LEDA lists the object as a nonexistent galaxy at the same position as the triple star (hence the PGC entry for it), while a Wikisky search for NGC 2433 shows a galaxy, but at a completely different location (RA 07 42 56.9, Dec 09 20 52), and with (by necessity) a completely different identification (PGC 21634). Corwin states that LEDA misidentifies the object as a faint galaxy to the northeast (which may be the reason for Wikisky's error), but as stated above, although LEDA misidentifies the object as a galaxy, it does use the position of the triple star. Since different references may give different identifications for the object, a search for NGC 2433 should use the coordinates listed above for the triple star.

Based on a recessional velocity of 18760 km/sec (per LEDA), a straightforward calculation indicates that PGC 21634 is about 875 million light-years away. However, for such distant objects, the expansion of the Universe during the time their light took to reach us must be taken into account. Doing that indicates that PGC 21634 was about 810 million light-years away when the light by which we see it was emitted, about 835 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light's journey). Given that and its apparent size of 0.5 by 0.5 arcmin, PGC 21634 is about 110 thousand light-years across. Note: NED lists the galaxy as a member of Abell 592.

Per Dreyer, NGC 2434 (= John Herschel's GC 1561, 1860 RA 07 35 10, NPD 158 58.1) is "pretty bright, small, round, pretty much brighter middle, three 11th-magnitude stars to north". The position precesses to RA 07 34 51.2, Dec -69 16 57, almost dead center on the galaxy, and there are three stars just to the north, so the identification is certain. Based on a recessional velocity of 1390 km/sec, NGC 2434 is about 65 million light-years away, in good agreement with redshift-independent distance estimates of 55 to 80 million light-years. Given that and its apparent size of 2.5 by 2.3 arcmin, it is about 45 thousand light-years across.

Per Dreyer, NGC 2435 (= John Herschel's GC 1562, 1860 RA 07 35 18, NPD 58 01.2) is "faint, small, slightly brighter middle". The position precesses to RA 07 44 13.5, Dec +31 39 04, dead center on the galaxy, so the identification is certain. Based on a recessional velocity of 4190 km/sec, NGC 2435 is about 195 million light-years away, in fair agreement with redshift-independent distance estimates of 150 to 170 million light-years. Taking an "average" distance of about 180 million light-years, its apparent size of 2.1 by 0.5 arcmin suggests that it is about 110 thousand light-years across.

Per Dreyer, NGC 2436 (= John Herschel's GC 1563, 1860 RA 07 35 19, NPD 37 35.9) is "very faint, very small, round, brighter middle". The position precesses to RA 07 46 07.8, Dec +52 04 12, an almost completely empty area of the sky that contains nothing resembling its description, so there is obviously something wrong with the younger Herschel's position. Per Corwin the probable explanation, based on the essentially identical description of NGC 2431 by William Herschel and NGC 2436 by his son, is that they might have observed the same object, and John simply recorded the Right Ascension 1 minute of time too large, and the North Polar Distance 1 degree too large. Such blunders are common in hand-reductions of positional measurements, and if that is what happened then the 1860 position should have been RA 07 34 19, NPD 36 35.9, and the 2000.0 position would be RA 07 45 16.3, Dec +53 04 22, which is only 0.7 arcmin southwest of the center of NGC 2431. Of course one can never be certain whether such explanations are correct, but in a case like this, where the descriptions match so well and the errors are so "simple", the tentative identity of the two NGC listings seems nearly certain. Given that, see NGC 2431 for a discussion and images of the object. (Note: A Wikisky search for NGC 2436 shows NGC 2431, demonstrating the essentially universal acceptance of this argument.)

Per Dreyer, NGC 2437 (= Messier 46, 1860 RA 07 35 24, NPD 104 29.8) is "a remarkable object, cluster, very bright, very rich, very large, involving a planetary nebula". The position precesses to RA 07 41 49.8, Dec -14 49 19, about 1 arcmin southeast of the center of the cluster, but between the difficulty of determining the center of such an object and the presence of the planetary nebula (NGC 2438) the identification is certain. M46 consists of several hundred stars scattered across a region nearly half a degree across, about 5500 light-years away. Given its distance and apparent size, the cluster is about 50 light-years across. Based on the turnoff point of its Hertzsprung-Russell Diagram, it is thought to have formed about 300 million years ago. As noted above there is a planetary nebula (NGC 2438) located near the northeastern edge of the cluster, but it does not have the same radial velocity as cluster members, and is almost certainly a foreground object (probably only about 3000 light-years away) which just happens to be in the same direction.

Above: A 28 arcmin wide composite of M46 (a Misti Mountain Observatory image superimposed on a wider NOAO view), also showing NGC 2438. (Background Image Credits: N.A.Sharp/AURA/NSF/NOAO; Foreground Image Credits and © Jim Misti, Misti Mountain Observatory; used by permission.) Also see NGC 2422 for a wide-field image showing several clusters in the region

Historical Identification: Per Dreyer, NGC 2438 (= John Herschel's GC 1565, 1860 RA 07 35 26, NPD 104 25.0) is a "planetary nebula, pretty bright, pretty small, very slightly extended, mottled but not resolved, 3.75 sec of time diameter". The position precesses to RA 07 41 52.0, Dec -14 44 31, about 0.5 arcmin southeast of the center of the planetary, but well within its border; and for such a unique feature, even if the measurement lay outside its boundary there would be no doubt of the identification.
PGC Designation Note: For purposes of completeness, LEDA assigns a PGC designation to NGC 2438, even though it is not a galaxy. However, a search of the database returns no result, so the designation is in quotes.
Physical Information: The actual size of the planetary is 1.1 by 1.1 arcmin, slightly larger than the size stated by Dreyer. The central star is an 18th-magnitude white dwarf. As noted for M46, the planetary nebula does not have the same radial velocity as the cluster members. Their radial velocities are all within about 4 km/sec of the same value, while the planetary nebula's radial velocity differs from the average by 30 km/sec; so it is not connected with the cluster, but is instead a foreground object (probably only about 3000 light-years away). Very long exposures show that the nebula has an extended halo, presumably from the expansion and dispersion of an early phase of its formation, while the more easily visible portion probably dates to the death of the red giant which collapsed to form the white dwarf in its center. Given the estimated distance of the nebula and its apparent size, the easily visible portion is about 1 light-year (approximately 60 thousand AUs) in diameter.

Per Dreyer, NGC 2439 (= John Herschel's GC 1566, 1860 RA 07 35 26, NPD 121 19.8) is a "cluster, bright, pretty rich, pretty large, slightly compressed, stars of 9th and 12th through 14th magnitude". The position precesses to RA 07 40 52.0, Dec -31 39 14, almost 3 arcmin to the north of the cluster, but still well within its outline, and close to one of its brightest members; so the identification is certain. A fairly recent study of the cluster indicates that it has over 100 members scattered across a 10 arcmin wide region about 13500 light-years away. Given the supposed distance and apparent size, the cluster is about 40 light-years across. The earliest main sequence star is of type B5, suggesting a relatively young age of about 20 million years.

Historical Identification: Per Dreyer, NGC 2440 (= John Herschel's GC 1567, 1860 RA 07 35 40, NPD 107 53.0) is "planetary nebula, considerably bright, not very well defined". The position precesses to RA 07 41 54.8, NPD -18 12 33, within 0.2 arcmin of the center of the nebula, so the identification is certain.
PGC Designation Note: For purposes of completeness, LEDA assigns a PGC designation to NGC 2438, even though it is not a galaxy. However, a search of the database returns no result, so the designation is in quotes.
Physical Information: NGC 2440 lies about 4000 light-years from the Sun, and given its size (about 74 by 42 arc-seconds), is nearly 100 thousand AUs (approximately 1 1/2 light-years) across its longest dimension, with a central star of 14th magnitude. The planetary nebula must be relatively young, as its white dwarf is one of the hottest known (more than 200 thousand Kelvins, or about 400 thousand Fahrenheit degrees), and despite its small size (about 1/40 the size of the Sun, or 2 to 3 Earth diameters), is about 250 times brighter than our Sun. The complex structure of the nebula (shown in more detail in the second image) indicates several episodes of mass ejection, in different directions. Both HST images are "false-color" images, meant to bring out detail which would not be visible in the essentially monochrome view that the human eye would perceive (even if close to the nebula), but the first is meant to approximate "natural" colors, while the second makes no effort to do so.

Per Dreyer, NGC 2441 (= Tempel's list VI (#1), 1860 RA 07 36 26, NPD 16 40.7) is "very faint, pretty small". The position precesses to RA 07 52 50.7, Dec +72 58 41, about 5 arcmin southeast of the galaxy identified as NGC 2441; but there is nothing else nearby, and no one has expressed any concern about the identification, so it is presumably reasonably certain. Based on a recessional velocity of 3470 km/sec, NGC 2441 is about 160 million light-years away, in better agreement with redshift-independent distance estimates of 125 to 400 million light-years than they are with each other. Given that and its apparent size of 2.0 by 1.7 arcmin, it is about 100 thousand light-years across.

Per Dreyer, NGC 2442 (= John Herschel's GC 1568, 1860 RA 07 36 44, NPD 159 12.8) is "considerably large, very faint, round", and NGC 2443 (= John Herschel's GC 1569, same coordinates) is "pretty large, very faint, round", and the pair are a "double nebula, 40° position angle, double star involved with middle". The position precesses to RA 07 36 20.6, Dec -69 31 56, about 0.8 arcmin west of the center of the galaxy, but well within its very large outline; so the identification is certain. Per Corwin, the reason for the double listing is that on Herschel's first sweep of the area, he observed the southwestern and northeastern parts of the galaxy as two faint nebulae separated by what appeared to be a stellar middle (which part being which is determined by the position angle, which indicates that the second object is to the northeast of the first); and although three subsequent observations stated that the two objects were actually a single large nebula, Dreyer's entry maintained the original double listing. Based on a recessional velocity of 1465 km/sec, NGC 2442/43 is about 68 million light-years away, in reasonable agreement with a redshift-independent distance estimate of 56 million light-years. Given that and its apparent size of 5.5 by 4.9 arcmin, it is about 110 thousand light-years across. Used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type SAB(s)bc pec.

Per Dreyer, NGC 2444 (= Stephan's list VIII (#22), 1860 RA 07 37 26, NPD 50 37.9) is "very faint, much brighter middle". The position precesses to RA 07 46 53.9, Dec +39 01 56, about 0.2 arcmin east of the center of the galaxy, but well within its outline, so the identification is certain. Based on a recessional velocity of 4050 km/sec, NGC 2444 is about 188 million light-years away. Given that and its apparent size of 1.2 by 0.8 arcmin, it is about 65 thousand light-years across. The galaxy is interacting with NGC 2445, hence their designation as Arp 143. Given the apparent magnitude of that interaction, the pair may be within a hundred thousand light-years of each other. Theoretical studies indicate that the two galaxies recently collided and may be about to undergo a second collision, which should eventually result in their merger into a single galaxy. Despite the close interaction (or even collision), NGC 2444's larger mass (about twice that of NGC 2445) has caused it to be much less distorted by their interaction.

Per Dreyer, NGC 2445 (= Stephan's list VIII (#23), 1860 RA 07 37 28, NPD 50 38.9) is "very faint, much brighter middle, small star attached to south". The position precesses to RA 07 46 55.8, Dec +39 00 55, about 0.2 arcmin east of the center of the galaxy and well within its outline, so the identification is certain. Based on a recessional velocity of 4000 km/sec, NGC 2445 is about 186 million light-years away. Given that and its apparent size of 1.4 by 1.1 arcmin, it is about 75 thousand light-years across. The galaxy is interacting with NGC 2444 (which see for images), hence their designation as Arp 143. Given the apparent magnitude of that interaction, the pair may be within a hundred thousand light-years of each other. Theoretical studies indicate that the two galaxies recently collided and may be about to undergo a second collision, which should eventually result in their merger into a single galaxy. Because of its smaller mass (about half that of NGC 2444), NGC 2445 has been more distorted by their interaction. Used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type Pec.

PGC 200237 appears to be a compact galaxy lying between us and NGC 2445 (available images show no interaction between them, but their quality leaves much to be desired, so a closer relationship is possible). Its apparent size is less than 0.1 arcmin; nothing else seems to be available. For images of it and NGC 2445, see NGC 2444.

Per Dreyer, NGC 2446 (= John Herschel's GC 1570, 1860 RA 07 37 36, NPD 35 03.4) is "faint, among 4 stars". The position precesses to RA 07 48 44.8, Dec +54 36 27, about 0.3 arcmin southeast of the center of the galaxy and well within its outline, so the identification is certain. Based on a recessional velocity of 5670 km/sec, NGC 2446 is about 265 million light-years away, in reasonable agreement with redshift-independent distance estimates of 210 to 255 million light-years. Given that and its apparent size of 1.9 by 1.0 arcmin, it is about 150 thousand light-years across.

Per Dreyer, NGC 2447 (= Messier 93, 1860 RA 07 38 39, NPD 113 32.7) is a "cluster, large, pretty rich, slightly compressed, stars from 8th to 13th magnitude". The position precesses to RA 07 44 35.0, Dec -23 52 46, almost 1.5 arcmin south of the putative center of the cluster, but well within its impressive structure, so the identification is certain. M93 is an open cluster which contains nearly a hundred fairly bright stars scattered across a region about 22 arcmin in diameter, around 3600 light-years away. Given that, it must be about 20 to 25 light-years in diameter. The brightest Main Sequence stars in the cluster are of spectral type B9, suggesting that the cluster is about 100 million years old. As shown in the image below, there is a strong concentration of stars near its center, and a sparser scattering to the east.

Per Dreyer, NGC 2448 (= John Herschel's GC 1572, 1860 RA 07 38 41, NPD 114 21.2) is a "cluster of 18 or 20 stars from 11th to 13th magnitude". The position precesses to RA 07 44 34.1, Dec -24 41 16, about 0.4 arcmin south of the putative center of the cluster, but both positions are within the glare of 6th magnitude HD 62747, which is generally taken as the center of the cluster, so the identification is certain. Most observers agree with Dreyer that the "cluster" appears to consist of 18 to 20 stars of 11th to 13th magnitude, scattered across a region about 5 arcmin in diameter. However, it is generally felt that this is not a true cluster, but merely a minor accidental grouping of stars in a region already filled with them, and in the image below stars seem to be randomly scattered across the entire region, without any sign of a particular grouping; so whatever the nature of NGC 2448, it is neither an obvious nor significant object.

Per Dreyer, NGC 2449 (= Stephan's list VI (#9), 1860 RA 07 38 45, NPD 62 43.8) is "extremely faint, extremely small, round, brighter middle, mottled but not resolved". The position precesses to RA 07 47 21.5, Dec +26 55 52, about 0.3 arcmin east of the center of the galaxy but within its outline, so the identification is certain. Based on a recessional velocity of 4890 km/sec, NGC 2449 is about 225 million light-years away. Given that and its apparent size of 1.3 by 0.6 arcmin, it is about 85 thousand light-years across.