Celestial Atlas
(NGC 2450 - 2499) ←NGC Objects: NGC 2500 - 2549 Link for sharing this page on Facebook→ (NGC 2550 - 2599)
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Last updated Nov 26, 2018
WORKING: Updating formatting to current standard
Checked Dreyer NGC entries, updated Steinicke historical/physical data, Corwin positions
NEXT: Update other historical references, uncertain IDs, etc
WORKING 2520: Add basic pix, tags
WORKING 2500: fix photomosaic artifacts

NGC 2500 (= PGC 22525)
Discovered (Mar 9, 1788) by
William Herschel
Also observed (Feb 16, 1831) by John Herschel
A magnitude 11.6 spiral galaxy (type SB(rs)d) in Lynx (RA 08 01 53.2, Dec +50 44 14)
Historical Identification: Per Dreyer, NGC 2500 (= GC 1607 = JH 478 = WH III 709, 1860 RA 07 51 25, NPD 38 52.1) is "faint, large, round, very gradually brighter middle, mottled but not resolved, among stars". The position precesses to RA 08 01 56.6, Dec +50 45 06, a little over an arcmin northeast of the center of the galaxy, but still within its outline, so the identification is certain.
Physical Information: Based on a recessional velocity of 505 km/sec, NGC 2500 is about 24 million light years away, but for small distances peculiar (non-Hubble expansion) velocities can significantly affect the accuracy of such distance estimates. As it happens, the only redshift-independent distance estimate isn't much larger -- just 33 million years -- so the galaxy is probably between 25 and 30 million light years away. Given that and its apparent size of 2.9 by 2.6 arcmin, NGC 2500 is only about 25 thousand light years across. The galaxy is listed in NED as an "isolated" galaxy, meaning one not associated with any other nearby galaxies or groups.
SDSS image of spiral galaxy NGC 2500
Above, a 3 arcmin wide closeup of NGC 2500 (the blue diagonal is a mosaic artifact)
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy NGC 2500
Below, a 4 arcmin wide GALEX ultraviolet image of the galaxy
GALEX image of spiral galaxy NGC 2500

NGC 2501 (= PGC 22354)
Discovered (Feb 14, 1836) by
John Herschel
A magnitude 13.4 lenticular galaxy (type SAB(r)0^0?) in Puppis (RA 07 58 30.0, Dec -14 21 15)
Historical Identification: Per Dreyer, NGC 2501 (= GC 1608 = JH 3108, 1860 RA 07 52 03, NPD 103 59.0) is "considerably faint, small, very little extended 90°, gradually a little brighter middle, among stars". The position precesses to RA 07 58 31.8, Dec -14 21 33, about 0.5 arcmin southeast of the center of the galaxy, but still within its outer glow, so the identification is certain.
Physical Information: Based on a recessional velocity of 2165 km/sec, NGC 2501 is about 100 million light years away. Given that and its apparent size of 1.4 by 0.9 arcmin, it is about 40 thousand light years across.
DSS image of lenticular galaxy NGC 2501
Above, a 2.4 arcmin wide closeup of NGC 2501
Below, a 12 arcmin wide region centered on the galaxy
DSS image of region near lenticular galaxy NGC 2501

NGC 2502 (= PGC 22210)
Discovered (Jan 5, 1837) by
John Herschel
A magnitude 12.0 lenticular galaxy (type SAB(s)0^0) in Carina (RA 07 55 51.6, Dec -52 18 24)
Historical Identification: Per Dreyer, NGC 2502 (= NGC 1609 = JH 3109, 1860 RA 07 52 12, NPD 141 55.2) is "pretty faint, small, round, very gradually pretty much brighter middle". The position precesses to RA 07 55 51.0, Dec -52 17 31, almost 1 arcmin north of the center of the galaxy, but very close to the outline of the galaxy, so the identification is certain.
Physical Information: Based on a recessional velocity of 1065 km/sec, NGC 2502 is about 50 million light years away. Given that and its apparent size of 2.0 by 1.3 arcmin, it is about 30 thousand light years across.
DSS image of lenticular galaxy NGC 2502
Above, a 2.4 arcmin wide closeup of NGC 2502
Below, a 12 arcmin wide region centered on the galaxy
DSS image of region near lenticular galaxy NGC 2502

NGC 2503 (= PGC 22453)
Discovered (Feb 17, 1865) by
Albert Marth
A magnitude 13.7 spiral galaxy (type SAB(rs)bc) in Cancer (RA 08 00 36.7, Dec +22 24 00)
Historical Identification: Per Dreyer, NGC 2503 (= GC 5403, Marth #112, 1860 RA 07 52 20, NPD 67 14) is "extremely faint, small, gradually a little brighter middle". The position precesses to RA 08 00 38.2, Dec +22 23 14, a little less than an arcmin southeast of the center of the galaxy, but the error is typical for Marth, and there is nothing else nearby which he could have seen; so the identification is essentially certain.
Physical Information: Based on a recessional velocity of 5505 km/sec, NGC 2503 is about 260 million light years away. Given that and its apparent size of 1.05 by 1.0 arcmin, the galaxy is about 80 thousand light years across. It is listed in NED as an "isolated" galaxy, meaning one not associated with any other nearby galaxies or groups.
SDSS image of spiral galaxy NGC 2503
Above, a 2.4 arcmin wide closeup of NGC 2503
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy NGC 2503

NGC 2504 (= PGC 22414)
Discovered (Mar 25, 1864) by
Albert Marth
A magnitude 13.3 peculiar galaxy (type S pec?) in Canis Major (RA 07 59 52.3, Dec +05 36 30)
Historical Identification: Per Dreyer, NGC 2504 (= GC 5404, Marth #113, 1860 RA 07 52 27, NPD 84 01) is "very faint, small, round". The position precesses to RA 07 59 53.8, Dec +05 36 17, about 0.4 arcmin southeast of the center of the galaxy, but close enough that the identification is certain.
Physical Information: Based on a recessional velocity of 2620 km/sec, NGC 2504 is about 120 million light years away. Given that and its apparent size of 0.65 by 0.6 arcmin, it is only about 25 thousand light years across.
SDSS image of peculiar galaxy NGC 2504
Above, a 2.4 arcmin wide closeup of NGC 2504
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near peculiar galaxy NGC 2504

NGC 2505 (= PGC 22644)
Discovered (Mar 18, 1790) by
William Herschel
A magnitude 13.2 spiral galaxy (type SBa?) in Lynx (RA 08 04 06.8, Dec +53 32 57)
Historical Identification: Per Dreyer, NGC 2505 (= GC 1610 = WH III 839, 1860 RA 07 53 15, NPD 36 10.5) is "extremely faint, very small". The position precesses to RA 08 04 06.0, Dec +53 26 21, over 6.5 arcmin south of the galaxy. If this was a region with a number of galaxies, a correct identification might be imposible; but there is nothing else nearby, and no one seems to have ever doubted the "official" designation, so the identification appears reasonably certain.
Physical Information: Based on a recessional velocity of 9750 km/sec, a straightforward calculation indicates a distance for NGC 2505 of 455 million light years, but for such distant objects the expansion of the Universe during the time the light took to reach us should be taken into account. Doing that shows that the galaxy was about 438 million light years away when the light by which we see it was emitted, about 445 million years ago (the difference between the two numbers being due to the expansion of the space through which the light traveled while on its journey). Given that and its apparent size of 1.2 by 0.6 arcmin, NGC 2505 is about 150 thousand light years across.
SDSS image of spiral galaxy NGC 2505
Above, a 2.4 arcmin wide closeup of NGC 2505
Below, a 15 arcmin wide region centered on the galaxy; the box at bottom shows Herschel's position
SDSS image of region near spiral galaxy NGC 2505

NGC 2506 (= OCL 593)
Discovered (Feb 23, 1791) by
William Herschel
Also observed (Mar 9, 1828) by John Herschel
Also observed (date?) by Karl Ludwig Harding
Also observed (date?) by Herbert Howe
A magnitude 7.6 open cluster (type I2r) in Monoceros (RA 08 00 02.0, Dec -10 46 24)
Historical Identification: Per Dreyer, NGC 2506 (= GC 1611 = JH 480 = WH VI 37, 1860 RA 07 53 16, NPD 100 14.4) is "a cluster, pretty large, very rich, compressed, stars from 11th to 20th magnitude". A note at the end of the NGC says that Dreyer reduced the NPD from that in the GC by 10 arcmin, to make it better agree with measurements by William Herschel and Harding; but the second IC notes (per Howe) that the GC's NPD of 100 24 was correct. So... using the RA from the NGC and the NPD from the GC, the position precesses to RA 07 59 55.7, Dec -10 46 47, about 1.5 arcmin southwest of the galaxy, but well within the boundary of this magnificent cluster; so the identification is certain.
Physical Information: NGC 2506 consists of several hundred faint stars thickly scattered across a region 8 to 12 arcmin in diameter. The cluster is not very impressive visually, as few of its stars are bright enough to be seen individually, and the rest merely form a faint hazy background; but it is a beautiful photographic object. Several color-magnitude studies have been carried out for NGC 2506, because its position -- several thousand light years further from the center of the galaxy than the Sun -- and the appearance of its Hertzsprung-Russell diagram suggest that it might have a relatively low abundance of heavy atoms (a low "metallicity") compared to clusters nearer the Sun and the center of the galaxy. A 1981 study estimates a distance of 9000 light years, an age of almost 3.5 billion years, and confirms a relatively low metallicity. 1997 and 2007 studies suggest a distance of 11000 light years and an age closer to 2 billion years, but also confirm the object as a low-metallicity cluster, and in fact as typical of a number of such old, distant, metal-poor clusters. Presuming the 11000 light year distance from the more recent studies is correct, the 8 to 12 arcmin apparent size would make NGC 2506 between 25 and 35 light years across.
Observatorio Antilhue image of open cluster NGC 2506
Above, a 12 minute region centered on NGC 2506
(Image Credit & © Daniel Verschatse, Observatorio Antilhue, Chile; used by permission)

NGC 2507 (= PGC 22510)
Discovered (Mar 18, 1786) by
William Herschel
Also observed (Jan 25, 1832) by John Herschel
A magnitude 12.2 lenticular galaxy (type S0/a pec) in Cancer (RA 08 01 37.2, Dec +15 42 35)
Historical Identification: Per Dreyer, NGC 2507 (= GC 1612 = JH 481 = WH II 554, 1860 RA 07 53 40, NPD 73 54.6) is "pretty bright, pretty large, irregularly round, very gradually brighter middle, extremely mottled but not resolved, star 80 arcsec away in position angle 232°". The position precesses to RA 08 01 36.7, Dec +15 42 26, only 0.2 arcmin southwest of the center of the galaxy, so the identification is certain.
Physical Information: Based on a recessional velocity of 4565 km/sec, NGC 2507 is about 210 million light years away. Given that and its apparent size of 2.2 by 1.8 arcmin, it is about 130 thousand light years across.
SDSS image of lenticular galaxy NGC 2507
Above, a 3 arcmin wide closeup of NGC 2507
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy NGC 2507

NGC 2508 (= PGC 22528)
Discovered (Jan 23, 1784) by
William Herschel
Also observed (Jan 18, 1828) by John Herschel
Also observed (date?) by Heinrich d'Arrest
A magnitude 12.7 lenticular galaxy (type E2/S0^0^ pec?) in Canis Minor (RA 08 01 57.2, Dec +08 33 07)
Historical Identification: Per Dreyer, NGC 2508 (= GC 1618 = JH 484 = WH III 7, d'Arrest, 1860 RA 07 54 19, NPD 81 03.8) is "faint, very small, very little extended, 2 stars to west". The position precesses to RA 08 01 54.3, Dec +08 33 09, about 0.7 arcmin west of the galaxy, but within its outer glow, and there are two stars just to its west, so the identification is certain.
Physical Information: Based on a recessional velocity of 4375 km/sec, NGC 2508 is about 205 million light years away. Given that and its apparent size of 1.3 by 1.1 arcmin, it is about 80 thousand light years across. There is a considerable faint extension of the galaxy to the northwest (not seen in the closeup) which suggests some kind of gravitational or collisional interaction, but no other galaxy appears to be nearby, so the cause of the distortion is a mystery.
SDSS image of lenticular galaxy NGC 2508
Above, a 3 arcmin wide closeup of NGC 2508
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy NGC 2508

NGC 2509 (= OCL 630)
Discovered (Dec 3, 1783) by
William Herschel
A magnitude 9.3 open cluster (type II1p) in Puppis (RA 08 00 47.0, Dec -19 03 12)
Historical Identification: Per Dreyer, NGC 2509 (= GC 1613 = WH VIII 1, 1860 RA 07 54 32, NPD 108 41.2) is "a cluster, bright, pretty rich, a little compressed, stars small (faint)". The position precesses to RA 08 00 46.5, Dec -19 04 11, about 1.2 arcmin to the southwest of the center of the cluster, but as usual for such objects, the difficulty of determining a center makes such an error insignificant, so the identification is certain.
Position Note: The position shown above is Corwin's estimate for the core of the cluster, but he puts the center of its overall extent at RA 08 00 50, Dec -19 05 00.
Physical Information: Most estimates of the apparent cluster size are in the range of 10 to 12 arcmin. A 2003 color-magnitude study estimates its distance at just under 3000 light years away, in the Orion arm of the galaxy, in which case its apparent size would correspond to a physical diameter of about 10 light years. The cluster's Main Sequence isochrone and turnoff point indicate an age between 5 and 8 billion years, so its present location has nothing to do with where it was formed.
DSS image of open cluster NGC 2509
Above, a 15 arcmin wide region centered on NGC 2509

NGC 2510 (= PGC 22541)
Discovered (Jan 31, 1851) by
Bindon Stoney
A magnitude 13.4 lenticular galaxy (type S0?) in Canis Minor (RA 08 02 10.7, Dec +09 29 10)
Historical Identification: Per Dreyer, NGC 2510 (= GC 1615, 3rd Lord Rosse, 1860 RA 07 54 33, NPD 80 07.7) is "γ in Lord Rosse's diagram". The position precesses to RA 08 02 11.0, Dec +09 29 12, almost dead center on the galaxy, so the identification is certain.
Discovery Note: Although Dreyer credits the report of the discovery to William Parsons, 3rd Earl of Rosse, he notes that many of Rosse's nebular discoveries were actually made by one of his assistants, in this case Bindon Stoney.
Physical Information: Based on a recessional velocity of 4025 km/sec, NGC 2510 is about 185 million light years away. Given that and its apparent size of 1.0 by 0.7 arcmin, it is about 55 thousand light years across.
SDSS image of lenticular galaxy NGC 2510
Above, a 2.4 arcmin wide closeup of NGC 2510
Below, a 12 arcmin wide region centered on the galaxy; also shown are NGC 2511 and 2513
SDSS image of region near lenticular galaxy NGC 2510, also showing NGC 2511 and NGC 2513

NGC 2511 (= PGC 22549)
Discovered (Jan 31, 1851) by
Bindon Stoney
Also observed (Jan 4, 1862) by Heinrich d'Arrest
A magnitude 14.2 spiral galaxy (type S?) in Canis Minor (RA 08 02 15.0, Dec +09 23 40)
Historical Identification: Per Dreyer, NGC 2511 (= GC 1616, 3rd Lord Rosse, d'Arrest, 1860 RA 07 54 41, NPD 80 12.7) is "extremely faint, III 512 to northeast, (= β) [in Lord Rosse's diagram]", (WH) III 512 being NGC 2513. The position precesses to RA 08 02 18.8, Dec +09 24 11, a little over an arcmin northeast of the center of the galaxy, but even if the error were larger, the reference to NGC 2513 would make the identification certain.
Discovery Note: Although Dreyer credits the report of the discovery to William Parsons, 3rd Earl of Rosse, he notes that many of Rosse's nebular discoveries were actually made by one of his assistants, in this case Bindon Stoney.
Physical Information: Based on a recessional velocity of 4465 km/sec, NGC 2511 is about 210 million light years away. Given that and its apparent size of 0.9 by 0.3 arcmin, it is about 55 thousand light years across.
SDSS image of spiral galaxy NGC 2511
Above, a 2.4 arcmin wide closeup of NGC 2511
Below, a 12 arcmin wide region centered on the galaxy; also shown are NGC 2510 and 2513
SDSS image of region near spiral galaxy NGC 2511, also showing NGC 2510 and NGC 2513

NGC 2512 (= PGC 22596)
Discovered (Feb 10, 1787) by
William Herschel
Also observed (Feb 24, 1827) by John Herschel
A magnitude 13.1 spiral galaxy (type SBb?) in Cancer (RA 08 03 07.8, Dec +23 23 30)
Historical Identification: Per Dreyer, NGC 2512 (= GC 1614 = JH 482 = WH III 605, 1860 RA 07 54 47, NPD 66 13.5) is "very faint, small, irregularly round". The position precesses to RA 08 03 08.2, Dec +23 23 18, within 0.3 arcmin of the center of the galaxy and well within its outline, so the identification is certain.
Physical Information: Based on a recessional velocity of 4700 km/sec, NGC 2512 is about 220 million light years away. Given that and its apparent size of 1.4 by 0.9 arcmin, it is about 90 thousand light years across. The galaxy has an unusually bright, "starburst" nucleus.
SDSS image of spiral galaxy NGC 2512
Above, a 2.4 arcmin wide closeup of NGC 2512
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy NGC 2512

NGC 2513 (= PGC 22555)
Discovered (Mar 3, 1786) by
William Herschel
Also observed (Jan 18, 1828) by John Herschel
A magnitude 11.6 elliptical galaxy (type E3?) in Cancer (RA 08 02 24.7, Dec +09 24 49)
Historical Identification: Per Dreyer, NGC 2513 (= GC 1617 = JH 483 = WH III 512, 1860 RA 07 54 47, NPD 80 12.2) is "faint, small, round, pretty suddenly much brighter middle, mottled but not resolved". The position precesses to RA 08 02 24.8, Dec +09 24 40, almost dead center on the galaxy, so the identification is certain.
Physical Information: Based on a recessional velocity of 4665 km/sec, NGC 2513 is about 215 million light years away, in fair agreement with redshift-independent distance estimates of 165 to 195 million light years. The galaxy is generally stated as being about 2.0 by 1.3 arcmin, but as shown in the images below, there is a considerable glow from its outer regions for half again that distance (making it about 3 by 2 arcmin). Given that and a distance in the range of 200 million light years, it is probably about 175 thousand light years across.
SDSS image of elliptical galaxy NGC 2513
Above, a 3.6 arcmin wide closeup of NGC 2513
Below, a 12 arcmin wide region centered on the galaxy; also shown are NGC 2510 and 2511
SDSS image of region near elliptical galaxy NGC 2513, also showing NGC 2510 and NGC 2511

NGC 2514 (= PGC 22581)
Discovered (Jan 19, 1885) by
Édouard Stephan
A magnitude 13.4 spiral galaxy (type SB(s)bc) in Cancer (RA 08 02 49.6, Dec +15 48 30)
Historical Identification: Per Dreyer, NGC 2514 (Stephan's list XIII (#36), 1860 RA 07 54 53, NPD 73 48.3) is "extremely faint, pretty small, irregularly round, diffuse". The position precesses to RA 08 02 49.9, Dec +15 48 31, almost dead center on the galaxy, so the identification is certain.
Physical Information: Based on a recessional velocity of 4855 km/sec, NGC 2514 is about 225 million light years away. Given that and its apparent size of 1.25 by 1.1 arcmin, the galaxy is about 80 thousand light years across.
SDSS image of spiral galaxy NGC 2514
Above, a 2.4 arcmin wide closeup of NGC 2514
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy NGC 2514

NGC 2515
Recorded (Sep 1, 1852) by
George Bond
A magnitude 12.0 double star in Cancer (RA 08 03 21.3, Dec +20 11 16)
Historical Identification: Per Dreyer, NGC 2515 (= GC 5066, G. P. Bond (11, HN 5), 1860 RA 07 55 13, NPD 69 25.3) is "very faint, cometic". The position precesses to RA 08 03 23.6, Dec +20 11 26, about 0.6 arcmin east of the double star considered to be Bond's object. It was an unfortunately common occurrence for double (or even single) stars to be misidentified as nebular in early Harvard Observatory reports, so the identification is reasonably certain.
Physical Information: Per The Guide Star Catalog v2.3.2 (2006), the western star is magnitude 13.8, while the eastern is magnitude 12.6.
SDSS image of region centered on the double star listed as NGC 2515
Above, a 12 arcmin wide region near "NGC 2515", the double star at center

NGC 2516 (= OCL 776)
Discovered (1751) by
Nicolas Lacaille
Also observed (Dec 26, 1834) by John Herschel
A magnitude 3.8 open cluster (type I3r) in Carina (RA 07 58 12.0, Dec -60 46 24)
Historical Identification: Per Dreyer, NGC 2516 (= GC 1619 = JH 3111, Lacaille's list II #3, 1860 RA 07 56 01, NPD 150 29.2) is "a cluster, very bright, very large, pretty rich, stars from 7th to 13th magnitude". The position precesses to RA 07 58 20.7, Dec -60 52 05, about 7 arcmin south of the center of the cluster, but still well within its field of view, so the identification is certain.
Physical Information: A grouping easily seen with the naked eye in a dark (southern hemisphere) sky, impressive with a pair of binoculars, and spectacular in a low-power telescope (using much more than 50 power, the cluster starts to extend beyond the field of view). More than a hundred bright stars fill its half degree diameter, the brightest of which are 5th-magnitude red giants already near the end of their lives, even though the cluster is only around 135 million years old. The cluster is about 1300 light years away; given that and its apparent size, it is about 12 light years in diameter.
DSS image of open cluster NGC 2516
Above, a 30 arcmin wide region centered on NGC 2516

NGC 2517 (= PGC 22578)
Discovered (Mar 16, 1836) by
John Herschel
A magnitude 11.8 lenticular galaxy (type SAB(rs)0^0) in Puppis (RA 08 02 47.1, Dec -12 19 04)
Historical Identification: Per Dreyer, NGC 2517 (= GC 1620 = JH 3110, 1860 RA 07 56 17, NPD 101 54.8) is "faint, very small, round, between three 13th to 14th magnitude stars". The position precesses to RA 08 02 52.4, Dec -12 18 07, almost an arcmin and a half northeast of the galaxy; but there is nothing else nearby, and the faint stars surrounding the galaxy more or less match the description, so the identification seems certain.
Physical Information: Based on a recessional velocity of 1300 km/sec, NGC 2517 is about 60 million light years away. Given that and its apparent size of 1.5 by 1.1 arcmin, it is about 25 thousand light years across.
DSS image of lenticular galaxy NGC 2517
Above, a 2.4 arcmin wide closeup of NGC 2517
Below, a 12 arcmin wide region centered on the galaxy
DSS image of region near lenticular galaxy NGC 2517

NGC 2518 (= PGC 22800)
Discovered (1886) by
Gerhard Lohse
A magnitude 13.0 lenticular galaxy (type S0?) in Lynx (RA 08 07 20.2, Dec +51 07 54)
Historical Identification: Per Dreyer, NGC 2518 (J. G. Lohse, 1860 RA 07 56 45±, NPD 38 29) is one of "two nebulae (the other being NGC 2519), faint, large, round, gradually brighter middle, with a difference of 42 seconds of time in right ascension". The position precesses to RA 08 07 16.6, Dec +51 07 15, about an arcmin southwest of the only reasonably bright galaxy in the region, so that is almost certainly one of Lohse's "two nebulae", and is generally assigned the designation NGC 2518. (Whether the other object exists, or is a star or group of stars is a matter of some debate, for which see NGC 2519.)
Physical Information: Based on a recessional velocity of 5265 km/sec, NGC 2518 is about 245 million light years away. Given that and its apparent size of 1.2 by 0.95 arcmin, it is about 85 thousand light years across.
SDSS image of lenticular galaxy NGC 2518
Above, a 2.4 arcmin wide closeup of NGC 2518
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy NGC 2518

NGC 2519 (not =
NGC 2518)
Recorded (1886) by Gerhard Lohse
A nonexistent object or group of stars in Lynx (RA 08 07 58.8, Dec +51 07 42)
Historical Identification: Per Dreyer, NGC 2519 (J. G. Lohse, 1860 RA 07 56 45±, NPD 38 29) is one of "two nebulae (the other being NGC 2518), faint, large, round, gradually brighter middle, with a difference of 42 seconds of time in right ascension". NGC 2518 is the only nebula which Lohse could have seen in the region, but per Corwin, there is a small group of stars about 40 seconds to the east which would have appeared about the same size and brightness in Lohse's instrument, and may be what he thought was another nebula. It is equally possible that Lohse was simply trying to see more than his instrument would allow, and there was no other object at all, hence the possibility of a nonexistent object mentioned above. However, since Corwin's suggestion seems reasonable, this entry treats the group of stars as the "missing" NGC 2519. (Note: LEDA lists NGC 2518 and 2519 as being the same object, namely the galaxy shown for the former listing; and following that lead, Wikisky shows the same object in a search for either entry. However, given Lohse's statement that the two nebulae were 42 seconds apart, they cannot be the same object; so whatever NGC 2519 is (or is not), it is not NGC 2518.)
Physical Information: (Steinicke's position corresponds to a single star of magnitude 14.6)
SDSS image of the star or group of stars that may be NGC 2519
Above, a 2.4 arcmin wide closeup of the star/group that Corwin suggests might be NGC 2519
Below, a 12 arcmin wide region centered on the "object"; also partially shown is NGC 2518
SDSS image of region near the star or group of stars that may be NGC 2519, also showing NGC 2518

NGC 2520 (=
NGC 2527 = OCL 685)
Discovered (Dec 9, 1784) by William Herschel (and later listed as NGC 2527)
Also observed (Jan 7, 1831) by John Herschel (and later listed as NGC 2527)
Recorded (Feb 5, 1837) by John Herschel (and later listed as NGC 2520)
A magnitude 6.5 open cluster (type III1p) in Puppis (RA 08 04 56.0, Dec -28 08 06)
Historical Identification: Per Dreyer, NGC 2520 (= GC 1621 = JH 3112, 1860 RA 07 56 49, NPD 117 47.7) is "a cluster, bright, pretty rich, pretty compressed".
Physical Information: Apparent size 10 arcmin.

NGC 2521 (= PGC 22866)
Discovered (Feb 9, 1831) by
John Herschel
A magnitude 12.8 lenticular galaxy (type E/S0?) in Lynx (RA 08 08 49.4, Dec +57 46 11)
Historical Identification: Per Dreyer, NGC 2521 (= GC 1622 = JH 485, 1860 RA 07 57 26, NPD 31 49.8) is "pretty faint, pretty large, round, pretty suddenly brighter middle, 9th magnitude star 3 arcmin to northwest".
Physical Information: Apparent size 1.2 by 0.7 arcmin.
Corwin lists a companion (NGC 2521 NED02) at RA 08 08 48.7, Dec +57 46 27

NGC 2522 (= PGC 22749)
Discovered (Jan 26, 1865) by
Albert Marth
A magnitude 13.8 lenticular galaxy (type S0/a?) in Cancer (RA 08 06 13.4, Dec +17 42 24)
Historical Identification: Per Dreyer, NGC 2522 (= GC 5405, Marth #114, 1860 RA 07 58 11, NPD 71 54) is "very faint, very small, extended, pretty suddenly brighter middle".
Physical Information: Apparent size 1.0 by 0.3 arcmin.

NGC 2523 (= PGC 23128 =
Arp 9)
Discovered (Sep 7, 1885) by Edward Swift
A magnitude 11.9 spiral galaxy (type SB(r)bc) in Camelopardalis (RA 08 15 00.2, Dec +73 34 44)
Historical Identification: Per Dreyer, NGC 2523 (Swift list II (#32), 1860 RA 07 58 38, NPD 15 59.6) is "pretty bright, pretty large, a little extended, a little brighter middle, star near".

Discovery Note: Swift's paper states that Edward Swift was the discoverer.
Physical Information: Based on a recessional velocity of 3470 km/sec, NGC 2523 is about 150 million light years away, in fair agreement with a redshift-independent distance estimate of 125 million light years. Given that and its apparent size of 3.0 by 1.8 arcmin, it is about 130 thousand light years across. The galaxy was used in Halton Arp's Atlas of Peculiar Galaxies as an example of spiral galaxies with split arms. It is also used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type SB(r)b.
NOAO image of spiral galaxy NGC 2523, also known as Arp 9
Above, an approximately 3 arcmin wide view of NGC 2523 (Image Credits: Adam Block/NOAO/AURA/NSF)
Below, a 12 arcmin wide region centered on the galaxy
DSS image of region near spiral galaxy NGC 2523, also known as Arp 9

PGC 22649 (= "NGC 2523A")
Not an NGC object but sometimes called NGC 2523A because in general area of
NGC 2523
A magnitude 13.8 spiral galaxy (type SBc?) in Camelopardalis (RA 08 04 08.4, Dec +74 02 52)
Physical Information: Apparent size 1.0 by 0.7 arcmin.

PGC 23025 (= "NGC 2523B")
Not an NGC object but sometimes called NGC 2523B because in general area of
NGC 2523
A magnitude 14.0 spiral galaxy (type Sb?) in Camelopardalis (RA 08 12 57.3, Dec +73 33 48)
Physical Information: Apparent size 2.0 by 0.3 arcmin.
NOAO image of spiral galaxy PGC 23025, sometimes referred to as NGC 2523B
Above, a closeup of PGC 23025, also known as NGC 2523B (Image Credits: Adam Block/NOAO/AURA/NSF)

PGC 23247 (= "NGC 2523C")
Not an NGC object but sometimes called NGC 2523C because in general area of
NGC 2523
A magnitude 13.3 elliptical galaxy (type E5?) in Camelopardalis (RA 08 17 44.3, Dec +73 19 04)
Physical Information: Apparent size 1.5 by 0.8 arcmin.

NGC 2524 (= PGC 22838)
Discovered (Jan 22, 1877) by
Édouard Stephan
A magnitude 12.7 lenticular galaxy (type S0/a?) in Lynx (RA 08 08 09.6, Dec +39 09 27)
Historical Identification: Per Dreyer, NGC 2524 (= GC 5406, Stephan list VIII (#25), 1860 RA 07 58 48, NPD 50 26.5) is "very faint, small".
Physical Information: Apparent size 1.4 by 1.0 arcmin.

NGC 2525 (= PGC 22721)
Discovered (Feb 23, 1791) by
William Herschel
Also observed (Mar 9, 1828) by John Herschel
A magnitude 11.6 spiral galaxy (type SBc pec?) in Puppis (RA 08 05 38.1, Dec -11 25 38)
Historical Identification: Per Dreyer, NGC 2525 (= GC 1623 = JH 486 = WH III 877, 1860 RA 07 59 01, NPD 101 02.1) is "considerably faint, pretty large, round, very gradually a very little brighter middle, among stars".
Physical Information: Apparent size 3.0 by 2.0 arcmin.

NGC 2526 (= PGC 22778)
Discovered (Mar 25, 1864) by
Albert Marth
A magnitude 13.8 spiral galaxy (type Sab?) in Cancer (RA 08 06 58.6, Dec +08 00 14)
Historical Identification: Per Dreyer, NGC 2526 (= GC 5407, Marth #115, 1860 RA 07 59 26, NPD 81 36) is "very faint, small, much extended".
Physical Information: Apparent size 1.2 by 0.7 arcmin.

Corwin lists a possibly different ID for 2527 than the one below, at RA 08 05 35, Dec -27 55 48
Need to check out his reasoning and add it to the historical identification (when get to that)

NGC 2527 (=
NGC 2520 = OCL 685)
Discovered (Dec 9, 1784) by William Herschel (and later listed as NGC 2527)
Also observed (Jan 7, 1831) by John Herschel (and later listed as NGC 2527)
Recorded (Feb 5, 1837) by John Herschel (and later listed as NGC 2520)
A magnitude 6.5 open cluster (type III1p) in Puppis (RA 08 04 56.0, Dec -28 08 06)
Historical Identification: Per Dreyer, NGC 2527 (= GC 1624 = JH 488 = WH VIII 30, 1860 RA 07 59 28, NPD 117 46.4) is "a cluster, very large, pretty rich, a little compressed, stars from 10th to 15th magnitude".
Physical Information: Given the duplicate entry, see NGC 2520 for anything else.

NGC 2528 (= PGC 22805)
Discovered (Jan 22, 1877) by
Édouard Stephan
A magnitude 13.3 spiral galaxy (type Sb?) in Lynx (RA 08 07 24.9, Dec +39 11 40)
Historical Identification: Per Dreyer, NGC 2528 (= GC 5408, Stephan list VIII (#24), 1860 RA 07 59 44, NPD 50 28.4) is "faint, small, round, brighter middle".
Physical Information: Apparent size 1.5 by 1.5 arcmin.

NGC 2529
Recorded (Jan 29, 1887) by
Guillaume Bigourdan
A nonexistent object in Cancer (RA 08 07 53.4, Dec +17 48 56)
(But see Query below)
Historical Identification: Per Dreyer, NGC 2529 (Bigourdan (list I #35), 1860 RA 07 59 51, NPD 71 47) is "extremely faint (suspected)", 'suspected' presumably meaning that Bigourdan thought he observed something, but wasn't sure. The position precesses to RA 08 07 53.4, Dec +17 48 56 (whence the position listed above), which is on the western edge of NGC 2530, which is not unreasonable, as Bigourdan stated it was only an arcmin to the southwest of that galaxy. However, there is nothing there save for NGC 2530 itself, and during four observation sessions in which Bigourdan saw NGC 2530 each time, he only saw what would have been NGC 2529 once; so the general opinion is that NGC 2529 was the result of trying to see more than what was there to be seen, and does not exist. (Note: Despite its nonexistence, NGC 2529 does crop up occasionally; for instance, a Wikisky search for NGC 2529 shows the galaxy that is actually NGC 2530, but labels it as NGC 2529.)
Query About Position: Corwin lists Bigourdan's position as RA 08 06 57.3, Dec +17 49 43. Need to check Bigourdan's records and see if that's correct, or if Dreyer's position correctly stated Bigourdan's observation.

NGC 2530 (= PGC 22827)
Discovered (Feb 22, 1789) by
William Herschel
Also observed (Mar 17, 1831) by John Herschel
A magnitude 13.6 spiral galaxy (type SBcd?) in Cancer (RA 08 07 55.6, Dec +17 49 06)
Historical Identification: Per Dreyer, NGC 2530 (= GC 1625 = JH 487 = WH VIII 752, 1860 RA 07 59 54, NPD 71 46.5) is "extremely faint, a little extended, a very small (faint) star to the north". The position precesses to RA 08 07 56.5, Dec +17 49 25, which lies on the northern arm of the galaxy, and there is a faint star just to the north, so the identification is certain. Despite this, there is some confusion about the proper listing for the galaxy, as both NGC 2529 and 2531, which do not exist, are occasionally misidentified as the galaxy properly listed as NGC 2530; for instance, a Wikisky search for NGC 2531 shows NGC 2530, labeled as NGC 2529.
Physical Information: Apparent size 1.4 by 0.9 arcmin.
SDSS image of spiral galaxy NGC 2530, which is occasionally misidentified as NGC 2529 or 2531
Above, a 2.4 arcmin wide closeup of NGC 2530
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy NGC 2530, which is occasionally misidentified as NGC 2529 or 2531

NGC 2531
Recorded (Jan 29, 1887) by
Guillaume Bigourdan
A nonexistent object in Cancer (RA 08 07 59.4, Dec +17 48 55)
(But see Query below)
Historical Identification: Per Dreyer, NGC 2531 (Bigourdan (list I #36), 1860 RA 07 59 57, NPD 71 47) is "very faint". The position precesses to RA 08 07 59.4, Dec +17 48 55 (hence the position listed above), which lies just east of NGC 2530, which is to be expected, as Bigourdan stated it was an arcmin east of that galaxy. However, there is nothing there save for NGC 2530 itself, and during four observation sessions in which Bigourdan saw NGC 2530 each time, he only saw what would have been NGC 2531 once; so the general opinion is that NGC 2531 was the result of trying to see more than what was there to be seen, and does not exist. (Note: Despite its nonexistence, NGC 2531 does crop up occasionally; for instance, a Wikisky search for NGC 2531 shows NGC 2530, labeled as NGC 2529.)
Query About Bigourdan's Position: Corwin lists Bigourdan's position as RA 08 07 55.7, Dec +17 50 02. As in the case of NGC 2529, this does not agree with the NGC position. Need to check Bigourdan's published paper.

NGC 2532 (= PGC 22922)
Discovered (Feb 5, 1788) by
William Herschel
Also observed (Jan 22, 1827) by John Herschel
A magnitude 12.4 spiral galaxy (type SBc?) in Lynx (RA 08 10 15.2, Dec +33 57 24)
Historical Identification: Per Dreyer, NGC 2532 (= GC 1626 = JH 489 = WH II 726, 1860 RA 08 01 16, NPD 55 38.2) is "pretty bright, pretty large, round, very gradually a little brighter middle, mottled but not resolved, 2 stars to northeast".
Physical Information: Apparent size 1.9 by 1.4 arcmin.

NGC 2533 (= OCL 695)
Discovered (Jan 22, 1835) by
John Herschel
A magnitude 7.6 open cluster (type III1p) in Puppis (RA 08 07 06.0, Dec -29 52 42)
Historical Identification: Per Dreyer, NGC 2533 (= GC 1627 = JH 3113, 1860 RA 08 01 22, NPD 119 29.9) is "a cluster, pretty large, rich, compressed, stars of 9th and 13th to 14th magnitude".
Physical Information: Apparent size 6.0 arcmin.

NGC 2534 (= PGC 23024)
Discovered (Mar 18, 1790) by
William Herschel
Also observed (Feb 10, 1831) by John Herschel
A magnitude 12.9 elliptical galaxy (type E1 pec?) in Lynx (RA 08 12 54.1, Dec +55 40 20)
Historical Identification: Per Dreyer, NGC 2534 (= GC 1628 = JH 490 = WH III 840, 1860 RA 08 01 49, NPD 33 54.8) is "pretty faint, pretty large, round, pretty suddenly brighter middle, 8th magnitude star at position angle 164°".
Physical Information: Apparent size 1.0 by 1.0 arcmin.

NGC 2535 (= PGC 22957, and with
NGC 2536 = Arp 82)
Discovered (Jan 22, 1877) by Édouard Stephan
A magnitude 12.8 spiral galaxy (type SA(r)c pec) in Cancer (RA 08 11 13.5, Dec +25 12 25)
Historical Identification: Per Dreyer, NGC 2535 (= GC 5409, Stephan list VIII (#26), 1860 RA 08 02 48, NPD 64 23.0) is "extremely faint, very small, round".
Physical Information: An interacting pair with NGC 2536, which is almost certainly the cause of its extended arms (particularly the very long one lying to its northwest), and led to its listing as Arp 82. Based on the nearly identical recessional velocities of the galaxies (4095 km/sec for NGC 2535 and 4120 km/sec for NGC 2536), the pair is about 190 million light years away. Given that and its apparent size of 2.5 by 1.2 arcmin, NGC 2535 is about 140 thousand light years across.
SDSS image of spiral galaxies NGC 2535 and 2536, also known as Arp 82
Above, a 4 arcmin wide closeup of NGC 2535 and 2536
Below, a 12 arcmin wide region centered on the larger galaxy; note the extended arm to the northwest
SDSS image of region near spiral galaxies NGC 2535 and 2536, also known as Arp 82

NGC 2536 (= PGC 22958, and with
NGC 2535 = Arp 82)
Discovered (Jan 22, 1877) by Édouard Stephan
A magnitude 14.2 spiral galaxy (type SB(rs)c pec) in Cancer (RA 08 11 15.9, Dec +25 10 46)
Historical Identification: Per Dreyer, NGC 2536 (= GC 5410, Stephan list VIII (#27), 1860 RA 08 02 51, NPD 64 24.6) is "very faint, very small, round".
Physical Information: An interacting pair with NGC 2535, which see for the distance calculation of about 190 million light years. Given that and its apparent size of 0.8 by 0.4 arcmin, NGC 2536 is about 45 thousand light years across.
SDSS image of spiral galaxy NGC 2536 and the southeastern arm of NGC 2535, which comprise Arp 82
Above, a 2.4 arcmin wide closeup of NGC 2536 and part of NGC 2535 (which see for a wider image)

NGC 2537 (= PGC 23040 =
Arp 6), The "Bear's Paw" Nebula
Discovered (Feb 6, 1788) by William Herschel
Also observed (Mar 19, 1828) by John Herschel
A magnitude 11.7 spiral galaxy (type SB(s)m pec) in Lynx (RA 08 13 14.6, Dec +45 59 30)
Historical Identification: Per Dreyer, NGC 2537 (= GC 1629 = JH 491 = WH IV 55, 1860 RA 08 03 19, NPD 43 35.6) is "a globular cluster, pretty bright, pretty large, round, well resolved, clearly consisting of stars, stars of 20th magnitude". (A DSS image of the galaxy shows a bright round object with a number of stars scattered around its periphery, so it might well have appeared to be a globular cluster to the Herschels. However, better images show that the stars visible to Herschel are foreground objects in our own galaxy, and NGC 2537 is actually a galaxy.)
Physical Information: The recessional velocity of NGC 2537 is only 430 km/sec, which is too small to be a reliable measure of its distance, since peculiar (non-Hubble-expansion) velocities can be a substantial fraction of the value. However, the Hubble velocity distance estimate of 20 million light years is reasonably close to redshift-independent distance estimates of 22 to 29 million light years. Assuming an "average" distance of 25 million light years, NGC 2537's apparent size of 1.7 by 1.5 arcmin suggests that the galaxy is about 12 thousand light years across. The galaxy is the last of six chosen by Halton Arp for his Atlas of Peculiar Galaxies as an example of spiral galaxies of low surface brightness, hence its designation as Arp 6. It is also used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type SB(s)m pec/BCD.
SDSS image of spiral galaxy NGC 2537, also known as Arp 6, or the Bear's Paw Nebula
Above, a 2.4 arcmin wide view of NGC 2537
Below, a 12 arcmin wide region centered on the galaxy, also showing PGC 23057
SDSS image of region near spiral galaxy NGC 2537, also known as Arp 6, or the Bear's Paw Nebula, also showing PGC 23057, which is sometimes referred to as NGC 2537A

PGC 23057 (= "NGC 2537A")
Not an NGC object, but sometimes called NGC 2537A because of its proximity to
NGC 2537
A magnitude 15.4 spiral galaxy (type SBc?) in Lynx (RA 08 13 41.0, Dec +45 59 38)
Physical Information: Apparent size 0.6 by 0.6 arcmin. Although in the same general direction as NGC 2537, and hence sometimes referred to as NGC 2537A, PGC 23057 is around half a billion light years away, and is a much larger, far more distant object.

NGC 2538 (= PGC 22962)
Discovered (Feb 2, 1877) by
Édouard Stephan
A magnitude 12.6 spiral galaxy (type SBa?) in Canis Minor (RA 08 11 23.1, Dec +03 37 59)
Historical Identification: Per Dreyer, NGC 2538 (= GC 5411, Stephan list VIII (#28), 1860 RA 08 04 03, NPD 85 57.2) is "very faint, very small, round, much brighter middle".
Physical Information: Apparent size 1.5 by 1.2 arcmin.

NGC 2539 (= OCL 611)
Discovered (Jan 31, 1785) by
William Herschel
Also observed (Feb 14, 1836) by John Herschel
A magnitude 6.5 open cluster (type II1m) in Puppis (RA 08 10 33.0, Dec -12 48 24)
Historical Identification: Per Dreyer, NGC 2539 (= GC 1630 = JH 3114 = WH VII 11, 1860 RA 08 04 08, NPD 102 25.0) is "a cluster, very large, rich, a little compressed, stars from 11th to 13th magnitude".
Physical Information: Apparent size 15 arcmin.

NGC 2540 (= PGC 23017)
Discovered (Feb 10, 1885) by
Édouard Stephan
A magnitude 13.5 spiral galaxy (type SBc?) in Cancer (RA 08 12 46.5, Dec +26 21 42)
Historical Identification: Per Dreyer, NGC 2540 (Stephan list XIII (#37), 1860 RA 08 04 18, NPD 63 13.3) is "very faint, pretty large, irregularly round, brighter middle, mottled but not resolved".
Physical Information: Apparent size 1.3 by 0.9 arcmin.

NGC 2541 (= PGC 23110)
Discovered (Mar 9, 1788) by
William Herschel
Also observed (Mar 7, 1831) by John Herschel
A magnitude 11.8 spiral galaxy (type SBc?) in Lynx (RA 08 14 40.1, Dec +49 03 42)
Historical Identification: Per Dreyer, NGC 2541 (= GC 1631 = JH 492 = WH III 710, 1860 RA 08 04 26, NPD 40 30.3) is "faint, large, extended, very gradually brighter middle".
Physical Information: Apparent size 6.3 by 3.2 arcmin.

NGC 2542 (= 19 Puppis)
Discovered (Dec 11, 1836) by
John Herschel
A magnitude 4.7 star in Puppis (RA 08 11 16.3, Dec -12 55 37)
Historical Identification: Per Dreyer, NGC 2542 (= GC 1632 = JH 3115, 1860 RA 08 04 42, NPD 102 30.9) is "a nebulous 5th magnitude star".
Physical Information:

NGC 2543 (=
IC 2232 = PGC 23028)
Discovered (Feb 3, 1788) by William Herschel (and later listed as NGC 2543)
Also observed (Feb 7, 1832) by John Herschel (and later listed as NGC 2543)
Also observed (Dec 24, 1891) by Rudolf Spitaler (while listed as NGC 2543)
Discovered (Feb 12, 1896) by Stephane Javelle (and later listed as IC 2232)
A magnitude 11.9 spiral galaxy (type SBb?) in Lynx (RA 08 12 57.9, Dec +36 15 16)
Historical Identification: Per Dreyer, NGC 2543 (= GC 1633 = JH 493 = WH II 719, 1860 RA 08 04 51, NPD 53 19.4) is "faint, pretty large, irregularly round, very gradually brighter middle, double star near". An NGC note quotes JH as having reduced h's RA by 1m for a 1m reduction error, which brings it nearer to Auwers' position. First IC lists corrected RA (per Spitaler) of 08 03 46.
Discovery Note: Auwers stated "(JH) doubts the identity (of WH II 719); its position is uncertain."
Physical Information: Apparent size 2.3 by 1.2 arcmin.

NGC 2544 (= PGC 23453)
Discovered (Sep 7, 1885) by
Lewis Swift
A magnitude 12.9 spiral galaxy (type SBa?) in Camelopardalis (RA 08 21 40.4, Dec +73 59 18)
Historical Identification: Per Dreyer, NGC 2544 (Swift list II (#33), 1860 RA 08 05 03, NPD 15 36.4) is "most extremely faint, pretty small, round, several bright stars around".
Physical Information: Apparent size 1.1 by 0.8 arcmin.
Corwin lists an apparent companion (PGC 23462) at RA 08 21 58.7, Dec +73 59 53

NGC 2545 (= PGC 23086)
Discovered (Jan 11, 1787) by
William Herschel
Also observed (Feb 24, 1827) by John Herschel
A magnitude 12.4 spiral galaxy (type SBab?) in Cancer (RA 08 14 14.2, Dec +21 21 20)
Historical Identification: Per Dreyer, NGC 2545 (= GC 1634 = JH 494 = WH II 627, 1860 RA 08 06 03, NPD 68 13.5) is "faint, small, a little extended 45°, 8th magnitude star 4 arcmin to northwest".
Physical Information: Apparent size 2.2 by 1.2 arcmin.

NGC 2546 (= OCL 726)
Discovered (1751) by
Nicolas Lacaille
Also observed (May 8, 1826) by James Dunlop
Also observed (Feb 1, 1835) by John Herschel
A magnitude 6.3 open cluster (type III2m) in Puppis (RA 08 12 24.0, Dec -37 37 00)
Historical Identification: Per Dreyer, NGC 2546 (= GC 1635 = JH 3116, Lacaille II #4, Dunlop #563, 1860 RA 08 06 26, NPD 126 58.4) is "a cluster, bright, large, a little compressed, irregularly extended, stars from 9th to 12th magnitude".
Query Re Position: Corwin lists two positions, one for NGC 2546 at RA 08 11 31, Dec -37 25.2, and the other for a northern 'component' (sub-cluster?) at RA 08 11 38, Dec -37 22.6; presumably because of the "irregularly extended" structure of the cluster.
Physical Information: Apparent size 70 arcmin.

NGC 2547 (= OCL 753)
Discovered (1751) by
Nicolas Lacaille
Also observed (May 28, 1826) by James Dunlop
Also observed (Dec 28, 1834) by John Herschel
A magnitude 4.7 open cluster (type II2p) in Vela (RA 08 10 04.0, Dec -49 13 30)
Historical Identification: Per Dreyer, NGC 2547 (= GC 1636 = JH 3117, Lacaille III #2, Dunlop #411, 1860 RA 08 06 32, NPD 138 51.0) is "a cluster, bright, large, a little compressed, stars from 7th to 16th magnitude".
Query re historical position: Corwin lists two positions by JH, one at RA 08 10 21, Dec -49 14.2, and the other at RA 08 10 56, Dec =49 17.6.
Physical Information: Apparent size 25 arcmin.

NGC 2548 (=
M48 = OCL 584)
Discovered (Feb 19, 1771) by Charles Messier (unnoticed until 1934)
Rediscovered (before 1782) by Johann Bode (unnoticed by Dreyer)
Discovered (Aug 3, 1783) by Caroline Herschel (and later listed as NGC 2548)
Also observed (Feb 1, 1786) by William Herschel
Also observed (Mar 12, 1826) by John Herschel
A magnitude 5.8 open cluster (type I2m) in Hydra (RA 08 13 43.1, Dec -05 45 02)
Corwin gives the position as RA 08 13 33, Dec -05 45 24
Historical Identification: Per Dreyer, NGC 2548 (= GC 1637 = JH 496 = WH VI 22, Caroline Herschel II, 1860 RA 08 06 50, NPD 95 22.5) is "a cluster, very large, pretty rich, pretty much compressed, stars from 9th to 13th magnitude". The position precesses to RA 08 13 44.8, Dec -05 47 41, essentially dead center on the cluster, in comparison to its large size, so the identification is certain. Dreyer's attribution of the discovery to Caroline Herschel was a matter of careless error and good luck. Although Messier is the first person known to have seen the cluster, his reduction of the position had a declination error of nearly four degrees, so even though Dreyer noted the absence of M48 in the NGC in the introduction to the first Index Catalog, mentioning "M48, 1860 RA 08 06 54, NPD 91 32.1, cluster of small stars", he had no reason to realize that the object had already been listed as Caroline Herschel's NGC 2548. In fact, the identity of the two objects wasn't realized until Oswald Thomas pointed it out in 1934, and even then wasn't generally accepted until the idea was independently suggested in 1959. So Messier's M48 was "lost" for nearly two centuries, despite being "known" under another name throughout practically the entire time. As for the good luck, Caroline Herschel's observation was a year or so later than Johann Bode's, but being the sister of William Herschel (in fact, it was her nebular discoveries that inspired him to take up his great work on the subject) her observation was of course recorded in his catalog, and in his son John's General Catalog, upon which the NGC was based; so Dreyer was aware of her observation right from the start, while either remaining ignorant of Bode's paper, or not noticing it until after the NGC was published (in which case, per his usual practice, he would not have bothered to mention the earlier discovery).
Physical Information: NGC 2548 is about 1500 light years away. Most of its stars are concentrated within a half degree region, but outliers extend to about 54 arcmin, which corresponsds to 25 light years across at the distance of the cluster. Based on the spectra of its brightest stars (of spectral class A2, and perhaps 70 solar masses) it is thought to be about 300 million years old.
DSS image of the core of open cluster NGC 2548, now also known as M48
Above, a half degree wide view of the central condensation of NGC 2548
Below, a 54 arcmin wide view of the entire cluster
DSS image of open cluster NGC 2548, now also known as M48

NGC 2549 (= PGC 23313)
Discovered (Feb 9, 1831) by
John Herschel
A magnitude 11.2 lenticular galaxy (type S0?) in Lynx (RA 08 18 58.4, Dec +57 48 11)
Historical Identification: Per Dreyer, NGC 2549 (= GC 1638 = JH 495, 1860 RA 08 07 38, NPD 31 46.1) is "pretty bright, small, much extended 0°, pretty suddenly much brighter middle".
Physical Information: Apparent size 3.8 by 1.2 arcmin.
SDSS image of lenticular galaxy NGC 2549
Above, a 4 arcmin wide closeup of NGC 2549
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near lenticular galaxy NGC 2549
Celestial Atlas
(NGC 2450 - 2499) ←NGC Objects: NGC 2500 - 2549→ (NGC 2550 - 2599)