Celestial Atlas
(NGC 3550 - 3599) ←     NGC Objects: NGC 3600 - 3649 Link for sharing this page on Facebook     → (NGC 3650 - 3699)
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Page last updated Sep 16, 2015
Done with NGC and all other Dreyer papers, GC notes, S 150910 discovery and Corwin positions
WORKING 3630: Update discovery information as needed based on the above
WORKING 3634: comments by Corwin)
WORKING 3619: Update everything to current standards
WORKING 3609: Comparing NGC entries to the original observations

NGC 3600 (= PGC 34353)
Discovered (Jan 14, 1788) by
William Herschel
Also observed (Apr 12, 1830) by John Herschel
A magnitude 11.7 spiral galaxy (type Sa?) in Ursa Major (RA 11 15 52.0, Dec +41 35 28)
Historical Identification: Per Dreyer, NGC 3600 (= GC 2353 = JH 842 = WH II 709, 1860 RA 11 08 07, NPD 47 38.5) is "pretty faint, small, a little extended 0°±, very gradually brighter middle" (save for round-off errors in the position, this is the same as the GC entry). The position precesses to RA 11 15 52.3, Dec +41 35 45, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Discovery Notes: William Herschel's position was only about 3.7 arcmin southeast of the galaxy despite his comparison star (56 UMa) being over 2 degrees away, his description (pretty bright, small, a little extended, brighter middle) is a good fit, and as already noted there is nothing else nearby, so the cross-identification of WH II 709 as GC 2353 and NGC 3600 is certain.
Physical Information: The 720 km/sec recessional velocity of NGC 3600 is too small to give a reliable distance, as peculiar (non-Hubble expansion) velocities can be a substantial portion of the value. Still, the corresponding distance of 30 to 35 million light years is in reasonable agreement with redshift-independent distance estimates of 35 to 50 million light years. Given that and its apparent size of about 4.1 by 0.8 arcmin, it is about 40 thousand light years across.
SDSS image of region near spiral galaxy NGC 3600
Above, a 12 arcmin wide SDSS image centered on NGC 3600
Below, a 4.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3600
Below, a 1.4 by 2.2 arcmin wide HST image of the galaxy's core (Image Credit Hubble Legacy Archive)
HST image of the central portion of spiral galaxy NGC 3600

NGC 3601 (= PGC 34335)
Discovered (Mar 22, 1865) by
Albert Marth
A magnitude 13.8 spiral galaxy (type SAB(rs)bc?) in Leo (RA 11 15 33.3, Dec +05 06 56)
Historical Identification: Per Dreyer, NGC 3601 (= GC 5556, Marth 218, 1860 RA 11 08 19, NPD 84 08) is "very faint, pretty small, almost stellar" (this is exactly the same as the entry in Marth's paper). The position precesses to RA 11 15 33.0, Dec +05 06 15, only 0.7 arcmin south of the galaxy listed above, the description is reasonable and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 8165 km/sec, a straightforward calculation indicates that NGC 3601 is about 380 million light years away. (NED lists a second radial velocity of 7860 km/sec, but the uncertainty in the two values is almost the same as their difference, and LEDA only lists the larger value.) However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was 365 to 370 million light years away at the time the light by which we see it was emitted, 370 to 375 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 0.85 by 0.55 arcmin, the galaxy is about 90 thousand light years across.
SDSS image of region near spiral galaxy NGC 3601
Above, a 12 arcmin wide SDSS image centered on NGC 3601
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3601

NGC 3602 (= PGC 34351)
Discovered (Mar 4, 1865) by
Albert Marth
A magnitude 15.0 spiral galaxy (type Sab?) in Leo (RA 11 15 48.3, Dec +17 24 58)
Historical Identification: Per Dreyer, NGC 3602 (= GC 5557, Marth 219, 1860 RA 11 08 27, NPD 71 49) is "most extremely faint, very small, almost stellar" (this is exactly the same as the entry in Marth's paper). The position precesses to RA 11 15 49.7, Dec +17 25 15, less than half an arcmin northeast of the galaxy listed above, the description is a reasonable fit and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 5995 km/sec, NGC 3602 is about 280 million light years away. Given that and its apparent size of about 0.8 by 0.2 arcmin, the galaxy is about 65 thousand light years across.
SDSS image of region near spiral galaxy NGC 3602
Above, a 12 arcmin wide SDSS image centered on NGC 3602
Below, a 0.8 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3602

NGC 3603 (= OCL 854 = "PGC 3518662")
Discovered (Mar 14, 1834) by
John Herschel
A magnitude 9.1 nebula and open cluster (type I1pn) in Carina (RA 11 15 07.3, Dec -61 15 39)
Historical Identification: Per Dreyer, NGC 3603 (= GC 2354 = JH 3334, 1860 RA 11 09 07, NPD 150 29.7) is a "globular cluster and nebula, stars 15th to 18th magnitude" (save for round-off errors in the position, this is the same as the GC entry). The position precesses to RA 11 15 07.6, Dec -61 15 38, less than 0.7 arcmin south southeast of the cluster listed above, the description fits and there is nothing comparable nearby so the identification is certain.
Physical Information: NGC 3603 is a young cluster of stars surrounded by clouds of gas and dust out of which it formed, which it is heating and lighting up. Located in the Carina arm of our galaxy, the nebula and cluster are about 20 thousand light years away, making them appear deceivingly unimpressive in comparison with much closer objects of similar nature. Given its distance and apparent brightness NGC 3603 is thought to be the intrinsically brightest star-forming region in our galaxy. The more than fifty O and B stars in the cluster contain several thousand solar masses and more than 100 times the ionizing power of the Trapezium, which energizes the much closer and therefore more famous Orion Nebula. The cluster's most massive "star" is actually a binary whose components have 116 and 89 solar masses, and orbit each other once every 3.77 days (which, using Kepler's Third Law, implies a separation of 26 million miles); as of 2015, this is the most massive binary star known in our galaxy.
     Normally clusters that contain very massive stars have relatively few lower-mass stars, because they take longer to form; but in this case a recent "starburst" of stellar formation has created large numbers of lower mass stars, as well as several massive stars. The oldest stars in the cluster are thought to be a few million years old, but the stars formed in the most recent episode of stellar formation are less than a million years old, and perhaps as young as only 300 thousand years. The cluster has an apparent size of 1.2 by 1 arcmin and is only about 7 light years in diameter, but the surrounding nebula has an apparent size of about 8 by 3.7 arcmin, which corresponds to about 45 light years. LEDA lists NGC 3603 as a cluster with the designation PGC 3518662, but a search of the database for that designation returns no result.
DSS image of region near open cluster NGC 3603, primarily showing the surrounding nebulosity
Above, a 12 arcmin wide DSS image centered on NGC 3603
Below, a roughly 8.5 arcmin wide image centered about 1.2 arcmin north of the cluster (Image Credit ESO)
ESO image of region near open cluster NGC 3603 and its surrounding nebulosity
Below, a roughly 2.2 by 2 arcmin wide HST image of the cluster (North at upper right)
(Image Credit NASA, ESA, R. O'Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy),
E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee,
and the Hubble Heritage Team (STScI/AURA) HubbleSite)

HST image of open cluster NGC 3603 and part of its surrounding nebulosity
Below, a 3.1 arcmin wide HST image of the cluster and part of the nebula (North at upper right)
(Image Credit NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration
Acknowledgment: J. Maíz Apellániz (Institute of Astrophysics of Andalucía, Spain))

HST image of region near open cluster NGC 3603, also showing part of the surrounding nebulosity

NGC 3604 (=
NGC 3611 = PGC 34478)
Discovered (Jan 27, 1786) by William Herschel (and later listed as NGC 3611)
Also observed (Apr 7, 1828) by John Herschel (and later listed as NGC 3611)
Also observed (Nov 3, 1877) by David Todd (and later listed as NGC 3611)
Discovered (Dec 30, 1786) by William Herschel (and later listed as NGC 3604)
Looked for but not found by Guillaume Bigourdan (while listed as NGC 3604)
A magnitude 12.2 spiral galaxy (type (R)SA(s)a? pec) in Leo (RA 11 17 30.2, Dec +04 33 20)
Historical Identification: Per Dreyer, NGC 3604 (= GC 2355 = WH II 626, 1860 RA 11 09 08, NPD 84 42.6) is "pretty bright, small, a little extended, much brighter middle" (save for round-off errors in the position, this is the same as the GC entry). The position precesses to RA 11 16 21.6, Dec +04 31 37, in a completely stellar field, and as a result of the problems discussed below it was decades before it was identified (by Reinmuth) as a duplicate of NGC 3611. However (per Corwin), the error in the elder Herschel's position was only a minute of time, and he made the same error for WH III 598 (= NGC 3509), found on the same night. Using a position one minute of time to the east of Herschel's original position places II 626 just over 2 arcmin southwest of the galaxy listed above, the description fits, there is nothing else nearby and the corresponding error for NGC 3509 makes the duplicate listing of NGC 3604 and 3611 certain.
Discovery Notes: Dreyer's note in 1912's "The Scientific Papers of Sir William Herschel" states "Not found by Bigourdan. Should probably be rejected, together with III 88 and III 598, the only other nebulae found this night, as there was fog ‘which indeed was so strong as to make everything swim about me’." (Bigourdan searched for NGC 3604 on March 28 and April 28 of 1894, and again on April 30 of 1907, repeatedly stating that no object of class II existed anywhere near the NGC position.)
Additional Note: An oddity noted by Corwin is that Dreyer's 1912 statement that WH III 88 was observed on the same night is wrong, as it was actually observed 2 1/2 years earlier, and Herschel only recorded two discoveries on Dec 30 of 1786. So what, if anything (taking into account the possibility that it was merely an editing error), Dreyer meant by "III 88" is a mystery.
About The Proper NGC Designation: Although NGC 3604 was not identified as a duplicate of NGC 3611 until decades after the NGC was published, modern usage almost invariably assigns duplicate entries to the lowest NGC number, so although this object should probably be called NGC 3611 (corresponding to its more accurate position), it is usually called NGC 3604. However, some references (such as LEDA) do list it as NGC 3611.
Physical Information: Based on a recessional velocity of 1585 km/sec, NGC 3604 is 70 to 75 million light years away, in fair agreement with redshift-independent distance estimates of 90 to 130 million light years. Given that and its apparent size of about 2.25 by 1.3 arcmin, the main part of the galaxy is 45 to 50 thousand light years across; however, the approximately 3.5 by 3.4 arcmin apparent size of its partial outer ring corresponds to about 75 thousand light years. (The fragmentary structure near the 10th magnitude star north northwest of NGC 3604 has a somewhat different recessional velocity, and is therefore thought to be an unrelated irregular galaxy (PGC 34476).)
SDSS image of region near spiral galaxy NGC 3604, also showing PGC 34476
Above, a 12 arcmin wide SDSS image centered on NGC 3604, also showing PGC 34476
Below, a 4.5 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3604

NGC 3605 (= PGC 34415)
Discovered (Mar 14, 1784) by
William Herschel
Also observed (Mar 25, 1827) by John Herschel
Also observed (Apr 18, 1882) by Édouard Stephan
A magnitude 12.3 elliptical galaxy (type E4?) in Leo (RA 11 16 46.6, Dec +18 01 02)
Historical Identification: Per Dreyer, NGC 3605 (= GC 2356 = JH 844 = WH III 27, 1860 RA 11 09 24, NPD 71 13.2) is "faint, small, round, southwestern of 3" (the description is the same as in the GC, but the position is a rough conversion of Stephan's position), the others being NGC 3607 and 3608. The position precesses to RA 11 16 46.9, Dec +18 01 00, right on the galaxy listed above, the description fits and there is nothing else nearby save the other nebulae mentioned in the description so the identification is certain.
Discovery Notes: William Herschel gave the same position for all three of the objects he observed in this region (III 27, II 50 and II 51), only distinguishing between them by his descriptions of the southern, middle and northern of the three. His position falls just east of the middle and brightest of the three (namely, NGC 3607), so there is no doubt which three galaxies he observed, and from their relative positions, which corresponds to which GC (and NGC) object. As a result, it is certain that NGC 3605 = GC 2356 = JH 844 is indeed III 27. The GC position was reasonably good, but Stephan's position for what he thought was a "nova" (namely, his list XII #43) was even better, and though not mentioned by Dreyer, it was essentially Stephan's position that he used in the NGC entry, not the one published in the GC. For that reason, the date of Stephan's observation is listed above.
Physical Information: The 660 km/sec recessional velocity of NGC 3605 is too small in comparison to peculiar (non-Hubble expansion) velocities to be a reliable indicator of its distance, and the corresponding distance of about 30 million light years is in poor agreement with redshift-independent distance estimates of 55 to 85 million light years, so I have adopted a provisional distance of about 70 million light years. Given that and its apparent size of about 1.1 by 0.65 arcmin, NGC 3605 is 20 to 25 thousand light years across.
SDSS image of region near elliptical galaxy NGC 3605, also showing NGC 3607
Above, a 12 arcmin wide SDSS image centered on NGC 3605, also showing NGC 3607
Below, a 1.4 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy NGC 3605

NGC 3606 (= PGC 34378 = PGC 670977)
Discovered (Apr 20, 1835) by
John Herschel
A magnitude 12.3 elliptical galaxy (type E0?) in Hydra (RA 11 16 15.6, Dec -33 49 39)
Historical Identification: Per Dreyer, NGC 3606 (= GC 2357 = JH 3335, 1860 RA 11 09 30, NPD 123 03.9) is "extremely faint, small, round, gradually brighter middle" (save for round-off errors in the position, this is the same as the GC entry). The position precesses to RA 11 16 15.0, Dec -33 49 41, on the western rim of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 3010 km/sec, NGC 3606 is about 140 million light years away, in reasonable agreement with redshift-independent distance estimates of 150 to 225 million light years. Given that and its apparent size of about 1.4 by 1.4 arcmin, it is 55 to 60 thousand light years across.
DSS image of region near elliptical galaxy NGC 3606
Above, a 12 arcmin wide DSS image centered on NGC 3606
Below, a 1.8 arcmin wide DSS image of the galaxy
DSS image of elliptical galaxy NGC 3606

NGC 3607 (= PGC 34426)
Discovered (Mar 14, 1784) by
William Herschel
Also observed (Mar 25, 1827) by John Herschel
Also observed (Apr 18, 1882) by Édouard Stephan
A magnitude 9.9 lenticular galaxy (type SA0(s)a?) in Leo (RA 11 16 54.7, Dec +18 03 06)
Historical Identification: Per Dreyer, NGC 3607 (= GC 2358 = JH 845 = WH II 50, 1860 RA 11 09 32, NPD 71 11.2) is "very bright, large, round, very much brighter middle, 2nd of 3" (the description is the same as in the GC, but the position is a rough conversion of Stephan's observation), the others being NGC 3605 and 3608. The position precesses to RA 11 16 54.9, Dec +18 03 00, right on the galaxy listed above, the description fits and there is nothing else nearby save for the other nebulae mentioned in the description so the identification is certain.
Discovery Notes: William Herschel gave the same position for all three of the objects he observed in this region (III 27, II 50 and II 51), only distinguishing between them by his descriptions of the southern, middle and northern of the three. His position falls just east of the middle and brightest of the three (namely, NGC 3607), so there is no doubt which three galaxies he observed, and from their relative positions, which corresponds to which GC (and NGC) object. As a result, it is certain that NGC 3607 = GC 2358 = JH 845 is indeed II 50. The GC position was reasonably good, but Stephan's position for what he thought was a "nova" (namely, his list XII #44) was even better, and though not mentioned by Dreyer, it was essentially Stephan's position that he used in the NGC entry, not the one published in the GC. For that reason, the date of Stephan's observation is listed above.
Physical Information: Based on a recessional velocity of 940 km/sec, NGC 3607 is 40 to 45 million light years away, in reasonable agreeement with redshift-independent distance estimates of 40 to 85 million light years. Given that and its apparent size of about 5.0 by 4.1 arcmin, it is 60 to 65 thousand light years across. It is listed as a Seyfert galaxy (type Sy 2). The core is surrounded by multiple rings of dusty material, hence its classification as an "(s)a" lenticular.
SDSS image of region near lenticular galaxy NGC 3607, also showing NGC 3605 and NGC 3608
Above, a 12 arcmin wide SDSS image centered on NGC 3607, also showing NGC 3605 and 3608
Below, a 6 arcmin wide SDSS image of the galaxy, also showing NGC 3605
SDSS image of lenticular galaxy NGC 3607
Below, a 45 arcsec wide HST image of the core of the galaxy
(Image Credit Hubble Legacy Archive, image processed by Judy Schmidt, modified by Courtney Seligman)
HST image of the dusty core of lenticular galaxy NGC 3607

NGC 3608 (= PGC 34433)
Discovered (Mar 14, 1784) by
William Herschel
Also observed (Mar 25, 1827) by John Herschel
Also observed (Apr 18, 1882) by Édouard Stephan
A magnitude 10.8 elliptical galaxy (type E2?) in Leo (RA 11 16 59.0, Dec +18 08 55)
Historical Identification: Per Dreyer, NGC 3608 (= GC 2359 = JH 846 = WH II 51, 1860 RA 11 09 36, NPD 71 05.3) is "bright, pretty large, round, pretty suddenly brighter middle, 3rd of 3" (the description is the same as in the GC, but the position is a rough conversion of Stephan's observation), the others being NGC 3605 and 3607. The position precesses to RA 11 16 59.0, Dec +18 08 54, right on the galaxy listed above, the description fits and there is nothing else nearby save the nebulae mentioned in the description so the identification is certain.
Discovery Notes: William Herschel gave the same position for all three of the objects he observed in this region (III 27, II 50 and II 51), only distinguishing between them by his descriptions of the southern, middle and northern of the three. His position falls just east of the middle and brightest of the three (namely, NGC 3607), so there is no doubt which three galaxies he observed, and from their relative positions, which corresponds to which GC (and NGC) object. As a result, it is certain that NGC 3608 = GC 2359 = JH 846 is indeed II 51. The GC position was reasonably good, but Stephan's position for what he thought was a "nova" (namely, his list XII #45) was even better, and though not mentioned by Dreyer, it was essentially Stephan's position that he used in the NGC entry, not the one published in the GC. For that reason, the date of Stephan's observation is listed above.
Physical Information: Based on a recessional velocity of 1225 km/sec, NGC 3608 is 55 to 60 million light years away, in reasonable agreement with redshift-independent distance estimates of 60 to 115 million light years. Given that and its apparent size of about 3.3 by 2.6 arcmin, it is about 55 thousand light years across. It is used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type E2.
SDSS image of region near elliptical galaxy NGC 3608, also showing NGC 3607
Above, a 12 arcmin wide SDSS image centered on NGC 3608, also showing NGC 3607
Below, a 4 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy NGC 3608

WORKING HERE
A bit of a mess with 3609 and 3612

NGC 3609 (= PGC 34511 =
NGC 3612)
Discovered (Mar 16, 1869) by Otto Struve (and later listed as NGC 3612)
Also observed (Mar 18, 1869) by Otto Struve (and later listed as NGC 3609)
A magnitude 13.3 spiral galaxy (type SA(rs)ab? pec) in Leo (RA 11 17 50.6, Dec +26 37 33)
Historical Identification: Per Dreyer, NGC 3609 (= GC 5558, Otto Struve, 1860 RA 11 10 07, NPD 62 36) is "pretty faint, small, brighter middle" (copied from Dreyer's 1877 Supplement to the GC). The position precesses to RA 11 17 36.4, Dec +26 38 10, over 3 arcmin west northwest of the galaxy listed above, but the description fits, most importantly concerning the position of the nearby star, and there is nothing comparable nearby so the identification is certain.
Discovery Notes: Struve discovered this object (among a number of others, while fruitlessly searching for Comet Winnecke in March and early April of 1869) in a nebula-filled region on the border of Leo and Coma Berenices. Per Steve Gottlieb, Struve's original paper ("Wiederkehr des Winneckeschen Cometen und Entdeckung einiger neuer Nebelflecke", dated April 20, 1869 and published in the Mélanges Math. Astron. IV, pp. 392-398) reads "March 18 [1869]. RA 11 10 36, Dec +27 21. Significantly brighter than the previous one [NGC 3534], 20" in diameter, with evident concentration towards the middle. Position angle from a 10th magnitude star = 226°." Dreyer's conversion of this to the entry in the 1877 Supplement is reasonably straightforward (save for leaving out the note about the star to the northeast), but his position is odd, as no equinox for Struve's coordinates properly converts to Dreyer's 1860 coordinates. Presuming that Struve's positions were for the equinox of 1869, the position precesses to RA 11 17 36.4, Dec +26 38 07, just over 3 arcmin west northwest of the galaxy listed above, but the description fits and there is nothing comparable nearby so the identification seems certain. (See NGC 3612 for a discussion of the duplicate listing.)
Physical Information: Based on a recessional velocity of 8080 km/sec, a straightforward calculation indicates that NGC 3609 is about 375 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 365 million light years away at the time the light by which we see it was emitted, about 370 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 1.1 by 0.95 arcmin, the galaxy is 115 to 120 thousand light years across.
SDSS image of region near spiral galaxy NGC 3609, also showing PGC 34546, which is often misidentified as NGC 3612 (which is actually a duplicate listing of NGC 3609)
Above, a 12 arcmin wide SDSS image centered on NGC 3609, also showing PGC 34546
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3609

NGC 3610 (= PGC 34566)
Discovered (Apr 8, 1793) by
William Herschel
Also observed (Nov 19, 1829) by John Herschel
A magnitude 10.8 lenticular galaxy (type (R)E/SB0? pec) in Ursa Major (RA 11 18 25.3, Dec +58 47 10)
Historical Identification: Per Dreyer, NGC 3610 (= GC 2360 = JH 847 = WH I 270, 1860 RA 11 10 13, NPD 30 27.0) is "very bright, pretty small, a little extended 90°±, very suddenly very much brighter middle and small nucleus". The position precesses to RA 11 18 25.3, Dec +58 47 10, dead center on the galaxy listed above, the description is a reasonable fit and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 1705 km/sec, NGC 3610 is about 80 million light years away, in good agreement with widely-varying redshift-independent distance estimates of 30 to 130 million light years. Given that and its apparent size of about 3.7 by 3.4 arcmin (counting most of its irregular outer shell), it is about 85 thousand light years across. For a long time NGC 3610 was thought to be an elliptical galaxy, but the 1990 discovery that it has a barred disk caused it to be reclassified as a peculiar lenticular galaxy. Used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type S0 pec / E (shell).
SDSS image of region near lenticular galaxy NGC 3610
Above, a 12 arcmin wide SDSS image centered on NGC 3610
Below, a 4 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy NGC 3610
Below, another 4 arcmin wide image (Image Credit ESA/HST/ESO, Francois Schweizer (CIW/DTM))
HST image of the barred core of lenticular galaxy NGC 3610
Below, an 18 arcsec wide image of the core of the galaxy (Image Credit Hubble Legacy Archive, Courtney Seligman)
HST image of the barred core of lenticular galaxy NGC 3610

NGC 3611 (= PGC 34478 =
NGC 3604)
Discovered (Jan 27, 1786) by William Herschel (and later listed as NGC 3611)
Also observed (Apr 7, 1828) by John Herschel (and later listed as NGC 3611)
Also observed (Nov 3, 1877) by David Todd (and later listed as NGC 3611)
Discovered (Dec 30, 1786) by William Herschel (and later listed as NGC 3604)
A magnitude 12.2 spiral galaxy (type (R)SA(s)a? pec) in Leo (RA 11 17 30.2, Dec +04 33 20)
Historical Identification: Per Dreyer, NGC 3611 (= GC 2361 = JH 849 = WH II 521, 1860 RA 11 10 17, NPD 84 40.9) is "pretty faint, considerably small, irregularly round, pretty suddenly much brighter middle, 10th magnitude star 3 arcmin to northwest". The position precesses to RA 11 17 30.5, Dec +04 33 16, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Discovery Notes: One of a number of nebulae observed by Todd during his search for a trans-Neptunian planet, and in fact the first object in his paper about those nebulae (hence sometimes referred to as Todd 1). For additional information about the history of the duplicate listing, see NGC 3604.
Physical Information: Given the duplicate listing, see NGC 3604 for anything else.

WORKING HERE

NGC 3612 (= PGC 34511 =
NGC 3609)
Discovered (Mar 16, 1869) by Otto Struve (and later listed as NGC 3612)
Also observed (Mar 18, 1869) by Otto Struve (and later listed as NGC 3609)
A magnitude 13.3 spiral galaxy (type SA(rs)ab? pec) in Leo (RA 11 17 50.6, Dec +26 37 33)
Historical Identification: Per Dreyer, NGC 3612 (= GC 5559, Otto Struve, 1860 RA 11 10 18, NPD 62 37) is "pretty large, diffuse, 10th or 11th magnitude star 2 arcmin to northeast" (copied from Dreyer's 1877 Supplement to the GC). The position precesses to RA 11 17 47.3, Dec +26 37 10, only 0.8 arcmin west southwest of the galaxy listed above, the description fits, most importantly concerning the position of the nearby star, and there is nothing comparable nearby so the identification is certain, as is the equality of the listings for NGC 3612 and 3609. NGC 3612 is sometimes misidentified as the fainter galaxy (PGC 34546) to its east, but that galaxy does not have a star to its northeast, and cannot be what Struve observed; so it is essentially certain, given the nearly identical description of NGC 3609 and 3612, that Struve's observations of "two nebulae" were actually two observations of the same object, and the entries are duplicates.
Discovery Notes: Struve discovered this object (among a number of others, while fruitlessly searching for Comet Winnecke in March and early April of 1869) in a nebula-filled region on the border of Leo and Coma Berenices. Per Steve Gottlieb, Struve's original paper ("Wiederkehr des Winneckeschen Cometen und Entdeckung einiger neuer Nebelflecke", dated April 20, 1869 and published in the Mélanges Math. Astron. IV, pp. 392-398) reads "March 16 [1869]. RA 11 10 47, Dec +27 20. Faint nebula about 30"-40" in diameter. Approximately 2 arcminutes north-following is a star (10. 11), from which the nebula is in position angle 225°." Dreyer's conversion of this to the entry in the 1877 Supplement is reasonably straightforward, but his position is odd, as no equinox for Struve's coordinates properly converts to Dreyer's 1860 coordinates. Presuming that Struve's positions were for the equinox of 1869, the position precesses to RA 11 17 47.3, Dec +26 37 06, less than an arcmin southwest of the galaxy listed above, which would seem to confirm the identification; but as noted in the entry for NGC 3612 (which see for a discussion of the duplicate listing) that leads to confusion with the position of another galaxy (PGC 34546) which cannot be the one in question, so the equinox appears to be unknown and the accuracy of Struve's position corespondingly uncertain.
Discovery Notes: (Per Corwin) Steve Gottlieb first noticed that Struve made two observations of this nebula, not two observations of separate nebulae. Although Struve's positions differed by about ten seconds of time, leading him and Dreyer to assume that he had observed two separate objects, his descriptions of the nebula are very similar. In particular, both give the position angle of the nebula relative to the nearby 10th magnitude star as being 225 or 226 degrees, and since there is nothing else in the region with such a relationship to any star, there is no doubt that the observations were of only one object. However, since Struve published his two observations of this object as observations of two separate objects, it has been a common mistake to presume that the eastern of the two observations refers to a galaxy to the east of NGC 3612/3609, namely PGC 34546, so that object is discussed immediately below as a warning about its misidentification as NGC 3612.
Physical Information: Given the duplicate listing, see NGC 3609 for anything else.

PGC 34546 (not =
NGC 3612)
Not an NGC object but listed here since usually misidentified as NGC 3612
A magnitude 14.1 spiral galaxy (type Sc? pec) in Leo (RA 11 18 14.7, Dec +26 37 14)
Discovery Notes: As noted in the discussion of NGC 3612, PGC 34546 is almost universally misidentified as that NGC object; however, there is no doubt that NGC 3612 is actually a duplicate listing of NGC 3609. For one thing, PGC 34546 is much fainter than NGC 3609 (which is undoubtedly Struve's "other" object), and Struve's descriptions of the two objects he supposedly observed are more similar than not. Most importantly, both of Struve's descriptions specify that there is a 10th or 11th magnitude star at a position angle of about 45 degrees relative to the nebula, and there is nothing of the sort near PGC 34546, so it cannot represent either of Struve's observations.
Physical Information: Based on a recessional velocity of 8360 km/sec, a straightforward calculation indicates that PGC 34546 is about 390 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was 375 to 380 million light years away at the time the light by which we see it was emitted, 380 to 385 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 0.9 by 0.9 arcmin, the galaxy is 95 to 100 thousand light years across.
SDSS image of region near spiral galaxy PGC 34546, which is usually misidentified as NGC 3612; also shown is NGC 3609, which is a duplicate listing of the actual NGC 3612
Above, a 12 arcmin wide SDSS image centered on PGC 34546, also showing NGC 3609
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of region near spiral galaxy PGC 34546, which is usually misidentified as NGC 3612

NGC 3613 (= PGC 34583)
Discovered (Apr 8, 1793) by
William Herschel
Also observed (Feb 9, 1831) by John Herschel
A magnitude 10.9 elliptical galaxy (type E5?) in Ursa Major (RA 11 18 36.1, Dec +58 00 00)
Historical Identification: Per Dreyer, NGC 3613 (= GC 2362 = JH 848 = WH I 271, 1860 RA 11 10 26, NPD 31 14.0) is "very bright, considerably large, much extended 305°, suddenly much brighter middle and nucleus". The position precesses to RA 11 18 36.2, Dec +58 00 09, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Discovery Notes: In Dreyer's notes for 1912's "The Scientific Papers of Sir William Herschel" he states "In Sweep 1038 is I 271, the PD of which is (also) 5 arcmin too small," (also) referring to the fact that the note is not shown at the entry for I 271, but in the entry for I 246, which was observed in the same sweep and had the same error. However, since the position for NGC 3613 was based on John Herschel's observation, it didn't need a correction for William Herschel's 5 arcmin error, making the 1912 note merely of historical interest.
Physical Information: Based on a recessional velocity of 2050 km/sec, NGC 3613 is about 95 million light years away, in good agreement with redshift-independent distance estimates of 60 to 115 million light years. Given that and its apparent size of about 3.9 by 2.0 arcmin, it is 105 to 110 thousand light years across.
SDSS image of region near elliptical galaxy NGC 3613
Above, a 12 arcmin wide SDSS image centered on NGC 3613
Below, a 4.2 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy NGC 3613

NGC 3614 (= PGC 34561)
Discovered (Feb 5, 1788) by
William Herschel
Also observed (Mar 19, 1828) by John Herschel
A magnitude 11.6 spiral galaxy (type SAB(rs)bc?) in Ursa Major (RA 11 18 21.3, Dec +45 44 54)
Historical Identification: Per Dreyer, NGC 3614 (= GC 2363 = JH 850 = WH II 729, 1860 RA 11 10 30, NPD 43 29.1) is "faint, pretty large, a little extended 90°±, gradually a little brighter middle, mottled but not resolved". The position precesses to RA 11 18 18.7, Dec +45 45 03, on the western rim of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2335 km/sec, NGC 3614 is 105 to 110 million light years away, in good agreement with redshift-independent distance estimates of 90 to 165 million light years. Given that and its apparent size of about 4.8 by 2.4 arcmin, it is 150 to 155 thousand light years across.
SDSS image of region near spiral galaxy NGC 3614, also showing PGC 34562
Above, a 12 arcmin wide SDSS image centered on NGC 3614, also showing PGC 34562
Below, a 5.4 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3614

PGC 34562 (= "NGC 3614A")
Not an NGC object but listed here since sometimes called NGC 3614A
A magnitude 14.4 spiral galaxy (type SB(s)m?) in
Ursa Major (RA 11 18 11.9, Dec +45 43 01)
Physical Information: Based on a recessional velocity of 7305 km/sec, a straightforward calculation indicates that PGC 34562 is about 340 million light years away. However, for objects at such distances we should take into account the expansion of the Universe during the time it took their light to reach us. Doing that shows that the galaxy was about 330 million light years away at the time the light by which we see it was emitted, about 335 million years ago (the difference between the two numbers being due to the expansion of the intervening space during the light-travel time). Given that and its apparent size of about 0.85 by 0.55 arcmin, the galaxy is 80 to 85 thousand light years across. PGC 34562 is sometimes described as being in a pair with NGC 3614, but since it is over three times further away, they are merely an optical double.
SDSS image of spiral galaxy PGC 34562, which is sometimes called NGC 3614A
Above, a 1 arcmin wide SDSS image of PGC 34562; see NGC 3614 for additional images

NGC 3615 (= PGC 34535)
Discovered (Apr 10, 1785) by
William Herschel
Also observed (Mar 28, 1832) by John Herschel
A magnitude 12.8 elliptical galaxy (type E4?) in Leo (RA 11 18 06.7, Dec +23 23 50)
Historical Identification: Per Dreyer, NGC 3615 (= GC 2364 = JH 851 = WH III 333, 1860 RA 11 10 40, NPD 65 49.8) is "considerably faint, very small, suddenly much brighter middle, stellar, preceding (western) of 2", the other being NGC 3618. The position precesses to RA 11 18 06.6, Dec +23 24 21, barely above the northern rim of the galaxy listed above, the description fits (including its relationship to NGC 3618) and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 6685 km/sec, NGC 3615 is about 310 million light years away. Given that and its apparent size of about 1.7 by 0.95 arcmin, it is about 155 thousand light years across.
SDSS image of region near elliptical galaxy NGC 3615, also showing NGC 3618
Above, a 12 arcmin wide SDSS image centered on NGC 3615, also showing NGC 3618
Below, a 2 arcmin wide SDSS image of the galaxy
SDSS image of elliptical galaxy NGC 3615

NGC 3616
Recorded (Apr 8, 1784) by
William Herschel
Looked for but not found (Apr 24, 1897 and Apr 30, 1907) by Guillaume Bigourdan
Looked for but not found (1907) by Max Wolf
A nonexistent object in Leo (RA 11 18 16.2, Dec +14 44 15)
Historical Identification: Per Dreyer, NGC 3616 (= GC 2366 = WH III 76, 1860 RA 11 10 53, NPD 74 29.6) is "extremely faint, pretty large". The position precesses to RA 11 18 13.2, Dec +14 44 33, in an essentially stellar field (there is a multitude of very distant galaxies, but Herschel could not have seen any of them). The lack of any suitable candidate in the region is emphasized by a note in the second Index Catalog, which reads "3616 = III 76. Not seen by M. Wolf, 1907", and by Dreyer's note for WH III 76 in 1912's "The Scientific Papers of Sir William Herschel" reads "III. 76. Same sweep (as III. 75, recorded in Sweep 187 of Apr 8, 1784). (Quoting Herschel:) ‘Some doubts were removed by putting on 240.’ Not found on plate by M. Wolf (1907, List VII.), not found by Bigourdan. In the sweep it is 3m.2 east, 3 arcmin south of II. 102, the place of which is correct." (WH) II 102 is NGC 3596, which had an NGC position of 1860 RA 11 07 44, NPD 74 26.9. Presuming that as in most cases Dreyer's offsets are for the equinox of 1860, (WH) III 76 should be at 1860 RA 11 10 56, NPD 74 29.9, essentially the same as the NGC position for NGC 3616 (and the source of the modern position given at the start of this entry), so the original statement about the essentially stellar region is unchanged. One possibility, given the description as "extremely faint, pretty large", is that what Herschel saw was an illusion caused by sky conditions or glare from some terrestrial or celestial light source; but whatever Herschel thought he saw, it is essentially certain that NGC 3616 does not correspond to any real object.
Additional Note: Corwin's discussion of his early efforts to identify NGC 3616 with one or more stars or double stars yields positions for two very doubtful stellar candidates, followed by the reason he believes that neither of them is likely to be what Herschel saw, as neither could have looked "pretty large". He also notes that none of the other objects observed by Herschel on the same night had positional problems that could suggest some other possible location for NGC 3616, so the end result is the same as above: NGC 3616 is either nonexistent, or so truly "lost" that it will never be identified.
SDSS image of region centered on the NGC position for the apparently nonexistent NGC 3616
Above, a 12 arcmin wide SDSS image centered on the position listed above for NGC 3616

NGC 3617 (= PGC 34513)
Discovered (Mar 22, 1836) by
John Herschel
A magnitude 12.8 elliptical galaxy (type E3?) in Hydra (RA 11 17 50.9, Dec -26 08 04)
Historical Identification: Per Dreyer, NGC 3617 (= GC 2367 = JH 3336, 1860 RA 11 11 00, NPD 115 21.9) is "faint, small, round, gradually brighter middle". The position precesses to RA 11 17 52.5, Dec -26 07 45, on the northeastern rim of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information: Based on a recessional velocity of 2165 km/sec, NGC 3617 is about 100 million light years away, in good agreement with two redshift-independent distance estimates of 100 to 110 million light years. Given that and its apparent size of about 1.75 by 1.15 arcmin, it is about 50 thousand light years across.
DSS image of region near elliptical galaxy NGC 3617
Above, a 12 arcmin wide DSS image centered on NGC 3617
Below, a 2.2 arcmin wide DSS image of the galaxy
DSS image of elliptical galaxy NGC 3617

NGC 3618 (= PGC 34575)
Discovered (Apr 10, 1785) by
William Herschel
Also observed (Mar 23, 1857) by R. J. Mitchell
Position recalculated (1854 to 1861?) by Arthur von Auwers
Also observed (May 5, 1864) by Heinrich d'Arrest
A magnitude 13.6 spiral galaxy (type SAB(rs)bc?) in Leo (RA 11 18 32.6, Dec +23 28 09)
Historical Identification: Per Dreyer, NGC 3618 (= GC 2365 = GC 2368 = WH III 334, 3rd Lord Rosse, d'Arrest, 1860 RA 11 11 07, NPD 65 46.5) is "very faint, small, following (eastern) of 2", the other being NGC 3615. The position precesses to RA 11 18 33.5, Dec +23 27 38, just off the southeastern rim of the galaxy listed above, the description fits (including the position relative to NGC 3615) and there is nothing else nearby so the identification is certain.
Discovery Notes: The equivalence of GC 2365 to GC 2368 (= WH III 334) was noted by Dreyer in his 1877 Supplement to the GC, and incorporated into the NGC as shown above. The 1877 Supplement also states that "Auwers' NPD is 3 arcmin greater (than Herschel's), which agrees with D'Arrest." In 1862, Auwers published a comprehensive review of all of William Herschel's published discoveries, comparing them with John Herschel's corresponding observations, and recalculating their positions taking into account various factors not taken into account by either Herschel; as a result he made a large number of corrections to their positions, and a substantial number of corrections to John Herschel's cross-identifications. Auwers must have also observed some of the objects, but for most of the thousands of entries his work appears to have been done strictly by mathematical calculations and comparisons; as a result, I have not listed him as an observer of this NGC object, but merely (due to Dreyer's mention of his work in the 1877 Supplement) given him credit for his improvement on the previous reductions.
Physical Information: Based on a recessional velocity of 6805 km/sec, NGC 3618 is 315 to 320 million light years away. Given that and its apparent size of about 1.0 by 0.75 arcmin, it is 90 to 95 thousand light years across.
SDSS image of region near spiral galaxy NGC 3618, also showing NGC 3615
Above, a 12 arcmin wide SDSS image centered on NGC 3618, also showing NGC 3615
Below, a 1.2 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3618

WORKING HERE

NGC 3619 (= PGC 34641)
Discovered (Mar 18, 1790) by
William Herschel
Also observed (Feb 9, 1831) by John Herschel
A magnitude 11.5 lenticular galaxy (type S0/a??) in Ursa Major (RA 11 19 21.6, Dec +57 45 28)
Historical Identification: Per Dreyer, NGC 3619 (= GC 2369 = JH 852 = WH I 244, 1860 RA 11 11 13, NPD 31 28.8) is "considerably bright, considerably large, round, very gradually much brighter middle". The position precesses to RA 11 19 21.6, Dec +57 45 19, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information:
Above, a 12 arcmin wide SDSS image centered on NGC 3619

NGC 3620 (= PGC 34366)
Discovered (Mar 31, 1837) by
John Herschel
A magnitude 13.3 spiral galaxy (type SBab??) in Chamaeleon (RA 11 16 04.7, Dec -76 12 59)
Historical Identification: Per Dreyer, NGC 3620 (= GC 2370 = JH 3338, 1860 RA 11 11 21, NPD 165 27.3) is "faint, pretty small, pretty much extended, gradually brighter middle". The position precesses to RA 11 16 02.4, Dec -76 13 08, within the southern outline of the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information:
Above, a 12 arcmin wide DSS image centered on NGC 3620

NGC 3621 (= PGC 34554)
Discovered (Feb 17, 1790) by
William Herschel
Also observed (May 7, 1826) by James Dunlop
Also observed (Apr 29, 1834) by John Herschel
A magnitude 9.7 spiral galaxy (type SBcd??) in Hydra (RA 11 18 16.5, Dec -32 48 51)
Historical Identification: Per Dreyer, NGC 3621 (= GC 2371 = JH 3337 = WH I 241, Dunlop 617 (= Dunlop 610), 1860 RA 11 11 30, NPD 122 02.8) is "considerably bright, very large, extended 160°, among 4 stars". The position precesses to RA 11 18 17.0, Dec -32 48 40, right on the galaxy listed above, the description fits and there is nothing else nearby so the identification is certain.
Physical Information:
Above, a ? arcmin wide image centered on NGC 3622 (Image Credit ESO and Joe DePasquale)
(Other partial images also available on the ESO site)
Carnegie image also available, but perhaps not of much use in this case

NGC 3622 (= PGC 34692)
Discovered (Apr 6, 1793) by
William Herschel
Also observed (Apr 3, 1832) by John Herschel
A magnitude 13.2 spiral galaxy (type S??) in Ursa Major (RA 11 20 12.4, Dec +67 14 31)
Historical Identification: Per Dreyer, NGC 3622 (= GC 2372 = JH 853 = WH II 879, 1860 RA 11 11 35, NPD 21 59.5) is "pretty bright, small, round, gradually brighter middle". Discovery Notes: Dreyer's note for 1912's "The Scientific Papers of Sir William Herschel" states: "II 879. Sweep 1036, the only one htat night (Apr 6, 1793); the stars disagree badly in RA. The resulting RA of the nebula is 1m 47s too great. There is a 7th magnitude star 10m 25 s east, 3 arcmin south of the nebula, which must be +68°.632, but though right in PD, it gives the RA 35s too small. Something has been erased in the transit column between this star and the nebula. II 880 comes next, the place being correct; then comes I 262 (q.v.)."
Physical Information:

NGC 3623 (=
M65 = PGC 34612)
Discovered (Mar 1, 1780) by Charles Messier and recorded as M65
Often misattributed to Pierre Méchain
Also observed (Apr 11, 1825) by John Herschel
A magnitude 9.3 spiral galaxy (type Sa??) in Leo (RA 11 18 55.9, Dec +13 05 32)
Historical Identification: Per Dreyer, NGC 3623 (= GC 2373 = JH 854, M65, 1860 RA 11 11 37, NPD 76 08.5) is "bright, very large, much extended 165°±, gradually brighter middle and bright nucleus".
Discovery Notes: Many of Messier's objects were originally discovered by his friend Pierre Méchain, in which case he noted the prior discovery in the various editions of his Catalog. In this case Messier makes no such reference, so it is virtually certain that he was the original discoverer, and not Méchain. However, Admiral Smyth (presumably in his 1844 Bedford Catalogues) mistakenly assigned this discovery (and those of M66 and M68) to Méchain, and thanks to Kenneth Glyn Jones' repetition of these attributions in the 1960's, many sources incorrectly list Pierre Méchain as the discoverer of this object.
Additional Notes: Herschel has a comment in the GC about errors and disagreements in the angle of extension (Dreyer adopted Herschel's correction of an error in his 1833 list), and in doing so mentions that Winnecke and Auwers also observed the object, so it might (or might not) be appropriate to mention their names as "also observed", along with the reason involved.
Physical Information:
(Chuck Greenberg, Scott Tucker, Adam Block, AURA, NSF, NOAO)
NOAO image of M65 (NGC 3623)

NGC 3624 (= PGC 34599)
Discovered (Dec 27, 1827) by
John Herschel
A magnitude 13.9 spiral galaxy (type SBb??) in Leo (RA 11 18 51.0, Dec +07 31 17)
Historical Identification: Per Dreyer, NGC 3624 (= GC 2374 = JH 855, 1860 RA 11 11 41, NPD 81 42.9) is "extremely faint".
Physical Information:

NGC 3625 (= PGC 34718)
Discovered (Apr 8, 1793) by
William Herschel
Also observed (date?) by Heinrich d'Arrest
A magnitude 13.1 spiral galaxy (type SBb??) in Ursa Major (RA 11 20 31.3, Dec +57 46 53)
Historical Identification: Per Dreyer, NGC 3625 (= GC 2375 = WH II 885, d'Arrest, 1860 RA 11 12 24, NPD 31 27.1) is "faint, small, a little extended 135°±".
Discovery Notes: D'Arrest's observation is noted in the NGC because, as stated in the Supplement to the GC, it showed that Herschel's NPD was 5 arcmin too small; but since that correction is already included in the NGC entry, whether this comment needs to be retained is another matter.
Physical Information:

NGC 3626 (= PGC 34684 =
NGC 3632)
Discovered (Feb 15, 1784) by William Herschel (and later listed as NGC 3632)
Discovered (Mar 14, 1784) by William Herschel (and later listed as NGC 3626)
Also observed (Mar 17, 1831) by John Herschel (and later listed as NGC 3626)
A magnitude 11.0 lenticular galaxy (type S0/a??) in Leo (RA 11 20 03.8, Dec +18 21 25)
Historical Identification: Per Dreyer, NGC 3626 (= GC 2376 = JH 856 = WH II 52, 1860 RA 11 12 42, NPD 70 52.7) is "bright, small, very little extended, suddenly brighter middle".
Physical Information:

NGC 3627 (=
M66 = Arp 16 = PGC 34695; part of Leo Triplet = Arp 317)
Discovered (Mar 1, 1780) by Charles Messier
Often misattributed to Pierre Méchain
Also observed (Apr 10, 1825) by John Herschel
A magnitude 8.9 spiral galaxy (type SAB(s)b?) in Leo (RA 11 20 15.0, Dec +12 59 30)
Historical Identification: Per Dreyer, NGC 3627 (= GC 2377 = JH 857 = JH 875, M66, 1860 RA 11 12 56, NPD 76 14.5) is "bright, very large, much extended 150°, much brighter middle, 2 stars to northwest".
Discovery Notes: Many of Messier's objects were originally discovered by his friend Pierre Méchain, in which case he noted the prior discovery in the various editions of his Catalog. In this case Messier makes no such reference, so it is virtually certain that he was the original discoverer, and not Méchain. However, Admiral Smyth (presumably in his 1844 Bedford Catalogues) mistakenly assigned this discovery (and those of M65 and M68) to Méchain, and thanks to Kenneth Glyn Jones' repetition of these attributions in the 1960's, many sources incorrectly list Pierre Méchain as the discoverer of this object.
Additional Note: Herschel himself noticed the equality of his observations (JH 857 and JH 875), noting it in the GC; so Dreyer merely copied his correction, instead of determining it on his own. However, in his 1877 Supplement to the GC he added the reason, namely that M65 and M66 were often mistaken for M66 and JH 875, and a paper by Steinicke shows that the observations of the two galaxies by the Herschels were riddled with errors (I think I mentioned this in the discussion of M65?), so the fact that Herschel corrected the error in the GC makes things far easier to deal with than having to worry about such details.
Physical Information: M66 is a member of the Leo Triplet of galaxies, which also includes M65 and NGC 3628. Gravitational interaction with the other members of the small group has influenced the structure of its dust-filled arms, and the formation of clusters of bright young stars which light up those arms. It is listed as #16 in Halton Arp's Atlas of Peculiar Galaxies, as an example of a spiral galaxy with detached segments. (The Leo Triplet is also used as an example of a group of galaxies, as Arp 317.) M66 has a recessional velocity of 725 km/sec, which is too small in comparison to peculiar (non-Hubble-expansion) velocities to provide a reliable indication of its distance. Ignoring that caveat yields a distance estimate of 32 million light years, which is in good agreement with redshift-independent distance estimates of 22 to 49 million light years. Given that and apparent size of 9.1 by 4.2 arcmin, about 90 thousand light years across.
ESO image of M66 (NGC 3627)
Above, an overall view of M66 (M. Neeser (Univ.-Sternwarte Munchen), P. Barthel (Kapteyn Astron. Institute), H. Heyer, H. Boffin (ESO), ESO, apod060902)
Below, a HST view of a portion of the galaxy (Image Credits: ESA, Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration. Acknowledgement: Davide De Martin, Robert Gendler NASA)
HST image of M66 (NGC 3627)
Below, an infrared view of the galaxy (JPL-Caltech/R. Kennicutt (University of Arizona), SINGS Team, NASA)
Spitzer infrared image of M66 (NGC 3627)
Below, a 0.8 degree wide SDSS image showing its position in the Leo Triplet
SDSS image of Leo Triplet

NGC 3628 (= PGC 34697; part of Leo Triplet =
Arp 317)
Discovered (Apr 8, 1784) by William Herschel
Also observed (Apr 3, 1826) by John Herschel
A magnitude 9.5 spiral galaxy (type Sb?? pec) in Leo (RA 11 20 17.0, Dec +13 35 22)
Historical Identification: Per Dreyer, NGC 3628 (= GC 2378 = JH 859 = WH V 8, 1860 RA 11 12 57, NPD 75 38.5) is "pretty bright, very large, very much extended 102°".
Physical Information: NGC 3628 is a member of the Leo Triplet of galaxies, which also includes M65 and M66. The triplet is used as an example of a group of galaxies in Halton Arp's Atlas of Peculiar Galaxies (as Arp 317). NGC 3628 has a recessional velocity of 845 km/sec, which is too small in comparison to peculiar (non-Hubble-expansion) velocities to provide a reliable indication of its distance. Ignoring that caveat yields a distance estimate of 38 million light years, which is in good agreement with redshift-independent distance estimates of 25 to 45 million light years. Given that and its 14.8 by 3.0 arcmin apparent size, about 165 thousand light years across.
SDSS image of NGC 3628
Above, a 15 arcmin wide closeup of NGC 3628
Below, a 0.8 degree wide region showing its position in the Leo Triplet
SDSS image of Leo Triplet

NGC 3629 (= PGC 34719)
Discovered (Apr 6, 1785) by
William Herschel
Also observed (Feb 17, 1827) by John Herschel
A magnitude 12.1 spiral galaxy (type SBc??) in Leo (RA 11 20 31.8, Dec +26 57 48)
Historical Identification: Per Dreyer, NGC 3629 (= GC 2380 = JH 860 = WH II 338, 1860 RA 11 13 03, NPD 62 16.2) is "considerably faint, large, round, very gradually very little brighter middle".
Physical Information:

WORKING HERE: Discovery dates

NGC 3630 (= PGC 34698 =
NGC 3645)
Discovered (Feb 23, 1784) by William Herschel (and later listed as NGC 3645)
Also observed (Apr 10, 1828) by John Herschel (and later listed as NGC 3645)
Also observed (Apr 5, 1877) by Wilhelm Tempel (and later listed as NGC 3645)
Discovered (Apr 7, 1828) by John Herschel (and later listed as NGC 3630)
A magnitude 12.0 lenticular galaxy (type S0/a??) in Leo (RA 11 20 17.0, Dec +02 57 52)
Historical Identification: Per Dreyer, NGC 3630 (= GC 2381 = JH 861, 1860 RA 11 13 05, NPD 86 16.2) is "pretty bright, small, round, suddenly much brighter middle and nucleus".
Physical Information:

NGC 3631 (=
Arp 27 = PGC 34767)
Discovered (Apr 14, 1789) by William Herschel
Also observed (date?) by John Herschel
A magnitude 10.4 spiral galaxy (type SA(s)c?) in Ursa Major (RA 11 21 02.9, Dec +53 10 10)
Historical Identification: Per Dreyer, NGC 3631 (= GC 2379 = JH 858 = WH I 226, 1860 RA 11 13 06, NPD 36 03.1) is "pretty bright, large, round, suddenly very much brighter middle and mottled but not resolved nucleus".
Physical Information: Based on recessional velocity of 1155 km/sec, about 50 million light years away, in fair agreement with a redshift-independent distance estimate of 70 million light years. Given those values and an apparent size of 4.5 by 4.5 arcmin, about 80 thousand light years across.
SDSS image of NGC 3631
Above, a 4.5 arcmin wide closeup of NGC 3631
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near NGC 3631

NGC 3632 (=
NGC 3626 = PGC 34684)
Discovered (Feb 15, 1784) by William Herschel (and later listed as NGC 3632)
Looked for but never found (date?) by Heinrich d'Arrest (while listed as NGC 3632)
Discovered (Mar 14, 1784) by William Herschel (and later listed as NGC 3626)
Also observed (date?) by John Herschel (and later listed as NGC 3626)
A magnitude 11.0 lenticular galaxy (type S0/a??) in Leo (RA 11 20 03.8, Dec +18 21 25)
Historical Identification: Per Dreyer, NGC 3632 (= GC 2382 = WH II 30, 1860 RA 11 13 06, NPD 71 04.6) is "pretty bright, star involved".
Discovery Notes: The GC includes a note stating that Auwers obtained an 1830 RA of 11 12 21 from William Herschel's observation of II 30, but Caroline Herschel's reduction of the same observation yielded an 1830 RA 0f 11 11 31, which was (per the GC) within 2 seconds of the correct result. This led to a note at the end of the NGC stating "3632 II 30. Auwers' RA is wrong (error of reduction)". Since Auwers' reduction was of William Herschel's observation and does not suggest that Auwers observed the object himself, his name is not shown in the list of observers.
Additional Note: Dreyer's 1912 supplement based on a study of William Herschel's observations states "3632. II 30 is = 3626". In other words, NGC 3632 is a duplicate observation (though with an incorrect position) of NGC 3626, as shown above. In Dreyer's notes to the 1912 "Scientific Papers of Sir William Herschel" he elaborates as follows: "II 30, sweep 146, Feb 15, 1784. 'A pretty bright nebula, it seems to contain stars; it is of some extent.' Not seen by d'Arrest (5 times), is no doubt = II. 52 (= NGC 3626) only 24 seconds west and 12 arcmin north. The latter was observed 14 March 1784, 'a nebula like II 51 but a little longish'."
Physical Information: Given the duplicate listing, see NGC 3626 for anything else.

NGC 3633 (= PGC 34711)
Discovered (Mar 23, 1887) by
Lewis Swift
A magnitude 13.5 spiral galaxy (type Sa??) in Leo (RA
Historical Identification: Per Dreyer, NGC 3633 (Swift list VI (#40), 1860 RA 11 13 13, NPD 85 39.0) is "very faint, small, round, 2 stars near".
(RA 11 20 26.2, Dec +03 35 08) Physical Information:

NGC 3634
Discovered (Jan 24, 1887) by
Francis Leavenworth
A magnitude 14.2 elliptical galaxy (type E3??) in Crater (RA 11 20 30.3, Dec -09 00 49)
Historical Identification: Per Dreyer, NGC 3634 (Leavenworth list II (#433), 1860 RA 11 13 17, NPD 98 14.2) is "extremely faint, extremely small, round, brighter middle and nucleus, 0.4 arcmin from NGC 3635 at position angle 85°".
Physical Information:

NGC 3635
Discovered (Jan 24, 1887) by
Francis Leavenworth
A magnitude 14.5 spiral galaxy (type Sbc??) in Crater (RA 11 20 31.4, Dec -09 00 49)
Historical Identification: Per Dreyer, NGC 3635 (Leavenworth list II (#434), 1860 RA 11 13 17, NPD 98 14.2) is "extremely faint, extremely small, round, brighter middle and nucleus, 0.4 arcmin from NGC 3634 at position angle 85°".
Physical Information:

NGC 3636
Discovered (Mar 4, 1786) by
William Herschel
Also observed (date?) by John Herschel
Also observed (1880) by Andrew Common
A magnitude 12.4 elliptical galaxy (type E0??) in Crater (RA 11 20 25.1, Dec -10 16 54)
Historical Identification: Per Dreyer, NGC 3636 (= GC 2383 = JH 862 = WH II 550, 1860 RA 11 13 22, NPD 99 30.7) is "faint, very small, round, a little brighter middle, 7th magnitude star to east, preceding (western) of 2", the other being NGC 3637.
Physical Information:

NGC 3637
Discovered (Mar 4, 1786) by
William Herschel
Also observed (date?) by John Herschel
Also observed (1880) by Andrew Common
A magnitude 12.7 lenticular galaxy (type SB0??) in Crater (RA 11 20 39.6, Dec -10 15 26)
Historical Identification: Per Dreyer, NGC 3637 (= GC 2384 = JH 863 = WH II 551, 1860 RA 11 13 36, NPD 99 28.9) is "faint, very small, round, pretty suddenly brighter middle, 7th magnitude star to west, following (eastern) of 2".
Physical Information:

NGC 3638
Discovered (1886) by
Ormond Stone
A magnitude 13.4 spiral galaxy (type Sb??) in Crater (RA 11 20 10.0, Dec -08 06 21)
Historical Identification: Per Dreyer, NGC 3638 (Ormond Stone list II (#435), 1860 RA 11 13 41, NPD 97 20.2) is "extremely faint, very small, 2 stars of 10th magnitude to east".
Physical Information:

NGC 3639
Discovered (Jan 21, 1855) by
R. J. Mitchell
A magnitude 13.7 spiral galaxy (type S??) in Leo (RA 11 21 35.7, Dec +18 27 31)
Historical Identification: Per Dreyer, NGC 3639 (= GC 2385, 3rd Lord Rosse, 1860 RA 11 13 46, NPD 70 52.9) is "pretty faint, small, round, very little brighter middle, 15 arcmin east of h856", h856 being NGC 3626.
Physical Information:

NGC 3640
Discovered (Feb 23, 1784) by
William Herschel
Also observed (date?) by John Herschel
A magnitude 10.4 elliptical galaxy (type E3??) in Leo (RA 11 21 06.9, Dec +03 14 06)
Historical Identification: Per Dreyer, NGC 3640 (= GC 2386 = JH 864 = WH II 33, 1860 RA 11 13 55, NPD 85 59.9) is "bright, pretty large, round, pretty suddenly brighter middle".
Physical Information:

NGC 3641
Discovered (Mar 22, 1865) by
Albert Marth
Also observed (Jan 24, 1876) by Wilhelm Tempel (S. merely says 1876)
A magnitude 13.2 elliptical galaxy (type E0??) in Leo (RA 11 21 08.8, Dec +03 11 41)
Historical Identification: Per Dreyer, NGC 3641 (= GC 5560, Marth 220, Tempel list I (#??), 1860 RA 11 13 56, NPD 86 02) is "faint, very small, almost stellar, (WH) II 33 (= NGC 3640) 2 arcmin to north".
Physical Information:

NGC 3642
Discovered (Mar 18, 1790) by
William Herschel
Also observed (date?) by John Herschel
A magnitude 11.2 spiral galaxy (type Sbc??) in Ursa Major (RA 11 22 17.9, Dec +59 04 28)
Historical Identification: Per Dreyer, NGC 3642 (= GC 2387 = JH 865 = WH I 245, 1860 RA 11 14 11, NPD 30 09.5) is "pretty bright, pretty large, round, very gradually brighter middle".
Physical Information:

NGC 3643
Discovered (Mar 22, 1865) by
Albert Marth
A magnitude 14.1 lenticular galaxy (type SB0/a??) in Leo (RA 11 21 25.0, Dec +03 00 50)
Historical Identification: Per Dreyer, NGC 3643 (= GC 5561, Marth 221, 1860 RA 11 14 11, NPD 86 13) is "extremely faint, very small".
Physical Information:

NGC 3644 (= PGC 34814 =
IC 684)
Discovered (Mar 22, 1865) by Albert Marth (and later listed as NGC 3644)
Discovered (Apr 14, 1888) by Guillaume Bigourdan (and later listed as IC 684)
A magnitude 13.7 spiral galaxy (type (R)SBa pec?) in Leo (RA 11 21 32.9, Dec +02 48 38)
Historical Identification: Per Dreyer, NGC 3644 (= GC 5562, Marth 222, 1860 RA 11 14 21, NPD 86 25) is "very faint, very small".
Discovery Notes: See IC 684 for a discussion of the duplicate listing.
Physical Information: Apparent size 1.4 by 0.55 arcmin.
SDSS image of spiral galaxy NGC 3644
Above, a 2.4 arcmin wide closeup of NGC 3644
Below, a 12 arcmin wide region centered on the galaxy, also showing IC 683
(NGC 3647 is one of the galaxies near the top, but which one is another matter)
SDSS image of region near spiral galaxy NGC 3644, also showing elliptical galaxy IC 683

NGC 3645 (= PGC 34698 =
NGC 3630)
Discovered (Feb 23, 1784) by William Herschel (and later listed as NGC 3645)
Also observed (Apr 10, 1828) by John Herschel (and later listed as NGC 3645)
Also observed (Apr 5, 1877) by Wilhelm Tempel (and later listed as NGC 3645)
Discovered (Apr 7, 1828) by John Herschel (and later listed as NGC 3630)
A magnitude 12.0 lenticular galaxy (type S0/a??) in Leo (RA 11 20 17.0, Dec +02 57 52)
Historical Identification: Per Dreyer, NGC 3645 (= GC 2388 = JH 867 = WH II 32, Tempel list I (in general notes), 1860 RA 11 14 21, NPD 86 16.8) is "pretty bright, small, extended, brighter middle".
Discovery Notes: A note in the GC suggests that JH 867 is probably the same as JH 861, as if one was observed in a given sweep the other should have been, as well; but concludes that since the descriptions are different and the RA's differ by enough that they might not have been observed in the same sweep, it would be best to keep both in the GC. It turns out that was the correct decision, as a note at the end of the NGC reads "3645 (JH) 867 and (JH) 861 are not the same (as suspected in GC); (JH) 867 was seen by Tempel A.N. 2212); hence Tempel's inclusion in the list of observers.
Additional Note: In Dreyer's 1877 Supplement to the GC he states "(GC) 2388 To be struck out, there are here only two Nebulae (2381 and 86)". As it turns out that (and Herschel's supposition about 2388) was wrong, as Tempel found FOUR nebulae in the region (German text and English translation below, to be incorporated into the appropriate NGC entries ASAP).
Physical Information: Given the duplicate entry, see NGC 3630 for anything else.

Tempel's text in German (for NGC 3645 = II 32, above)
Unter diesen sind einige hochst interessante: II. 32, GC 2388 = h 867 = h861?, ist von D'Arrest, and auch von mir hier in Arcetri, vergeblich gesucht worden, wo ich doch mit Amici I den kleinen Nebelbegleiter von II 33, der 14' nur nördlicher als II32 und sicher I Classe ist, wie ihn auch D'Arrest schützt, am 24 Jan 76 aufgefunden habe und erst später sah, dass dieser kleine Begleiter schon früher von Lassell entdeckt war, und mit Hilfe der Chacornac'schen Karte nach II 32 suchte und ihn nicht fand. Später, 5 Apr 1877 and 22 April 1878 habe ich aber diesen Nebel gut gesehen und war verwundert, wie er mir früher hat entgehen können. Derselbe ist rund, III Classe von 1' Durchmesser und v Chacornac'schen Sternchen, das auf seiner Karte = RA 11 14 11, Dec +03 44 verzeichnet ist, doch sind ganz nahe dem Nebel, ihm folgend, noch zwei feinere Sternchen.
Im GC Pag 26 steht folgendes: "2388 = h 867 = h 861? These are very probably the same. But as, after all, the difference of the observed RA's is sufficient to have allowed one to escape while observing the other, so that they may be different, and as moreover one is described as round and the other as extended, both are retained."
D'Arrest sat, Pag 158 (Nacht 228): Neb. h867 inconspicun, ex errore numerorum probabiliter orta. Erat nox illunis, auraque defaecatissima. Rectissime igitur Jun. Herschelius: "these are very probably the same" und Nacht 162: "Neb. h867 non inventa. Splendor Lunae fortassis impedimento erat."
Dr. Dreyer sagt nun in seinem Supplement-Cataloge, Pag 392: "2388 to be struck out, there are her only two Nebulae (GC 2381 and 2386)". Also alle diese Bemerkungen fallen nun fort. denn der Nebel existirt: es sind aber nicht zwei, sondern 4 Nebel nicht weit von einander, woven zwei I-II Classe und zwei III Classe sind, wenn man den kleinen Begleiter von II 33 und Herschel's II 32 zur III Classe aufnimmt. Nachdem ich nun diesen Ort gut kenne, glaube ich nicht dass der Nebel veränderlich ist. Nur das Suchen unter so verschiedenen lichtausstrahlenden Sternchen und das Ungewisse des Ortes ist fürs Auge störend den Nebel gleich zu erkennen. Hat man aber die genaue Lage des Nebels zwischen oder bei gewissen Sternchen in Erinnerung, so wird man auch den schwächsten Nebel bei nicht ganz günstiger Luft leicht wiederfinden. Der Mangel an eingetheilten Kreisen und aller Mikrometer zwingt mein Auge die umliegenden Sternchen als Leitfaden zu gebrauchen und dies hat zuweilen seinen Nutzen.

A rough translation (using the meaning of the text, instead of attempting a word-for-word translation)
(Following a list of William Herschel's objects observed by Tempel, he states that among those he found of most interest was WH II 32 = GC 2388 = JH 867 = JH 861?)
This was searched for by d'Arrest, and also by me in Arcetri in vain, though with the Amici telescope on Jan 24, 1876 I saw the small nebular companion (now called NGC 3641) of WH II 33, which is certainly Class I, as also stated by d'Arrest, only 14 arcmin north of (the newly determined position of) II 32, though I later learned that this little companion was earlier discovered by Lassell (actually by Marth, Lassell's assistant), and using Chacornac's Chart I looked for II 32 but did not find it. But later, on Apr 5, 1877 and Apr 22, 1878 I did observe II 32, so easily that I was puzzled by the fact that it previously escaped my observation. It is about the same as II 33, 1 arcmin in diameter, III class, and lies 14s west of a Chacornac Chart star, listed on that map as (1860) RA 11 14 11, Dec +03 44; also very close to the nebula, follwing its lead, are two fainter stars. (Note: The position given for the brighter star falls due east of II 32, and the star itself lies to the southeast of the galaxy, though not as close as stated.)
Tempel then quotes JH's note in the GC expressing the opinion that JH 867 is very probably JH 861 but might not be, so he has retained both entries; then quotes d'Arrest's observations of Jan 25, 1865 and Mar 16, 1864, in which he looked for h867 while observing h861 and h864 and on both occasions failed to find it. Finally, he quotes Dreyer's 1877 Supplement to the GC, "striking out" GC 2388 since there are only two nebulae in the region. He then concludes as follows:
But all these (other astronomers') remarks (by d'Arrest, Herschel and Dreyer) are now of no consequence, because the nebula h867 does exist; and there are not two, but four nebulae not far from each other in this region, one each of classes I and II, and two of class III if the fainter companion of II 33 and II 32 are moved to class III. I now know this region so well I do not believe that the nebulae are variable (the implication being that if they were, they might have been harder to see on some nights). It is just that searching among various stars, an uncertain position makes it difficult for the eye to recognize nebulae. But if one remembers the position of a nebula and its neighboring stars, one can find even the faintest nebula even if the atmospheric conditions are not ideal. The lack of setting circles and micrometers on my instrument forces me to use the surrounding stars as a guide, and sometimes (such as this case) that has its benefits.

NGC 3646 (= PGC 34836)
Discovered (Feb 15, 1784) by
William Herschel
Also observed (Feb 24, 1827) by John Herschel
A magnitude 11.1 spiral galaxy (type Sbc?? pec) in Leo (RA 11 21 43.1, Dec +20 10 10)
Historical Identification: Per Dreyer, NGC 3646 (= GC 2389 = JH 866 = WH III 15, 1860 RA 11 14 21, NPD 69 04.3) is "considerably faint, considerably large, a little extended, gradually brighter middle, southwestern of 2", the other being NGC 3649.
Physical Information: Apparent size about 3.9 by 2.2?? arcmin.

NGC 3647
Discovered (Mar 22, 1865) by
Albert Marth
A magnitude 14.2 elliptical galaxy (type E1??) in Leo (RA 11 21 32.6, Dec +02 53 14)
Historical Identification: Per Dreyer, NGC 3647 (= GC 5563, Marth 223, 1860 RA 11 14 26, NPD 86 20) is an "extremely faint nebulous star".
Discovery Notes: (There appears to be considerable confusion about which of five galaxies is NGC 3647; that will be dealt with in the next iteration of this page.)
Physical Information:

NGC 3648
Discovered (Mar 18, 1831) by
John Herschel
A magnitude 12.6 lenticular galaxy (type S0??) in Ursa Major (RA 11 22 31.5, Dec +39 52 37)
Historical Identification: Per Dreyer, NGC 3648 (= GC 2390 = JH 868, 1860 RA 11 14 52, NPD 49 22.6) is "pretty bright, small, pretty much extended, brighter middle and nucleus perhaps a close double star?"
Physical Information:

NGC 3649 (= PGC 34883 =
IC 682)
Discovered (Feb 15, 1784) by William Herschel (and later listed as NGC 3649)
Also observed (Feb 24, 1827) by John Herschel (and later listed as NGC 3649)
Discovered (Apr 22, 1889) by Lewis Swift (and later listed as IC 682)
A magnitude 13.7 spiral galaxy (type SB(rs)a?) in Leo (RA 11 22 14.7, Dec +20 12 31)
Historical Identification: Per Dreyer, NGC 3649 (= GC 2391 = JH 869 = WH III 16, 1860 RA 11 14 53, NPD 69 01.7) is "very faint, pretty small, round, gradually brighter middle, northeastern of 2", the other being NGC 3646.
Discovery Notes: See IC 682 for a discussion of the double listing
Physical Information: Apparent size 1.6 by 0.5?? arcmin.
SDSS image of spiral galaxy NGC 3649
Above, a 2.4 arcmin wide closeup of NGC 3649
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near spiral galaxy NGC 3649
Celestial Atlas
(NGC 3550 - 3599) ←     NGC Objects: NGC 3600 - 3649     → (NGC 3650 - 3699)