Celestial Atlas
(NGC 3850 - 3899) ←     NGC Objects: NGC 3900 - 3949 Link for sharing this page on Facebook     → (NGC 3950 - 3999)
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3900, 3901, 3902, 3903, 3904, 3905, 3906, 3907, 3908, 3909, 3910, 3911, 3912, 3913, 3914, 3915, 3916,
3917, 3918, 3919, 3920, 3921, 3922, 3923, 3924, 3925, 3926, 3927, 3928, 3929, 3930, 3931, 3932, 3933,
3934, 3935, 3936, 3937, 3938, 3939, 3940, 3941, 3942, 3943, 3944, 3945, 3946, 3947, 3948, 3949

Page last updated Oct 19, 2018
Added Steinicke physical data/IDs, Dreyer NGC/IC listings, Corwin positions, discovery data
WORKING 3911/20, 3915, 3922/24, 3926+: Verifying identifications

NGC 3900 (= PGC 36914)
Discovered (Apr 6, 1785) by
William Herschel
Also observed (Feb 17, 1827) by John Herschel
A magnitude 11.4 lenticular galaxy (type S0/a?) in Leo (RA 11 49 09.5, Dec +27 01 19)
Historical Identification: Per Dreyer, NGC 3900 (= GC 2566 = JH 988 = WH I 82, 1860 RA 11 41 53, NPD 62 13.0) is "bright, pretty large, very little extended 0°±, brighter middle and nucleus". The position precesses to RA 11 49 09.4, Dec +27 00 19, only an arcmin south of the nucleus of the galaxy listed above and just beyond its southern extension, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:
SDSS image of NGC 3900
Above, a 4 arcmin wide closeup of NGC 3900
Below, a 12 arcmin wide region centered on the galaxy
SDSS image of region near NGC 3900

NGC 3901 (= PGC 36386)
Discovered (Apr 2, 1801) by
William Herschel
A magnitude 13.7 spiral galaxy (type Sc?) in Camelopardalis (RA 11 42 49.2, Dec +77 22 23)
Historical Identification: Per Dreyer, NGC 3901 (= GC 2567 = WH III 970, 1860 RA 11 41 59, NPD 11 08.0) is "pretty faint, pretty large, mottled but not resolved. Place doubtful". The position precesses to RA 11 50 05.2, Dec +78 05 19, but there is nothing there nor anywhere near there. However, per Corwin, all 15 nebulae found by Herschel in the single sweep done on the night in question had a large, systematic error caused by a misalignment of his telescope in early April of 1801. Herschel himself realized that this was a problem for observations done on April 5, 1801, and wrote a note stating that none of them should be published; and in the early 1900's Dreyer realized that there must be a similar problem for the observations of April 2 and requested that the Astronomer Royal take 30-inch plates of the region covered by Herschel's observations of that night. As a result, (mostly) corrected positions and identifications were published in 1911 (presumably by then-Astronomer Royal Frank Dyson), and in 1912 (in Dreyer's corrections to Herschel's observations based on a survey of all of Herschel's work). In the 1912 paper Dreyer states that the position of NGC 3901 is 1860 RA 11 34 19, NPD 11 51.0, which precesses to RA 11 42 49.8, Dec +77 22 26, dead center on the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3902 (= PGC 36923)
Discovered (Apr 6, 1785) by
William Herschel
Also observed (Feb 19, 1827) by John Herschel
A magnitude 12.8 spiral galaxy (type SBbc?) in Leo (RA 11 49 18.8, Dec +26 07 18)
Historical Identification: Per Dreyer, NGC 3902 (= GC 2568 = JH 989 = WH III 321, 1860 RA 11 42 01, NPD 63 05.8) is "faint, pretty small, a little extended, very gradually a little brighter middle". The position precesses to RA 11 49 17.1, Dec +26 07 31, on the northwestern rim of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3903 (= PGC 36906)
Discovered (Apr 21, 1835) by
John Herschel
A magnitude 12.8 spiral galaxy (type SBc?) in Centaurus (RA 11 49 03.5, Dec -37 31 02)
Historical Identification: Per Dreyer, NGC 3903 (= GC 2569 = JH 3362, 1860 RA 11 42 01, NPD 126 44.4) is "pretty bright, considerably small, very little extended, a little brighter middle". The position precesses to RA 11 49 02.3, Dec -37 31 05, within the western outline of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3904 (= PGC 36918)
Discovered (Mar 7, 1791) by
William Herschel
Also observed (May 10, 1834) by John Herschel
A magnitude 10.9 elliptical galaxy (type E2?) in Hydra (RA 11 49 13.2, Dec -29 16 36)
Historical Identification: Per Dreyer, NGC 3904 (= GC 2570 = JH 3363 = WH II 864, 1860 RA 11 42 09, NPD 118 32.5) is "pretty bright, small, round, much brighter middle". The position precesses to RA 11 49 12.8, Dec -29 19 11, about 2.6 arcmin south of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3905 (= PGC 36909)
Discovered (1880) by
Andrew Common
Also observed (1886) by Ormand Stone
A magnitude 12.8 spiral galaxy (type SBbc?) in Crater (RA 11 49 04.9, Dec -09 43 48)
Historical Identification: Per Dreyer, NGC 3905 (Common (#24), Ormond Stone list I (#192), 1860 RA 11 42 14, NPD 98 59.0) is "very faint, large, diffuse". The position precesses to RA 11 49 22.4, Dec -09 45 41, about 4.7 arcmin east southeast of the galaxy listed above, but the description fits and there is nothing else nearby, so the identification is certain.
Discovery Notes: Stone's position (1890 RA 11 44, Dec -09 07) precesses to RA 11 49 36.7, Dec -09 43 41. Common's position (1880 RA 11 43 15, Dec -09 06) precesses to RA 11 49 22.3, Dec -09 46 01, so Stone's declination is correct, but both right ascensions are east of the galaxy.
Physical Information:

NGC 3906 (= PGC 36953)
Discovered (Mar 9, 1788) by
William Herschel
A magnitude 12.9 spiral galaxy (type SBcd?) in Ursa Major (RA 11 49 40.6, Dec +48 25 34)
Historical Identification: Per Dreyer, NGC 3906 (= GC 2571 = WH III 715, 1860 RA 11 42 15, NPD 40 48.0) is "extremely faint, pretty large". The position precesses to RA 11 49 38.4, Dec +48 25 19, within the western outline of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3907 (= PGC 36941)
Discovered (Apr 15, 1828) by
John Herschel
A magnitude 13.1 lenticular galaxy (type E/S0?) in Virgo (RA 11 49 30.2, Dec -01 05 12)
Historical Identification: Per Dreyer, NGC 3907 (= GC 2572 = JH 990, 1860 RA 11 42 20, NPD 90 19.1) is "extremely faint, small, pretty suddenly brighter middle". The position precesses to RA 11 49 30.1, Dec -01 05 47, only 0.6 arcmin south of the galaxy listed above, the description fits and although there is another galaxy (PGC 36928) only 1.8 arcmin to the west northwest, its low surface brightness would have made it impossible for Herschel to see, so the identification is certain.
Physical Information:

PGC 36928 (= "NGC 3907B")
Not an NGC object but listed here since sometimes called NGC 3907B
A magnitude 13.1 spiral galaxy (type Sb?) in
Virgo (RA 11 49 23.5, Dec -01 05 02)
Physical Information:

NGC 3908 (perhaps = PGC 36967)
Discovered (Apr 10, 1885) by
Lewis Swift
A magnitude 15.0 elliptical galaxy (type E0?) in Leo (RA 11 49 52.7, Dec +12 11 09)
Historical Identification: Per Dreyer, NGC 3908 (Swift list I (#17), 1860 RA 11 42 28, NPD 77 09.0) is "faint, very small, round, much brighter middle". The position precesses to RA 11 49 40.8, Dec +12 04 19, about 7.5 arcmin south southwest of the galaxy listed above, and since it is the only nebular object in the region, it is generally considered to be what Swift saw. However, both Corwin and Gottlieb note that it is much fainter than implied by Swift's description and may have been too faint for him to see at all; and although the error in right ascension matches that of the only other object discovered by Swift on the same night (NGC 5304), the declination error is more than 5 arcmin larger than for the other galaxy. So although it is possible that PGC 36967 is NGC 3908, it is just as likely that the object is "lost" and the presence of any galaxy near Swift's position is merely a coincidence.
Physical Information:
(Note to self: Image of PGC 36967 should be labeled "NGC 3908 (?)")

NGC 3909 (= OCL = "PGC 3518295")
Discovered (Mar 1, 1835) by
John Herschel
A magnitude 7(?) open cluster in Centaurus (RA 11 50 07, Dec -48 14 40)
Historical Identification: Per Dreyer, NGC 3909 (= GC 2573 = JH 3364, 1860 RA 11 42 34, NPD 137 29.4) is "a cluster, very large, a little compressed, stars from 9th to 14th magnitude". The position precesses to RA 11 49 31.7, Dec -48 16 05, near a pair of 9th magnitude stars on the western rim of the cluster listed above, which pair was used by Herschel to determine the position of the cluster, but using the reddish stars that make up most of the brighter stars in that region makes the cluster less than "very large". The ESO position used by Corwin (and in this entry, above) is near the center of a much larger roughly circular grouping of 50 or so bright to fairly bright stars (and a number of fainter stars, though they are not so obvious).
Note About the PGC Designation: For purposes of completeness, LEDA assigns a PGC designation to almost all NGC/IC objects, whether they are galaxies or not. However, as in almost all such cases, a search of the database for the PGC designation shown above returns no result, so it is noted in quotes.
Physical Information: Approximately two dozen or so stars ranging from magnitude 9.8 to 11, plus another two dozen or so slightly fainter stars loosely scattered over a region measuring about 14 to 18 arcmin from north to south, and 20 to 24 arcmin from east to west. Whether this is an actual "cluster" or merely a chance alignment of "background" stars is uncertain, and would require reasonably accurate estimates of the distances of the individual stars to determine.
DSS image centered on open cluster NGC 3909
Above, a 27 arcmin wide DSS image centered on NGC 3909

NGC 3910 (= PGC 36971)
Discovered (Dec 27, 1786) by
William Herschel
Discovered (Mar 3, 1869) by Otto Struve
A magnitude 12.8 lenticular galaxy (type E/S0?) in Leo (RA 11 49 59.3, Dec +21 20 01)
Historical Identification: Per Dreyer, NGC 3910 (= GC 5584, Otto Struve, 1860 RA 11 42 43, NPD 67 53) is "small, round, much brighter middle, 10th or 11th magnitude star 50 arcsec to north". The position precesses to RA 11 49 57.7, Dec +21 20 19, less than 0.5 arcmin northwest of the nucleus of the galaxy listed above, the description fits (including the position of the nearby star) and there is nothing else nearby, so the identification is certain.
William Herschel's Observation: Herschel did not publish his observation of this object, so Struve's observation was the first one known to exist, but Steinicke lists it as recorded in Herschel's Sweep Records of Sep 1786 to Oct 1787 (Steinicke's historical reference S179).
Physical Information: Apparent size about 1.6 by 1.35 arcmin (from the images below).
SDSS image of region near lenticular galaxy NGC 3910
Above, a 12 arcmin wide SDSS image centered on NGC 3910
Below, a 2.4 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy NGC 3910

WORKING 3911 & 3920: NGC position = JH position, which is WRONG
(Will finish up with these two entries after dealing with the rest of the page)

NGC 3911 (= PGC 36926)
Disovered (Mar 28, 1832) by
John Herschel
A magnitude 14.5 spiral galaxy (type SBbc?) in Leo (RA 11 49 22.1, Dec +24 56 18)
Historical Identification: Per Dreyer, NGC 3911 (= GC 2574 = JH 991 (but not = WH III 341), 1860 RA 11 42 48, NPD 64 18.0) is "very faint, small, western of 2", the other being NGC 3920. The position precesses to RA 11 50 03.5, Dec +24 55 19, but there is nothing there. (To be explained ASAP; see the Note immediately below.)
Discovery Notes: JH (and therefore Dreyer) used his own very poor positions for the two galaxies in the region, and assumed that WH observed the fainter western galaxy. But WH actually observed the brighter eastern galaxy, so the discovery information for both NGC entries is wrong. This can be treated as a misidentification of the two galaxies (as Corwin has done, with NGC 3911 being 3920 and vice-versa), but since the NGC is arranged in order of right ascension, tradition requires the eastern galaxy to be NGC 3920, and the western one NGC 3911, as they have been labeled ever since Dreyer published the NGC. Only the discovery information should be changed to reflect the errors in the GC, as I have done on this page by moving WH III 341 to the entry for NGC 3920.
Analysis of WH III 341: In William Herschel's first list of 1000 New Nebulae and Clusters of Stars, III 341 (observed April 10, 1785) is listed as "very faint, very small, ver. 240. easily", the latter comment meaning that it was easily visible at 240 power through his telescope. Its position is listed as 26 minutes and 41 seconds of time west and 56 arcmin north of 7 Comae Berenices. The J2000 position of the comparison star is RA 12 16 20.54, Dec +23 56 43.5, and its proper motion is -25.991 milli-arcsec per year in right ascension, and -7.538 milli-arcsec per year in declination. This means that in the 215 years since Herschel's observation, the star moved 5.59 arcsec to the west (or 0.37 seconds of time), and 1.6 seconds of time to the south, giving it a position in 1785 (in J2000 coordinates) of RA 12 16 20.91, Dec +23 56 45.1, or precessing this to 1785 coordinates, RA 12 05 26.53, Dec +25 08 30.1. Applying the recorded offsets from the star to III 341, that nebula was at (1785) RA 11 38 45.5, Dec +26 04 30, or (precessing to modern coordinates) J2000 RA 11 49 55.5, Dec +24 52 50 (the apparent precision of these numbers is far greater than Herschel's measurements, but I did not want to introduce any round-off errors, so it seemed better to use more rather than less precise calculations). This position lies about 3.4 arcmin southwest of NGC 3920, which Herschel should have been able to see, and about 8.4 arcmin east southeast of NGC 3911, which was almost certainly too faint for him to see; so it seems certain that WH III 341 is not NGC 3911, but NGC 3920, and I have adjusted Dreyer's NGC discovery data for both entries to reflect that.
Physical Information:
SDSS image of region near spiral galaxy NGC 3911
Above, a 12 arcmin wide SDSS image centered on NGC 3911

NGC 3912 (=
NGC 3899 = PGC 36979)
Discovered (Apr 6, 1785) by William Herschel (and later listed as NGC 3912)
Also observed (Apr 13, 1831) by John Herschel (and later listed as NGC 3912)
Discovered (Mar 26, 1827) by John Herschel (and later listed as NGC 3899)
A magnitude 12.4 spiral galaxy (type SBb?) in Leo (RA 11 50 04.4, Dec +26 28 45)
Historical Identification: Per Dreyer, NGC 3912 (= GC 2575 = JH 992 = WH II 342, 1860 RA 11 42 49, NPD 62 44.0) is "faint, pretty large, round, pretty gradually brighter middle". The position precesses to RA 11 50 04.9, Dec +26 29 19, just off the northern rim of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3913 (= PGC 37024 =
IC 740)
Discovered (Apr 14, 1789) by William Herschel (and later listed as NGC 3913)
Discovered (May 8, 1890) by Lewis Swift (and later listed as IC 740)
A magnitude 12.6 spiral galaxy (type (R)SA(rs)d?) in Ursa Major (RA 11 50 38.9, Dec +55 21 14)
Historical Identification: Per Dreyer, NGC 3913 (= GC 2576 = WH II 786, 1860 RA 11 43 01, NPD 33 53.0) is "faint, extended". The position precesses to RA 11 50 27.2, Dec +55 20 19, about 1.9 arcmin southwest of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:Apparent size 2.9 by 2.9 arcmin. See IC 740 for a discussion of the duplicate listing (more to follow in the next iteration of this page).
SDSS image of region near spiral galaxy NGC 3913
Above, a 12 arcmin wide SDSS image centered on NGC 3913
Below, a 3 arcmin wide SDSS image of the galaxy
SDSS image of spiral galaxy NGC 3913

NGC 3914 (= PGC 37014)
Discovered (Apr 13, 1784) by
William Herschel
Also observed (Dec 27, 1827) by John Herschel
A magnitude 13.2 spiral galaxy (type SBb?) in Virgo (RA 11 50 32.6, Dec +06 34 03)
Historical Identification: Per Dreyer, NGC 3914 (= GC 2580 = JH 995 = WH III 90, 1860 RA 11 43 21, NPD 82 38.9) is "faint, very small, round, a little brighter middle, 13th magnitude star 80 arcsec to northwest". The position precesses to RA 11 50 32.6, Dec +06 34 24, just above the northern rim of the galaxy listed above, the description fits (including the star to the north northwest) and there is nothing else nearby, so the identification is certain.
Physical Information:

WORKING HERE: Identification uncertain (at best?)

NGC 3915 (probably =
IC 2963 = PGC 36933, but not = IC 738)
Discovered (Apr 24, 1784) by William Herschel (and later listed as NGC 3915)
Also observed (1881?) by Christian Peters (and later listed as NGC 3915)
Discovered (Mar 30, 1892) by Guillaume Bigourdan (and later listed as IC 2963)
A magnitude 13.9 lenticular galaxy (type S0/a?) in Virgo (RA 11 49 24.6, Dec -05 07 05)
Historical Identification: Per Dreyer, NGC 3915 (= GC 2577 = WH III 113, Peters, 1860 RA 11 43 23, NPD 94 22.2) is "extremely faint, extremely small, between 2 stars". The position precesses to RA 11 50 32.4, Dec -05 08 54, but there is nothing there. As the notes above and below show there are several "educated guesses" as to what Herschel saw, which I will deal with after finishing the identifications for the rest of the objects on this page.
Discovery Notes: The NGC position is taken from Peters' paper (Copernicus, 1881, pp. 51 - 54), but the description is from Herschel, while Peters writes that the nebula is very large.
Possible identifications (per Corwin): ? at RA 11 46 55.6, Dec -05 11 16; ?? = IC 738 at RA 11 48 54.9, Dec -04 40 55; ?? = IC 2963
Physical Information:

NGC 3916 (= PGC 37047)
Discovered (Apr 14, 1789) by
William Herschel
Also observed (Feb 10, 1831) by John Herschel
A magnitude 13.9 spiral galaxy (type Sb?) in Ursa Major (RA 11 50 51.0, Dec +55 08 37)
Historical Identification: Per Dreyer, NGC 3916 (= GC 2578 = JH 993 = WH II 787, 1860 RA 11 43 24, NPD 34 04.5) is "extremely faint, round, gradually brighter middle". The position precesses to RA 11 50 49.6, Dec +55 08 48, less than 0.3 arcmin northwest of the nucleus of the galaxy listed above, the description fits (keeping in mind that visual observers could not see the fainter outer regions of their nebulae) and there is nothing nearby, so the identification is certain.
Physical Information:

NGC 3917 (= PGC 37036)
Discovered (Mar 17, 1790) by
William Herschel
Also observed (Feb 17, 1831) by John Herschel
A magnitude 11.8 spiral galaxy (type Sc?) in Ursa Major (RA 11 50 45.4, Dec +51 49 28)
Historical Identification: Per Dreyer, NGC 3917 (= GC 2579 = GC 2583 = JH 994 = WH II 824, 1860 RA 11 43 24, NPD 37 23.7) is "faint, large, very much extended, very gradually brighter middle". The position precesses to RA 11 50 47.9, Dec +51 49 36, right on the galaxy listed above, the description fits and there is nothing comparable nearby, so the identification is certain.
Physical Information:

PGC 39073 (=
NGC 3931 = "NGC 3917A")
Listed here since sometimes incorrectly called NGC 3917A
A magnitude 13.4 lenticular galaxy (type E/S0?) in Ursa Major (RA 11 51 13.4, Dec +52 00 03)
Warning About Non-Standard Designations: As noted in many places in this catalog, the use of non-standard "letter" designations should always be avoided, due to the confusion resulting from irregular application of the letters; but it is especially egregious when, as in this case, the object has a perfectly good NGC designation of its own.
Physical Information: Given the above, see NGC 3931 for anything else.


NGC 3918 (= P-K 294+04.1 = "PGC 3517767"), the Blue Planetary
Discovered (Apr 3, 1834) by
John Herschel
A magnitude 8.1 planetary nebula in Centaurus (RA 11 50 17.8, Dec -57 10 56)
Historical Identification: Per Dreyer, NGC 3918 (= GC 2581 = JH 3365, 1860 RA 11 43 24, NPD 146 24.1) is "a planetary nebula, a remarkable object, small, round, blue, = to a 7th magnitude star, diameter = 1.5 seconds of time". The position precesses to RA 11 50 17.9, Dec -57 10 48, almost dead center on the nebula listed above, the description fits and there is nothing else nearby, so the identification is certain.
PGC Designation Note: For purposes of completeness, LEDA assigns a PGC designation to this object, even though it is not a galaxy; but a search of the database returns no result, so the designation is shown in quotes.
Physical Information NGC 3918 is about 4900 light years away from us. Given that and its apparent size of about 1.95 by 1.9 arcmin (from the images below), the outer structure is about 2.8 light years across, while the roughly circular central region shown in the HST image is about half a lightyear across. The jets of material extending to the east and west are moving away from the white dwarf in the center of the nebula (the remnants of a collapsed red giant) at over 200 thousand miles per hour, or about 60 miles per second.
DSS image centered on region near planetary nebula NGC 3918
Above, a 12 arcmin wide DSS image centered on NGC 3918
Below, a 3 arcmin wide DSS image of the planetary nebula
DSS image of planetary nebula NGC 3918
Below, a 0.6 arcmin wide HST image of the center of the planetary nebula
HST image of planetary nebula NGC 3918

NGC 3919 (= PGC 37032)
Discovered (Apr 6, 1864) by
Heinrich d'Arrest
A magnitude 13.3 elliptical galaxy (type E0?) in Leo (RA 11 50 41.5, Dec +20 00 55)
Historical Identification: Per Dreyer, NGC 3919 (= GC 5585, d'Arrest, 1860 RA 11 43 28, NPD 69 12.1) is "faint, small, round". The position precesses to RA 11 50 42.2, Dec +20 01 12, less than 0.3 arcmin from the center of the galaxy listed above, the description fits and there is nothing comparable nearby, so the identification is certain.
Physical Information:

WORKING 3911 & 3920: NGC position = JH position, which is WRONG
(Will finish up with these two entries after dealing with the rest of the page)

NGC 3920 (= PGC 36981)
Discovered (Apr 10, 1785) by
William Herschel
Also observed (Mar 28, 1832) by John Herschel
A magnitude 13.3 spiral galaxy (type SBbc?) in Leo (RA 11 50 05.9, Dec +24 55 12)
Historical Identification: Per Dreyer, NGC 3920 (= GC 2582 = JH 996 (and = WH III 341), 1860 RA 11 43 34±, NPD 64 17.8) is "nebula, eastern of 2", the other being NGC 3911. The position precesses to RA 11 50 49.2, Dec +24 55 30, well to the east of the nearest galaxy. (To be explained ASAP; see the Note immediately following.)
Discovery Notes: JH (and therefore Dreyer) used his own very poor positions for the two galaxies in the region, and assumed that WH observed the fainter western galaxy. But WH actually observed the brighter eastern galaxy, so the discovery information for both NGC entries is wrong. This can be treated as a misidentification of the two galaxies (as Corwin has done, with NGC 3911 being 3920 and vice-versa), but since the NGC is arranged in order of right ascension, tradition requires the eastern galaxy to be NGC 3920, and the western one NGC 3911, as they have been labeled ever since Dreyer published the NGC. Only the discovery information should be changed to reflect the errors in the GC, as I have done on this page by moving WH III 341 to the entry for NGC 3920.
Analysis of WH III 341: In William Herschel's first list of 1000 New Nebulae and Clusters of Stars, III 341 (observed April 10, 1785) is listed as "very faint, very small, ver. 240. easily", the latter comment meaning that it was easily visible at 240 power through his telescope. Its position is listed as 26 minutes and 41 seconds of time west and 56 arcmin north of 7 Comae Berenices. The J2000 position of the comparison star is RA 12 16 20.54, Dec +23 56 43.5, and its proper motion is -25.991 milli-arcsec per year in right ascension, and -7.538 milli-arcsec per year in declination. This means that in the 215 years since Herschel's observation, the star moved 5.59 arcsec to the west (or 0.37 seconds of time), and 1.6 seconds of time to the south, giving it a position in 1785 (in J2000 coordinates) of RA 12 16 20.91, Dec +23 56 45.1, or precessing this to 1785 coordinates, RA 12 05 26.53, Dec +25 08 30.1. Applying the recorded offsets from the star to III 341, that nebula was at (1785) RA 11 38 45.5, Dec +26 04 30, or (precessing to modern coordinates) J2000 RA 11 49 55.5, Dec +24 52 50 (the apparent precision of these numbers is far greater than Herschel's measurements, but I did not want to introduce any round-off errors, so it seemed better to use more rather than less precise calculations). This position lies about 3.4 arcmin southwest of NGC 3920, which Herschel should have been able to see, and about 8.4 arcmin east southeast of NGC 3911, which was almost certainly too faint for him to see; so it seems certain that WH III 341 is not NGC 3911, but NGC 3920, and I have adjusted Dreyer's NGC discovery data for both entries to reflect that.
Physical Information:
SDSS image of region near spiral galaxy NGC 3920
Above, a 12 arcmin wide SDSS image centered on NGC 3920

NGC 3921 (= PGC 37063)
Discovered (Apr 14, 1789) by
William Herschel
Also observed (Feb 10, 1831) by John Herschel
A magnitude 12.4 lenticular galaxy (type S0/a? pec) in Ursa Major (RA 11 51 06.9, Dec +55 04 43)
Historical Identification: Per Dreyer, NGC 3921 (= GC 2584 = JH 997 = WH II 788, 1860 RA 11 43 39, NPD 34 08.5) is "pretty faint, small, round, pretty suddenly pretty much brighter middle". The position precesses to RA 11 51 04.3, Dec +55 04 48, on the eastern rim of the galaxy listed above, the description fits and there is nothing comparable nearby, so the identification is certain.
Physical Information:

NGC 3922 (=
NGC 3924 = PGC 37072)
Discovered (Mar 9, 1788) by William Herschel (and later listed as NGC 3922)
Discovered (Mar 17, 1790) by William Herschel (and later listed as NGC 3924)
A magnitude 12.8 lenticular galaxy (type S0/a?) in Ursa Major (RA 11 51 13.4, Dec +50 09 25)
Historical Identification: Per Dreyer, NGC 3922 (= GC 2585 = WH III 716, 1860 RA 11 43 48, NPD 39 01.0) is "very faint, very small". The position precesses to RA 11 51 10.7, Dec +50 12 18, almost 3 arcmin north northwest of the galaxy listed above, but the description is reasonable (keeping in mind that the fainter outer regions of the galaxy would not have been visible to Herschel) and there is nothing else nearby, so the identification is certain.
Discovery Notes: Two years later Herschel observed the same region and presumably saw the same galaxy, but obtained a measurement of its position that was even further from the other side of the galaxy, so it was listed twice by Dreyer, as NGC 3922 and 3924. In his 1912 study of Herschel's papers Dreyer notes that III 716 is a duplicate of II 825 (= NGC 3924), with a position "which agrees very well with the place of III 716". He therefore stated that since NGC 3924 was the same object as NGC 3922, it should be deleted from the NGC listings. As a result, the earlier observation (in terms of numerical order and date of observation) is considered the proper designation for the galaxy. There appears to be a disconnect between the very different positions given in the NGC for the two objects and Dreyer's 1912 statement; so there must have been an error of reduction in one or both of Herschel's positions, and as a result, this entry and the one for NGC 3922 will not be considered finalized until I have had a chance to verify Dreyer's statements.
Physical Information:

NGC 3923 (= PGC 37061)
Discovered (Mar 7, 1791) by
William Herschel
Also observed (May 5, 1834) by John Herschel
A magnitude 9.8 elliptical galaxy (type E4?) in Hydra (RA 11 51 01.7, Dec -28 48 22)
Historical Identification: Per Dreyer, NGC 3923 (= GC 2586 = JH 3366 = WH I 259, 1860 RA 11 43 58, NPD 118 03.1) is "bright, pretty large, a little extended, gradually much brighter middle, mottled but not resolved, very small (faint) star involved on southwest". The position precesses to RA 11 51 02.8, Dec -28 49 48, barely off the southern rim of the galaxy listed above, the description fits (including the star to the southwest) and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3924 (=
NGC 3922 = PGC 37072)
Discovered (Mar 9, 1788) by William Herschel (and later listed as NGC 3922)
Discovered (Mar 17, 1790) by William Herschel (and later listed as NGC 3924)
A magnitude 12.8 lenticular galaxy (type S0/a?) in Ursa Major (RA 11 51 13.4, Dec +50 09 25)
Historical Identification: Per Dreyer, NGC 3924 (= GC 2587 = WH II 825, 1860 RA 11 43 59, NPD 39 08.0) is "pretty bright, small, irregular figure, brighter middle". The position precesses to RA 11 51 21.5, Dec +50 05 18, about 4.3 arcmin south southeast of the galaxy listed above, but the description fits and there is nothing else nearby, so the identification is certain.
Discovery Notes: In Herschel's published papers, the position of II 825 is compared to 26 Ursae (Majoris), with an offset of more than 2 hours of time and nearly 2 degrees in declination; but in Dreyer's 1912 notes to Herschel's collected papers he states "III. 716. This occurs also in Sweep 946, March 17, 1790, where it is called II. 825, and where a much better star is G. 1807, east 13m 46s south 0° 25', which agrees very well with the place of III. 716." The "better star" refers to the fact that G 1807 is much closer to the nebula than 26 Ursae, so the offsets are probably more accurate.
Analysis of Herschel's Offsets From Groombridge 1807: The nebula is listed as 13m 46s east of and 25 arcmin south of the star. The star itself is (from Groombridge's posthumously published Catalog of Circumpolar Stars, 1838) at (1810) RA 11 27 32.66, NPD 38 19 46.2, which precesses to J2000 RA 11 37 53.9, Dec +50 37 12, dead-on the spectroscopic binary HD 101013. Precessing from the 1810 position to Herschel's 1790 observation yields a position of (1790) RA 11 26 26.4, Dec +51 46 51, from which we subtract 25 arcmin of declination and to which we add 13m 46s of right ascension to find the position of WH II 825, namely (1790) RA 11 20 12.4, Dec +51 21 51, which precesses to J2000 RA 11 51 19.0, Dec +50 11 50, about 2.6 arcmin north northeast of the galaxy listed above, and while that is not as accurate as might be hoped for, it isn't far from Herschel's published position for III 716 (= NGC 3922), so Dreyer felt justified in equating the two NGC entries, and in his 1912 paper of corrections to the NGC based on his study of Herschel's papers, he stated that NGC 3924 was the same as NGC 3922 and should be struck out.
Physical Information: Given the duplicate entry, see NGC 3922 for anything else.

NGC 3925 (= PGC 37078)
Discovered (Feb 19, 1863) by
Heinrich d'Arrest
A magnitude 14.5 spiral galaxy (type Sb?) in Leo (RA 11 51 21.0, Dec +21 53 21)
Historical Identification: Per Dreyer, NGC 3925 (= GC 2588, d'Arrest, 1860 RA 11 44 05, NPD 67 20.1) is "very faint, very small". The position precesses to RA 11 51 19.4, Dec +21 53 12, only 0.4 arcmin southwest of the center of the galaxy listed above, the description fits and there is nothing else nearby, so the identification is certain.
Physical Information:

NGC 3926 (= PGC 37079 ("NGC 3926A") + PGC 37080 ("NGC 3926B"))
Discovered (Apr 26, 1785) by
William Herschel
Also observed (Mar 25, 1830) by John Herschel
A pair of galaxies in Leo
PGC 37079 is a magnitude 14.3 lenticular galaxy (type E/S0?) at RA 11 51 26.6, Dec +22 01 41
PGC 37080 is a magnitude 14.7 lenticular galaxy (type E/S0?) at RA 11 51 28.2, Dec +22 01 34
Historical Identification: Per Dreyer, NGC 3926 (= GC 2589 = JH 998 = WH III 379, 1860 RA 11 44 11, NPD 67 12.3) is "extremely faint, extremely small, very little extended, extremely mottled but not resolved, star near".
Possible Alternate Designation: Corwin lists only PGC 37080 as NGC 3926, and PGC 37079 as merely a companion
Physical Information:

NGC 3927 (= PGC 35546 =
NGC 3713)
Discovered (Apr 27, 1864) by Heinrich d'Arrest
A magnitude 13.2 lenticular galaxy (type E/S0?) in Leo (RA 11 31 42.0, Dec +28 09 13)
Historical Identification: Per Dreyer, NGC 3927 (= GC 5586, d'Arrest, 1860 RA 11 44 17, NPD 61 04.9) is "pretty faint, pretty small".
Physical Information:

NGC 3928 (= PGC 37136), the Miniature Spiral
Discovered (Mar 9, 1788) by
William Herschel
Also observed (Mar 7, 1831) by John Herschel
A magnitude 12.6 lenticular galaxy (type S0/a? pec) in Ursa Major (RA 11 51 47.6, Dec +48 40 59)
Historical Identification: Per Dreyer, NGC 3928 (= GC 2590 = JH 999 = WH II 740, 1860 RA 11 44 25, NPD 40 31.9) is "pretty faint, small, round, pretty suddenly pretty much brighter middle".
Physical Information: Why this is called the Miniature Spiral is a mystery to me, since it appears perfectly elliptical in older photographs, and even what "spiral" structure can be seen with current technology is only visible in very good images.

NGC 3929 (= PGC 37126)
Discovered (Dec 4, 1861) by
Heinrich d'Arrest
A magnitude 14.0 elliptical galaxy (type E3?) in Leo (RA 11 51 42.5, Dec +21 00 10)
Historical Identification: Per Dreyer, NGC 3929 (= GC 5587, d'Arrest, 1860 RA 11 44 28, NPD 68 13.3) is "a cluster, small, stars faint, very compressed".
Physical Information:

NGC 3930 (= PGC 37132)
Discovered (Mar 17, 1787) by
William Herschel
Also observed (Mar 11, 1831) by John Herschel
A magnitude 12.4 spiral galaxy (type SBc?) in Ursa Major (RA 11 51 45.8, Dec +38 00 54)
Historical Identification: Per Dreyer, NGC 3930 (= GC 2591 = JH 1000 = WH III 616, 1860 RA 11 44 30, NPD 51 13.3) is "extremely faint, considerably large, irregular figure, gradually a little brighter middle, 7th magnitude star to east". The first IC notes "The star is Groombridge 1830, the large proper motion of which is illustrated by the change of relative position of nebula and star".
Physical Information:

PGC 213893 (= "NGC 3930A")
Not an NGC object, but listed here since sometimes called NGC 3930A
A magnitude 15.7 spiral galaxy (type S?) in
Ursa Major (RA 11 52 02.3, Dec +38 01 13)
Physical Information:

NGC 3931 (= PGC 37073 = "NGC 3917A")
Discovered (Apr 12, 1789) by
William Herschel
A magnitude 13.4 lenticular galaxy (type E/S0?) in Ursa Major (RA 11 51 13.4, Dec +52 00 03)
Historical Identification: Per Dreyer, NGC 3931 (= GC 2592 = WH III 769, 1860 RA 11 44 40, NPD 37 16.0) is "extremely faint, small".
Physical Information:Apparent size 1.1 by 0.9 arcmin. Used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type SA0°.
SDSS image of region near lenticular galaxy NGC 3931
Above, a 12 arcmin wide SDSS image centered on NGC 3931
Below, a 2.4 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy NGC 3931

NGC 3932
Recorded (Dec 4, 1861) by
Heinrich d'Arrest
A magnitude 14 star in Ursa Major (RA 11 51 53.0, Dec +48 40 03)
Historical Identification: Per Dreyer, NGC 3932 (= GC 2593, d'Arrest (#125), 1860 RA 11 44 49, NPD 40 35.7) is "very faint, very difficult, II 740 to northwest", (WH) II 740 being NGC 3928.
Alternate Designations: Corwin lists NGC 3932 as the magnitude 13.3 star at RA 11 52 10.8, Dec +48 37 13. LEDA lists it as PGC 37194 at RA 11 52 29.2, Dec +48 27 32
Physical Information:

NGC 3933 (= PGC 37156)
Discovered (1871) by
Alphonse Borrelly
Also observed (1884) by Frederick Pechüle
A magnitude 13.6 spiral galaxy (type S?) in Leo (RA 11 52 02.0, Dec +16 48 35)
Historical Identification: Per Dreyer, NGC 3933 (= GC 5588, Borelly (#5), 1860 RA 11 44 49, NPD 72 24.3) is "pretty faint, a little extended".
Physical Information:

NGC 3934 (= PGC 37170)
Discovered (1871) by
Alphonse Borrelly
Also observed (1884) by Frederick Pechüle
A magnitude 13.6 spiral galaxy (type Sb?) in Leo (RA 11 52 12.6, Dec +16 51 06)
Historical Identification: Per Dreyer, NGC 3934 (= GC 5589, Borelly (#6), 1860 RA 11 44 58, NPD 72 21.8) is "extremely faint, round".
Physical Information:

NGC 3935 (= PGC 37183)
Discovered (Apr 29, 1827) by
John Herschel
A magnitude 13.3 spiral galaxy (type Sb?) in Ursa Major (RA 11 52 24.1, Dec +32 24 14)
Historical Identification: Per Dreyer, NGC 3935 (= GC 2594 = JH 1001, 1860 RA 11 45 09, NPD 56 48.8) is "pretty faint, small, a little extended, pretty suddenly brighter middle".
Physical Information:

NGC 3936 (= PGC 37178)
Discovered (Mar 24, 1835) by
John Herschel
A magnitude 12.1 spiral galaxy (type SBbc?) in Hydra (RA 11 52 20.6, Dec -26 54 21)
Historical Identification: Per Dreyer, NGC 3936 (= GC 2595 = JH 3367, 1860 RA 11 45 20, NPD 116 07.4) is "very faint, considerably large, very much extended 59°".
Physical Information:

NGC 3937 (= PGC 37219)
Discovered (Apr 27, 1785) by
William Herschel
Also observed (Apr 29, 1832) by John Herschel
A magnitude 12.5 lenticular galaxy (type E/S0?) in Leo (RA 11 52 42.6, Dec +20 37 53)
Historical Identification: Per Dreyer, NGC 3937 (= GC 2596 = JH 1003 = WH III 389, 1860 RA 11 45 29, NPD 68 35.1) is "very faint, considerably small, round".
Physical Information:

NGC 3938 (= PGC 37229)
Discovered (Feb 6, 1788) by
William Herschel
Also observed (Mar 19, 1828) by John Herschel
A magnitude 10.4 spiral galaxy (type Sc?) in Ursa Major (RA 11 52 49.4, Dec +44 07 15)
Historical Identification: Per Dreyer, NGC 3938 (= GC 2597 = JH 1002 = WH I 203, 1860 RA 11 45 31, NPD 45 05.6) is "bright, very large, round, brighter middle and pretty bright nucleus, extremely mottled but not resolved".
Physical Information:

NGC 3939 (=
NGC 3890 = PGC 36925)
Discovered (Dec 12, 1797) by William Herschel (and later listed as NGC 3890)
Discovered (Apr 2, 1801) by William Herschel (and later listed as NGC 3939)
A magnitude 13.3 spiral galaxy (type Sc?) in Draco (RA 11 49 19.8 Dec +74 18 08)
Historical Identification: Per Dreyer, NGC 3939 (= GC 2598 = WH III 971, 1860 RA 11 45 31, NPD 14 07.0) is "extremely faint, very small, round (Place doubtful)".
Physical Information:

NGC 3940 (= PGC 37224)
Discovered (Apr 26, 1785) by
William Herschel
Also observed (Feb 24, 1827) by John Herschel
A magnitude 12.8 elliptical galaxy (type E1?) in Leo (RA 11 52 46.4, Dec +20 59 21)
Historical Identification: Per Dreyer, NGC 3940 (= GC 2599 = JH 1004 = WH III 380, 1860 RA 11 45 34, NPD 68 14.0) is "very faint, considerably small, round".
Physical Information:

NGC 3941 (= PGC 37235)
Discovered (Mar 19, 1787) by
William Herschel
Also observed (Apr 23, 1827) by John Herschel
A magnitude 10.3 lenticular galaxy (type SB0?) in Ursa Major (RA 11 52 55.4, Dec +36 59 11)
Historical Identification: Per Dreyer, NGC 3941 (= GC 2600 = JH 1005 = WH I 173, 1860 RA 11 45 38, NPD 52 14.4) is "very bright, pretty large, round, suddenly much brighter middle equal to 9th magnitude star".
Physical Information:Apparent size 3.5 by 2.5 arcmin.
SDSS image of region near lenticular galaxy NGC 3941
Above, a 12 arcmin wide SDSS image centered on NGC 3941
Below, a 3.6 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy NGC 3941

NGC 3942 (= PGC 37099)
Discovered (1886) by
Francis Leavenworth
A magnitude 13.2 spiral galaxy (type Sc?) in Crater (RA 11 51 30.0, Dec -11 25 28)
Historical Identification: Per Dreyer, NGC 3942 (Leavenworth list II (#451), 1860 RA 11 45 40, NPD 100 39.0) is "extremely faint, pretty small, extended 160°, gradually a very little brighter middle".
Physical Information:

NGC 3943 (= PGC 37237)
Discovered (Apr 27, 1865) by
Heinrich d'Arrest
A magnitude 13.4 spiral galaxy (type S?) in Leo (RA 11 52 56.6, Dec +20 28 45)
Historical Identification: Per Dreyer, NGC 3943 (= GC 5590, d'Arrest, 1860 RA 11 45 43, NPD 68 44.4) is "pretty faint, pretty small, extended, 8th magnitude star 24 seconds to west".
Physical Information:

NGC 3944 (= PGC 37244)
Discovered (Apr 6, 1785) by
William Herschel
Also observed (Dec 24, 1827) by John Herschel
A magnitude 12.9 lenticular galaxy (type E/S0?) in Leo (RA 11 53 05.1, Dec +26 12 25)
Historical Identification: Per Dreyer, NGC 3944 (= GC 2601 = JH 1007 = WH III 322, 1860 RA 11 45 50, NPD 63 00.7) is "pretty faint, pretty small, round, pretty suddenly brighter middle".
Physical Information:

NGC 3945 (= PGC 37258)
Discovered (Mar 19, 1790) by
William Herschel
Also observed (Apr 14, 1831) by John Herschel
A magnitude 10.9 lenticular galaxy (type (R)SB(rl)0+) in Ursa Major (RA 11 53 13.6, Dec +60 40 32)
Historical Identification: Per Dreyer, NGC 3945 (= GC 2602 = JH 1006 = WH I 251, 1860 RA 11 45 51, NPD 28 32.9) is "bright, pretty large, round, gradually much brighter middle, mottled but not resolved, 12th magnitude star to southwest".
Physical Information:Apparent size 5.2 by 3.5 arcmin. Used by the de Vaucouleurs Atlas of Galaxy Types as an example of galaxy type (R)SB(rl)0+.
SDSS image of region near lenticular galaxy NGC 3945
Above, a 12 arcmin wide SDSS image centered on NGC 3945
Below, a 6 arcmin wide SDSS image of the galaxy
SDSS image of lenticular galaxy NGC 3945

NGC 3946 (= PGC 37268)
Discovered (Apr 23, 1886) by
Guillaume Bigourdan
A magnitude 14.3 lenticular galaxy (type S0/a?) in Leo (RA 11 53 20.6, Dec +21 01 17)
Historical Identification: Per Dreyer, NGC 3946 (Bigourdan (list I #49), 1860 RA 11 46 07, NPD 68 12) is "very faint, very little brighter middle, diffuse".
Physical Information:

NGC 3947 (= PGC 37264)
Discovered (Apr 26, 1785) by
William Herschel
Also observed (Mar 25, 1830) by John Herschel
A magnitude 13.2 spiral galaxy (type SBb?) in Leo (RA 11 53 20.3, Dec +20 45 06)
Historical Identification: Per Dreyer, NGC 3947 (= GC 2603 = JH 1008 = WH II 403, 1860 RA 11 46 08, NPD 68 28.0) is "faint, pretty small, irregularly extended, a little brighter middle, double star to west".
Physical Information:

NGC 3948 (= "PGC ")
Recorded (Apr 23, 1886) by
Guillaume Bigourdan
A magnitude 14.7 star in Leo (RA 11 53 36.7, Dec +20 57 03)
Historical Identification: Per Dreyer, NGC 3948 (Bigourdan (list I #50), 1860 RA 11 46 21, NPD 68 16) is "very faint, stellar".
Physical Information:

NGC 3949 (= PGC 37290)
Discovered (Feb 5, 1788) by
William Herschel
Also observed (Mar 7, 1831) by John Herschel
A magnitude 11.1 spiral galaxy (type SA(s)bc?) in Ursa Major (RA 11 53 41.7, Dec +47 51 31)
Historical Identification: Per Dreyer, NGC 3949 (= GC 2604 = JH 1009 = WH I 202, 1860 RA 11 46 22, NPD 41 22.0) is "considerably bright, pretty large, pretty much extended, very gradually brighter middle".
Physical Information:NGC 3949's recessional velocity of 800 km/sec is too small in comparison to peculiar (non-Hubble-expansion) velocities to provide a reliable distance estimate. Taken at face value, it implies a distance of only 37 million light years, in poor agreement with redshift-independent distance estimates of 50 to 70 million light years. Presuming a distance of around 60 million light years, the galaxy's apparent size of 2.9 by 1.25 arcmins corresponds to about 50 thousand light years.
SDSS image of region near NGC 3949
Above, a 12 arcmin wide SDSS image centered on NGC 3949, also showing NGC 3950 to its north
Below, a 3 arcmin wide SDSS image of the galaxy
SDSS image of NGC 3949
Celestial Atlas
(NGC 3850 - 3899) ←     NGC Objects: NGC 3900 - 3949     → (NGC 3950 - 3999)