NGC 604 is an H II region inside the Triangulum Galaxy. It was discovered by William Herschel on September 11, 1784. It is among the largest H II regions in the Local Group of galaxies; at the galaxy's estimated distance of 2.7 million light-years, its longest diameter is roughly 1,520 light years (~460 parsecs), over 40 times the size of the visible portion of the Orion Nebula. It is over 6,300 times more luminous than the Orion Nebula, and if it were at the same distance it would outshine Venus. Its gas is ionized by a cluster of massive stars at its center with 200 stars of spectral type O and WR, a mass of 105 solar masses, and an age of 3.5 million years; however, unlike the Large Magellanic Cloud's Tarantula Nebula central cluster (R136), NGC 604's one is much less compact and more similar to a large stellar association.
Messier 36 or M36, also known as NGC 1960 or the Pinwheel Cluster, is an open cluster of stars in the somewhat northern Auriga constellation. It was discovered by Giovanni Batista Hodierna before 1654, who described it as a nebulous patch. The cluster was independently re-discovered by Guillaume Le Gentil in 1749, then Charles Messier observed it in 1764 and added it to his catalogue. It is about 1,330 pc away from Earth. The cluster is very similar to the Pleiades cluster (M45), and if as far away it would be of similar apparent magnitude.
Messier 46 or M46, also known as NGC 2437, is an open cluster of stars in the slightly southern constellation of Puppis. It was discovered by Charles Messier in 1771. Dreyer described it as "very bright, very rich, very large." It is about 5,000 light-years away. There are an estimated 500 stars in the cluster with a combined mass of 453 M☉, and it is thought to be a mid-range estimate of 251.2 million years old.
NGC 2546 is a pair of independent but overlapping open clusters located in the southern constellation of Puppis. This grouping was discovered by French astronomer Abbe Lacaille in 1751-1752 from South Africa. NGC 2546 is just visible to the naked eye as a fuzzy patch; the brightest component has an apparent visual magnitude of 6.44. The brighter members are readily resolved with a pair of 10×50 binoculars.
NGC 5749 is an open cluster of stars positioned near the southwest border of the southern constellation of Lupus. It is located at a distance of 3,548 light years from the Sun. This is a poorly populated cluster that shows a low level of concentration; the Trumpler class is IV1p. There are 112 stars brighter than magnitude 14.4 within an angular radius of ~15′ of the cluster center, but only about 30% of these are members. NGC 5749 is 27 million years old with a tidal radius of 11.7 light years and a mass of ~21 M☉. Polarization measurements suggest there is a dust cloud within the cluster.
NGC 265 is an open cluster of stars in the southern constellation of Tucana. It is located in the Small Magellanic Cloud, a nearby dwarf galaxy. The cluster was discovered by English astronomer John Herschel on April 11, 1834. J. L. E. Dreyer described it as, "faint, pretty small, round", and added it as the 265th entry in his New General Catalogue.
NGC 6709 is an open cluster of stars in the equatorial constellation of Aquila, some 5° to the southwest of the star Zeta Aquilae. It is situated toward the center of the galaxy at a distance of 3,510 light-years.
NGC 2374 is an open cluster of stars in the Canis Major constellation. It was discovered on January 31, 1785 by the German-British astronomer William Herschel. This cluster is relatively rich in stars but is scattered across an angular diameter of 19.0′. It has an integrated visual magnitude of 8.0 and can be viewed with a modest amateur telescope. NGC 2374 is located at a distance of approximately 3,950 light-years (1,212 pc) from the Sun.
NGC 2506 is a mildly-elongated open cluster of stars in the equatorial constellation of Monoceros, located at a distance of 12.7 kly from the Sun near the Galactic anti-center. It was discovered by William Herschel in 1791. The cluster lies around 10,000 ly from the Galactic Center and about 1,600 ly above the Galactic plane. It is of intermediate age, estimated at around two billion years. The cluster has an angular radius of 12′ and a core radius of 4.8′.
NGC 1901 is an open cluster in the Dorado Constellation. It has a bright middle and is a little rich, with stars from 7th magnitude downwards. The celestial object was discovered on 30 December 1836 by the British astronomer John Herschel. The cluster is sparsely populated with GAIA data suggesting a membership of around 80 stars. It is considered unlikely it will survive its next pass through the Milky Way’s galactic plane in about 18 million years time.
NGC 146 is a small open cluster in the constellation Cassiopeia. It was discovered by John Herschel in 1829 using his father's 18.7 inch reflecting telescope.
NGC 299 is an open cluster of stars in the main body of the Small Magellanic Cloud – a nearby dwarf galaxy. It is located in the southern constellation of Tucana, just under 200,000 light years distant from the Sun. The cluster was discovered on August 12, 1834, by English astronomer John Herschel.
NGC 376 is a young open cluster of stars in the southern constellation of Tucana. It was discovered on September 2, 1826, by Scottish astronomer James Dunlop. Dreyer, a Danish/British astronomer, described it as a "globular cluster, bright, small, round." It is irregular in form, with a central spike.
NGC 419 is a globular cluster located approximately 57,000 pc (190,000 ly) from Earth in the constellation Tucana. It was discovered on September 2, 1826, by James Dunlop. It was described by Dreyer as "pretty large, pretty bright, round, gradually brighter middle". At a distance of about 186,000 light years, it is located within the Small Magellanic Cloud. At an aperture of 50 arcseconds, its apparent V-band magnitude is 10.30, but at this wavelength, it has 0.15 magnitudes of interstellar extinction.
NGC 6045 is a barred spiral galaxy located about 450 million light-years away in the constellation Hercules. NGC 6045 was discovered by astronomer Lewis Swift on June 27, 1886 and is a member of the Hercules Cluster. It is also a LINER galaxy.
NGC 4570 is an edge-on lenticular galaxy located about 57 million light-years away in the constellation Virgo. NGC 4570 was discovered by astronomer William Herschel on April 13, 1784 and is a member of the Virgo Cluster.
NGC 1272 is a massive elliptical galaxy located about 230 million light-years away in the constellation Perseus. It was discovered by astronomer Heinrich d'Arrest on February 14, 1863. NGC 1272 has an active nucleus and is the second brightest member of the Perseus Cluster after NGC 1275.
NGC 1279 is a lenticular galaxy estimated to be 324 million light-years away from the Milky Way in the constellation Perseus. It has diameter of about 110,000 ly, and is a member of the Perseus Cluster.
NGC 2404 is a massive H II region inside NGC 2403, a spiral galaxy in Camelopardalis. It was discovered on February 2, 1886 by Gulliaume Bigourdan. NGC 2404 is approximately 940 ly in diameter, making it one of the largest H II regions so far known. It is the largest H II region in NGC 2403, and lies at the outskirts of the galaxy, making for a striking similarity with NGC 604 in M33, both in size and location in the host galaxy. This H II region contains 30-40 Wolf-Rayet stars, and unlike the Tarantula Nebula, but similar to NGC 604, NGC 2404's open cluster is probably much less compact, so it probably looks like a large stellar association. This H II region is probably only a few million years old.
NGC 1444 is a small open cluster of stars in the northern constellation of Perseus, about 2-1⁄4° to the northwest of 43 Persei. It has an angular diameter of 4 arcminutes and a brightness of 6.60 in visual magnitude. The cluster has sixty members of seventh magnitude or fainter, and is better appreciated in larger telescopes. NGC 1444 was discovered on 18 December 1788 by the German-British astronomer William Herschel. It is located at a distance of 4,200 light-years from the Sun and is about 7.1 million years old. The cluster has a physical core radius of 1.73 ± 0.42 ly and a tidal radius of 17.4 ± 4.2 ly. The most prominent member is the triple star system Σ446, with a magnitude 6.7 primary. The cluster is a member of the Camelopardalis OB1 association.
