Messier object explained

Messier Catalog
Type:	Astronomical catalogue
Namedafter:	Charles Messier
Published:	1774 (preliminary version)
Commons:	Messier Catalog
Onlysourced:	yes
Editonwikidata:	no

The Messier objects are a set of 110 astronomical objects catalogued by the French astronomer Charles Messier in his (Catalogue of Nebulae and Star Clusters). Because Messier was interested only in finding comets, he created a list of those non-comet objects that frustrated his hunt for them. This list, which Messier created in collaboration with his assistant Pierre Méchain, is now known as the Messier catalogue. The Messier catalogue is one of the most famous lists of astronomical objects, and many objects on the list are still referenced by their Messier numbers.^[1] The catalogue includes most of the astronomical deep-sky objects that can be easily observed from Earth's Northern Hemisphere; many Messier objects are popular targets for amateur astronomers.^[2]

A preliminary version of the catalogue first appeared in 1774 in the Memoirs of the French Academy of Sciences for the year 1771.^{[3] [4] [5]} The first version of Messier's catalogue contained 45 objects, which were not numbered. Eighteen of the objects were discovered by Messier; the rest had been previously observed by other astronomers.^[6] By 1780 the catalogue had increased to 70 objects.^[7] The final version of the catalogue containing 103 objects was published in 1781 in the Connaissance des Temps for the year 1784.^{[8] [4]} However, due to what was thought for a long time to be the incorrect addition of Messier 102, the total number remained 102. Other astronomers, using side notes in Messier's texts, eventually filled out the list up to 110 objects.^[9]

The catalogue consists of a diverse range of astronomical objects, from star clusters and nebulae to galaxies. For example, Messier 1 is a supernova remnant, known as the Crab Nebula, and the great spiral Andromeda Galaxy is M31. Further inclusions followed; the first addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding Messier's side note in his 1781 edition exemplar of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.^[10]

Lists and editions

The first edition of 1774 covered 45 objects (M1 to M45). The total list published by Messier in 1781 contained 103 objects, but the list was expanded through successive additions by other astronomers, motivated by notes in Messier's and Méchain's texts indicating that at least one of them knew of the additional objects. The first such addition came from Nicolas Camille Flammarion in 1921, who added Messier 104 after finding a note Messier made in a copy of the 1781 edition of the catalogue. M105 to M107 were added by Helen Sawyer Hogg in 1947, M108 and M109 by Owen Gingerich in 1960, and M110 by Kenneth Glyn Jones in 1967.^[11] M102 was observed by Méchain, who communicated his notes to Messier. Méchain later concluded that this object was simply a re-observation of M101, though some sources suggest that the object Méchain observed was the galaxy NGC 5866 and identify that as M102.^[12]

Messier's final catalogue was included in the [''Knowledge of the Times for the Year 1784''], the French official yearly publication of astronomical ephemerides.^{[8] [4]}

Messier lived and did his astronomical work at the Hôtel de Cluny (now the Musée national du Moyen Âge), in Paris, France. The list he compiled contains only objects found in the sky area he could observe: from the north celestial pole to a celestial latitude of about −35.7° . He did not observe or list objects visible only from farther south, such as the Large and Small Magellanic Clouds.^[13]

Observations

The Messier catalogue comprises nearly all of the most spectacular examples of the five types of deep-sky object – diffuse nebulae, planetary nebulae, open clusters, globular clusters, and galaxies – visible from European latitudes. Furthermore, almost all of the Messier objects are among the closest to Earth in their respective classes, which makes them heavily studied with professional class instruments that today can resolve very small and visually significant details in them. A summary of the astrophysics of each Messier object can be found in the Concise Catalog of Deep-sky Objects.^[14]

Since these objects could be observed visually with the relatively small-aperture refracting telescope (approximately 100 mm ≈ 4 inches) used by Messier to study the sky, they are among the brightest and thus most attractive astronomical objects (popularly called deep-sky objects) observable from Earth, and are popular targets for visual study and astrophotography available to modern amateur astronomers using larger aperture equipment. In early spring, astronomers sometimes gather for "Messier marathons", when all of the objects can be viewed over a single night.^{[15] [16]}

Messier objects

Messier number	NGC/IC number	Common name	Image	Object type	Distance (kly)	Constellation	Apparent magnitude	Apparent dimensions	Right ascension	data-sort-type=number scope="col"	Declination
M1^[17]	NGC 1952	Crab Nebula		Supernova remnant	4.9–8.1	Taurus	8.4	420″ × 290″	05^h 34^m 31.94^s	+22° 00′ 52.2″
M2^[18]	NGC 7089					Aquarius	6.5	16'	21^h 33^m 27.02^s	−00° 49′ 23.7″
M3^[19]	NGC 5272					Canes Venatici	6.2	18'	13^h 42^m 11.62^s	+28° 22′ 38.2″
M4^[20]	NGC 6121	Spider Globular Cluster				Scorpius	5.6	26'	16^h 23^m 35.22^s	−26° 31′ 32.7″
M5^[21]	NGC 5904	Rose Cluster				Serpens	5.6	23'	15^h 18^m 33.22^s	+02° 04′ 51.7″
M6^[22]	NGC 6405	Butterfly Cluster				Scorpius	4.2	25'	17^h 40.1^m	−32° 13′
M7^[23]	NGC 6475	Ptolemy's Cluster			0.65–1.31	Scorpius	3.3	80'	17^h 53^m 51.2^s	−34° 47′ 34″
M8^[24]	NGC 6523	Lagoon Nebula		Nebula with cluster		Sagittarius	4.6	90′ × 40′	18^h 03^m 37^s	−24° 23′ 12″
M9^[25]	NGC 6333					Ophiuchus	7.7	9.3'	17^h 19^m 11.78^s	−18° 30′ 58.5″
M10^[26]	NGC 6254					Ophiuchus	6.6	20'	16^h 57^m 8.92^s	−04° 05′ 58.07″
M11	NGC 6705	Wild Duck Cluster				Scutum	5.8	22.8'	18^h 51.1^m	−06° 16′
M12^[27]	NGC 6218					Ophiuchus	6.7	16'	16^h 47^m 14.18^s	−01° 56′ 54.7″
M13^[28]	NGC 6205	Great Hercules Cluster				Hercules	5.8	20'	16^h 41^m 41.24^s	+36° 27′ 35.5″
M14^[29]	NGC 6402					Ophiuchus	7.6	11'	17^h 37^m 36.15^s	−03° 14′ 45.3″
M15^[30]	NGC 7078	Great Pegasus Cluster				Pegasus	6.2	18'	21^h 29^m 58.33^s	+12° 10′ 01.2″
M16^[31]	NGC 6611	Eagle Nebula				Serpens	6.4	70' x 50'	18^h 18^m 48^s	−13° 49′
M17^[32]	NGC 6618	Omega, Swan, Horseshoe, Lobster, or Checkmark Nebula			5–6	Sagittarius	6.0	11'	18^h 20^m 26^s	−16° 10′ 36″
M18^[33]	NGC 6613	Black Swan Cluster				Sagittarius	7.5	9.8'	18^h 19.9^m	−17° 08′
M19^[34]	NGC 6273					Ophiuchus	6.8	17'	17^h 02^m 37.69^s	−26° 16′ 04.6″
M20^[35]	NGC 6514	Trifid Nebula		with cluster		Sagittarius	6.3	28'	18^h 02^m 23^s	−23° 01′ 48″
M21^[36]	NGC 6531	Webb's Cross Cluster				Sagittarius	6.5	14'	18^h 04.6^m	−22° 30′
M22^[37]	NGC 6656	Great Sagittarius Cluster			9.6–11.6	Sagittarius	5.1	32'	18^h 36^m 23.94^s	−23° 54′ 17.1″
M23	NGC 6494					Sagittarius	5.5	35'	17^h 56.8^m	−19° 01′
M24^[38]	IC 4715	Small Sagittarius Star Cloud		Milky Way star cloud	~10	Sagittarius	2.5	2°x1°	18^h 17^m	−18° 33′
M25^[39]	IC 4725					Sagittarius	4.6	36'	18^h 31.6^m	−19° 15′
M26^[40]	NGC 6694					Scutum	8.0	14'	18^h 45.2^m	−09° 24′
M27^[41]	NGC 6853	Dumbbell Nebula			1.148–1.52	Vulpecula	7.4	8.0' × 5.6'	19^h 59^m 36.340^s	+22° 43′ 16.09″
M28^[42]	NGC 6626					Sagittarius	6.8	11.2'	18^h 24^m 32.89^s	−24° 52′ 11.4″
M29^[43]	NGC 6913	Cooling Tower Cluster				Cygnus	7.1	7'	20^h 23^m 56^s	+38° 31′ 24″
M30^[44]	NGC 7099	Jellyfish Cluster			27.8–31	Capricornus	7.2	12'	21^h 40^m 22.12^s	−23° 10′ 47.5″
M31^[45]	NGC 224	Andromeda Galaxy			2,430–2,650	Andromeda	3.4	3.167° × 1°	00^h 42^m 44.3^s	+41° 16′ 09″
M32^[46]	NGC 221	Andromeda Satellite #1			2,410–2,570	Andromeda	8.1	8.7' × 6.5'	00^h 42^m 41.8^s	+40° 51′ 55″
M33^[47]	NGC 598	Triangulum/Pinwheel Galaxy			2,380–3,070	Triangulum	5.7	70.8' x 41.7'	01^h 33^m 50.02^s	+30° 39′ 36.7″
M34^[48]	NGC 1039	Spiral Cluster				Perseus	5.5	35'	02^h 42.1^m	+42° 46′
M35^[49]	NGC 2168	Shoe-Buckle Cluster				Gemini	5.3	28'	06^h 09.1^m	+24° 21′
M36^[50]	NGC 1960	Pinwheel Cluster				Auriga	6.3	12'	05^h 36^m 12^s	+34° 08′ 04″
M37^[51]	NGC 2099	Salt and Pepper Cluster				Auriga	6.2	24'	05^h 52^m 18^s	+32° 33′ 02″
M38^[52]	NGC 1912	Starfish Cluster				Auriga	7.4	21'	05^h 28^m 42^s	+35° 51′ 18″
M39^[53]	NGC 7092					Cygnus	4.6	29'	21^h 31^m 42^s	+48° 26′ 00″
M40^[54]		Winnecke 4		Optical Double		Ursa Major	8.4	51.7″	12^h 22^m 12.5^s	+58° 04′ 59″
M41^[55]	NGC 2287	Little Beehive Cluster				Canis Major	4.5	38'	06^h 46.0^m	−20° 46′
M42^[56]	NGC 1976	Great Orion Nebula			1.324–1.364	Orion	4.0	65' x 60'	05^h 35^m 17.3^s	−05° 23′ 28″
M43^[57]	NGC 1982	De Mairan's Nebula				Orion	9.0	20' x 15'	05^h 35.6^m	−05° 16′
M44^[58]	NGC 2632	Beehive Cluster or Praesepe				Cancer	3.7	95'	08^h 40.4^m	+19° 59′
M45^[59]		Pleiades, Seven Sisters or Subaru			0.39–0.46	Taurus	1.6	2°	03^h 47^m 24^s	+24° 07′ 00″
M46^[60]	NGC 2437					Puppis	6.0	22.8'	07^h 41.8^m	−14° 49′
M47^[61]	NGC 2422					Puppis	4.4	30'	07^h 36.6^m	−14° 30′
M48^[62]	NGC 2548					Hydra	5.5	30'	08^h 13.7^m	−05° 45′
M49^[63]	NGC 4472				53,600–58,200	Virgo	8.4	10.2' × 8.3'	12^h 29^m 46.7^s	+08° 00′ 02″
M50^[64]	NGC 2323	Heart-Shaped Cluster				Monoceros	5.9	16'	07^h 03.2^m	−08° 20′
M51^[65]	NGC 5194, NGC 5195	Whirlpool Galaxy			19,000–27,000	Canes Venatici	8.4	11.2′ × 6.9′	13^h 29^m 52.7^s	+47° 11′ 43″
M52^[66]	NGC 7654	Scorpion Cluster				Cassiopeia	7.3	13'	23^h 24.2^m	+61° 35′
M53^[67]	NGC 5024					Coma Berenices	7.6	13'	13^h 12^m 55.25^s	+18° 10′ 05.4″
M54^[68]	NGC 6715					Sagittarius	7.6	12'	18^h 55^m 03.33^s	−30° 28′ 47.5″
M55^[69]	NGC 6809	Specter Cluster				Sagittarius	6.3	19'	19^h 39^m 59.71^s	−30° 57′ 53.1″
M56^[70]	NGC 6779					Lyra	8.3	8.8'	19^h 16^m 35.57^s	+30° 11′ 00.5″
M57^[71]	NGC 6720	Ring Nebula			1.6–3.8	Lyra	8.8	230" × 230"	18^h 53^m 35.079^s	+33° 01′ 45.03″
M58^[72]	NGC 4579				~63,000	Virgo	9.7	5.9' × 4.7'	12^h 37^m 43.5^s	+11° 49′ 05″
M59^[73]	NGC 4621				55,000–65,000	Virgo	9.6	5.4' × 3.7'	12^h 42^m 02.3^s	+11° 38′ 49″
M60^[74]	NGC 4649				51,000–59,000	Virgo	8.8	7.4' × 6.0'	12^h 43^m 39.6^s	+11° 33′ 09″
M61^[75]	NGC 4303	Swelling Spiral Galaxy			50,200–54,800	Virgo	9.7	6.5' × 5.8'	12^h 21^m 54.9^s	+04° 28′ 25″
M62^[76]	NGC 6266	Flickering Globular				Ophiuchus	6.5	15'	17^h 01^m 12.60^s	−30° 06′ 44.5″
M63^[77]	NGC 5055	Sunflower Galaxy				Canes Venatici	8.6	12.6' × 7.2'	13^h 15^m 49.3^s	+42° 01′ 45″
M64^[78]	NGC 4826	Black Eye Galaxy			22,000–26,000	Coma Berenices	8.5	10.7' × 5.1'	12^h 56^m 43.7^s	+21° 40′ 58″
M65^[79]	NGC 3623	Leo Triplet			41,000–42,000	Leo	9.3	8.7' × 2.5'	11^h 18^m 55.9^s	+13° 05′ 32″
M66^[80]	NGC 3627	Leo Triplet			31,000–41,000	Leo	8.9	9.1' × 4.2'	11^h 20^m 15.0^s	+12° 59′ 30″
M67^[81]	NGC 2682	King Cobra or Golden Eye Cluster			2.61–2.93	Cancer	6.1	30'	08^h 51.3^m	+11° 49′
M68^[82]	NGC 4590					Hydra	7.8	11'	12^h 39^m 27.98^s	−26° 44′ 38.6″
M69^[83]	NGC 6637					Sagittarius	7.6	10.8'	18^h 31^m 23.10^s	−32° 20′ 53.1″
M70^[84]	NGC 6681					Sagittarius	7.9	8'	18^h 43^m 12.76^s	−32° 17′ 31.6″
M71^[85]	NGC 6838	Angelfish Cluster				Sagitta	8.2	7.2'	19^h 53^m 46.49^s	+18° 46′ 45.1″
M72^[86]	NGC 6981				53.40–55.74	Aquarius	9.3	6.6'	20^h 53^m 27.70^s	−12° 32′ 14.3″
M73^[87]	NGC 6994			Asterism	~2.5	Aquarius	9.0	2.8'	20^h 58^m 54^s	−12° 38′
M74^[88]	NGC 628	Phantom Galaxy^[89]			24,000–36,000	Pisces	9.4	10.5' x 9.5'	01^h 36^m 41.8^s	+15° 47′ 01″
M75^[90]	NGC 6864					Sagittarius	8.5	6.8'	20^h 06^m 04.75^s	−21° 55′ 16.2″
M76^[91]	NGC 650, NGC 651	Little Dumbbell Nebula				Perseus	10.1	2.7' × 1.8'	01^h 42.4^m	+51° 34′ 31″
M77^[92]	NGC 1068	Cetus A or Squid Galaxy				Cetus	8.9	7.1' × 6.0'	02^h 42^m 40.7^s	−00° 00′ 48″
M78^[93]	NGC 2068					Orion	8.3	8' × 6'	05^h 46^m 46.7^s	+00° 00′ 50″
M79^[94]	NGC 1904					Lepus	7.7	8.7'	05^h 24^m 10.59^s	−24° 31′ 27.3″
M80^[95]	NGC 6093					Scorpius	7.3	10'	16^h 17^m 02.41^s	−22° 58′ 33.9″
M81^[96]	NGC 3031	Bode's Galaxy			11,400–12,200	Ursa Major	6.9	26.9' × 14.1'	09^h 55^m 33.2^s	+69° 03′ 55″
M82^[97]	NGC 3034	Cigar Galaxy			10,700–12,300	Ursa Major	8.4	11.2' × 4.3'	09^h 55^m 52.2^s	+69° 40′ 47″
M83^[98]	NGC 5236	Southern Pinwheel Galaxy				Hydra	7.6	12.9' × 11.5'	13^h 37^m 00.9^s	−29° 51′ 57″
M84^[99]	NGC 4374				57,000–63,000	Virgo	9.1	6.5' × 5.6'	12^h 25^m 03.7^s	+12° 53′ 13″
M85^[100]	NGC 4382				56,000–64,000	Coma Berenices	9.1	7.1' × 5.5'	12^h 25^m 24.0^s	+18° 11′ 28″
M86^[101]	NGC 4406				49,000–55,000	Virgo	8.9	8.9' × 5.8'	12^h 26^m 11.7^s	+12° 56′ 46″
M87^[102]	NGC 4486	Virgo A or Smoking Gun Galaxy			51,870–55,130	Virgo	8.6	7.2' × 6.8'	12^h 30^m 49.42338^s	+12° 23′ 28.0439″
M88^[103]	NGC 4501				39,000–56,000	Coma Berenices	9.6	6.9' × 3.7'	12^h 31^m 59.2^s	+14° 25′ 14″
M89^[104]	NGC 4552				47,000–53,000	Virgo	9.8	5.1' × 4.7'	12^h 35^m 39.8^s	+12° 33′ 23″
M90^[105]	NGC 4569				55,900–61,500	Virgo	9.5	9.5' × 4.4'	12^h 36^m 49.8^s	+13° 09′ 46″
M91^[106]	NGC 4548				47,000–79,000	Coma Berenices	10.2	5.4' × 4.3'	12^h 35^m 26.4^s	+14° 29′ 47″
M92^[107]	NGC 6341					Hercules	6.4	14'	17^h 17^m 07.39^s	+43° 08′ 09.4″
M93^[108]	NGC 2447	Critter Cluster				Puppis	6.0	10'	07^h 44.6^m	−23° 52′
M94^[109]	NGC 4736	Crocodile Eye or Cat's Eye Galaxy			14,700–17,300	Canes Venatici	8.2	11.2' × 9.1'	12^h 50^m 53.1^s	+41° 07′ 14″
M95^[110]	NGC 3351				31,200–34,000	Leo	9.7	3.1' × 2.9'	10^h 43^m 57.7^s	+11° 42′ 14″
M96^[111]	NGC 3368				28,000–34,000	Leo	9.2	7.6' × 5.2'	10^h 46^m 45.7^s	+11° 49′ 12″
M97^[112]	NGC 3587	Owl Nebula				Ursa Major	9.9	3.4' × 3.3'	11^h 14^m 47.734^s	+55° 01′ 08.50″
M98^[113]	NGC 4192					Coma Berenices	10.1	9.8' × 2.8'	12^h 13^m 48.292^s	+14° 54′ 01.69″|- style="background:#ffc;"! scope="row" | M99^[114] | NGC 4254| St. Catherine's Wheel| style="text-align:center;"| | | 44,700–55,700| Coma Berenices| 9.9|5.4' × 4.7'|12^h 18^m 49.6^s| +14° 24′ 59″|- style="background:#ffc;"! scope="row" | M100^[115] | NGC 4321| Mirror Galaxy| style="text-align:center;"| | | | Coma Berenices| 9.3|7.4' × 6.3'|12^h 22^m 54.9^s| +15° 49′ 21″|- style="background:#ffc;"! scope="row" | M101^[116] | NGC 5457| Pinwheel Galaxy| style="text-align:center;"| | | 19,100–22,400| Ursa Major| 7.9|28.8' × 26.9'|14^h 03^m 12.6^s| +54° 20′ 57″|- style="background:#ffc;"! scope="row" | M102^[117] | NGC 5866| Spindle Galaxy| style="text-align:center;"|| | 50,000| Draco| 9.9|4.7' x 1.9'|15^h 06^m 29.5^s|+55° 45′ 48″
M103^[118]	NGC 581					Cassiopeia	7.4	6'	01^h 33.2^m	+60° 42′
M104^[119]	NGC 4594	Sombrero Galaxy			28,700–30,900	Virgo	8.0	9' x 4'	12^h 39^m 59.4^s	−11° 37′ 23″
M105^[120]	NGC 3379				30,400–33,600	Leo	9.3	5.4' × 4.8'	10^h 47^m 49.6^s	+12° 34′ 54″
M106^[121]	NGC 4258				22,200–25,200	Canes Venatici	8.4	18.6' × 7.2'	12^h 18^m 57.5^s	+47° 18′ 14″
M107^[122]	NGC 6171	Crucifix Cluster				Ophiuchus	7.9	10'	16^h 32^m 31.86^s	−13° 03′ 13.6″
M108^[123]	NGC 3556	Surfboard Galaxy				Ursa Major	10.0	8.7' × 2.2'	11^h 11^m 31.0^s	+55° 40′ 27″
M109^[124]	NGC 3992	Vacuum Cleaner Galaxy			59,500–107,500	Ursa Major	9.8	7.6' × 4.7'	11^h 57^m 36.0^s	+53° 22′ 28″
M110^[125]	NGC 205				2,600–2,780	Andromeda	8.5	21.9' × 11.0'	00^h 40^m 22.1^s	+41° 41′ 07″

See also

• Lists of astronomical objects
• Caldwell catalogue
• Deep-sky object
• Herschel 400 Catalogue
• New General Catalogue

External links

• Web site: SEDS Messier Database . Students for the Exploration and Development of Space (SEDS) . — includes images
• Web site: Messier gallery . Messier Objects 101 .
• Web site: Messier objects . Deep Sky Videos .
• Web site: Messier Objects Ranked By Viewing Difficulty . Starlust .

Notes and References

1. Web site: Original Messier Catalog of 1781 . . 10 November 2007 .
2. Web site: Garner . Rob . 18 December 2018 . Hubble's Messier catalog . . . 17 January 2019.
3. Charles . Messier . 16 February 1771 . Catalogue des Nébuleuses et des amas d'Étoiles, que l'on découvre parmi les Étoiles fixes, sur l'horizon de Paris. Observées à l'Observatoire de la Marine, avec differens instrumens . Histoire de l'Académie Royale des Sciences . année 1774 . 435 . Avec les Mémoires de Mathématique & de Physique, pour la même Année, Tirés des Registres de cette Académie . Paris, FR . L'Imprimerie Royale . Gallica (Archives de l'Académie des sciences) . 2021-01-07.
4. Web site: Charles Messier's original catalog of 1771 . 15 June 2007 . Students for the Exploration and Development of Space (SEDS) . 5 November 2015 .
5. Encyclopedia: Messier catalog . Encyclopædia Britannica . 27 May 2015.
6. Gingerich . Owen . September 1953 . Messier and his catalogue II . Sky & Telescope . 142 . archive.org.
7. Charles . Messier . 1780 . Catalogue des Nébuleuses et des amas d'Étoiles, Observées à Paris, par M. Messier, à l'Observatoire de la Marine, hôtel de Clugni, rue des Mathurins . . pour l'année commune 1783 . 225–249, & 408 . Paris, FR . L'Imprimerie Royale . Gallica (Archives de l'Académie des sciences).
8. Charles . Messier . 1781 . Catalogue des Nébuleuses et des amas d'Étoiles, Observées à Paris, par M. Messier, à l'Observatoire de la Marine, hôtel de Clugni, rue des Mathurins . Connoissance des Temps, ou Connoissance des mouvemens célestes . pour l'année bissextile 1784 . 227–267 . 1781cote.rept..227M . Paris, FR . L'Imprimerie Royale . Gallica .
9. Web site: The Messier Catalogue . SEDS Messier Database . 27 May 2015 . .
10. Book: Moore , Patrick . 1979 . The Guinness Book of Astronomy . . 978-0-900424-76-2 . registration . archive.org.
11. Book: Moore , Patrick . 1979 . The Guinness Book of Astronomy . . 0-900424-76-1 . registration . archive.org.
12. Frommert . Hartmut . 10 May 1995 . Messier 102 . MSFC X-Ray Astronomy (InterNetNews) . . 24 February 2019.
13. Book: English, Neil . 2018 . Chronicling the Golden Age of Astronomy: A history of visual observing from Harriot to Moore . 91 . Springer . 978-3319977072 . 9 October 2019.
14. Book: Finlay , W.H. . 2003 . Concise Catalog of Deep-sky Objects: Astrophysical information for 500 galaxies . . 1-85233-691-9.
15. Web site: 19 March 2013 . The Messier Marathon . Students for the Exploration and Development of Space (SEDS) . 17 May 2014.
16. Book: Stoyan . Ronald . Binnewies . Stefan . Friedrich . Susanne . Atlas of the Messier Objects: Highlights of the Deep Sky . 2008 . Cambridge University Press . 9783319977072.
17. Web site: Messier 1 . 17 March 2014 . SEDS Messier catalog.
18. Web site: Messier 2 . 17 March 2014 . SEDS Messier catalog.
19. Web site: Messier 3 . 17 March 2014 . SEDS Messier catalog.
20. Web site: Messier 4 . 17 March 2014 . SEDS Messier catalog.
21. Web site: Messier 5 . 17 March 2014 . SEDS Messier catalog.
22. Web site: Messier 6 . 17 March 2014 . SEDS Messier catalog.
23. Web site: Messier 7 . 17 March 2014 . SEDS Messier catalog.
24. Book: Stoyan, Ronald. Atlas of the Messier Objects: Highlights of the Deep Sky . 88 . Cambridge University Press . 2008 . 978-0521895545 .
25. Web site: Messier 9 . 17 March 2014 . SEDS Messier catalog.
26. Web site: Messier 10 . 17 March 2014 . SEDS Messier catalog.
27. Web site: Messier 12 . 17 March 2014 . SEDS Messier catalog.
28. Web site: Messier 13 . 17 March 2014 . SEDS Messier catalog.
29. Web site: Messier 14 . 17 March 2014 . SEDS Messier catalog.
30. Web site: Messier 15 . 17 March 2014 . SEDS Messier catalog.
31. Web site: Messier 16 . 17 March 2014 . SEDS Messier catalog.
32. Web site: Messier 17 . 17 March 2014 . SEDS Messier catalog.
33. Web site: Messier 18 . 17 March 2014 . SEDS Messier catalog.
34. Web site: Messier 19 . 17 March 2014 . SEDS Messier catalog.
35. Web site: Messier 20 (The Trifid Nebula) . 28 April 2022 . Hubble's Messier Catalog. 6 October 2017 .
36. Web site: Messier 21 . 17 March 2014 . SEDS Messier catalog.
37. Web site: Messier 22 . 17 March 2014 . SEDS Messier catalog.
38. French . Sue . July 2015 . Small Sagittarius star cloud: The Sagittarius Milky Way is host to dark nebulae and open clusters . Sky & Telescope . en . 56.
39. Web site: Messier 25 . 17 March 2014 . SEDS Messier catalog.
40. Web site: Messier 26 . 17 March 2014 . SEDS Messier catalog.
41. Web site: Messier 27 . 17 March 2014 . SEDS Messier catalog.
42. Web site: Messier 28 . 17 March 2014 . SEDS Messier catalog.
43. Web site: Messier 29 . 17 March 2014 . SEDS Messier catalog.
44. Web site: Messier 30 . 17 March 2014 . SEDS Messier catalog.
45. Web site: Messier 31 . 17 March 2014 . SEDS Messier catalog.
46. Web site: Messier 32 . 17 March 2014 . SEDS Messier catalog.
47. Web site: Messier 33 . 17 March 2014 . SEDS Messier catalog.
48. Web site: Messier 34 . 17 March 2014 . SEDS Messier catalog.
49. Web site: Messier 35 . 17 March 2014 . SEDS Messier catalog.
50. Web site: Messier 36 . 17 March 2014 . SEDS Messier catalog.
51. Web site: Messier 37 . 17 March 2014 . SEDS Messier catalog.
52. Web site: Messier 38 . 17 March 2014 . SEDS Messier catalog.
53. Web site: Messier 39 . 17 March 2014 . SEDS Messier catalog.
54. Web site: Messier 40 . 17 March 2014 . SEDS Messier catalog.
55. Web site: Messier 41 . 17 March 2014 . SEDS Messier catalog.
56. Web site: Messier 42 . 17 March 2014 . SEDS Messier catalog.
57. Web site: Messier 43 . 17 March 2014 . SEDS Messier catalog.
58. Web site: Messier 44 . 17 March 2014 . SEDS Messier catalog.
59. Web site: Messier 45 . 17 March 2014 . SEDS Messier catalog.
60. Web site: Messier 46 . 17 March 2014 . SEDS Messier catalog.
61. Book: Stoyan, Ronald. Atlas of the Messier Objects: Highlights of the Deep Sky . 195 . Cambridge University Press . 2008 . 978-0521895545 .
62. Web site: Messier 48 . 17 March 2014 . SEDS Messier catalog.
63. Web site: Messier 49 . 17 March 2014 . SEDS Messier catalog.
64. Web site: Messier 50 . 17 March 2014 . SEDS Messier catalog.
65. Web site: Messier 51 . 18 March 2014 . SEDS Messier catalog.
66. Web site: Messier 52 . 18 March 2014 . SEDS Messier catalog.
67. Web site: Messier 53 . 18 March 2014 . SEDS Messier catalog.
68. Web site: Messier 54 . 18 March 2014 . SEDS Messier catalog.
69. Web site: Messier 55 . 18 March 2014 . SEDS Messier catalog.
70. Web site: Messier 56 . 18 March 2014 . SEDS Messier catalog.
71. Web site: Messier 57 . 18 March 2014 . SEDS Messier catalog.
72. Web site: Messier 58 . 18 March 2014 . SEDS Messier catalog.
73. Web site: Messier 59 . 18 March 2014 . SEDS Messier catalog.
74. Web site: Messier 60 . 18 March 2014 . SEDS Messier catalog.
75. Web site: Messier 61 . 18 March 2014 . SEDS Messier catalog.
76. Web site: Messier 62 . 18 March 2014 . SEDS Messier catalog.
77. Web site: Messier 63 . 18 March 2014 . SEDS Messier catalog.
78. Web site: Messier 64 . 18 March 2014 . SEDS Messier catalog.
79. Web site: Messier 65 . 18 March 2014 . SEDS Messier catalog.
80. Web site: Messier 66 . 18 March 2014 . SEDS Messier catalog.
81. Web site: Messier 67 . 18 March 2014 . SEDS Messier catalog.
82. Web site: Messier 68 . 18 March 2014 . SEDS Messier catalog.
83. Web site: Messier 69 . 18 March 2014 . SEDS Messier catalog.
84. Web site: Messier 70 . 18 March 2014 . SEDS Messier catalog.
85. Web site: Messier 71 . 18 March 2014 . SEDS Messier catalog.
86. Web site: Messier 72 . 18 March 2014 . SEDS Messier catalog.
87. Web site: Messier 73 . 18 March 2014 . SEDS Messier catalog.
88. Web site: Messier 74 . 18 March 2014 . SEDS Messier catalog.
89. Web site: Messier 74 Phantom Galaxy . 24 July 2015 . 20 April 2020.
90. Web site: Messier 75 . 18 March 2014 . SEDS Messier catalog.
91. Web site: Messier 76 . 18 March 2014 . SEDS Messier catalog.
92. Web site: Messier 77 . 18 March 2014 . SEDS Messier catalog.
93. Web site: Messier 78 . 18 March 2014 . SEDS Messier catalog.
94. Web site: Messier 79 . 18 March 2014 . SEDS Messier catalog.
95. Web site: Messier 80 . 18 March 2014 . SEDS Messier catalog.
96. Web site: Messier 81 . 18 March 2014 . SEDS Messier catalog.
97. Web site: Messier 82 . 18 March 2014 . SEDS Messier catalog.
98. Web site: Messier 83 . 18 March 2014 . SEDS Messier catalog.
99. Web site: Messier 84 . 18 March 2014 . SEDS Messier catalog.
100. Web site: Messier 85 . 18 March 2014 . SEDS Messier catalog.
101. Web site: Messier 86 . 18 March 2014 . SEDS Messier catalog.
102. Web site: Messier 87 . 18 March 2014 . SEDS Messier catalog.
103. Web site: Messier 88 . 18 March 2014 . SEDS Messier catalog.
104. Web site: Messier 89 . 18 March 2014 . SEDS Messier catalog.
105. Web site: Messier 90 . 18 March 2014 . SEDS Messier catalog.
106. Web site: Messier 91 . 18 March 2014 . SEDS Messier catalog.
107. Web site: Messier 92 . 18 March 2014 . SEDS Messier catalog.
108. Web site: Messier 93 . 18 March 2014 . SEDS Messier catalog.
109. Web site: Messier 94 . 18 March 2014 . SEDS Messier catalog.
110. Web site: Messier 95 . 18 March 2014 . SEDS Messier catalog.
111. Web site: Messier 96 . 18 March 2014 . SEDS Messier catalog.
112. Web site: Messier 97 . 18 March 2014 . SEDS Messier catalog.
113. Web site: Messier 98 . 18 March 2014 . SEDS Messier catalog.
114. Web site: Messier 99 . 18 March 2014 . SEDS Messier catalog.
115. Web site: Messier 100 . 18 March 2014 . SEDS Messier catalog.
116. Web site: Messier 101 . 18 March 2014 . SEDS Messier catalog.
117. Web site: Messier 102 . 28 December 2016 . SEDS Messier catalog.
118. Web site: Messier 103 . 18 March 2014 . SEDS Messier catalog.
119. Web site: Messier 104 . 18 March 2014 . SEDS Messier catalog.
120. Web site: Messier 105 . 18 March 2014 . SEDS Messier catalog.
121. Web site: Messier 106 . 18 March 2014 . SEDS Messier catalog.
122. Web site: Messier 107 . 18 March 2014 . SEDS Messier catalog.
123. Web site: Messier 108 . 18 March 2014 . SEDS Messier catalog.
124. Web site: Messier 109 . 18 March 2014 . SEDS Messier catalog.
125. Web site: Messier 110 . 18 March 2014 . SEDS Messier catalog.