Astronomy:Aquila (constellation)

From HandWiki
Short description: Constellation near the celestial equator
Pronunciation/ˈækwɪlə/ Áquila,
occasionally /əˈkwɪlə/;
genitive /ˈækwɪl/
Symbolismthe Eagle[1]
Right ascension 18h 41m 18.2958s– 20h 38m 23.7231s[2]
Area652 sq. deg. (22nd)
Main stars10[1]
Stars with planets9
Stars brighter than 3.00m3
Stars within 10.00 pc (32.62 ly)2
Brightest starAltair (α Aql) (0.76m)
Messier objects0
Meteor showers
  • June Aquilids
  • Epsilon Aquilids
Visible at latitudes between +90° and −75°.
Best visible at 21:00 (9 p.m.) during the month of August.

Aquila is a constellation on the celestial equator. Its name is Latin for 'eagle' and it represents the bird that carried Zeus/Jupiter's thunderbolts in Greek-Roman mythology.

Its brightest star, Altair, is one vertex of the Summer Triangle asterism. The constellation is best seen in the northern summer, as it is located along the Milky Way. Because of this location, many clusters and nebulae are found within its borders, but they are dim and galaxies are few.


The constellation Aquila as it can be seen by the naked eye.

Aquila was one of the 48 constellations described by the second-century astronomer Ptolemy. It had been earlier mentioned by Eudoxus in the fourth century BC and Aratus in the third century BC.[3]

It is now one of the 88 constellations defined by the International Astronomical Union. The constellation was also known as Vultur volans (the flying vulture) to the Romans, not to be confused with Vultur cadens which was their name for Lyra. It is often held to represent the eagle which held Zeus's/Jupiter's thunderbolts in Greco-Roman mythology. Aquila is also associated with the eagle that kidnapped Ganymede, a son of one of the kings of Troy (associated with Aquarius), to Mount Olympus to serve as cup-bearer to the gods.[1]

Ptolemy catalogued 19 stars jointly in this constellation and in the now obsolete constellation of Antinous, which was named in the reign of the emperor Hadrian (AD 117–138), but sometimes erroneously attributed to Tycho Brahe, who catalogued 12 stars in Aquila and seven in Antinous. Hevelius determined 23 stars in the first[4] and 19 in the second.[4][3]

The Greek Aquila is probably based on the Babylonian constellation of the Eagle, but is sometimes mistakenly thought as a seagull which is located in the same area as the Greek constellation.[5]

Notable features


Aquila, which lies in the Milky Way, contains many rich starfields and has been the location of many novae.[1]


  • α Aql (Altair) is the brightest star in this constellation and one of the closest naked-eye stars to Earth at a distance of 17 light-years. Its name comes from the Arabic phrase al-nasr al-tair, meaning "the flying eagle". Altair has a magnitude of 0.76.[1] It is one of the three stars of the Summer Triangle, along with Vega and Deneb.[6][7][8] It is an A-type main-sequence star with 1.8 times the mass of the Sun and 11 times its luminosity.[9][10] The star rotates quickly, and this gives the star an oblate shape where it is flattened towards the poles.[9][10][11]
  • β Aql (Alshain) is a yellow-hued star of magnitude 3.7, 45 light-years from Earth. Its name comes from the Arabic phrase shahin-i tarazu, meaning "the balance"; this name referred to Altair, Alshain, and Tarazed.[1] The primary is a G-type subgiant star with a spectral type of G9.5 IV and the secondary is a red dwarf.[12][13] The subgiant primary has three times the radius of the Sun and six times the luminosity.[14]
  • γ Aql (Tarazed) is an orange-hued giant star of around magnitude 2.7,[15] 460 light-years from Earth. Its name, like that of Alshain, comes from the Arabic for "the balance".[1] It is the second-brightest star in the constellation and is an unconfirmed variable star.[16]
  • ζ Aql (Okab[17]) is a binary star[18] of magnitude 3.0, 83 light-years from Earth.[1] The primary is an A-type main sequence star,[19] and the secondary has half the mass of the Sun.[18]
  • η Aql is a yellow-white-hued supergiant star, 1200 light-years from Earth. Among the brightest Cepheid variable stars, it has a minimum magnitude of 4.4 and a maximum magnitude of 3.5 with a period of 7.2 days.[1] The variability was originally observed by Edward Pigott in 1784.[20] There are also two companion stars which orbit the supergiant: a B-type main sequence star[21] and an F-type main sequence star.[22]
  • ρ Aql moved across the border into neighboring Delphinus in 1992,[23][24] and is an A-type star with a lower metallicity than the Sun.[25]
  • 15 Aql is an optical double star. The primary is an orange-hued giant of magnitude 5.41 and a spectral type of K1 III,[26][27] 325 light-years from Earth. The secondary is a purple-hued star of magnitude 7.0, 550 light-years from Earth. The pair is easily resolved in small amateur telescopes.[1]
  • 57 Aql is a binary star. The primary is a blue-hued star of magnitude 5.7 and the secondary is a white star of magnitude 6.5. The system is approximately 350 light-years from Earth; the pair is easily resolved in small amateur telescopes.[1] Both stars in the system rotate rapidly.[28]
  • R Aql is a red-hued giant star 690 light-years from Earth. It is a Mira variable with a minimum magnitude of 12.0, a maximum magnitude of 6.0, and a period around 9 months. It has a diameter of 400 D.[1]
  • V Aql is a typical Cool Carbon Star. It's one of the most red-colored examples of this sort of stars, observable through common amateur telescopes.
  • FF Aql is a yellow-white-hued supergiant star, 2500 light-years from Earth. It is a Cepheid variable star with a minimum magnitude of 5.7, a maximum magnitude of 5.2, and a period of 4.5 days.[1] It is a spectroscopic binary with a spectral type of F6Ib.[29] A third star is also a member of the system,[30] and there is also a fourth star which is probably unconnected with the main system.[31][32]


A bright nova was observed in Aquila in 1918 (Nova Aquilae 1918) and briefly shone brighter than Altair, the brightest star in Aquila. It was first seen by Zygmunt Laskowski[33] and was confirmed on the night of 8 June 1918.[34] Nova Aquilae reached a peak apparent magnitude of −0.5 and was the brightest nova recorded since the invention of the telescope.[35]

Deep-sky objects

IRAS 19024+0044 is a protoplanetary nebula in Aquila.

Three interesting planetary nebulae lie in Aquila:

  • NGC 6804 shows a small but bright ring.
  • NGC 6781 bears some resemblance with the Owl Nebula in Ursa Major. It was discovered by William Herschel in 1788.[36]
  • NGC 6751, also known as the Glowing Eye, is a planetary nebula. The nebula is estimated to be roughly 0.8 light-years in diameter.[37]

More deep-sky objects:

  • NGC 6709 is a loose open cluster containing roughly 40 stars, which range in magnitude from 9 to 11. It is about 3000 light-years from Earth.[1] It has an overall magnitude of 6.7 and is about 9100 light-years from Earth. NGC 6709 appears in a rich Milky Way star field and is classified as a Shapley class d and Trumpler class III 2 m cluster. These designations mean that it does not have many stars, is loose, does not show greater concentration at the center, and has a moderate range of star magnitudes.[38] There are 305 confirmed member stars[39] and one candidate red giant.[40]
  • NGC 6755 is an open cluster of 7.5 m; it is made up of about a dozen stars with magnitudes 12 through 13. It is located approximately 8,060 light-years from the Solar System.[41]
  • NGC 6760 is a globular cluster of 9.1 m. At least two pulsars have been discovered in the globular cluster,[42] and it has a Shapley-Sawyer Concentration Class of IX.[43]
  • NGC 6749 is an open cluster.
  • NGC 6778 is a planetary nebula located about 10,300 light-years away from the Solar System.[44]
  • NGC 6741 is a planetary nebula.
  • NGC 6772 is a planetary nebula.
  • W51 (3C400) is one of the largest stellar nurseries in the Milky Way. Located about 17,000 light-years from Earth, W51 is about 350 light-years – or about 2 quadrillion miles – across. However, it's located in an area so thick with interstellar dust that it's opaque to visible light. Observations by the Chandra X-Ray Observatory and the Spitzer Infrared Telescope reveal W51 would appear about as large as the full Moon in visible light.[45][46]

Aquila also holds some extragalactic objects. One of them is what may be the largest single mass concentration of galaxies in the Universe known, the Hercules–Corona Borealis Great Wall. It was discovered in November 2013, and has the size of 10 billion light years. It is the biggest and the most massive structure in the Universe known.


NASA's Pioneer 11 space probe, which flew by Jupiter and Saturn in the 1970s, is expected to pass near the star Lambda (λ) Aquilae in about 4 million years.[47]


In illustrations of Aquila that represent it as an eagle, a nearly straight line of three stars symbolizes part of the wings. The center and brightest of these three stars is Altair.[citation needed]


Aquila, with the now-obsolete figure of Antinous, as depicted by Sidney Hall in Urania's Mirror,[48] a set of constellation cards published in London around 1825. At left is Delphinus.

According to Gavin White, the Babylonian Eagle carried the constellation called the Dead Man in its talons. The author also draws a comparison to the classical stories of Antinous and Ganymede.[5]

In classical Greek mythology, Aquila was identified as Αετός Δίας (Aetos Dios), the eagle that carried the thunderbolts of Zeus and was sent by him to carry the shepherd boy Ganymede, whom he desired, to Mount Olympus; the constellation of Aquarius is sometimes identified with Ganymede.[1]

In the Chinese love story of Qi Xi, Niu Lang (Altair) and his two children (β and γ Aquilae) are separated forever from their wife and mother Zhi Nu (Vega), who is on the far side of the river, the Milky Way.[49]

In Hinduism, the constellation Aquila is identified with the half-eagle half-human deity Garuda.[50][51]

In ancient Egypt, Aquila possibly was seen as the falcon of Horus.[52] According to Berio, the identification of Aquila as an Egyptian constellation, and not merely Graeco-Babylonian, is corroborated by the Daressy Zodiac.[53] It depicts an outer ring showing the Sphaera Graeca, the familiar Hellenistic zodiac, while the middle ring depicts the Sphaera Barbarica or foreigner's zodiac with the zodiacal signs of the Egyptian dodekaoros which were also recorded by Teucros of Babylon.[54] Under the sign of Sagittarius is the falcon of Horus, presumably because Aquila rises with Sagittarius.


In Chinese astronomy, ζ Aql is located within the Heavenly Market Enclosure (天市垣, Tiān Shì Yuán), and the other stars of the constellation are placed within the Black Tortoise of the North (北方玄武, Běi Fāng Xuán Wǔ).

Several different Polynesian equivalents to Aquila as a whole are known. On the island of Futuna, it was called Kau-amonga, meaning "Suspended Burden". Its name references the Futunan name for Orion's belt and sword, Amonga.[55] In Hawaii, Altair was called Humu, translated to English as "to sew, to bind together parts of a fishhook." "Humu" also refers to the hole by which parts of a hook are bound together.[56] Humu-ma was said to influence the astrologers.[57] Pao-toa was the name for the entire constellation in the Marquesas Islands; the name meant "Fatigued Warrior".[58] Also, Polynesian constellations incorporated the stars of modern Aquila. The Pukapuka constellation Tolu, meaning "three", was made up of Alpha, Beta, and Gamma Aquilae.[59] Altair was commonly named among Polynesian peoples, as well. The people of Hawaii called it Humu, the people of the Tuamotus called it Tukituki ("Pound with a hammer")[60] - they named Beta Aquilae Nga Tangata ("The Men")[61] - and the people of Pukapuka called Altair Turu and used it as a navigational star.[62] The Māori people named Altair Poutu-te-rangi, "Pillar of the Sky", because of its important position in their cosmology. It was used differently in different Māori calendars, being the star of February and March in one version and March and April in the other. Altair was also the star that ruled the annual sweet potato harvest.[63]

See also

  • Aquila (Chinese astronomy)


  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 1.13 1.14 1.15 Ridpath 2001, pp. 80–82
  2. 2.0 2.1 "Aquila, constellation boundary". The Constellations (International Astronomical Union). Retrieved 14 February 2014. 
  3. 3.0 3.1 Chisholm 1911.
  4. 4.0 4.1 "Prodromus astronomiae". 1690. pp. 272–273. 
  5. 5.0 5.1 White 2008, p. 95
  6. NAME ALTAIR -- Variable Star of delta Sct type, database entry, SIMBAD. Accessed on line November 25, 2008.
  7. Altair, entry, The Internet Encyclopedia of Science, David Darling. Accessed on line November 25, 2008.
  8. Summer Triangle, entry, The Internet Encyclopedia of Science, David Darling. Accessed on line November 26, 2008.
  9. 9.0 9.1 Monnier, J. D.; Zhao, M; Pedretti, E; Thureau, N; Ireland, M; Muirhead, P; Berger, J. P.; Millan-Gabet, R et al. (2007). "Imaging the surface of Altair". Science 317 (5836): 342–345. doi:10.1126/science.1143205. PMID 17540860. Bibcode2007Sci...317..342M. See second column of Table 1 for stellar parameters. 
  10. 10.0 10.1 Peterson, D. M.; Hummel, C. A.; Pauls, T. A. et al. (2006). "Resolving the Effects of Rotation in Altair with Long‐Baseline Interferometry". The Astrophysical Journal 636 (2): 1087–1097. doi:10.1086/497981. Bibcode2006ApJ...636.1087P.  See Table 2 for stellar parameters.
  11. Belle, Gerard T. van; Ciardi, David R.; Thompson, Robert R.; Akeson, Rachel L.; Lada, Elizabeth A. (2001). "Altair's Oblateness and Rotation Velocity from Long-Baseline Interferometry" (in en). The Astrophysical Journal 559 (2): 1155–1164. doi:10.1086/322340. ISSN 0004-637X. Bibcode2001ApJ...559.1155V. 
  12. Gray, R. O. et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal 132 (1): 161–170, doi:10.1086/504637, Bibcode2006AJ....132..161G. 
  13. Montes, D. et al. (September 2018), "Calibrating the metallicity of M dwarfs in wide physical binaries with F-, G-, and K-primaries - I: High-resolution spectroscopy with HERMES: stellar parameters, abundances, and kinematics", Monthly Notices of the Royal Astronomical Society 479 (1): 1332–1382, doi:10.1093/mnras/sty1295, Bibcode2018MNRAS.479.1332M. 
  14. Rains, Adam D. et al. (April 2020), "Precision angular diameters for 16 southern stars with VLTI/PIONIER", Monthly Notices of the Royal Astronomical Society 493 (2): 2377–2394, doi:10.1093/mnras/staa282, Bibcode2020MNRAS.493.2377R 
  15. Cousins, A. W. J. (1984), "Standardization of Broadband Photometry of Equatorial Standards", South African Astronomical Observatory Circulars 8: 59, Bibcode1984SAAOC...8...59C 
  16. Kornilov, V. G.; Volkov, I. M.; Zakharov, A. I.; Kozyreva, V. S.; Kornilova, L. N.; Krutyakov, A. N.; Krylov, A. V.; Kusakin, A. V. et al. (1991). "Catalogue of WBVR-magnitudes of bright stars of the northern sky". Trudy Gosudarstvennogo Astronomicheskogo Instituta 63: 1. Bibcode1991TrSht..63....1K. 
  17. "Naming Stars". 
  18. 18.0 18.1 De Rosa, R. J. et al. (2014), "The VAST Survey - III. The multiplicity of A-type stars within 75 pc", Monthly Notices of the Royal Astronomical Society 437 (2): 1216–1240, doi:10.1093/mnras/stt1932, Bibcode2014MNRAS.437.1216D. 
  19. Cowley, A. et al. (April 1969), "A study of the bright A stars. I. A catalogue of spectral classifications", Astronomical Journal 74: 375–406, doi:10.1086/110819, Bibcode1969AJ.....74..375C 
  20. Pigott, Edward (1785). "Observations of a New Variable Star. In a Letter from Edward Pigott, Esq. to Sir H. C. Englefield, Bart. F. R. S. and A. S.". Philosophical Transactions of the Royal Society of London 75: 127–136. doi:10.1098/rstl.1785.0007. Bibcode1785RSPT...75..127P. 
  21. Remage Evans, Nancy; Bond, Howard E.; Schaefer, Gail H.; Mason, Brian D.; Karovska, Margarita; Tingle, Evan (2013). "Binary Cepheids: Separations and Mass Ratios in 5 M ⊙ Binaries". The Astronomical Journal 146 (4): 93. doi:10.1088/0004-6256/146/4/93. Bibcode2013AJ....146...93E. 
  22. Gallenne, A.; Kervella, P.; Mérand, A.; Evans, N. R.; Girard, J. H. V.; Gieren, W.; Pietrzyński, G. (2014). "Searching for visual companions of close Cepheids". Astronomy & Astrophysics 567: A60. doi:10.1051/0004-6361/201423872. Bibcode2014A&A...567A..60G. 
  23. Patrick Moore (29 June 2013). The Observer's Year: 366 Nights of the Universe. Springer Science & Business Media. pp. 132–. ISBN 978-1-4471-3613-2. 
  24. Hirshfeld, A. et al. (August 1992), "Book-Review - Sky Catalogue 2000.0 - V.1 - Stars to Magnitude 8.0 ED.2", Journal of the Royal Astronomical Society of Canada 86 (4): 221, Bibcode1992JRASC..86..221L 
  25. Anders, F.; Khalatyan, A.; Chiappini, C.; Queiroz, A. B.; Santiago, B. X.; Jordi, C.; Girardi, L.; Brown, A. G. A. et al. (1 August 2019), "Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18", Astronomy and Astrophysics 628: A94, doi:10.1051/0004-6361/201935765, ISSN 0004-6361, Bibcode2019A&A...628A..94A. 
  26. Frasca, A. et al. (December 2009), "REM near-IR and optical photometric monitoring of pre-main sequence stars in Orion. Rotation periods and starspot parameters", Astronomy and Astrophysics 508 (3): 1313–1330, doi:10.1051/0004-6361/200913327, Bibcode2009A&A...508.1313F. 
  27. Cousins, A. W. J. (1964), "Photometric Data for Stars in the Equatorial Zone (Seventh List)", Monthly Notes of the Astronomical Society of Southern Africa 23: 175, Bibcode1964MNSSA..23..175C. 
  28. Abt, Helmut A.; Levato, Hugo; Grosso, Monica (July 2002), "Rotational Velocities of B Stars", The Astrophysical Journal 573 (1): 359–365, doi:10.1086/340590, Bibcode2002ApJ...573..359A. 
  29. Abt, Helmut A. (2009). "MK Classifications of Spectroscopic Binaries". The Astrophysical Journal Supplement 180 (1): 117–118. doi:10.1088/0067-0049/180/1/117. Bibcode2009ApJS..180..117A. 
  30. Evans, Nancy Remage; Welch, Douglas L.; Scarfe, Colin D.; Teays, Terry J. (1990). "The orbit and companions of the classical Cepheid FF AQL". Astronomical Journal 99: 1598–1611. doi:10.1086/115442. ISSN 0004-6256. Bibcode1990AJ.....99.1598E. 
  31. Gallenne, A.; Kervella, P.; Mérand, A.; Evans, N. R.; Girard, J. H. V.; Gieren, W.; Pietrzyński, G. (2014). "Searching for visual companions of close Cepheids". Astronomy & Astrophysics 567: A60. doi:10.1051/0004-6361/201423872. Bibcode2014A&A...567A..60G. 
  32. Udalski, A.; Evans, Nancy R. (1993). "The visual companion of the classical Cepheid FF AQL". Astronomical Journal 106 (1): 348–51. doi:10.1086/116643. ISSN 0004-6256. Bibcode1993AJ....106..348U. 
  33. The Contribution of Amateurs to Astronomy, Proceedings of Colloquium 98 of the International Astronomical Union, June 20–24, 1987, page 41
  34. Mobberley, Martin (2009). Cataclysmic Cosmic Events and How to Observe Them. Springer. pp. 46. ISBN 978-0-387-79946-9. 
  35. Johnson, Christopher B.; Schaefer, Bradley E.; Kroll, Peter; Henden, Arne A. (2013). "Nova Aquilae 1918 (V603 Aql) Faded by 0.44 mag/century from 1938-2013". The Astrophysical Journal 780 (2): L25. doi:10.1088/2041-8205/780/2/L25. Bibcode2014ApJ...780L..25J. 
  36. Seligman, Courtney. "NGC Objects: NGC 6750 - 6799". Celestial Atlas. 
  37. "The Glowing Eye of Planetary Nebula NGC 6751". 2000-04-06. 
  38. Levy 2005, pp. 79-80.
  39. Cole-Kodikara, Elizabeth M.; Barnes, Sydney; Weingrill, Jörg; Fritzewski, Dario; Gruner, David (March 2021). "NGC 6709: A Faint Zero-Age Main Sequence Open Cluster". The 20.5th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS20.5), virtually anywhere, March 2–4, 2021. doi:10.5281/zenodo.4565515. 175. Bibcode2021csss.confE.175C. 
  40. Subramaniam, Annapurni; Sagar, Ram (February 1999). "Multicolor CCD Photometry and Stellar Evolutionary Analysis of NGC 1907, NGC 1912, NGC 2383, NGC 2384, and NGC 6709 Using Synthetic Color-Magnitude Diagrams". The Astronomical Journal 117 (2): 937–961. doi:10.1086/300716. Bibcode1999AJ....117..937S. 
  41. Cantat-Gaudin, T.; Anders, F. (January 2020). "Clusters and mirages: cataloguing stellar aggregates in the Milky Way". Astronomy & Astrophysics 633: 22. doi:10.1051/0004-6361/201936691. A99. Bibcode2020A&A...633A..99C. 
  42. Freire, Paulo C. C.; Hessels, Jason W. T.; Nice, David J.; Ransom, Scott M.; Lorimer, Duncan R.; Stairs, Ingrid H. (2005-03-10). "The Millisecond Pulsars in NGC 6760" (in en). The Astrophysical Journal 621 (2): 959–965. doi:10.1086/427748. ISSN 0004-637X. Bibcode2005ApJ...621..959F. 
  43. Shapley, Harlow; Sawyer, Helen B. (August 1927), "A Classification of Globular Clusters", Harvard College Observatory Bulletin 849 (849): 11–14, Bibcode1927BHarO.849...11S. 
  44. Paturel, G. et al. (December 2003), "HYPERLEDA. I. Identification and designation of galaxies", Astronomy and Astrophysics 412: 45–55, doi:10.1051/0004-6361:20031411, Bibcode2003A&A...412...45P. 
  45. "Spitzer Image of Star Factory W51". 
  46. "Chandra :: Photo Album :: W51 :: July 12, 2017". 
  47. Hardware, Leaving the Solar System:Where are they now? 
  48. "Urania's Mirror c.1825 – Ian Ridpath's Antique Star Atlases". 
  49. "Star Tales – Lyra". 
  50. Raymond L. Langsten; Marc Jason Gilbert (1983), Research on Bengal: proceedings of the 1981 Bengal Studies Conference, Issue 34 of South Asia series, Michigan State University Asian Studies Center, Asian Studies Center, Michigan State University, 1983,, "... and the appearance of the constellation Aquila that marks ... As Aquila was an eagle for the Greeks, it is the Garuda kite to Hindus..." 
  51. V.Chandran (1993), Astronomy Quiz Book, Pustak Mahal, 1993, ISBN 978-81-223-0366-7,, "... later spread to other cultures such as Arab, Hindu, Greek and Roman where the names were reinterpreted to suit the local cultures. Hence Aquila/Garuda, Leo/Singha, Hydra/Vasuki and other similarities in names ..." 
  52. Berio, Alessandro (2014). "The Celestial River: Identifying the Ancient Egyptian Constellations". Sino-Platonic Papers 253: 7. Bibcode2014SPP...253....1B. 
  53. Daressy, Georges (1916). "L'Égypte céleste". Bulletin de l'Institut Français d'Archéologie Orientale 12: 1–37. 
  54. "Boll, Franz: Sphaera: neue griechische Texte und Untersuchungen zur Geschichte der Sternbilder (Leipzig, 1903)". 
  55. Makemson 1941, p. 218.
  56. Nā Puke Wehewehe ʻŌlelo Hawaiʻi
  57. Makemson 1941, p. 212.
  58. Makemson 1941, p. 240.
  59. Makemson 1941, p. 262.
  60. Makemson 1941, p. 263.
  61. Makemson 1941, p. 256.
  62. Makemson 1941, p. 264.
  63. Makemson 1941, p. 245.

External links

Coordinates: Sky map 20h 00m 00s, +05° 00′ 00″