Wednesday, October 23, 2019

Star Hopping South of Markab Leads to Barred Spiral Galaxy NGC 7479


Summary: Star hopping south of Markab leads to barred spiral galaxy NGC 7479, discovered Oct. 19, 1784, by Uranus discoverer Sir William Herschel.


Alpha Pegasi, known traditionally as Markab, serves as a reliable guide for star hopping to the area of the sky for finding barred spiral galaxy NGC 7479: RobertBurnhamJr @RobertBurnhamJr, via Twitter Oct. 28, 2018

Star hopping south of Markab leads to barred spiral galaxy NGC 7479, discovered Oct. 19, 1784, by Uranus discoverer Sir William Herschel and observed over four decades later by Sir William’s son, English polymath Sir John Herschel.
NGC 7479 claims Pegasus the Winged Horse as parent constellation. Constellation Pegasus lies in the Northern Celestial Hemisphere. The Winged Horse’s southern border approaches the celestial equator by about two degrees.
Star hopping is a technique for locating celestial objects in the night sky. The strategy entails using bright stars and asterisms (recognizable patterns of stars) as guides for celestial objects that are faint or that require binoculars or telescopes.
The star hop to NGC 7479 involves the naked eye visibility of bright star Markab. NGC 7479 is located in south central Pegasus. Astronomy magazine senior editor Michael E. Bakich identifies NGC 7479’s location as 2.9 degrees south of Markab. Star hopping south of Markab leads to NGC 7479.
Alpha Pegasi (α Pegasi; Alpha Peg, α Peg) bears the traditional name of Markab. The traditional name either derives from the Arabic phrase for “saddle of the horse” or represents a mistranscription of “shoulder of the horse.” The International Astronomical Union approved Markab June 30, 2016, as Alpha Pegasi’s official proper name.
Markab shines as the third brightest star in Pegasus the Winged Horse constellation. Markab has an apparent visual magnitude of 2.49. The fairly rapidly spinning star qualifies as “just barely second magnitude,” according to University of Illinois Professor Emeritus James B. “Jim” Kaler.
Markab participates in the quartet that forms the Great Square of Pegasus asterism, or recognizable pattern of stars. The quartet comprises three stars from constellation Pegasus and one star from the Winged Horse’s northeastern neighbor, Andromeda the Chained Princess constellation. Markab occupies the southwestern corner of the Great Square of Pegasus.
Astronomy magazine senior editor Michael E. Bakich describes NGC 7479 as a “showpiece galaxy through a large scope.” A low power scope reveals the central bulge that surrounds the galaxy’s bright core as well as NGC 7479’s north-to-south elongated bar. Bakich recommends the spiral arm at the bar’s south end as the best feature of NGC 7479.
The barred spiral galaxy now known as NGC 7479 appears as entry I-55 in Sir William Herschel’s Catalogue of One Thousand New Nebulae and Clusters of Stars, published in 1786. Sir William’s designation reveals his discovery as object number 55 in Sir William’s category of “Firſt claſs. Bright nebulae.”
The nomenclature of NGC 7479 for Sir William’s I-55 derives from the New General Catalogue, published in 1888 by Danish-Irish astronomer John Louis Emil Dreyer (Feb. 13, 1852-Sept. 14, 1926). Dreyer’s catalogue assigned NGC (New General Catalogue) numbers to its compilation of discoveries and observations by Sir William Herschel (Nov. 15, 1738-Aug. 25, 1822); his astronomer sister Caroline Herschel (March 16, 1750-Jan. 9, 1848); his son, Sir John Herschel (March 7, 1792-May 11, 1871); and other observational astronomers.
Equatorial coordinates are the celestial equivalent of terrestrial coordinates. Equatorial coordinates are expressed as right ascension, the celestial equivalent of terrestrial longitude, and as declination, the celestial equivalent of terrestrial latitude. Equatorial coordinates for NGC 7479 are right ascension 23 hours 04 minutes 49.61 seconds and declination plus 12 degrees 20 minutes 37.3 seconds (epoch J2000.0), according to NASA/IPAC Extragalactic Database (NED).
Alpha Pegasi bears the Hipparcos designation of HIP 113963. Alpha Pegasi’s Hipparcos designation reflects its participation in The European Space Agency’s Hipparcos (High Precision Parallax Collecting Satellite) space astrometry mission, which operated from 1989 to 1993. The Hipparcos Catalogue, released in June 1997, presented precise astrometric data collected by the scientific satellite for 118,218 stars.
Equatorial coordinates for HIP 113963 are right ascension 23 hours 04 minutes 45.654 seconds and declination plus 13 degrees 12 minutes 18.96 seconds, according to Hubble Legacy Archive (HLA). Hubble Legacy Archive is an online project of Hubble products jointly administered by the Space Telescope Science Institute (STScI), the Space Telescope European Coordinating Facility (ST-ECF) and the Canadian Astronomy Data Centre (CADC).
The takeaway for star hopping south of Markab to reach barred spiral galaxy NGC 7479 is that Markab shines as the third brightest star in Pegasus the Winged Horse constellation and participates in the prominent Great Square of Pegasus asterism.

Discovered by Uranus discoverer Sir William Herschel in October 1784, NGC 7479 lies 2.9 degrees south of second magnitude star Markab (Alpha Pegasi) in Pegasus the Winged Horse constellation: RobertBurnhamJr @RobertBurnhamJr, via Twitter Oct. 28, 2018

Acknowledgment
My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:
Alpha Pegasi, known traditionally as Markab, serves as a reliable guide for star hopping to the area of the sky for finding barred spiral galaxy NGC 7479: RobertBurnhamJr @RobertBurnhamJr, via Twitter Oct. 28, 2018, @ https://twitter.com/RobertBurnhamJr/status/1056586556104957952
Discovered by Uranus discoverer Sir William Herschel in October 1784, NGC 7479 lies 2.9 degrees south of second magnitude star Markab (Alpha Pegasi) in Pegasus the Winged Horse constellation: RobertBurnhamJr @RobertBurnhamJr, via Twitter Oct. 28, 2018, @ https://twitter.com/RobertBurnhamJr/status/1056619188310159360

For further information:
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Dreyer, J.L.E. (John Louis Emil). “No. 7479.” In: “A New General Catalogue of Nebulae and Clusters of Stars, Being the Catalogue of the Late Sir John F.W. Herschel, Bart., Revised, Corrected, and Enlarged.” Memoirs of the Royal Astronomical Society, vol. XLIX, part I: 202. London, England: Royal Astronomical Society, 1888.
Available @ https://ia800501.us.archive.org/14/items/newgeneralcatalo00dreyrich/newgeneralcatalo00dreyrich.pdf
Available via HathiTrust @ https://hdl.handle.net/2027/osu.32435078053089?urlappend=%3Bseq=208
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Available via Biodiversity Heritage Library (Natural History Museum Library, London) @ https://biodiversitylibrary.org/page/54093297
Available via JSTOR @ https://www.jstor.org/stable/108864?seq=134#metadata_info_tab_contents
Herschel, William. “I-55.” In: “Catalogue of One Thousand New Nebulae and Clusters of Stars. Read April 27, 1786.” Philosophical Transactions of the Royal Society of London, vol. LXXVI, part II (1786): 472. London, England: Lockyer Davis and Peter Elmsly, Printers to The Royal Society, MDCCLXXXVI.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/48283828
Available via JSTOR @ https://www.jstor.org/stable/106639?seq=16#metadata_info_tab_contents
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Marriner, Derdriu. “Sir John Herschel Observed NGC 7479 in October 1823 and October 1830.” Earth and Space News. Wednesday, Oct. 9, 2019.
Available @ https://earth-and-space-news.blogspot.com/2019/10/sir-john-herschel-observed-ngc-7479-in.html
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O’Meara, Steve. Herschel 400 Observing Guide: How to Find and Explore 400 Star Clusters, Nebulae, and Galaxies Discovered by William and Caroline Herschel. Cambridge, England; New York NY; Melbourne, Australia; Madrid, Spain; Cape Town, South Africa; Singapore; São Paulo, Brazil: Cambridge University Press, 2007.
RobertBurnhamJr @RobertBurnhamJr. Oct 28 “Alpha Pegasi: MARKAB or MARCHAB, from the Arabian word for Saddle, though the term might also refer to a ship. The star marks the southwest corner of the "Great Square of Pegasus." Twitter. Oct. 28, 2018.
Available @ https://twitter.com/RobertBurnhamJr/status/1056586556104957952
RobertBurnhamJr @RobertBurnhamJr. “MARKAB: Other names were 'Matn al Faras,' the Horse's Shoulder, and 'Yed Alpheras,' the Horse's Forearm. The star lies in a rather blank part of sky; the interesting spiral galaxy NGC 7479, however, will be found about 2.9° almost directly south. [Photo: https://astrob.in/367250/0/?nc= ].” Twitter. Oct. 28, 2018.
Available @ https://twitter.com/RobertBurnhamJr/status/1056619188310159360


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