William Herschel Discovered Bow Tie Nebula NGC 40 Nov. 25, 1788

Summary: Uranus discoverer William Herschel discovered the Bow Tie Nebula NGC 40, Nov. 25, 1788, seven years eight-plus months after discovering Uranus March 13, 1781.

Two Micron All Sky Survey’s (2MASS) Atlas Image of planetary nebula NGC 40 covers 5.0’ x 5.0’ on the sky; bright source within NGC 40 is the nebula’s hot central star: "Atlas Image courtesy of 2MASS/UMass/IPAC-Caltech/NASA/NSF": NASA/JPL-Caltech IPAC (Infrared Processing and Analysis Center)

Uranus discoverer William Herschel discovered the Bow Tie Nebula NGC 40 in Cepheus the King constellation Nov. 25, 1788, seven years eight-plus months after his March 13, 1781, discovery of the solar system’s third-largest planet, blue-green ice giant Uranus.

German-British astronomer and composer Sir Frederick William Herschel (Nov. 15, 1738-Aug. 25, 1822) discovered NGC 40 at Observatory House, his residence on Windsor Road in Slough, Royal County of Berkshire, South East England. Herschel and his sister Caroline (March 16, 1750-Jan. 9, 1848) moved into Observatory House, his final residence, April 3, 1786.

Sir William discovered NGC 40 with his 20-foot reflector telescope. The Newtonian-styled model had an 18.7-inch aperture. He made his discovery with the telescope in his specially designed front view mode. Newtonian reflector telescope’s paired a spherical mirror with a diagonally mounted secondary mirror. Dispensing with the secondary mirror, Sir William tilted the primary mirror for viewing at the front of the tube. Sir William’s self-designated front view form has been renamed as the Herschelian form in recognition of Sir William’s invention.

Sir William’s discovery Nov. 25, 1788, appeared as number 58 under “IV. Fourth claſs. Planetary nebulae” in his Catalogue of a Second Thousand of New Nebulae and Clusters of Stars, published in 1789. A subtitle for the classification explained: “Stars with burs, with milky chevelure, with ſhort rays, remarkable ſhapes, &c.”

Sir William organized his discoveries of new nebulae and star clusters into eight classes. His classifications were labeled as: “I. First claſs. Bright nebulae”; “II. Second claſs. Faint nebulae”; “III. Third claſs. Very faint nebulae”; “IV. Fourth claſs. Planetary nebulae”; “V. Fifth claſs. Very large nebulae”; “VI. Sixth claſs. Very compreſſed and rich cluſters of ſtars”; “VII. Seventh claſs. Pretty much compreſſed cluſters of large or ſmall ſtars”; “VIII. Eighth claſs. Coarſely ſcattered cluſters of ſtars.”

Sir William identified “24 Cephei” as the star determining the placement of IV-58. According to his calculations, IV-58 followed 24 Cephei by a sidereal time of 116 minutes 28 seconds. Sir William determined that object IV-58 lay 0 degrees 02 minutes to the north of 24 Cephei.

In the summary of his solitary observation of IV-58, Sir William noted: “A ſt 9 m. ſurrounded with vF. M. nebuloſity. The ſt. is either double, or not R. Leſs than 1’ dia.” His abbreviated description translates as: “A 9th magnitude star. Surrounded with very faint milky nebulosity. The star is either double, or not round. Less than 1 arc second in diameter.”

Sir William’s IV-58 entry appears as NGC 40 in A New General Catalogue, published in 1888 by Danish-Irish astronomer John Louis Emil Dreyer (Feb. 13, 1852-Sept. 14, 1926). Dreyer assigned NGC (New General Catalogue) numbers to the discoveries and observations recorded by Sir William; his son, Sir John; his sister Caroline; and other observational astronomers.

Dreyer’s description for his entry number 40 (NGC 40) summarized Sir William’s and Sir John’s observational remarks as: “F, vS, R, vsmbM, * 12 sp.” His description translates as: “Faint; very small; round; very suddenly much brighter in the middle; a star of the 12th magnitude, south preceding.”

NGC 40 is also known as the Bow Tie Nebula. The planetary nebula in Cepheus shares its moniker of Bow Tie Nebula with a Puppid planetary nebula, NGC 2440, and also with a Centaurid protoplanetary nebula, PGC 3074547. NGC 2440 is located in Puppis the Poop Deck, a constellation in the Southern Celestial Hemisphere. The discovery of NGC 2440 is also credited to NGC 40’s discoverer, William Herschel. Sir William discovered NGC 2440 March 4, 1790, which he listed as object IV-64.

The takeaway for Uranus discoverer William Herschel’s discovery of the Bow Tie Nebula NGC 40 Nov. 25, 1785, is that the planetary nebula lies in Cepheus the King constellation.

Uranus discoverer Sir William Herschel discovered NGC 40 (off-center left), a planetary nebula in Cepheus the King constellation, Nov. 25, 1788: John Walker/Your Sky, Public Domain, via Fourmilab Switzerland

Acknowledgment

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

Image credits:

Two Micron All Sky Survey’s (2MASS) Atlas Image of planetary nebula NGC 40 covers 5.0’ x 5.0’ on the sky; bright source within NGC 40 is the nebula’s hot central star; "Atlas Image [or Atlas Image mosaic] obtained as part of the Two Micron All Sky Survey (2MASS), a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation.": Public Domain, via NASA/JPL-Caltech IPAC (Infrared Processing and Analysis Center) @ https://old.ipac.caltech.edu/2mass/gallery/images_pne.html

Uranus discoverer Sir William Herschel discovered NGC 40 (off-center left), a planetary nebula in Cepheus the King constellation, Nov. 25, 1788; aim point RA: 21h 26m 15s Dec: +70°13'35" Tue 1788 Nov 25 4:14 UTC: John Walker/Your Sky, Public Domain, via Fourmilab Switzerland @ http://www.fourmilab.ch/cgi-bin/Yourtel

For further information:

Bratton, Mark. The Complete Guide to the Herschel Objects: Sir William Herschel’s Star Clusters, Nebulae and Galaxies. Cambridge, UK; New York NY; Melbourne, Australia; Madrid, Spain; Cape Town, South Africa; Singapore; São Paulo, Brazil; Delhi, India; Tokyo, Japan; Mexico City, Mexico: Cambridge University Press, 2011.

Dreyer, J.L.E. (John Louis Emil). “No. 40.” 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: 15. 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=21

Dreyer, J.L.E. (John Louis Emil). “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. 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

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Herschel, William. “IV. 58.” In: “Catalogue of a Second Thousand of New Nebulae and Clusters of Stars; With a Few Introductory Remarks on the Construction of the Heavens. Read June 11, 1789.” Philosophical Transactions of the Royal Society of London, vol. LXXIX, part II (1789): 248. London, England: Lockyer Davis and Peter Elmsly, Printers to The Royal Society, MDCCLXXXIX.
Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51828778
Available via JSTOR @ https://www.jstor.org/stable/106695?seq=37#metadata_info_tab_contents

Herschel, William. “IV-64.” In: “Catalogue of 500 New Nebulae, Nebulous Stars, Planetary Nebulae, and Clusters of Stars; With Remarks on the Construction of the Heavens. Read July 1, 1802.” Philosophical Transactions of the Royal Society of London. For the Year MDCCCII [1802] [vol. 92], part II: 520. London, England: W. Bulmer and Co., MDCCCII.
Available via Biodiversity Heritage Library (Smithsonian Libraries) @ https://biodiversitylibrary.org/page/49130839
Available via Biodiversity Heritage Library (University of Toronto -- Robarts Library) @ https://biodiversitylibrary.org/page/22894708
Available via JSTOR @ https://www.jstor.org/stable/107131?seq=45#metadata_info_tab_contents

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Available via Biodiversity Heritage Library (Smithsonian Libraries) @ https://biodiversitylibrary.org/page/49130796
Available via Biodiversity Heritage Library (University of Toronto -- Robarts Library) @ https://biodiversitylibrary.org/page/22894665
Available via JSTOR @ https://www.jstor.org/stable/107131

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Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/51828742
Available via JSTOR @ https://www.jstor.org/stable/106695

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Available via Biodiversity Heritage Library @ https://biodiversitylibrary.org/page/48283813
Available via JSTOR @ https://www.jstor.org/stable/106639

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