Why Was the Companion of Sirius Not Seen Prior to 1862?

Bessel F. W. , “On the variation of proper motions of Procyon and Sirius”, Monthly notices of the Royal Astronomical Society, vi (1844), 136–44. Because of its anticipated faintness, the ‘unseen companion’ was occasionally referred to as a planet (see, e.g., Le Verrier U. J. , “Rapport sur l'Observatoire Impérial de Paris et projet d'organisation”, Annales de l'Observatoire Impérial de Paris, i (1855), 1855–68, p. 7).

Holberg J. B. Wesemael F. , “The discovery of the companion of Sirius and its aftermath”, Journal for the history of astronomy, xxxviii (2007), 161–74.

Holberg J. B. , Sirius: Brightest diamond in the night sky (Chichester, 2007).

Peters C. A. F. , “Ueber die eigene Bewegung des Sirius”, Astronomische Nachrichten, xxxii (1851), cols 1–58.

This question was first raised by Burnham S. W. , “Double stars discovered by Mr. Alvan G. Clark”, American journal of science , xvii (1879), 283–9, p. 284. Related issues are also discussed by Lippincott S. L. , “Sirius and its companion”, Astronomical Society of the Pacific leaflets, viii (1961), 1961–18.

Sir Frank Dyson, president of the Optical Society, referred to the discovery as the “triumphant verification … made not by an astronomer but by an optician” (“Large telescopes”, Transactions of the Optical Society, xxiv (1923), 60–68, p. 64).

Burnham , op. cit. (ref. 5), 284.

Holberg , op. cit. (ref. 3), 231.

The last reported observation (1890.27) before periapsis is that of Burnham S. W. , “Companion of Sirius”, Publications of the Astronomical Society of the Pacific , ii (1890), 138. The angular distance was 4.19″. The subsequent recovery (1896.81) of the companion after periapsis is due to Aitken R. G. , “Measures of Sirius”, Publications of the Astronomical Society of the Pacific, viii (1896), 314; also “Measures of Sirius”, The astronomical journal, xvii (1896), 27, and “Measures of Sirius”, Astronomische Nachrichten, cxlii (1897), cols 77–78. The angular distance was 3.67″.

Hoskin Michael A. , William Herschel and the construction of the heavens (New York, 1963), 31.

RAS MS Herschel W.4/1, folio 4.

The scientific papers of Sir William Herschel, ed. by Dreyer J. L. E. (2 vols, London, 1912; hereafter: Dreyer), i, 109.

Dreyer, i, 167–222.

RAS MS Herschel W.4/2.

Steavenson W. H. , “A peep into Herschel's workshop”, Transactions of the Optical Society, xxvi (1925), 210–20, pp. 212–13. See also King H. C. , The history of the telescope (High Wycombe, 1955; reprinted Mineola, 2003), 133–4.

Herschel J. F. W. , “Schreiben des Herrn J. F. W. Herschel F.R.S. an den Herausgeber”, Astronomische Nachrichten, iv (1826), cols 231–6.

Buttmann G. , Wilhelm Herschel: Leben und Werk (Stuttgart, 1961), 92.

Dreyer, ii, 34.

Herschel J. F. W. , “Auszug aus einem Brief des Herrn J. F. W. Herschel an dem Herausgeber”, Astronomische Nachrichten, ii (1824), cols 389–90.

Herschel J. F. W. South J. , “Observations of the apparent distances and positions of 380 double and triple stars, made in the years 1821, 1822, and 1823, and compared with those of other astronomers; together with an account of such changes as appear to have taken place in them since their first discovery. Also a description of a five-feet equatorial instrument employed in the observations”, Philosophical transactions, cxiv (1824), 1–412.

South J. , “Observations of the apparent distances and positions of 458 double and triple stars, made in the years 1823, 1824, and 1825; together with a re-examination of 36 stars of the same description, the distances and positions of which were communicated in a former memoir”, Philosophical transactions, cxvi (1826), 1–391.

The complete references to J. F. W. Herschel's six-part catalogue of binaries are given in Buttmann G. , The shadow of the telescope: A biography of John Herschel (New York, 1970), 197, note 2.

Herschel J. F. W. , “Observations of nebulae and clusters, made at Slough, with a 20-feet reflector, between the years 1825–1833”, Philosophical transactions, cxxiii (1833), 359–505.

Evans D. S. , Herschel at the Cape: Diaries and correspondence of Sir John Herschel 1834–1838 (Austin, 1969), 12.

Evans , op. cit. (ref. 24), 331.

King , op. cit. (ref. 15), 248.

Clerke Agnes M. , A popular history of astronomy (Edinburgh, 1885), 53.

Struve F. G. W. , Études d'astronomie stellaire (St-Petersburg, 1847; reprinted New York, 1981), 26–27 and 53–57, p. 57.

Hoskin Michael , “The Leviathan of Parsonstown: Ambitions and achievements”, Journal for the history of astronomy, xxxiii (2002), 57–70. A later observation (11 March) of the bright star Regulus (V = 1.35) with the same instrument is described by South (Astronomische Nachrichten, xxiii (1846), cols 113–18, col. 116) and attests to the capacity of this telescope to deliver images of bright stars “free from wings, tails, or optical appendages”.

Verrier Le , op. cit. (ref. 1), 7.

Holberg Wesemael , op. cit. (ref. 2).

Bond G. P. , “On the companion of Sirius”, Astronomische Nachrichten, lvii (1862), cols 131–2; “On the companion of Sirius”, American journal of science and arts, xxxiii (1862), 1862–7; “Discovery of a companion of Sirius”, Monthly notices of the Royal Astronomical Society, xxii (1862), 170; Astronomische Nachrichten, lviii (1862), cols 85–90, col. 88.

Rutherfurd L. M. , “Companion to Sirius”, American journal of science and arts, xxxiv (1862), 294–5.

Chacornac Jean , Astronomische Nachrichten , lvii (1862), cols 175–6; Le Verrier U. , Comptes rendus des séances de l'Académie des Sciences, liv (1862), 1862–8.

Lassell W. , “Schreiben des Herrn W. Lassell an den Herausgeber”, Astronomische Nachrichten, lvii (1862), cols 251–2.

Struve O. , “On the satellite of Sirius”, Monthly notices of the Royal Astronomical Society, xxiv (1864), 149–51.

Struve O. , “On the satellite of Sirius”, Monthly notices of the Royal Astronomical Society, xxvi (1866), 268–71.

Dawes W. R. , “On the companion of Sirius”, Monthly notices of the Royal Astronomical Society, xxiv (1864), 144–5.

Dawes W. R. , Monthly notices of the Royal Astronomical Society, xxiv (1864), 151–2, p. 151. Sirius culminates at 21.5° at Hopefield Observatory.

Hodgson R. , Monthly notices of the Royal Astronomical Society , xxiv (1864), 151–2, p. 152. 41. Knott G. , “On the companion to Sirius”, Monthly notices of the Royal Astronomical Society, xxvi (1866), 1866–4.

Auwers A. , “Beiträge zur Kenntniss des Sirius-Systems”, Astronomische Nachrichten, cxxix (1892), cols 185–222.

Rutherfurd , op. cit. (ref. 33).

King , op. cit. (ref. 15), 180–4. The survey for binary stars undertaken at Dorpat by Wilhelm Struve, which lasted from November 1824 to February 1827, was restricted to declinations above −15°. Sirius, at δ₁₈₀₀ = −16°31″, would have been nominally excluded from that search.

Couteau P. , Observing visual double stars (Cambridge MA, 1981), 8.

Dawes W. R. , “The companions of Sirius”, Astronomical register, i (1863), 94; see also “Companion of Sirius”, Monthly notices of the Royal Astronomical Society, xxiii (1863), 1863–3. Dawes was commenting on the visibility of several additional companions, five in total, which had been reported by H. Goldschmidt in 1863 and whose existence was subsequently not confirmed.

Pease F. G. , “On the design of very large telescopes”, Publications of the Astronomical Society of the Pacific, xxxviii (1926), 192–207, pp. 203–4.

Meadows A. J. , “Observational defects in eighteenth-century British telescopes”, Annals of science, xxvi (1970), 305–17, p. 309. The critical importance of diffuse light is perhaps best illustrated by the failure by Robert Lewis J. Ellery and his staff to see the satellites of Mars with the Great Melbourne Telescope, a large reflector equipped with a 48-inch speculum. Despite repeated attempts, in the course of sixteen nights in September and October 1877, to see the satellites discovered the previous month by Asaph Hall with the U.S. Naval Observatory 26-inch refractor, they failed to do so — Most likely because of the halo of scattered light surrounding the bright planet, which was near closest approach at the time ( Gascoigne S. C. B. , “The great Melbourne telescope and other 19th century reflectors”, Historical records of Australian science, x (1995), 1995–45, p. 234).

De La Rue W. , “On the figuring of specula”, Monthly notices of the Royal Astronomical Society, xiii (1852), 44–51.

Any seeing-disc value quoted in this paper is to be understood as a full width at half maximum (FWHM) central intensity.

Racine R. Wesemael F. , “Two centuries of image quality estimates from multiple star data”, in preparation.

Chacornac , op. cit. (ref. 34).

Marois C. , “La recherche des naines brunes et d'exoplanètes: Développement d'une technique multibande”, Ph.D. thesis, Université de Montréal, 2005.

Chacornac's log books, Bibliothèque de l'Observatoire de Paris, call number F14, 20 March 1862. The complete quote appears in Holberg and Wesemael, op. cit. (ref. 2), 170.

Barstow M. A. , “Hubble Space Telescope spectroscopy of the Balmer lines in Sirius B”, Monthly notices of the Royal Astronomical Society, ccclxii (2005), 1134–42.

Auwers , op. cit. (ref. 42).

van den Bos W. H. , “The orbit of Sirius, ADS 5423”, Journal des observateurs, xliii (1960), 145–51.

van den Bos , op. cit. (ref. 57).

Auwers , op. cit. (ref. 42).

For completeness, albeit unnecessarily for the demonstration, we set the absolute values of the seeing disc estimates by imposing that the single-observation error be equal to half the width at half peak intensity of the image in unit contrast conditions. This appears reasonable and yields “best seeing values” consistent with modern estimates for the sites.

Hickson P. Racine R. , “Image quality of liquid-mirror telescopes”, Publications of the Astronomical Society of the Pacific, cxix (2007), 456–65.

Newton I. , Opticks, 4th edn (London, 1730; reprinted Amherst, 2003), 111.

See the compilation of Burnham S. W. , “Sirius”, Monthly notices of the Royal Astronomical Society , li (1891), 378–88. Auwers , op. cit. (ref. 42), 199, presumes the unpublished USNO measurement to be a private communication from A. Hall to S. W. Burnham.

Burnham S. W. , “The orbit of Sirius”, Monthly notices of the Royal Astronomical Society, lvii (1897), 453–6. Interestingly T. J. J. See (“Theoretical position of the companion of Sirius”, Astronomische Nachrichten, cxxxix (1896), cols 367–68) gives his own version of the same observation by stating that “the object was comparatively easy with the 36 inch”. The companion was looked for by Burnham later in 1890 and in 1891, and also by Barnard “in the two or three succeeding years”, to no avail.

Dreyer, i, 47.

Rutherfurd , op. cit. (ref. 33).

For example, King, op. cit. (ref. 15), 259, as well as Erck W. , “Satellites of Mars”, Astronomy register, xv (1877), 293–4, and xvi (1878), 20–25.

Dreyer, i, 131–56.

Pelli D. G. , “Uncertainty explains many aspects of visual contrast detection and discrimination”, Journal of the Optical Society of America, A ii (1985), 1508–32, p. 1508.

Knott , op. cit. (ref. 41).

Dreyer , op. cit. (ref. 18).

Lassell , op. cit. (ref. 35).

This measurement dates from 1863.15 and is listed by Burnham, op. cit. (ref. 63).

Burnham S. W. , “The orbit of Sirius”, Monthly notices of the Royal Astronomical Society, liii (1893), 482–3: “For the present, all we need is the apparent orbit, in order to know about where to look for the small star”.

Mason B. D. Wycoff G. L. , and Hartkopf W. I. , “The Washington Double Star Catalogue” (2007), http://ad.usno.navy.mil/wds/wdstext.html.

Barstow After (ref. 55).