Comet of 1729
|Discovered by||Fr. Nicolas Sarabat|
|Discovery date||August 1, 1729|
|C/1729 P1, 1729,
Comet of 1729
|Orbital characteristics A|
(June 16, 1729)
|Last perihelion||June 16, 1729|
The Comet of 1729, also known as C/1729 P1 or Comet Sarabat, was a non-periodic comet with an absolute magnitude of −3, the brightest ever observed for a comet; it is therefore considered to be potentially the largest comet ever seen.
Observing with the naked eye, he saw an object resembling a faint, nebulous star: he was at first unsure if it was a comet or part of the Milky Way. Moonlight interfered with Sarabat's observations until August 9, but after recovering the object and attempting to detect its motion without the aid of any measuring instruments, he became convinced that he had found a new comet.
News of the discovery was passed to Jacques Cassini in Paris. He was able to confirm the comet's position, though with extreme surprise at how little it had moved since the first observation nearly a month previously. Cassini was able to continue observation until 18 January 1730, by which time the comet was located in Vulpecula. This was an extraordinarily long period for observation of a comet, though it never rose above apparent magnitude 3–4.
The comet's orbit, later computed by John Russell Hind, showed a perihelion distance (closest approach to the Sun) of 4.05 AU which is just within the orbit of Jupiter. However despite this it became visible, although faintly, to the naked eye, and indeed remained visible for six months in total. This suggests that its absolute magnitude or intrinsic brightness was unusually high, possibly as high as −3.0. It is therefore likely that the Comet of 1729 was an exceptionally large object, with a cometary nucleus of the order of 100 km in diameter. The JPL small-body database only uses three observations, a two-body model, and an assumed epoch to compute the orbit of this parabolic comet.
- "JPL Small-Body Database Browser: C/1729 P1". Jet Propulsion Laboratory. 1730-01-16 last obs (only 3 observations using a two-body model; very poorly determined). Retrieved 2011-07-26. Check date values in:
- Kidger, M. 'Comet Hale-Bopp Light Curve', NASA JPL, accessed 24-Nov-2008
- Comet Caesar (C/-43 K1) has, however, been calculated to have possibly had the brightest absolute magnitude in recorded history: −3.3 at the time of discovery and −4.0 during a later flare-up; cp. John T. Ramsey & A. Lewis Licht, The Comet of 44 B.C. and Caesar's Funeral Games, Atlanta, 1997, ISBN 0-7885-0273-5.
- Moore, P. The Data Book of Astronomy, CRC, 2000, p.232
- Lynn, W. T. 'Sarrabat and the comet of 1729', The Observatory, Vol. 19, p. 239–240 (1896). Sarabat (1698–1737), also known as "de la Baisse", a Jesuit and professor at Marseilles university, himself spelt his name "Sarrabat", but Cassini's spelling is generally used in reference to this comet.
- Kronk, G. W. Cometography: A Catalog of Comets, Cambridge University Press, 1999, p.394
- Sagan, C. and Druyan, A. Comet, Ballantine, 1997