15P/Finlay

Comet Finlay is a periodic comet in the Solar System discovered by William Henry Finlay (Royal Observatory, Cape of Good Hope, South Africa) on September 26, 1886. It came to perihelion (closest approach to the Sun) on December 27, 2014,[4] at around apparent magnitude 10.[5]

15P/Finlay
Discovery
Discovered byWilliam Henry Finlay
Discovery dateSeptember 26, 1886
Alternative
designations		1886 S1; 1886 VII;
1886e; 1893 K1;
1893 III; 1893a;
1906 V; 1906d;
1919 II; 1919d;
1926 V; 1926d;
1953 VII; 1953i;
1960 VIII; 1960d;
1967 IX; 1967g;
1974 X; 1974d;
1981 XII; 1981e;
1988 IX; 1988f
Orbital characteristics A
Epoch2014-Dec-09
(JD 2457000.5)
Aphelion6.019 AU
Perihelion0.976 AU
Semi-major axis3.488 AU
Eccentricity0.7202
Orbital period6.51 a
Inclination6.799°
Earth MOID0.009 AU (1,300,000 km)[1]
Jupiter MOID0.16 AU (24,000,000 km)[1]
Dimensions1.8 km (uncertain)[2]
Last perihelionDecember 27, 2014[3][4]
June 22, 2008
Next perihelionJuly 13, 2021[3]

Description
Perihelion distance
at different epochs[3]
EpochPerihelion
(AU)
18661.0
19060.96
19191.0
19811.1
20080.97
20210.99

When the first parabolic orbit calculations were made in 1886, there was a similarity between this orbit and that of Francesco de Vico's lost periodic comet of 1844 (54P/de Vico-Swift-NEAT). Lewis Boss (Dudley Observatory, Schenectady, United States) noted large discrepancies between the orbits and after further observations concluded that de Vico's comet could not be the same as Finlay's.[6]

The 1899 apparition was missed, in 1910 a close pass with Jupiter increased the orbital period, in 1919 the path was off predictions and a new comet discovered by Sasaki (Kyoto Observatory, Japan) on October 25, 1919, was discovered to be Finlay's.

The magnitude of the comet declined after 1926, and it was not until 1953 that it has been observed on every return.

During the 2015 perihelion passage the comet outburst on 16 December 2014 from magnitude 11 to magnitude 9 becoming bright enough to be seen in common binoculars with a 50 mm objective lens.[7] On December 23, 2014, 15P and Mars were only 1/6 of a degree apart in the sky after sunset.[7] But by December 23, 2014, the comet had dimmed considerably since the outburst. On 16 January 2015, the comet outburst to magnitude 8.[8]

The comet currently has an Earth-MOID of 0.01 AU (1,500,000 km; 930,000 mi).[1] On October 25, 2060, the comet will pass roughly 0.04 AU (6,000,000 km; 3,700,000 mi) from the Earth.[1]

References
  1. "JPL Close-Approach Data: 15P/Finlay" (last observation: 2015-04-20). Retrieved 2014-11-01.
  2. M. Festou; H. U. Keller; Harold A. Weaver (2004). Comets II. University of Arizona Press. p. 242. ISBN 978-0-8165-2450-1.
  3. "15P/Finlay Orbit". Minor Planet Center. Retrieved 2014-06-21.
  4. Syuichi Nakano (2011-11-05). "15P/Finlay (NK 2161)". OAA Computing and Minor Planet Sections. Retrieved 2012-02-18.
  5. Seiichi Yoshida (2010-07-31). "15P/Finlay (2014)". Seiichi Yoshida's Comet Catalog. Retrieved 2012-02-22.
  6. Kronk, Gary W. "15P/Finlay". Cometography. Retrieved 2007-01-31.
  7. Bob King (2014-12-18). "Comet Finlay in Bright Outburst, Visible in Small Telescopes". Universe Today. Retrieved 2014-12-20.
  8. Michael Mattiazzo. "24324Re: [comets-ml] Re: Possible another outburst of 15P/Finlay?". Yahoo: comet-ml. Retrieved 2015-01-17.
Numbered comets
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16P/Brooks
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