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Comet C/2011 L4 was discovered on 6 June 2011 with Pan-STARRS 1 telescope (Haleakala); that is about a year and 9 months before its perihelion passage. Next, pre-discovery images of the comet taken on 21 May (Pan-STARRS 1), 24 May (Mt. Lemmon Survey), and 30 May (iTelescope Observatory, Mayhill), 2011 were found. The comet was observed until 27 August 2014.
Comet had its closest approach to the Earth on 5 March 2013 (1.097 au), 5 days before its perihelion passage.
Preferred solution given here is based on data spanning over 3.27 yr in a range of heliocentric distances: 3.27 au – 0.302 au (perihelion) – 6.97 au. The non-gravitational solution was chosen as preferred orbit; however, uncertainties of NG parameters are relatively large. Additionally, there are two further nongravitational solutions: NG orbit for pre-perihelion arc of data, and NG orbit based on post-perihelion data. All solutions (NG and GR type) give a narrow range of original 1/a values from 29.7 to 32.0 in units of 10-6 au-1.
This Oort spike comet suffers moderate planetary perturbations during its passage through the planetary system; these perturbations lead to a more tight future orbit (see future barycentric orbits).
See also Królikowska 2020.

solution description
number of observations 5501
data interval 2011 05 21 – 2014 08 27
data type perihelion within the observation arc (FULL)
data arc selection entire data set (STD)
range of heliocentric distances 8.04 au – 0.30 au (perihelion) – 6.97 au
type of model of motion NS - non-gravitational orbits for standard g(r)
data weighting YES
number of residuals 10911
RMS [arcseconds] 0.44
orbit quality class 1a+
previous orbit elements (barycentric ecliptic J2000)
no. of returning VCs in the swarm 5001 *
no. of escaping VCs in the swarm 0
no. of hyperbolas among escaping VCs in the swarm 0
previous recip semi-major axis [10-6 au-1] 30.41 ± 0.47
previous perihelion distance [au] 63.315 – 70.29 – 77.989
previous aphelion distance [103 au] 65.7 ± 1
time interval to previous perihelion [Myr] 5.871 ± 0.133
percentage of VCs with q > 20100
dynamical status definitely dynamically new (DN+)
Time distribution of positional observations with corresponding heliocentric (red curve) and geocentric (green curve) distance at which they were taken. The horizontal dotted line shows the perihelion distance for a given comet whereas vertical dotted line – the moment of perihelion passage