C/1904 Y1 Giacobini
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Comet C/1904 Y1 was discovered on 18 December 1904 by Michel Giacobini (Nice Observatory, France), that is one and a half of month after perihelion passage, and it was last seen on 1 June 1905 [Kronk, Cometography: Volume 3].
This comet made its closest approach to the Earth on 31 May 1904 (1.94 au), that is more than 6.5 months before its discovery. During the observed period it was closest to the Earth on 19 January (2.21 au) that is one month after discovery.
Solution given here is based on data spanning over 0.370 yr in a narrow range of heliocentric distances from 1.96 au through perihelion (1.88 au) to 2.86 au.
This marginally Oort spike comet suffers small planetary perturbations during its passage through the planetary system that lead to more tight future orbit (see future barycentric orbit).
More details in Królikowska et al. 2014.

solution description
number of observations 164
data interval 1904 12 18 – 1905 05 02
data type observed only after perihelion (POST)
data arc selection entire data set (STD)
range of heliocentric distances 1.96 au – 2.86au
detectability of NG effects in the comet's motion NG effects not determinable
type of model of motion GR - gravitational orbit
data weighting YES
number of residuals 164
RMS [arcseconds] 2.87
orbit quality class 2b
orbital elements (heliocentric ecliptic J2000)
Epoch 1904 11 16
perihelion date 1904 11 03.77411106 ± 0.01331171
perihelion distance [au] 1.88176420 ± 0.00010009
eccentricity 1.00034373 ± 0.00022266
argument of perihelion [°] 40.723034 ± 0.006760
ascending node [°] 219.786197 ± 0.000583
inclination [°] 99.600058 ± 0.000577
recip semi-major axis [10-6 au-1] -182.66 ± 118.32
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