C/2015 G2 MASTER
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Comet C/2015 G2 was discovered on 7 April 2015 using Mobile Astronomical System of the Telescope-Robots (MASTER, South African Astronomical Observatory), that is about 1.5 month before its perihelion passage. Next, a series of six measurements from March 30 were found from the same place. Comet was observed until 7 February 2016. This comet had closest approach to the Earth on 12 May 2015 (0.471 au, 11 days before the perihelion passage).
This is a comet with NG effects strongly manifested in positional data fitting. Solutions 'a5' and 'n5' (preferred) are based on data spanning over 0.86 yr in a range of heliocentric distances: 1.28 au – 0.780 au (perihelion) – 3.85 au. Though many trends visible in [O-C] for the GR solution are eliminated thanks to the NG solution, large residuals in alpha in the data from the beginning of the arc performed by MASTER (arc data: March 30 – April 8) are still worrying, which resulted in ejecting these positions in alpha (and leaving them in delta; see the [O-C] picture for solutions 'a5' and 'n5').
According to GR solution, this comet seems to come from the Oort Cloud, however NG solution indicates C/2015 G2 with an original semimajor axis of about 7400–8300 au. This comet suffers moderate planetary perturbations during its passage through the planetary system; these perturbations lead to escape the comet from the planetary zone on a hyperbolic orbit (see future barycentric orbits) for both orbits (GR and NG) given here.
This is a comet with NG effects strongly manifested in positional data fitting. Solutions 'a5' and 'n5' (preferred) are based on data spanning over 0.86 yr in a range of heliocentric distances: 1.28 au – 0.780 au (perihelion) – 3.85 au. Though many trends visible in [O-C] for the GR solution are eliminated thanks to the NG solution, large residuals in alpha in the data from the beginning of the arc performed by MASTER (arc data: March 30 – April 8) are still worrying, which resulted in ejecting these positions in alpha (and leaving them in delta; see the [O-C] picture for solutions 'a5' and 'n5').
According to GR solution, this comet seems to come from the Oort Cloud, however NG solution indicates C/2015 G2 with an original semimajor axis of about 7400–8300 au. This comet suffers moderate planetary perturbations during its passage through the planetary system; these perturbations lead to escape the comet from the planetary zone on a hyperbolic orbit (see future barycentric orbits) for both orbits (GR and NG) given here.
| solution description | ||
|---|---|---|
| number of observations | 599 | |
| data interval | 2015 03 30 – 2016 02 07 | |
| data type | perihelion within the observation arc (FULL) | |
| data arc selection | entire data set (STD) | |
| range of heliocentric distances | 1.28 au – 0.78 au (perihelion) – 3.85 au | |
| type of model of motion | NS - non-gravitational orbits for standard g(r) | |
| data weighting | YES | |
| number of residuals | 1119 | |
| RMS [arcseconds] | 0.39 | |
| orbit quality class | 1b | |
| orbital elements (heliocentric ecliptic J2000) | ||
|---|---|---|
| Epoch | 2015 06 27 | |
| perihelion date | 2015 05 23.78589864 | ± 0.00001931 |
| perihelion distance [au] | 0.77987143 | ± 0.00000029 |
| eccentricity | 1.00034811 | ± 0.00000156 |
| argument of perihelion [°] | 257.458275 | ± 0.000047 |
| ascending node [°] | 110.058228 | ± 0.000016 |
| inclination [°] | 147.563732 | ± 0.000022 |
| reciprocal semi-major axis [10-6 au-1] | -446.37 | ± 2.01 |
Upper panel: 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.
Middle panel(s): O-C diagram for a given solution (sometimes in comparison to another solution available in CODE), where residuals in right ascension are shown using magenta dots and in declination by blue open circles.
Lowest panel: Relative weights for a given data set(s).
Middle panel(s): O-C diagram for a given solution (sometimes in comparison to another solution available in CODE), where residuals in right ascension are shown using magenta dots and in declination by blue open circles.
Lowest panel: Relative weights for a given data set(s).
| non-gravitational parameters | ||
|---|---|---|
| A1 [10-8au/day2] | 0.95121 | ± 0.05269 |
| A2 [10-8au/day2] | 0.40445 | ± 0.03647 |
| A3 [10-8au/day2] | -0.35162 | ± 0.0133 |
| m | -2.15 | |
| n | 5.093 | |
| k | -4.6142 | |
| r0 [au] | 2.808 | |
| α | 0.1113 | |