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 | |
| next orbit statistics, both Galactic and stellar perturbations were taken into account | ||
|---|---|---|
| no. of returning VCs in the swarm | 0 | |
| no. of escaping VCs in the swarm | 5001 | |
| no. of hyperbolas among escaping VCs in the swarm | 5001 | * |
| next reciprocal semi-major axis [10-6 au-1] | -397.25 – -395.24 – -393.29 | |
| next perihelion distance [au] | 0.4168 – 0.4191 – 0.4215 | |
| synchronous stop epoch [Myr] | 0.884 | S |
| percentage of VCs with qnext < 10 | 100 | |
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).
| next_g orbit statistics, here only the Galactic tide has been included | ||
|---|---|---|
| no. of returning VCs in the swarm | 0 | |
| no. of escaping VCs in the swarm | 5001 | |
| no. of hyperbolas among escaping VCs in the swarm | 5001 | * |
| next reciprocal semi-major axis [10-6 au-1] | -397.27 – -395.26 – -393.31 | |
| next perihelion distance [au] | 0.4779 – 0.481 – 0.4842 | |
| synchronous stop epoch [Myr] | 0.9 | S |
| percentage of VCs with qnext < 10 | 100 | |