C/2017 T1 Heinze
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Comet C/2017 T1 was discovered on 2 October 2017 by Aren Heinze (Asteroid Terrestrial-impact Last Alert System (ATLAS) search program), that is about 4.7 months before its perihelion passage. Next, pre-discovery data were found going back to September 28. Comet was observed extensively before perihelion passage and notable less frequently after perihelion until 25 March 2018. At the endof data arc is a series of three measurements from June 18, preceded by a 2.7-month break in the data. C/2017 T1 had closest approach to the Earth on 4 January 2018 (0.222 au, 17 days before the perihelion passage).
This is a comet with NG effects strongly manifested in positional data fitting and during GR orbit determination the series of three measurements from June 17 were ejected due to large residuals and systematically small weights were obtained for all remaining post-perihelion observations. Therefore, this GR orbit (solutions 'a5') is based on data spanning over 0.488 yr in a range of heliocentric distances: 2.60 au – 0.581 au (perihelion) – 0.90 au. During NG orbit determination weights in post-perihelion leg are also systematically small; however, series of last three measurements were not ejected. So, NG orbit ('n5') is based on data spanning over 0.718 yr in a range of heliocentric distances: 2.60 au – 0.581 au (perihelion) – 2.18 au. However, we suggest the solution 'pn' (based on the pre-perihelion orbital leg up to heliocentric distance of 0.782 au) to be treated as 'preferred' orbit for the study of the origin of this comet.
Only solution 'n1' suggest that this is an Oort spike comet; all remaining (including the 'preferred orbit') give similar values for original semimajor axis, that is from 3560 au to 4050 au (uncertainty of one sigma is applied). According to solutions 'a5' and 'n5' this comet suffers small planetary perturbations while passing through the planetary system; these perturbations lead to a sligthy more tight orbit after passage through the planetary zone (see future barycentric orbits).
See also: Sekanina 2019.
This is a comet with NG effects strongly manifested in positional data fitting and during GR orbit determination the series of three measurements from June 17 were ejected due to large residuals and systematically small weights were obtained for all remaining post-perihelion observations. Therefore, this GR orbit (solutions 'a5') is based on data spanning over 0.488 yr in a range of heliocentric distances: 2.60 au – 0.581 au (perihelion) – 0.90 au. During NG orbit determination weights in post-perihelion leg are also systematically small; however, series of last three measurements were not ejected. So, NG orbit ('n5') is based on data spanning over 0.718 yr in a range of heliocentric distances: 2.60 au – 0.581 au (perihelion) – 2.18 au. However, we suggest the solution 'pn' (based on the pre-perihelion orbital leg up to heliocentric distance of 0.782 au) to be treated as 'preferred' orbit for the study of the origin of this comet.
Only solution 'n1' suggest that this is an Oort spike comet; all remaining (including the 'preferred orbit') give similar values for original semimajor axis, that is from 3560 au to 4050 au (uncertainty of one sigma is applied). According to solutions 'a5' and 'n5' this comet suffers small planetary perturbations while passing through the planetary system; these perturbations lead to a sligthy more tight orbit after passage through the planetary zone (see future barycentric orbits).
See also: Sekanina 2019.
| solution description | ||
|---|---|---|
| number of observations | 1016 | |
| data interval | 2017 09 28 – 2018 01 28 | |
| data arc selection | data generally limited to pre-perihelion (PRE) | |
| range of heliocentric distances | 2.6 au – 0.782au | |
| type of model of motion | NS - non-gravitational orbits for standard g(r) | |
| data weighting | YES | |
| number of residuals | 2015 | |
| RMS [arcseconds] | 0.55 | |
| orbit quality class | 2b | |
| previous orbit statistics, both Galactic and stellar perturbations were taken into account | ||
|---|---|---|
| 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 reciprocal semi-major axis [10-6 au-1] | 242.90 – 264.67 – 285.69 | |
| previous perihelion distance [au] | 0.5825 – 0.58263 – 0.5827 | |
| previous aphelion distance [103 au] | 7 – 7.56 – 8.23 | |
| time interval to previous perihelion [Myr] | 0.21 – 0.23 – 0.26 | |
| percentage of VCs with qprev < 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).
| previous_g orbit statistics, here only the Galactic tide has been included | ||
|---|---|---|
| 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 reciprocal semi-major axis [10-6 au-1] | 242.91 – 264.67 – 285.70 | |
| previous perihelion distance [au] | 0.5817 – 0.58189 – 0.58202 | |
| previous aphelion distance [103 au] | 7 – 7.56 – 8.23 | |
| time interval to previous perihelion [Myr] | 0.21 – 0.23 – 0.26 | |
| percentage of VCs with qprev < 10 | 100 | |