C/2017 S3 PanSTARRS
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Comet C/2017 S3 was discovered on 23 September 2017 by Pan-STARRS 1 telescope (Haleakala), that is more than a year before its perihelion passage. Next, a series of pre-discovery measurements were found going to August 17. Comet was followed until 3 August 2018 (12 days before perihelion), because next it disrupted completely: according toCombi et al. 2019 the final disintegration took place just 11 days before its perihelion onAugust 15. If not disrupted, the comet would make its closest approach to the Earth on 6 August 2018 (0.758 au, a week before the perihelion passage).
Combi et al. 2019 noticed that water production had a small outburst on July 8 at a heliocentric distance of 1.1 au and then a much larger one on July 20 at 0.8 au. Sekanina and Kracht 2018 described that the first outburst of this comet was reported by M. Jäger, who noticed this event in an image that he had obtained with a 30-cm f/4 telescope at Stixendorf, Austria, on July 1.98 UT.They also showed evidence that C/2017 S3 started to disrupt even earlier.
Therefore, we give here two pairs of orbits (GR nd NG). First using the entire available data arc (solutions 'a1' and 'n1'), that is based on data spanning over 0.962 yr in a range of heliocentric distances from 5.41 au to 0.48 au. Due to destruction process, the GR solution ('a1') gives spectacular picture of time distribution of residuals (see [O-C] picture associated with solution 'a1'). Analogous signature in [O-C] was previously obtained by Sekanina and Kracht 2018 .The NG solution ('n1') based on constant NG parameters only partially reduces these trends in [O-C]; however, the improvement is only visible until heliocentric distances larger than about 1.5 au (mid-June). Thus, the second pair of solutions ('a3' and 'n3') is based on a shorter pre-perihelion data arc spanning 0.82 yr to a heliocentric distance of 1.56 au. Then both orbits give satisfactory [O-C] (see the pictures for 'a3' and 'n3' solutions); however, the [O-C] seems slightly better for the 'n3' orbit. GR orbit 'a3' have about two times larger uncertainties of orbital elements than the solution based on data up to the end of June given by Sekanina and Kracht in Table 5 (2018). However, thanks to shorter data arc than in Sekanina and Kracht, we have similar predictions on reciprocals of original semimajor axis for GR and NG orbits.
According to both solutions based on this shorter data arc ('a3' and 'n3'), C/2017 S3 was an Oort spike comet with original semimajor axis of about 44,700–108,000 au (uncertainty of one sigma is applied).
See also: Sekanina 2019.
Combi et al. 2019 noticed that water production had a small outburst on July 8 at a heliocentric distance of 1.1 au and then a much larger one on July 20 at 0.8 au. Sekanina and Kracht 2018 described that the first outburst of this comet was reported by M. Jäger, who noticed this event in an image that he had obtained with a 30-cm f/4 telescope at Stixendorf, Austria, on July 1.98 UT.They also showed evidence that C/2017 S3 started to disrupt even earlier.
Therefore, we give here two pairs of orbits (GR nd NG). First using the entire available data arc (solutions 'a1' and 'n1'), that is based on data spanning over 0.962 yr in a range of heliocentric distances from 5.41 au to 0.48 au. Due to destruction process, the GR solution ('a1') gives spectacular picture of time distribution of residuals (see [O-C] picture associated with solution 'a1'). Analogous signature in [O-C] was previously obtained by Sekanina and Kracht 2018 .The NG solution ('n1') based on constant NG parameters only partially reduces these trends in [O-C]; however, the improvement is only visible until heliocentric distances larger than about 1.5 au (mid-June). Thus, the second pair of solutions ('a3' and 'n3') is based on a shorter pre-perihelion data arc spanning 0.82 yr to a heliocentric distance of 1.56 au. Then both orbits give satisfactory [O-C] (see the pictures for 'a3' and 'n3' solutions); however, the [O-C] seems slightly better for the 'n3' orbit. GR orbit 'a3' have about two times larger uncertainties of orbital elements than the solution based on data up to the end of June given by Sekanina and Kracht in Table 5 (2018). However, thanks to shorter data arc than in Sekanina and Kracht, we have similar predictions on reciprocals of original semimajor axis for GR and NG orbits.
According to both solutions based on this shorter data arc ('a3' and 'n3'), C/2017 S3 was an Oort spike comet with original semimajor axis of about 44,700–108,000 au (uncertainty of one sigma is applied).
See also: Sekanina 2019.
| solution description | ||
|---|---|---|
| number of observations | 156 | |
| data interval | 2017 08 17 – 2018 06 14 | |
| data arc selection | data generally limited to pre-perihelion (PRE) | |
| range of heliocentric distances | 5.41 au – 1.56au | |
| type of model of motion | NS - non-gravitational orbits for standard g(r) | |
| data weighting | YES | |
| number of residuals | 303 | |
| RMS [arcseconds] | 0.34 | |
| orbit quality class | 1b | |
| orbital elements (heliocentric ecliptic J2000) | ||
|---|---|---|
| Epoch | 2018 03 23 | |
| perihelion date | 2018 08 15.94438860 | ± 0.00063465 |
| perihelion distance [au] | 0.20843084 | ± 0.00000295 |
| eccentricity | 1.00008168 | ± 0.00000101 |
| argument of perihelion [°] | 255.891905 | ± 0.000230 |
| ascending node [°] | 171.037270 | ± 0.000261 |
| inclination [°] | 99.039848 | ± 0.000046 |
| reciprocal semi-major axis [10-6 au-1] | -391.89 | ± 4.83 |
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] | 15.511 | ± 5.508 |
| A2 [10-8au/day2] | 3.6715 | ± 1.8792 |
| A3 [10-8au/day2] | 0 | (assumed) |
| m | -2.15 | |
| n | 5.093 | |
| k | -4.6142 | |
| r0 [au] | 2.808 | |
| α | 0.1113 | |