| epoch = 23 March 2018 (JD 2458200.5)
| observation_arc = 27 days
| eccentricity = {{val|1.00385|0.0072|fmt=none}}{{efn|name=min_eccentricity}} (JPL)
{{val|1.0130|0.0046|fmt=none}} (MPC)
| perihelion = {{val|3.44584|0.0029|fmt=none}} AU
| inclination = {{val|78.2971|0.19|fmt=none}}°
| jupiter_moid = {{Convert|0.60|AU|e6km|abbr=unit|lk=on}}
| dimensions = {{val|10|-|20|ul=km}} {{small|(assumed)}}[4]
| abs_magnitude = {{val|11.8|0.5}}
}}C/2018 F4 (PANSTARRS) is a hyperbolic comet (previously classified as A/2018 F4, a hyperbolic asteroid). Overview
It would be no problem to fit a parabolic orbit to the C/2018 F4 data,
It will come to perihelion around 3 December 2019 when it will be 3.4 AU from the Sun.
Further observations will be necessary to determine if the orbit is hyperbolic. As a comet this object became known as C/2018 F4 (PANSTARRS).
The somewhat short observation arc of 35 days suggests that before entering the planetary region of the Solar System (epoch 1950), the comet had an orbital period on the order of a hundred thousand years. The heliocentric eccentricity became greater than 1 in November 2016 when the comet was {{Convert|9.6|AU|e9km|abbr=unit|lk=on}} from the Sun.
{{clear|left}} Inbound velocity at 200 AU from the Sun
compared to Oort cloud objects[13]| Object | Year | Velocity
km/s | # of observations
and obs arc |
|---|
| 90377 Sedna | 1746 | 1.99|0.00}} | 196 in 9240 days |
| C/1980 E1 (Bowell) | 1765 | 2.95|0.00}} | 179 in 2514 days |
| C/1997 P2 (Spacewatch) | 1779 | 2.96|0.01}} | 94 in 49 days |
| C/2010 X1 (Elenin) | 1798 | 2.96|0.00}} | 2222 in 235 days |
| C/2012 S1 (ISON) | 1801 | 2.99|0.00}} | 6514 in 784 days |
| C/2008 J4 (McNaught) | 1855 | 4.88|5.44}} | 22 in 15 days |
| C/2018 F4 | 1799 | 2.89|0.79}} | 144 in 35 days |
| C/1999 U2 (SOHO) | 1947 | 17|447}} | 41 in 1 day |
| 1I/2017 U1 (ʻOumuamua) | 1982 | 26.49|0.03}} | 121 in 34 days |
In the above table, the only outlier is ʻOumuamua with a confident 34 day observation arc. Comet C/2008 J4 (McNaught) has a short observation arc with large uncertainties. Comet C/1999 U2 (SOHO) has a meaningless 1 day observation arc. Comet C/2018 F4 has a common Oort cloud velocity when 200 AU from the Sun.[1]
Notes
{{notelist|refs={{efn|name=min_eccentricity|1=A/2018 F4 could have an orbital eccentricity as low as 0.996. (Math: 1.0039-0.0072)}}}}
References
1. ^1 2 {{cite journal|last1=Licandro |first1=Javier |last2=de la Fuente Marcos |first2=Carlos |last3=de la Fuente Marcos |first3=Raúl |last4=de Leon |first4=Julia |last5=Serra-Ricart |first5=Miquel|last6=Cabrera-Lavers|first6=Antonio |title=Spectroscopic and dynamical properties of comet C/2018 F4, likely a true average former member of the Oort cloud|url=http://adsabs.harvard.edu/abs/2019arXiv190310838L|journal=Astronomy and Astrophysics |volume= |issue= |pages= |year=2019|date=29 March 2019 |doi=10.1051/0004-6361/201834902|bibcode=2019arXiv190310838L|arxiv = 1903.10838 }}
2. ^1 2 {{cite web |title=MPEC 2018-F139: A/2018 F4 |publisher=IAU Minor Planet Center |date=2018-03-28 |url=https://minorplanetcenter.net/mpec/K18/K18FD9.html |accessdate=2018-03-28}} (AK18F040)
3. ^1 {{cite web |title=MPEC 2018-H21 : COMET C/2018 F4 (PANSTARRS) |publisher=IAU Minor Planet Center |date=2018-04-17 |url=https://minorplanetcenter.net/mpec/K18/K18H21.html |accessdate=2018-04-17}} (CK18F040)
4. ^1 {{cite web |title=HORIZONS Web-Interface |website=Solar System Dynamics Group |publisher=JPL |url=https://ssd.jpl.nasa.gov/horizons.cgi?find_body=1&body_group=sb&sstr=2018F4 }} Results produced with JPL Horizons On-Line Ephemeris System using Soln.date: 2018-Apr-29. Observer Location: "@sun" / Table settings: "20. Observer range & range-rate", "39. Range & range-rate 3-sigmas". Columns: deldot, RNGRT_3sig
5. ^1 {{cite web |title = Asteroid Size Estimator |url = https://cneos.jpl.nasa.gov/tools/ast_size_est.html |publisher = Jet Propulsion Laboratory |accessdate = 28 March 2018}}