C/2020 R6 (Rankin)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	15 Apr 2019	18.7	3.429 AU	3.010 AU	08h48m	-67°07'	106.3°	16.3°	76°
Perihelion	6 Sep 2019	18.5	3.140 AU	3.210 AU	08h14m	-63°58'	76.9°	18.2°	222°
Today	22 Oct 2025	29.0	16.130 AU	15.393 AU	23h38m	+44°46'	136.5°	2.4°	130°

The interactive orbit chart above shows the comet's path through the solar system and its position at the given date. Green and blue lines are shown perpendicular to the ecliptic plane: Green if the path is above the ecliptic plane, blue if it is below. (Left-click and drag to rotate the view; Right-click and drag to move the view; Use scroll wheel to zoom in our out.)

Light curve

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations from COBS. The light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (11.0 + 5 log[∆] + 10.0 log[r]). An additional green curve is displayed when an increase in apparent brightness is expected due to forward scattering of sunlight, which occurs when a dust-rich comet is located between the Earth and the Sun. (See Marcus 2007)

Charts

The all-sky chart below shows the path of the comet over the same period as the light curve. The comet's current position is marked yellow.

The following chart shows the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Orbital elements

The orbital elements of C/2020 R6 (Rankin) are:

    e (Eccentricity)                : 0.9891600
    q (Perihelion distance)         : 3.1395930
    i (Inclination)                 : 82.90950
    Ω (Longitude of ascending node) : 12.25060
    ω (Argument of perihelion)      : 271.99430
    L (Longitude of perihelion)     : -61.99581
    B (Latitude of perihelion)      : -82.63576
    T (Time of perihelion passage)  : 2458733.19370
    P (Orbital period in years)     : 4929.08

    Epoch                           : 2025 Oct 21
    Reference                       : MPEC 2021-Y10

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-21 00:00 UT   23 39 15.3   +44 49 01    15.381   16.121  136.8    2.4   133   29.0 
2025-10-22 00:00 UT   23 38 57.7   +44 47 04    15.389   16.127  136.6    2.4   131   29.0 
2025-10-22 12:49 UT   23 38 48.4   +44 46 01    15.393   16.130  136.5    2.4   130   29.0 
2025-10-23 00:00 UT   23 38 40.3   +44 45 05    15.397   16.132  136.3    2.4   130   29.0 
2025-10-24 00:00 UT   23 38 23.2   +44 43 04    15.406   16.137  136.1    2.5   128   29.0 
2025-10-25 00:00 UT   23 38 06.3   +44 41 02    15.414   16.143  135.8    2.5   127   29.0 
2025-10-26 00:00 UT   23 37 49.7   +44 38 57    15.423   16.148  135.5    2.5   125   29.0 
2025-10-27 00:00 UT   23 37 33.4   +44 36 52    15.432   16.153  135.2    2.5   124   29.0 
2025-10-28 00:00 UT   23 37 17.2   +44 34 44    15.442   16.159  134.9    2.5   122   29.0 
2025-10-29 00:00 UT   23 37 01.4   +44 32 35    15.451   16.164  134.5    2.5   121   29.0 
2025-10-30 00:00 UT   23 36 45.8   +44 30 25    15.461   16.170  134.2    2.5   120   29.0 
2025-10-31 00:00 UT   23 36 30.5   +44 28 13    15.471   16.175  133.8    2.5   118   29.0 
2025-11-01 00:00 UT   23 36 15.5   +44 26 00    15.482   16.180  133.4    2.6   117   29.0 

    Terminology:
            
    delta:  distance between comet and earth in AU
    radius: distance between comet and sun in AU
    magn:   magnitude (brightness) estimate    
    ra:     right ascension in hours (24h = 360deg)
    dec:    declination in degrees
    elong:  elongation in degrees (angle sun-earth-comet)    
    phase:  phase angle in degrees (angle sun-comet-earth)        
    AU:     Astronomical Unit (mean distance between earth and sun: 149597870.7 km      
    

Orbital elements usually provided by the MPC (Minor Planet Center).
Observations contributed by observers worldwide, via COBS (Comet Observation Database) or the MPC (Minor Planet Center)
Calculations by a modified version of AAPlus, a C# implementation of the AA+ project by PJ Naughter from the algorithms presented in the book "Astronomical Algorithms" by Jean Meeus.
NGC2000 dso catalog and star labels from VizieR as provided by the Strasbourg astronomical Data Center.
Tycho2 catalog from the ESO archive.