C/2020 B3 (Rankin)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	21 Oct 2019	21.2	3.328 AU	3.972 AU	10h47m	-02°55'	44.0°	12.0°	282°
Nearest approach	13 Mar 2020	20.6	3.589 AU	2.614 AU	12h18m	-03°56'	167.0°	3.6°	301°
Today	31 May 2026	31.4	17.056 AU	16.233 AU	18h38m	-01°18'	143.2°	2.0°	234°

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. (13.0 + 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 B3 (Rankin) are:

    e (Eccentricity)                : 0.9972030
    q (Perihelion distance)         : 3.3275620
    i (Inclination)                 : 20.70730
    Ω (Longitude of ascending node) : 185.67630
    ω (Argument of perihelion)      : 325.01800
    L (Longitude of perihelion)     : 152.47013
    B (Latitude of perihelion)      : -11.69619
    T (Time of perihelion passage)  : 2458778.06950
    P (Orbital period in years)     : 41034.63

    Epoch                           : 2026 May 29
    Reference                       : MPC194165

    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
2026-05-30 00:00 UT   18 39 10.5   -01 19 11    16.238   17.046  141.7    2.1   235   31.4 
2026-05-31 00:00 UT   18 39 00.3   -01 18 42    16.235   17.051  142.5    2.1   234   31.4 
2026-05-31 21:37 UT   18 38 50.9   -01 18 16    16.233   17.056  143.2    2.0   234   31.4 
2026-06-01 00:00 UT   18 38 49.9   -01 18 13    16.232   17.057  143.3    2.0   233   31.4 
2026-06-02 00:00 UT   18 38 39.4   -01 17 47    16.230   17.062  144.1    2.0   232   31.4 
2026-06-03 00:00 UT   18 38 28.8   -01 17 21    16.227   17.067  144.9    2.0   231   31.4 
2026-06-04 00:00 UT   18 38 18.1   -01 16 57    16.225   17.072  145.6    1.9   230   31.4 
2026-06-05 00:00 UT   18 38 07.2   -01 16 34    16.223   17.078  146.4    1.9   229   31.4 
2026-06-06 00:00 UT   18 37 56.3   -01 16 12    16.222   17.083  147.1    1.8   228   31.4 
2026-06-07 00:00 UT   18 37 45.3   -01 15 52    16.220   17.088  147.8    1.8   226   31.4 
2026-06-08 00:00 UT   18 37 34.1   -01 15 33    16.219   17.093  148.5    1.8   225   31.4 
2026-06-09 00:00 UT   18 37 22.9   -01 15 15    16.218   17.099  149.2    1.7   224   31.4 
2026-06-10 00:00 UT   18 37 11.6   -01 14 59    16.218   17.104  149.9    1.7   222   31.4 

    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.