C/2021 V1 (Rankin)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	31 Oct 2021	20.6	3.498 AU	2.718 AU	23h29m	+35°33'	135.8°	11.4°	108°
Perihelion	30 Apr 2022	20.8	3.020 AU	3.998 AU	02h23m	+02°48'	12.1°	4.0°	187°
Today	7 Jan 2026	28.7	11.152 AU	11.093 AU	11h26m	-46°00'	90.9°	5.1°	304°

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/2021 V1 (Rankin) are:

    e (Eccentricity)                : 0.9958320
    q (Perihelion distance)         : 3.0202620
    i (Inclination)                 : 71.42490
    Ω (Longitude of ascending node) : 207.71160
    ω (Argument of perihelion)      : 195.22670
    L (Longitude of perihelion)     : 212.66714
    B (Latitude of perihelion)      : -14.41581
    T (Time of perihelion passage)  : 2459700.07960
    P (Orbital period in years)     : 19506.32

    Epoch                           : 2025 Nov 12
    Reference                       : MPEC 2022-CN4

    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
2026-01-06 00:00 UT   11 26 44.7   -45 56 44    11.103   11.142   89.7    5.1   303   28.7 
2026-01-07 00:00 UT   11 26 37.4   -45 59 07    11.097   11.148   90.4    5.1   304   28.7 
2026-01-07 14:51 UT   11 26 32.6   -46 00 34    11.093   11.152   90.9    5.1   304   28.7 
2026-01-08 00:00 UT   11 26 29.6   -46 01 28    11.091   11.154   91.2    5.1   305   28.7 
2026-01-09 00:00 UT   11 26 21.3   -46 03 45    11.084   11.160   91.9    5.1   305   28.7 
2026-01-10 00:00 UT   11 26 12.6   -46 05 59    11.078   11.167   92.6    5.0   306   28.7 
2026-01-11 00:00 UT   11 26 03.4   -46 08 10    11.072   11.173   93.3    5.0   307   28.7 
2026-01-12 00:00 UT   11 25 53.8   -46 10 18    11.066   11.179   94.1    5.0   308   28.7 
2026-01-13 00:00 UT   11 25 43.6   -46 12 22    11.060   11.185   94.8    5.0   308   28.7 
2026-01-14 00:00 UT   11 25 33.1   -46 14 23    11.054   11.191   95.5    5.0   309   28.7 
2026-01-15 00:00 UT   11 25 22.0   -46 16 20    11.048   11.197   96.2    5.0   310   28.7 
2026-01-16 00:00 UT   11 25 10.6   -46 18 14    11.042   11.204   96.9    5.0   311   28.7 
2026-01-17 00:00 UT   11 24 58.7   -46 20 04    11.036   11.210   97.7    5.0   311   28.7 

    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.