C/2021 R2 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	20 Sep 2021	20.2	7.340 AU	6.392 AU	23h17m	+18°06'	159.3°	2.8°	155°
Perihelion	28 Dec 2021	20.5	7.313 AU	7.598 AU	22h29m	+13°54'	69.6°	7.2°	58°
Today	23 Oct 2026	24.2	12.795 AU	13.364 AU	16h54m	+16°12'	53.3°	3.6°	62°

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. (7.5 + 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 R2 (PANSTARRS) are:

    e (Eccentricity)                : 0.9995690
    q (Perihelion distance)         : 7.3128480
    i (Inclination)                 : 134.47200
    Ω (Longitude of ascending node) : 16.38160
    ω (Argument of perihelion)      : 32.55190
    L (Longitude of perihelion)     : 352.28745
    B (Latitude of perihelion)      : 22.57908
    T (Time of perihelion passage)  : 2459576.94450

    Epoch                           : 2026 Oct 22
    Reference                       : MPC194176

    Classification(s):              : Nearly isotropic; New (a > 10000 AU)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-10-22 00:00 UT   16 54 16.7   +16 15 34    13.347   12.789   54.1    3.6    63   24.2 
2026-10-23 00:00 UT   16 54 24.7   +16 12 57    13.360   12.794   53.5    3.6    62   24.2 
2026-10-23 05:54 UT   16 54 26.7   +16 12 19    13.364   12.795   53.3    3.6    62   24.2 
2026-10-24 00:00 UT   16 54 32.8   +16 10 23    13.374   12.798   52.9    3.6    61   24.2 
2026-10-25 00:00 UT   16 54 41.2   +16 07 51    13.387   12.803   52.3    3.5    60   24.2 
2026-10-26 00:00 UT   16 54 49.8   +16 05 21    13.400   12.807   51.7    3.5    59   24.2 
2026-10-27 00:00 UT   16 54 58.6   +16 02 53    13.413   12.812   51.1    3.5    58   24.2 
2026-10-28 00:00 UT   16 55 07.5   +16 00 27    13.425   12.816   50.5    3.4    57   24.2 
2026-10-29 00:00 UT   16 55 16.7   +15 58 03    13.438   12.820   49.9    3.4    56   24.2 
2026-10-30 00:00 UT   16 55 26.0   +15 55 41    13.450   12.825   49.3    3.4    55   24.2 
2026-10-31 00:00 UT   16 55 35.5   +15 53 22    13.462   12.829   48.8    3.3    54   24.2 
2026-11-01 00:00 UT   16 55 45.2   +15 51 05    13.474   12.834   48.2    3.3    53   24.2 
2026-11-02 00:00 UT   16 55 55.1   +15 48 50    13.485   12.838   47.7    3.3    52   24.2 

    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.