C/2021 R2 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	20 Sep 2021	20.2	7.342 AU	6.395 AU	23h17m	+18°05'	159.3°	2.8°	155°
Perihelion	28 Dec 2021	20.5	7.316 AU	7.603 AU	22h29m	+13°54'	69.4°	7.2°	58°
Today	23 Jan 2026	23.6	11.595 AU	12.166 AU	17h48m	+17°03'	52.6°	3.9°	312°

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)                : 0.9996020
    q (Perihelion distance)         : 7.3155280
    i (Inclination)                 : 134.47860
    Ω (Longitude of ascending node) : 16.35740
    ω (Argument of perihelion)      : 32.56160
    L (Longitude of perihelion)     : 352.25278
    B (Latitude of perihelion)      : 22.58270
    T (Time of perihelion passage)  : 2459577.10090

    Epoch                           : 2026 Jan 22
    Reference                       : MPEC 2022-X67

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-01-22 00:00 UT   17 47 52.1   +17 01 05    12.172   11.588   51.6    3.8   314   23.6 
2026-01-23 00:00 UT   17 48 02.3   +17 02 33    12.169   11.592   52.2    3.8   313   23.6 
2026-01-23 16:12 UT   17 48 09.1   +17 03 33    12.166   11.595   52.6    3.9   312   23.6 
2026-01-24 00:00 UT   17 48 12.4   +17 04 03    12.165   11.596   52.8    3.9   312   23.6 
2026-01-25 00:00 UT   17 48 22.2   +17 05 36    12.161   11.601   53.4    3.9   311   23.6 
2026-01-26 00:00 UT   17 48 31.8   +17 07 11    12.157   11.605   54.0    3.9   310   23.6 
2026-01-27 00:00 UT   17 48 41.1   +17 08 50    12.152   11.609   54.5    4.0   309   23.6 
2026-01-28 00:00 UT   17 48 50.3   +17 10 31    12.148   11.614   55.2    4.0   308   23.6 
2026-01-29 00:00 UT   17 48 59.2   +17 12 14    12.143   11.618   55.8    4.0   307   23.6 
2026-01-30 00:00 UT   17 49 08.0   +17 14 01    12.138   11.622   56.4    4.0   306   23.6 
2026-01-31 00:00 UT   17 49 16.4   +17 15 49    12.133   11.627   57.0    4.1   305   23.6 
2026-02-01 00:00 UT   17 49 24.7   +17 17 41    12.128   11.631   57.6    4.1   304   23.6 
2026-02-02 00:00 UT   17 49 32.7   +17 19 35    12.123   11.635   58.3    4.1   304   23.6 

    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.