C/2021 R2 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	20 Sep 2021	20.2	7.342 AU	6.394 AU	23h17m	+18°06'	159.3°	2.8°	155°
Perihelion	28 Dec 2021	20.5	7.315 AU	7.603 AU	22h29m	+13°54'	69.4°	7.2°	58°
Today	20 Apr 2026	23.6	11.974 AU	11.520 AU	17h43m	+20°54'	114.6°	4.4°	246°

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)                : 0.9996470
    q (Perihelion distance)         : 7.3148000
    i (Inclination)                 : 134.47650
    Ω (Longitude of ascending node) : 16.36600
    ω (Argument of perihelion)      : 32.56130
    L (Longitude of perihelion)     : 352.26242
    B (Latitude of perihelion)      : 22.58336
    T (Time of perihelion passage)  : 2459577.09860

    Epoch                           : 2026 Apr 19
    Reference                       : MPEC 2026-E44

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-04-19 00:00 UT   17 43 40.1   +20 50 17    11.530   11.967  113.6    4.4   247   23.6 
2026-04-20 00:00 UT   17 43 21.3   +20 52 57    11.523   11.972  114.3    4.4   246   23.6 
2026-04-20 12:07 UT   17 43 11.7   +20 54 18    11.520   11.974  114.6    4.4   246   23.6 
2026-04-21 00:00 UT   17 43 02.2   +20 55 36    11.517   11.976  114.9    4.4   245   23.6 
2026-04-22 00:00 UT   17 42 42.7   +20 58 12    11.511   11.980  115.6    4.3   244   23.6 
2026-04-23 00:00 UT   17 42 22.9   +21 00 47    11.505   11.985  116.3    4.3   244   23.6 
2026-04-24 00:00 UT   17 42 02.8   +21 03 19    11.500   11.989  116.9    4.3   243   23.6 
2026-04-25 00:00 UT   17 41 42.3   +21 05 49    11.494   11.993  117.6    4.3   242   23.6 
2026-04-26 00:00 UT   17 41 21.6   +21 08 17    11.489   11.998  118.2    4.2   241   23.6 
2026-04-27 00:00 UT   17 41 00.5   +21 10 43    11.484   12.002  118.9    4.2   240   23.6 
2026-04-28 00:00 UT   17 40 39.0   +21 13 06    11.479   12.007  119.5    4.2   239   23.6 
2026-04-29 00:00 UT   17 40 17.3   +21 15 27    11.474   12.011  120.1    4.2   238   23.6 
2026-04-30 00:00 UT   17 39 55.3   +21 17 46    11.469   12.015  120.7    4.1   237   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.