C/2021 R2 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	20 Sep 2021	20.2	7.341 AU	6.393 AU	23h17m	+18°06'	159.3°	2.8°	155°
Perihelion	28 Dec 2021	20.5	7.314 AU	7.600 AU	22h29m	+13°54'	69.5°	7.2°	58°
Today	2 Jul 2026	23.7	12.297 AU	11.624 AU	17h11m	+21°47'	129.6°	3.7°	151°

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)                : 0.9996120
    q (Perihelion distance)         : 7.3139110
    i (Inclination)                 : 134.47460
    Ω (Longitude of ascending node) : 16.37310
    ω (Argument of perihelion)      : 32.55690
    L (Longitude of perihelion)     : 352.27386
    B (Latitude of perihelion)      : 22.58127
    T (Time of perihelion passage)  : 2459577.02470

    Epoch                           : 2026 Jul 02
    Reference                       : MPC194176

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-07-01 00:00 UT   17 12 02.7   +21 50 32    11.605   12.288  130.3    3.6   154   23.7 
2026-07-02 00:00 UT   17 11 36.1   +21 49 05    11.615   12.293  129.9    3.6   152   23.7 
2026-07-02 21:21 UT   17 11 12.6   +21 47 44    11.624   12.297  129.6    3.7   151   23.7 
2026-07-03 00:00 UT   17 11 09.7   +21 47 34    11.625   12.297  129.5    3.7   151   23.7 
2026-07-04 00:00 UT   17 10 43.5   +21 45 60    11.635   12.302  129.1    3.7   150   23.7 
2026-07-05 00:00 UT   17 10 17.5   +21 44 22    11.645   12.306  128.7    3.7   149   23.7 
2026-07-06 00:00 UT   17 09 51.7   +21 42 41    11.656   12.310  128.2    3.7   147   23.7 
2026-07-07 00:00 UT   17 09 26.1   +21 40 56    11.666   12.315  127.7    3.7   146   23.7 
2026-07-08 00:00 UT   17 09 00.7   +21 39 09    11.677   12.319  127.2    3.8   145   23.7 
2026-07-09 00:00 UT   17 08 35.6   +21 37 17    11.688   12.324  126.8    3.8   144   23.7 
2026-07-10 00:00 UT   17 08 10.6   +21 35 23    11.699   12.328  126.2    3.8   143   23.7 
2026-07-11 00:00 UT   17 07 45.9   +21 33 25    11.711   12.332  125.7    3.8   142   23.8 
2026-07-12 00:00 UT   17 07 21.5   +21 31 24    11.723   12.337  125.2    3.9   141   23.8 

    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.