C/2021 J2 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	12 May 2021	21.7	4.810 AU	3.823 AU	15h06m	-04°23'	166.0°	2.9°	170°
Perihelion	19 Sep 2021	22.5	4.703 AU	5.563 AU	13h36m	-07°04'	28.4°	5.8°	106°
Today	10 Sep 2026	28.8	12.963 AU	13.396 AU	07h03m	-00°08'	62.6°	4.0°	264°

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. (12.0 + 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 J2 (PANSTARRS) are:

    e (Eccentricity)                : 0.9570400
    q (Perihelion distance)         : 4.7029490
    i (Inclination)                 : 156.21250
    Ω (Longitude of ascending node) : 23.28260
    ω (Argument of perihelion)      : 171.83980
    L (Longitude of perihelion)     : 30.75777
    B (Latitude of perihelion)      : 3.28206
    T (Time of perihelion passage)  : 2459477.25880
    P (Orbital period in years)     : 1145.40

    Epoch                           : 2026 May 29
    Reference                       : MPC194174

    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
2026-09-09 00:00 UT   07 03 06.1   +00 06 21    13.407   12.956   61.5    3.9   264   28.8 
2026-09-10 00:00 UT   07 03 09.7   +00 07 54    13.398   12.962   62.3    3.9   264   28.8 
2026-09-10 06:02 UT   07 03 10.5   +00 08 18    13.396   12.963   62.6    4.0   264   28.8 
2026-09-11 00:00 UT   07 03 13.0   +00 09 28    13.389   12.967   63.2    4.0   265   28.8 
2026-09-12 00:00 UT   07 03 16.0   +00 11 02    13.380   12.972   64.1    4.0   265   28.8 
2026-09-13 00:00 UT   07 03 18.7   +00 12 37    13.371   12.977   64.9    4.0   265   28.8 
2026-09-14 00:00 UT   07 03 21.2   +00 14 12    13.362   12.982   65.8    4.1   266   28.8 
2026-09-15 00:00 UT   07 03 23.4   +00 15 47    13.352   12.987   66.7    4.1   266   28.8 
2026-09-16 00:00 UT   07 03 25.4   +00 17 23    13.343   12.993   67.6    4.1   267   28.8 
2026-09-17 00:00 UT   07 03 27.0   +00 18 59    13.333   12.998   68.4    4.1   267   28.8 
2026-09-18 00:00 UT   07 03 28.4   +00 20 36    13.323   13.003   69.3    4.1   268   28.8 
2026-09-19 00:00 UT   07 03 29.5   +00 22 13    13.313   13.008   70.2    4.2   268   28.8 
2026-09-20 00:00 UT   07 03 30.3   +00 23 50    13.303   13.013   71.1    4.2   268   28.8 

    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.