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	13 Aug 2026	28.7	12.818 AU	13.580 AU	07h00m	+00°30'	39.7°	2.9°	247°

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
2026-08-12 00:00 UT   06 59 54.7   +00 31 53    13.585   12.811   38.8    2.8   246   28.7 
2026-08-13 00:00 UT   07 00 04.2   +00 30 44    13.581   12.817   39.5    2.9   247   28.7 
2026-08-13 04:57 UT   07 00 06.1   +00 30 30    13.580   12.818   39.7    2.9   247   28.7 
2026-08-14 00:00 UT   07 00 13.5   +00 29 34    13.577   12.822   40.3    2.9   248   28.7 
2026-08-15 00:00 UT   07 00 22.7   +00 28 23    13.573   12.827   41.1    3.0   249   28.7 
2026-08-16 00:00 UT   07 00 31.6   +00 27 10    13.569   12.832   41.8    3.0   249   28.7 
2026-08-17 00:00 UT   07 00 40.4   +00 25 57    13.564   12.837   42.6    3.1   250   28.7 
2026-08-18 00:00 UT   07 00 49.1   +00 24 43    13.559   12.843   43.4    3.1   251   28.7 
2026-08-19 00:00 UT   07 00 57.5   +00 23 27    13.554   12.848   44.1    3.1   252   28.7 
2026-08-20 00:00 UT   07 01 05.8   +00 22 11    13.549   12.853   44.9    3.2   252   28.7 
2026-08-21 00:00 UT   07 01 13.8   +00 20 53    13.544   12.858   45.7    3.2   253   28.8 
2026-08-22 00:00 UT   07 01 21.7   +00 19 35    13.538   12.863   46.5    3.3   254   28.8 
2026-08-23 00:00 UT   07 01 29.3   +00 18 15    13.532   12.868   47.3    3.3   254   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.