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 Jun 2026	28.6	12.488 AU	13.342 AU	06h47m	+00°57'	31.5°	2.4°	136°

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
2026-06-09 00:00 UT   06 46 59.6   +00 56 11    13.320   12.478   32.7    2.5   134   28.6 
2026-06-10 00:00 UT   06 47 11.5   +00 56 39    13.332   12.484   32.1    2.5   135   28.6 
2026-06-10 20:34 UT   06 47 21.9   +00 57 02    13.342   12.488   31.5    2.4   136   28.6 
2026-06-11 00:00 UT   06 47 23.6   +00 57 05    13.344   12.489   31.4    2.4   136   28.6 
2026-06-12 00:00 UT   06 47 35.7   +00 57 30    13.355   12.494   30.8    2.4   138   28.6 
2026-06-13 00:00 UT   06 47 48.0   +00 57 53    13.367   12.499   30.2    2.3   139   28.6 
2026-06-14 00:00 UT   06 48 00.3   +00 58 14    13.378   12.505   29.6    2.3   140   28.6 
2026-06-15 00:00 UT   06 48 12.6   +00 58 34    13.388   12.510   29.0    2.3   142   28.6 
2026-06-16 00:00 UT   06 48 25.1   +00 58 51    13.399   12.515   28.4    2.2   143   28.6 
2026-06-17 00:00 UT   06 48 37.6   +00 59 07    13.409   12.520   27.8    2.2   145   28.6 
2026-06-18 00:00 UT   06 48 50.2   +00 59 22    13.419   12.525   27.3    2.1   146   28.6 
2026-06-19 00:00 UT   06 49 02.8   +00 59 34    13.429   12.531   26.8    2.1   148   28.6 
2026-06-20 00:00 UT   06 49 15.5   +00 59 45    13.438   12.536   26.3    2.1   150   28.6 

    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.