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C/2017 K2 (PANSTARRS)
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach13 Jul 20229.02.644 AU1.792 AU 16h59m-03°42'138.9°14.6°119°
Perihelion18 Dec 20228.51.800 AU2.485 AU 17h52m-60°22'37.0°19.2°176°
Today15 Dec 202516.510.169 AU9.195 AU 05h55m+30°35'170.8°0.9°219°
C/2017 K2 (PANSTARRS)- 2025-12-15
astro.vanbuitenen.nl


 
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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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 4.8 + 5 log[∆] + 6.9 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/2017 K2 (PANSTARRS) are: 

    e (Eccentricity)                : 0.9986150
    q (Perihelion distance)         : 1.8001440
    i (Inclination)                 : 87.63870
    Ω (Longitude of ascending node) : 88.22160
    ω (Argument of perihelion)      : 236.15580
    L (Longitude of perihelion)     : 91.73757
    B (Latitude of perihelion)      : -56.08332
    T (Time of perihelion passage)  : 2459931.66410
    P (Orbital period in years)     : 46858.27

    Epoch                           : 2025 Dec 14
    Reference                       : MPEC 2025-XC7

    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
2025-12-14 00:00 UT   05 56 19.0   +30 34 07     9.189   10.159  169.8    1.0   226   16.5 
2025-12-15 00:00 UT   05 55 48.9   +30 35 20     9.194   10.166  170.5    0.9   221   16.5 
2025-12-15 07:43 UT   05 55 39.2   +30 35 43     9.195   10.169  170.8    0.9   219   16.5 
2025-12-16 00:00 UT   05 55 18.7   +30 36 32     9.199   10.173  171.2    0.8   215   16.5 
2025-12-17 00:00 UT   05 54 48.5   +30 37 42     9.205   10.180  171.8    0.8   208   16.5 
2025-12-18 00:00 UT   05 54 18.4   +30 38 51     9.211   10.187  172.3    0.7   201   16.5 
2025-12-19 00:00 UT   05 53 48.2   +30 39 58     9.217   10.194  172.6    0.7   193   16.6 
2025-12-20 00:00 UT   05 53 18.0   +30 41 04     9.224   10.201  172.7    0.7   184   16.6 
2025-12-21 00:00 UT   05 52 47.9   +30 42 09     9.231   10.208  172.7    0.7   175   16.6 
2025-12-22 00:00 UT   05 52 17.8   +30 43 12     9.238   10.215  172.5    0.7   166   16.6 
2025-12-23 00:00 UT   05 51 47.7   +30 44 14     9.246   10.222  172.2    0.8   158   16.6 
2025-12-24 00:00 UT   05 51 17.7   +30 45 14     9.254   10.228  171.7    0.8   151   16.6 
2025-12-25 00:00 UT   05 50 47.8   +30 46 13     9.262   10.235  171.1    0.9   144   16.6 




    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.

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