C/2017 K1 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	12 Mar 2018	19.7	7.264 AU	6.670 AU	15h06m	-15°25'	123.3°	6.6°	285°
Nearest approach	29 Apr 2018	19.6	7.270 AU	6.265 AU	14h30m	-10°50'	176.2°	0.5°	201°
Today	24 Dec 2025	25.6	17.655 AU	16.873 AU	08h46m	+45°20'	141.6°	2.0°	248°

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. (7.0 + 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/2017 K1 (PANSTARRS) are:

    e (Eccentricity)                : 0.9995760
    q (Perihelion distance)         : 7.2640250
    i (Inclination)                 : 154.02540
    Ω (Longitude of ascending node) : 225.65300
    ω (Argument of perihelion)      : 4.15350
    L (Longitude of perihelion)     : 221.91780
    B (Latitude of perihelion)      : 1.81783
    T (Time of perihelion passage)  : 2458190.24250

    Epoch                           : 2025 Dec 23
    Reference                       : MPC115882

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-23 00:00 UT   08 47 17.8   +45 18 09    16.878   17.648  140.5    2.0   250   25.6 
2025-12-24 00:00 UT   08 46 57.9   +45 19 57    16.874   17.653  141.3    2.0   249   25.6 
2025-12-24 10:36 UT   08 46 49.1   +45 20 44    16.873   17.655  141.6    2.0   248   25.6 
2025-12-25 00:00 UT   08 46 37.8   +45 21 44    16.871   17.657  142.1    2.0   248   25.6 
2025-12-26 00:00 UT   08 46 17.5   +45 23 29    16.868   17.662  142.8    1.9   246   25.6 
2025-12-27 00:00 UT   08 45 56.9   +45 25 14    16.865   17.666  143.5    1.9   245   25.6 
2025-12-28 00:00 UT   08 45 36.1   +45 26 58    16.863   17.671  144.2    1.9   244   25.6 
2025-12-29 00:00 UT   08 45 15.1   +45 28 40    16.861   17.675  144.9    1.8   242   25.6 
2025-12-30 00:00 UT   08 44 53.9   +45 30 21    16.859   17.680  145.6    1.8   240   25.6 
2025-12-31 00:00 UT   08 44 32.5   +45 32 01    16.857   17.684  146.3    1.8   239   25.6 
2026-01-01 00:00 UT   08 44 10.9   +45 33 40    16.856   17.688  146.9    1.7   237   25.6 
2026-01-02 00:00 UT   08 43 49.2   +45 35 17    16.855   17.693  147.5    1.7   236   25.6 
2026-01-03 00:00 UT   08 43 27.2   +45 36 53    16.854   17.697  148.1    1.7   234   25.6 

    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.