C/2018 X3 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	8 Dec 2018	20.0	2.706 AU	1.729 AU	04h45m	+14°33'	171.0°	3.3°	24°
Perihelion	1 Jan 2019	20.1	2.697 AU	1.823 AU	04h20m	+21°22'	146.3°	11.7°	80°
Today	7 Dec 2025	31.9	14.280 AU	15.145 AU	15h52m	+00°29'	27.6°	1.8°	328°

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. (14.5 + 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/2018 X3 (PANSTARRS) are:

    e (Eccentricity)                : 0.7828440
    q (Perihelion distance)         : 2.6968280
    i (Inclination)                 : 43.42200
    Ω (Longitude of ascending node) : 78.80040
    ω (Argument of perihelion)      : 359.89380
    L (Longitude of perihelion)     : 78.72327
    B (Latitude of perihelion)      : -0.07300
    T (Time of perihelion passage)  : 2458485.22940
    P (Orbital period in years)     : 43.76

    Epoch                           : 2025 Nov 12
    Reference                       : MPC114604

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (P < 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-06 00:00 UT   15 51 43.2   +00 30 35    15.147   14.276   26.9    1.8   329   31.9 
2025-12-07 00:00 UT   15 51 59.7   +00 29 43    15.145   14.279   27.5    1.8   328   31.9 
2025-12-07 03:23 UT   15 52 02.0   +00 29 36    15.145   14.280   27.6    1.8   328   31.9 
2025-12-08 00:00 UT   15 52 16.0   +00 28 53    15.143   14.282   28.2    1.9   326   31.9 
2025-12-09 00:00 UT   15 52 32.3   +00 28 05    15.140   14.286   28.8    1.9   325   31.9 
2025-12-10 00:00 UT   15 52 48.5   +00 27 18    15.137   14.289   29.5    1.9   323   32.0 
2025-12-11 00:00 UT   15 53 04.6   +00 26 33    15.134   14.292   30.2    2.0   322   32.0 
2025-12-12 00:00 UT   15 53 20.7   +00 25 50    15.131   14.295   30.9    2.0   321   32.0 
2025-12-13 00:00 UT   15 53 36.7   +00 25 08    15.128   14.299   31.6    2.1   320   32.0 
2025-12-14 00:00 UT   15 53 52.6   +00 24 28    15.124   14.302   32.3    2.1   318   32.0 
2025-12-15 00:00 UT   15 54 08.4   +00 23 49    15.120   14.305   33.0    2.1   317   32.0 
2025-12-16 00:00 UT   15 54 24.1   +00 23 13    15.116   14.308   33.8    2.2   316   32.0 
2025-12-17 00:00 UT   15 54 39.7   +00 22 37    15.111   14.312   34.5    2.2   315   32.0 

    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.