C/2018 X2 (Fitzsimmons)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	5 Jan 2019	18.0	2.982 AU	2.248 AU	03h32m	+51°19'	130.5°	14.5°	105°
Perihelion	10 Jul 2019	16.5	2.110 AU	2.985 AU	09h04m	+21°49'	25.2°	11.9°	96°
Today	11 Dec 2025	33.1	17.283 AU	18.127 AU	19h09m	-41°03'	30.1°	1.6°	118°

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 9.7 + 5 log[∆] + 13.8 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 X2 (Fitzsimmons) are:

    e (Eccentricity)                : 0.9851180
    q (Perihelion distance)         : 2.1103720
    i (Inclination)                 : 23.11630
    Ω (Longitude of ascending node) : 340.59880
    ω (Argument of perihelion)      : 162.04230
    L (Longitude of perihelion)     : 324.00046
    B (Latitude of perihelion)      : 6.95236
    T (Time of perihelion passage)  : 2458674.74680
    P (Orbital period in years)     : 1688.68

    Epoch                           : 2025 Nov 12
    Reference                       : MPC119996

    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
2025-12-10 00:00 UT   19 08 49.5   -41 05 11    18.107   17.274   31.3    1.7   116   33.1 
2025-12-11 00:00 UT   19 09 07.1   -41 04 16    18.119   17.279   30.6    1.7   117   33.1 
2025-12-11 14:42 UT   19 09 17.9   -41 03 42    18.127   17.283   30.1    1.6   118   33.1 
2025-12-12 00:00 UT   19 09 24.8   -41 03 21    18.131   17.285   29.8    1.6   118   33.1 
2025-12-13 00:00 UT   19 09 42.6   -41 02 26    18.143   17.290   29.1    1.6   120   33.1 
2025-12-14 00:00 UT   19 10 00.5   -41 01 33    18.155   17.295   28.4    1.5   121   33.1 
2025-12-15 00:00 UT   19 10 18.5   -41 00 40    18.166   17.301   27.7    1.5   122   33.1 
2025-12-16 00:00 UT   19 10 36.6   -40 59 48    18.177   17.306   27.0    1.5   124   33.1 
2025-12-17 00:00 UT   19 10 54.8   -40 58 57    18.188   17.311   26.3    1.4   125   33.1 
2025-12-18 00:00 UT   19 11 13.1   -40 58 06    18.198   17.316   25.6    1.4   127   33.1 
2025-12-19 00:00 UT   19 11 31.5   -40 57 16    18.208   17.322   25.0    1.4   128   33.1 
2025-12-20 00:00 UT   19 11 49.9   -40 56 27    18.218   17.327   24.3    1.3   130   33.1 
2025-12-21 00:00 UT   19 12 08.4   -40 55 39    18.228   17.332   23.7    1.3   132   33.1 

    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.