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	18 Jan 2026	33.2	17.485 AU	18.393 AU	19h21m	-40°38'	22.0°	1.2°	206°

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
2026-01-17 00:00 UT   19 20 38.2   -40 39 18    18.389   17.475   21.0    1.2   202   33.2 
2026-01-18 00:00 UT   19 20 57.0   -40 38 55    18.391   17.480   21.5    1.2   205   33.2 
2026-01-18 22:07 UT   19 21 14.1   -40 38 34    18.393   17.485   22.0    1.2   206   33.2 
2026-01-19 00:00 UT   19 21 15.6   -40 38 32    18.393   17.485   22.0    1.2   207   33.2 
2026-01-20 00:00 UT   19 21 34.2   -40 38 10    18.395   17.491   22.6    1.2   209   33.2 
2026-01-21 00:00 UT   19 21 52.7   -40 37 50    18.396   17.496   23.1    1.3   211   33.2 
2026-01-22 00:00 UT   19 22 11.2   -40 37 30    18.397   17.501   23.7    1.3   213   33.2 
2026-01-23 00:00 UT   19 22 29.6   -40 37 11    18.398   17.506   24.3    1.3   214   33.2 
2026-01-24 00:00 UT   19 22 47.9   -40 36 53    18.399   17.512   25.0    1.4   216   33.2 
2026-01-25 00:00 UT   19 23 06.2   -40 36 37    18.399   17.517   25.6    1.4   218   33.2 
2026-01-26 00:00 UT   19 23 24.3   -40 36 21    18.399   17.522   26.3    1.4   219   33.2 
2026-01-27 00:00 UT   19 23 42.4   -40 36 06    18.399   17.527   27.0    1.5   221   33.2 
2026-01-28 00:00 UT   19 24 00.4   -40 35 52    18.398   17.533   27.7    1.5   222   33.2 

    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.