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	29 Dec 2025	33.1	17.380 AU	18.303 AU	19h14m	-40°49'	19.5°	1.1°	152°

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
2025-12-28 00:00 UT   19 14 19.4   -40 50 24    18.288   17.369   20.2    1.1   147   33.1 
2025-12-29 00:00 UT   19 14 38.3   -40 49 43    18.296   17.375   19.8    1.1   149   33.1 
2025-12-29 23:38 UT   19 14 57.0   -40 49 02    18.303   17.380   19.5    1.1   152   33.1 
2025-12-30 00:00 UT   19 14 57.3   -40 49 02    18.303   17.380   19.5    1.1   152   33.1 
2025-12-31 00:00 UT   19 15 16.2   -40 48 22    18.310   17.385   19.2    1.1   155   33.1 
2026-01-01 00:00 UT   19 15 35.2   -40 47 43    18.317   17.390   18.9    1.1   157   33.1 
2026-01-02 00:00 UT   19 15 54.2   -40 47 04    18.324   17.396   18.7    1.0   160   33.1 
2026-01-03 00:00 UT   19 16 13.1   -40 46 27    18.330   17.401   18.5    1.0   163   33.1 
2026-01-04 00:00 UT   19 16 32.2   -40 45 51    18.336   17.406   18.4    1.0   166   33.1 
2026-01-05 00:00 UT   19 16 51.2   -40 45 15    18.341   17.412   18.4    1.0   169   33.1 
2026-01-06 00:00 UT   19 17 10.2   -40 44 40    18.347   17.417   18.3    1.0   172   33.1 
2026-01-07 00:00 UT   19 17 29.2   -40 44 06    18.352   17.422   18.4    1.0   175   33.1 
2026-01-08 00:00 UT   19 17 48.2   -40 43 33    18.357   17.427   18.4    1.0   178   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.