C/2018 X2 (Fitzsimmons)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	5 Jan 2019	18.0	2.981 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°50'	25.3°	11.9°	96°
Today	27 Oct 2025	32.9	17.041 AU	17.369 AU	18h58m	-41°55'	69.1°	3.1°	91°

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)                : 0.9851060
    q (Perihelion distance)         : 2.1103770
    i (Inclination)                 : 23.11540
    Ω (Longitude of ascending node) : 340.60240
    ω (Argument of perihelion)      : 162.03810
    L (Longitude of perihelion)     : 324.00004
    B (Latitude of perihelion)      : 6.95368
    T (Time of perihelion passage)  : 2458674.70430
    P (Orbital period in years)     : 1686.64

    Epoch                           : 2025 Oct 26
    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
2025-10-26 00:00 UT   18 58 32.1   -41 56 44    17.346   17.035   70.2    3.1    91   32.9 
2025-10-27 00:00 UT   18 58 40.9   -41 55 26    17.366   17.041   69.3    3.1    91   32.9 
2025-10-27 03:57 UT   18 58 42.4   -41 55 13    17.369   17.041   69.1    3.1    91   32.9 
2025-10-28 00:00 UT   18 58 50.0   -41 54 09    17.386   17.046   68.4    3.1    92   32.9 
2025-10-29 00:00 UT   18 58 59.3   -41 52 52    17.406   17.051   67.5    3.1    92   32.9 
2025-10-30 00:00 UT   18 59 08.9   -41 51 35    17.426   17.056   66.6    3.1    92   32.9 
2025-10-31 00:00 UT   18 59 18.8   -41 50 18    17.446   17.062   65.7    3.0    93   32.9 
2025-11-01 00:00 UT   18 59 28.9   -41 49 02    17.466   17.067   64.8    3.0    93   32.9 
2025-11-02 00:00 UT   18 59 39.3   -41 47 46    17.486   17.072   63.9    3.0    93   32.9 
2025-11-03 00:00 UT   18 59 49.9   -41 46 30    17.505   17.078   63.0    3.0    94   32.9 
2025-11-04 00:00 UT   19 00 00.8   -41 45 15    17.525   17.083   62.1    2.9    94   32.9 
2025-11-05 00:00 UT   19 00 11.9   -41 43 60    17.544   17.088   61.2    2.9    95   32.9 
2025-11-06 00:00 UT   19 00 23.2   -41 42 45    17.563   17.094   60.3    2.9    95   32.9 

    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.