C/2018 X2 (Fitzsimmons)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	5 Jan 2019	18.0	2.986 AU	2.252 AU	03h31m	+51°18'	130.5°	14.5°	105°
Perihelion	10 Jul 2019	16.5	2.111 AU	2.988 AU	09h05m	+21°46'	25.0°	11.7°	96°
Today	25 May 2026	33.3	18.145 AU	17.452 AU	19h34m	-41°51'	132.0°	2.4°	279°

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)                : 0.9852340
    q (Perihelion distance)         : 2.1107720
    i (Inclination)                 : 23.12570
    Ω (Longitude of ascending node) : 340.56150
    ω (Argument of perihelion)      : 162.09170
    L (Longitude of perihelion)     : 324.01037
    B (Latitude of perihelion)      : 6.93645
    T (Time of perihelion passage)  : 2458675.19750
    P (Orbital period in years)     : 1709.10

    Epoch                           : 2026 May 24
    Reference                       : MPC194158

    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
2026-05-24 00:00 UT   19 35 08.0   -41 49 32    17.461   18.137  130.6    2.4   278   33.3 
2026-05-25 00:00 UT   19 34 58.2   -41 50 35    17.455   18.143  131.5    2.4   279   33.3 
2026-05-25 11:51 UT   19 34 53.3   -41 51 06    17.452   18.145  132.0    2.4   279   33.3 
2026-05-26 00:00 UT   19 34 48.1   -41 51 37    17.449   18.148  132.4    2.4   280   33.3 
2026-05-27 00:00 UT   19 34 37.8   -41 52 39    17.443   18.153  133.3    2.3   280   33.3 
2026-05-28 00:00 UT   19 34 27.3   -41 53 40    17.437   18.158  134.2    2.3   281   33.3 
2026-05-29 00:00 UT   19 34 16.5   -41 54 41    17.432   18.163  135.0    2.3   282   33.3 
2026-05-30 00:00 UT   19 34 05.6   -41 55 41    17.426   18.168  135.9    2.2   282   33.3 
2026-05-31 00:00 UT   19 33 54.4   -41 56 41    17.421   18.174  136.8    2.2   283   33.3 
2026-06-01 00:00 UT   19 33 42.9   -41 57 40    17.416   18.179  137.6    2.2   284   33.3 
2026-06-02 00:00 UT   19 33 31.3   -41 58 39    17.412   18.184  138.5    2.1   285   33.3 
2026-06-03 00:00 UT   19 33 19.5   -41 59 37    17.407   18.189  139.3    2.1   285   33.3 
2026-06-04 00:00 UT   19 33 07.4   -42 00 35    17.403   18.194  140.2    2.0   286   33.3 

    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.