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C/2018 W1 (Catalina)
ephemeris date magn radius delta ra dec elong phase PA
Perihelion14 May 201911.21.348 AU1.929 AU 04h23m-20°09'41.4°29.7°159°
Nearest approach26 Jun 201912.21.478 AU1.674 AU 07h17m-35°57'61.0°37.0°164°
Today10 Aug 202653.417.626 AU17.501 AU 16h17m+25°54'95.4°3.3°110°
C/2018 W1 (Catalina)- 2026-08-10
astro.vanbuitenen.nl


 
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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 5.4 + 5 log[∆] + 33.5 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 W1 (Catalina) are: 

    e (Eccentricity)                : 0.9380400
    q (Perihelion distance)         : 1.3483000
    i (Inclination)                 : 83.32030
    Ω (Longitude of ascending node) : 233.59830
    ω (Argument of perihelion)      : 251.12350
    L (Longitude of perihelion)     : 252.38634
    B (Latitude of perihelion)      : -70.01718
    T (Time of perihelion passage)  : 2458618.35020
    P (Orbital period in years)     : 101.51

    Epoch                           : 2026 May 29
    Reference                       : MPC194158

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (P < 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-08-09 00:00 UT   16 18 06.9   +25 58 28    17.470   17.618   96.7    3.3   111   53.4 
2026-08-10 00:00 UT   16 18 02.7   +25 56 34    17.486   17.622   96.1    3.3   111   53.4 
2026-08-10 23:18 UT   16 17 58.9   +25 54 41    17.501   17.626   95.4    3.3   110   53.4 
2026-08-11 00:00 UT   16 17 58.8   +25 54 38    17.502   17.627   95.4    3.3   110   53.4 
2026-08-12 00:00 UT   16 17 55.2   +25 52 41    17.517   17.631   94.7    3.3   109   53.4 
2026-08-13 00:00 UT   16 17 51.7   +25 50 43    17.533   17.635   94.1    3.3   109   53.4 
2026-08-14 00:00 UT   16 17 48.6   +25 48 44    17.549   17.639   93.4    3.3   108   53.4 
2026-08-15 00:00 UT   16 17 45.6   +25 46 45    17.565   17.643   92.8    3.3   107   53.4 
2026-08-16 00:00 UT   16 17 43.0   +25 44 44    17.581   17.647   92.1    3.3   107   53.4 
2026-08-17 00:00 UT   16 17 40.5   +25 42 43    17.597   17.652   91.4    3.3   106   53.4 
2026-08-18 00:00 UT   16 17 38.3   +25 40 42    17.613   17.656   90.8    3.3   105   53.4 
2026-08-19 00:00 UT   16 17 36.4   +25 38 39    17.629   17.660   90.1    3.3   104   53.4 
2026-08-20 00:00 UT   16 17 34.7   +25 36 36    17.645   17.664   89.4    3.3   104   53.5 




    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.

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