C/2018 W1 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	14 May 2019	11.2	1.350 AU	1.929 AU	04h22m	-20°17'	41.5°	29.7°	158°
Nearest approach	26 Jun 2019	12.3	1.481 AU	1.673 AU	07h17m	-36°07'	61.2°	37.0°	164°
Today	14 Nov 2025	52.4	16.470 AU	17.183 AU	16h25m	+21°15'	42.7°	2.3°	23°

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)                : 0.9379270
    q (Perihelion distance)         : 1.3500950
    i (Inclination)                 : 83.37340
    Ω (Longitude of ascending node) : 233.60970
    ω (Argument of perihelion)      : 251.15800
    L (Longitude of perihelion)     : 252.29357
    B (Latitude of perihelion)      : -70.06669
    T (Time of perihelion passage)  : 2458617.84280
    P (Orbital period in years)     : 101.44

    Epoch                           : 2025 Nov 12
    Reference                       : MPEC 2021-P47

    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
2025-11-13 00:00 UT   16 24 36.1   +21 16 59    17.172   16.462   43.0    2.3    26   52.4 
2025-11-14 00:00 UT   16 24 50.9   +21 16 16    17.178   16.466   42.8    2.3    24   52.4 
2025-11-14 21:17 UT   16 25 04.0   +21 15 41    17.183   16.470   42.7    2.3    23   52.4 
2025-11-15 00:00 UT   16 25 05.7   +21 15 36    17.184   16.471   42.7    2.3    23   52.4 
2025-11-16 00:00 UT   16 25 20.6   +21 14 58    17.189   16.475   42.6    2.3    22   52.4 
2025-11-17 00:00 UT   16 25 35.5   +21 14 22    17.195   16.479   42.5    2.3    20   52.4 
2025-11-18 00:00 UT   16 25 50.5   +21 13 49    17.200   16.484   42.4    2.3    19   52.4 
2025-11-19 00:00 UT   16 26 05.5   +21 13 17    17.205   16.488   42.3    2.3    17   52.4 
2025-11-20 00:00 UT   16 26 20.5   +21 12 48    17.210   16.493   42.3    2.3    16   52.4 
2025-11-21 00:00 UT   16 26 35.6   +21 12 22    17.214   16.497   42.3    2.3    15   52.4 
2025-11-22 00:00 UT   16 26 50.8   +21 11 57    17.219   16.502   42.3    2.3    13   52.4 
2025-11-23 00:00 UT   16 27 05.9   +21 11 35    17.223   16.506   42.3    2.3    12   52.4 
2025-11-24 00:00 UT   16 27 21.1   +21 11 15    17.227   16.510   42.3    2.3    10   52.4 

    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.