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	8 Jan 2026	52.6	16.711 AU	17.200 AU	16h38m	+21°38'	58.7°	2.9°	316°

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
2026-01-07 00:00 UT   16 37 58.8   +21 36 21    17.208   16.703   57.7    2.9   317   52.6 
2026-01-08 00:00 UT   16 38 11.4   +21 37 48    17.204   16.708   58.3    2.9   317   52.6 
2026-01-08 17:03 UT   16 38 20.2   +21 38 52    17.200   16.711   58.7    2.9   316   52.6 
2026-01-09 00:00 UT   16 38 23.7   +21 39 18    17.199   16.712   58.9    2.9   316   52.6 
2026-01-10 00:00 UT   16 38 36.0   +21 40 50    17.194   16.716   59.5    2.9   315   52.6 
2026-01-11 00:00 UT   16 38 48.0   +21 42 25    17.189   16.721   60.1    2.9   314   52.6 
2026-01-12 00:00 UT   16 38 60.0   +21 44 01    17.184   16.725   60.7    2.9   313   52.6 
2026-01-13 00:00 UT   16 39 11.7   +21 45 40    17.179   16.729   61.3    3.0   312   52.6 
2026-01-14 00:00 UT   16 39 23.4   +21 47 21    17.174   16.734   61.9    3.0   311   52.6 
2026-01-15 00:00 UT   16 39 34.8   +21 49 04    17.169   16.738   62.5    3.0   310   52.6 
2026-01-16 00:00 UT   16 39 46.1   +21 50 49    17.163   16.743   63.2    3.0   310   52.6 
2026-01-17 00:00 UT   16 39 57.2   +21 52 37    17.158   16.747   63.8    3.0   309   52.6 
2026-01-18 00:00 UT   16 40 08.1   +21 54 26    17.152   16.751   64.4    3.0   308   52.6 

    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.