C/2018 W1 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	14 May 2019	11.2	1.349 AU	1.929 AU	04h23m	-20°10'	41.4°	29.7°	159°
Nearest approach	26 Jun 2019	12.2	1.479 AU	1.674 AU	07h17m	-36°00'	61.0°	37.0°	164°
Today	12 May 2026	53.0	17.246 AU	16.561 AU	16h35m	+26°35'	131.4°	2.5°	205°

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)                : 0.9380160
    q (Perihelion distance)         : 1.3486770
    i (Inclination)                 : 83.33730
    Ω (Longitude of ascending node) : 233.61590
    ω (Argument of perihelion)      : 251.12420
    L (Longitude of perihelion)     : 252.36036
    B (Latitude of perihelion)      : -70.02331
    T (Time of perihelion passage)  : 2458618.21430
    P (Orbital period in years)     : 101.49

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    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
2026-05-11 00:00 UT   16 35 53.7   +26 32 54    16.558   17.238  131.1    2.5   208   53.0 
2026-05-12 00:00 UT   16 35 39.6   +26 34 26    16.560   17.243  131.2    2.5   206   53.0 
2026-05-12 19:51 UT   16 35 27.8   +26 35 40    16.561   17.246  131.4    2.5   205   53.0 
2026-05-13 00:00 UT   16 35 25.3   +26 35 55    16.562   17.247  131.4    2.5   205   53.0 
2026-05-14 00:00 UT   16 35 11.0   +26 37 22    16.564   17.251  131.5    2.5   203   53.0 
2026-05-15 00:00 UT   16 34 56.6   +26 38 46    16.567   17.255  131.6    2.5   202   53.0 
2026-05-16 00:00 UT   16 34 42.2   +26 40 08    16.570   17.260  131.7    2.5   201   53.0 
2026-05-17 00:00 UT   16 34 27.6   +26 41 27    16.573   17.264  131.8    2.5   199   53.0 
2026-05-18 00:00 UT   16 34 13.0   +26 42 43    16.576   17.268  131.9    2.5   198   53.0 
2026-05-19 00:00 UT   16 33 58.3   +26 43 57    16.580   17.272  131.9    2.5   197   53.0 
2026-05-20 00:00 UT   16 33 43.6   +26 45 07    16.583   17.277  132.0    2.5   195   53.0 
2026-05-21 00:00 UT   16 33 28.8   +26 46 16    16.587   17.281  132.0    2.5   194   53.0 
2026-05-22 00:00 UT   16 33 14.0   +26 47 21    16.591   17.285  132.0    2.5   193   53.0 

    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.