C/2018 W1 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	14 May 2019	11.2	1.348 AU	1.929 AU	04h23m	-20°09'	41.4°	29.7°	159°
Nearest approach	26 Jun 2019	12.2	1.478 AU	1.674 AU	07h17m	-35°57'	61.0°	37.0°	164°
Today	11 Jul 2026	53.2	17.500 AU	17.057 AU	16h21m	+26°42'	114.3°	3.0°	134°

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
2026-07-10 00:00 UT   16 21 58.4   +26 44 51    17.031   17.492  115.4    3.0   135   53.2 
2026-07-11 00:00 UT   16 21 47.6   +26 43 45    17.044   17.496  114.9    3.0   134   53.2 
2026-07-11 22:45 UT   16 21 37.6   +26 42 40    17.057   17.500  114.3    3.0   134   53.2 
2026-07-12 00:00 UT   16 21 37.0   +26 42 36    17.057   17.501  114.3    3.0   133   53.2 
2026-07-13 00:00 UT   16 21 26.6   +26 41 25    17.071   17.505  113.7    3.0   133   53.2 
2026-07-14 00:00 UT   16 21 16.4   +26 40 12    17.084   17.509  113.1    3.1   132   53.3 
2026-07-15 00:00 UT   16 21 06.4   +26 38 57    17.098   17.513  112.5    3.1   131   53.3 
2026-07-16 00:00 UT   16 20 56.6   +26 37 40    17.112   17.517  111.9    3.1   130   53.3 
2026-07-17 00:00 UT   16 20 47.0   +26 36 22    17.126   17.522  111.3    3.1   129   53.3 
2026-07-18 00:00 UT   16 20 37.6   +26 35 01    17.140   17.526  110.7    3.1   128   53.3 
2026-07-19 00:00 UT   16 20 28.4   +26 33 38    17.154   17.530  110.1    3.1   128   53.3 
2026-07-20 00:00 UT   16 20 19.4   +26 32 13    17.168   17.534  109.5    3.1   127   53.3 
2026-07-21 00:00 UT   16 20 10.6   +26 30 47    17.182   17.539  108.9    3.1   126   53.3 

    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.