C/2013 U1 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	4 Sep 2013	18.6	2.520 AU	1.655 AU	20h49m	+17°24'	141.0°	14.6°	127°
Perihelion	20 Nov 2013	19.0	2.400 AU	2.140 AU	21h51m	+03°56'	92.8°	24.3°	70°
Today	22 Jun 2025	32.6	18.509 AU	18.864 AU	10h09m	-08°31'	68.1°	2.9°	120°

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.)

The orbital elements of C/2013 U1 (Catalina) are:

            e (Eccentricity)                : 0.7977070
            q (Perihelion distance)         : 2.4001990
            i (Inclination)                 : 23.96080
            Ω (Longitude of ascending node) : 211.11160
            ω (Argument of perihelion)      : 143.04200
            L (Longitude of perihelion)     : 176.60052
            B (Latitude of perihelion)      : 14.13256
            T (Time of perihelion passage)  : 2456617.49060
            P (Orbital period in years)     : 40.87

            Epoch                           : 2020 Sep 26
            Reference                       : MPC 86643

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. The light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (13.50 + 5 log[∆] + 10.00 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-06-22 00:00 UT   10 09 42.9   -08 31 23    18.859   18.509   68.4    2.9   119   32.6 
2025-06-22 06:08 UT   10 09 44.8   -08 31 18    18.864   18.509   68.1    2.9   120   32.6 
2025-06-23 00:00 UT   10 09 50.3   -08 31 04    18.876   18.511   67.5    2.9   120   32.6 
2025-06-24 00:00 UT   10 09 57.8   -08 30 45    18.892   18.513   66.6    2.9   120   32.6 
2025-06-25 00:00 UT   10 10 05.5   -08 30 28    18.908   18.514   65.8    2.9   121   32.6 
2025-06-26 00:00 UT   10 10 13.3   -08 30 13    18.925   18.516   64.9    2.8   121   32.6 
2025-06-27 00:00 UT   10 10 21.3   -08 29 59    18.941   18.518   64.0    2.8   121   32.6 
2025-06-28 00:00 UT   10 10 29.5   -08 29 47    18.957   18.520   63.2    2.8   122   32.6 
2025-06-29 00:00 UT   10 10 37.7   -08 29 36    18.972   18.522   62.3    2.8   122   32.6 
2025-06-30 00:00 UT   10 10 46.2   -08 29 26    18.988   18.524   61.4    2.8   122   32.6 
2025-07-01 00:00 UT   10 10 54.7   -08 29 18    19.004   18.525   60.6    2.7   123   32.6 
2025-07-02 00:00 UT   10 11 03.5   -08 29 11    19.019   18.527   59.7    2.7   123   32.6 

    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.