C/2013 US10 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	16 Nov 2015	6.3	0.820 AU	1.739 AU	14h24m	-19°17'	14.6°	17.6°	270°
Nearest approach	17 Jan 2016	6.1	1.378 AU	0.718 AU	13h53m	+54°52'	107.2°	43.0°	282°
Today	14 Jul 2025	23.0	24.752 AU	25.101 AU	02h22m	+34°41'	68.8°	2.2°	258°

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 US10 (Catalina) are:

            e (Eccentricity)                : 1.0006210
            q (Perihelion distance)         : 0.8202940
            i (Inclination)                 : 148.75930
            Ω (Longitude of ascending node) : 186.41870
            ω (Argument of perihelion)      : 340.59350
            L (Longitude of perihelion)     : 203.18104
            B (Latitude of perihelion)      : -9.92307
            T (Time of perihelion passage)  : 2457343.40160

            Epoch                           : 2020 Dec 03
            Reference                       : MPC110080

            Classification(s):              : Nearly isotropic; New (a > 10000 AU)
        

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 gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (4.40 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 5.77 + 5 log[∆] + 7.37 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
2025-07-14 00:00 UT   02 22 14.5   +34 40 57    25.109   24.748   68.0    2.2   258   23.0 
2025-07-14 20:12 UT   02 22 16.5   +34 41 41    25.101   24.752   68.8    2.2   258   23.0 
2025-07-15 00:00 UT   02 22 16.9   +34 41 50    25.100   24.753   68.9    2.2   258   23.0 
2025-07-16 00:00 UT   02 22 19.0   +34 42 42    25.090   24.758   69.8    2.2   257   23.0 
2025-07-17 00:00 UT   02 22 21.1   +34 43 35    25.079   24.762   70.7    2.2   257   23.0 
2025-07-18 00:00 UT   02 22 22.9   +34 44 26    25.069   24.767   71.6    2.2   257   23.0 
2025-07-19 00:00 UT   02 22 24.6   +34 45 17    25.059   24.772   72.4    2.2   256   23.0 
2025-07-20 00:00 UT   02 22 26.1   +34 46 08    25.049   24.777   73.3    2.3   256   23.0 
2025-07-21 00:00 UT   02 22 27.4   +34 46 58    25.038   24.782   74.2    2.3   256   23.0 
2025-07-22 00:00 UT   02 22 28.6   +34 47 48    25.028   24.787   75.1    2.3   255   23.0 
2025-07-23 00:00 UT   02 22 29.5   +34 48 37    25.017   24.791   76.0    2.3   255   23.0 
2025-07-24 00:00 UT   02 22 30.3   +34 49 26    25.006   24.796   76.9    2.3   255   23.0 

    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.