C/2013 US10 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	12 Nov 2015	6.3	0.812 AU	1.749 AU	14h15m	-18°33'	12.6°	15.5°	268°
Nearest approach	15 Jan 2016	6.2	1.403 AU	0.744 AU	13h42m	+55°22'	107.7°	41.9°	282°
Today	16 Jan 2026	23.2	25.632 AU	25.396 AU	02h00m	+33°21'	102.8°	2.1°	73°

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 5.8 + 5 log[∆] + 7.4 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/2013 US10 (Catalina) are:

    e (Eccentricity)                : 1.0001650
    q (Perihelion distance)         : 0.8123510
    i (Inclination)                 : 148.89100
    Ω (Longitude of ascending node) : 186.21220
    ω (Argument of perihelion)      : 340.22130
    L (Longitude of perihelion)     : 203.32509
    B (Latitude of perihelion)      : -10.06901
    T (Time of perihelion passage)  : 2457339.13550

    Epoch                           : 2026 Jan 16
    Reference                       : MPC xxxxx

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-01-15 00:00 UT   02 00 54.0   +33 23 38    25.358   25.623  104.6    2.1    74   23.2 
2026-01-16 00:00 UT   02 00 52.3   +33 22 37    25.378   25.628  103.6    2.1    74   23.2 
2026-01-16 20:40 UT   02 00 51.0   +33 21 45    25.396   25.632  102.8    2.1    73   23.2 
2026-01-17 00:00 UT   02 00 50.8   +33 21 36    25.399   25.633  102.6    2.1    73   23.2 
2026-01-18 00:00 UT   02 00 49.5   +33 20 37    25.420   25.638  101.7    2.2    73   23.2 
2026-01-19 00:00 UT   02 00 48.4   +33 19 38    25.441   25.642  100.7    2.2    72   23.2 
2026-01-20 00:00 UT   02 00 47.5   +33 18 39    25.462   25.647   99.7    2.2    72   23.2 
2026-01-21 00:00 UT   02 00 46.7   +33 17 42    25.483   25.652   98.8    2.2    72   23.2 
2026-01-22 00:00 UT   02 00 46.2   +33 16 45    25.504   25.656   97.8    2.2    71   23.2 
2026-01-23 00:00 UT   02 00 45.8   +33 15 50    25.525   25.661   96.8    2.2    71   23.2 
2026-01-24 00:00 UT   02 00 45.6   +33 14 55    25.546   25.666   95.9    2.2    71   23.2 
2026-01-25 00:00 UT   02 00 45.6   +33 14 01    25.567   25.671   94.9    2.2    70   23.2 
2026-01-26 00:00 UT   02 00 45.8   +33 13 09    25.588   25.675   94.0    2.2    70   23.2 

    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.