C/2013 US10 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	12 Nov 2015	6.3	0.813 AU	1.750 AU	14h15m	-18°31'	12.6°	15.3°	268°
Nearest approach	15 Jan 2016	6.2	1.404 AU	0.746 AU	13h41m	+55°23'	107.8°	41.8°	282°
Today	3 Mar 2026	23.3	25.850 AU	26.343 AU	02h02m	+32°52'	59.2°	1.9°	57°

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)                : 1.0001600
    q (Perihelion distance)         : 0.8129900
    i (Inclination)                 : 148.90310
    Ω (Longitude of ascending node) : 186.19240
    ω (Argument of perihelion)      : 340.21170
    L (Longitude of perihelion)     : 203.31582
    B (Latitude of perihelion)      : -10.07019
    T (Time of perihelion passage)  : 2457338.92000

    Epoch                           : 2026 Mar 03
    Reference                       : MPC xxxxx

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-03-02 00:00 UT   02 02 39.1   +32 53 03    26.306   25.841   61.0    1.9    58   23.3 
2026-03-03 00:00 UT   02 02 45.0   +32 52 48    26.325   25.845   60.0    1.9    57   23.3 
2026-03-03 22:27 UT   02 02 50.7   +32 52 35    26.343   25.850   59.2    1.9    57   23.3 
2026-03-04 00:00 UT   02 02 51.1   +32 52 34    26.344   25.850   59.1    1.9    57   23.3 
2026-03-05 00:00 UT   02 02 57.3   +32 52 21    26.363   25.855   58.2    1.9    56   23.3 
2026-03-06 00:00 UT   02 03 03.6   +32 52 10    26.381   25.860   57.3    1.9    56   23.3 
2026-03-07 00:00 UT   02 03 10.1   +32 51 59    26.399   25.864   56.4    1.8    56   23.3 
2026-03-08 00:00 UT   02 03 16.6   +32 51 50    26.417   25.869   55.5    1.8    55   23.3 
2026-03-09 00:00 UT   02 03 23.3   +32 51 42    26.435   25.874   54.6    1.8    55   23.3 
2026-03-10 00:00 UT   02 03 30.1   +32 51 34    26.453   25.878   53.7    1.8    54   23.3 
2026-03-11 00:00 UT   02 03 37.0   +32 51 28    26.471   25.883   52.8    1.8    54   23.3 
2026-03-12 00:00 UT   02 03 44.0   +32 51 23    26.488   25.888   51.9    1.7    53   23.3 
2026-03-13 00:00 UT   02 03 51.1   +32 51 19    26.505   25.893   51.0    1.7    53   23.3 

    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.