C/2013 US10 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	11 Nov 2015	6.3	0.815 AU	1.754 AU	14h14m	-18°25'	12.4°	15.1°	268°
Nearest approach	15 Jan 2016	6.2	1.409 AU	0.749 AU	13h39m	+55°23'	108.0°	41.6°	282°
Today	15 Jun 2026	23.4	26.338 AU	27.053 AU	02h17m	+33°46'	44.4°	1.5°	270°

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)                : 1.0001560
    q (Perihelion distance)         : 0.8147910
    i (Inclination)                 : 148.93050
    Ω (Longitude of ascending node) : 186.14760
    ω (Argument of perihelion)      : 340.19530
    L (Longitude of perihelion)     : 203.29016
    B (Latitude of perihelion)      : -10.07021
    T (Time of perihelion passage)  : 2457338.46180

    Epoch                           : 2026 Jun 15
    Reference                       : MPC194135

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-06-14 00:00 UT   02 17 03.3   +33 44 18    27.064   26.329   42.8    1.5   271   23.4 
2026-06-15 00:00 UT   02 17 09.6   +33 45 13    27.059   26.334   43.6    1.5   271   23.4 
2026-06-15 23:24 UT   02 17 15.7   +33 46 07    27.053   26.338   44.4    1.5   270   23.4 
2026-06-16 00:00 UT   02 17 15.8   +33 46 08    27.053   26.338   44.5    1.5   270   23.4 
2026-06-17 00:00 UT   02 17 21.9   +33 47 03    27.047   26.343   45.3    1.6   269   23.4 
2026-06-18 00:00 UT   02 17 27.9   +33 47 58    27.041   26.348   46.1    1.6   269   23.4 
2026-06-19 00:00 UT   02 17 33.8   +33 48 53    27.035   26.352   47.0    1.6   268   23.4 
2026-06-20 00:00 UT   02 17 39.5   +33 49 48    27.028   26.357   47.8    1.6   268   23.4 
2026-06-21 00:00 UT   02 17 45.1   +33 50 43    27.021   26.362   48.6    1.7   267   23.4 
2026-06-22 00:00 UT   02 17 50.6   +33 51 38    27.015   26.366   49.5    1.7   267   23.4 
2026-06-23 00:00 UT   02 17 55.9   +33 52 33    27.007   26.371   50.3    1.7   266   23.4 
2026-06-24 00:00 UT   02 18 01.2   +33 53 28    27.000   26.376   51.2    1.7   266   23.4 
2026-06-25 00:00 UT   02 18 06.3   +33 54 22    26.993   26.380   52.0    1.7   265   23.4 

    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.