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	9 May 2025	23.0	24.430 AU	25.377 AU	02h14m	+33°40'	19.8°	0.8°	322°

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
2025-05-09 00:00 UT   02 14 40.9   +33 39 52    25.375   24.428   19.7    0.8   323   23.0 
2025-05-09 08:36 UT   02 14 44.4   +33 40 08    25.377   24.430   19.8    0.8   322   23.0 
2025-05-10 00:00 UT   02 14 50.7   +33 40 39    25.379   24.433   20.0    0.8   321   23.0 
2025-05-11 00:00 UT   02 15 00.4   +33 41 27    25.382   24.438   20.3    0.8   318   23.0 
2025-05-12 00:00 UT   02 15 10.1   +33 42 15    25.385   24.443   20.6    0.8   316   23.0 
2025-05-13 00:00 UT   02 15 19.8   +33 43 04    25.388   24.448   21.0    0.8   313   23.0 
2025-05-14 00:00 UT   02 15 29.4   +33 43 53    25.390   24.452   21.4    0.9   311   23.0 
2025-05-15 00:00 UT   02 15 39.0   +33 44 43    25.392   24.457   21.8    0.9   309   23.0 
2025-05-16 00:00 UT   02 15 48.5   +33 45 33    25.394   24.462   22.3    0.9   307   23.0 
2025-05-17 00:00 UT   02 15 58.0   +33 46 24    25.396   24.467   22.8    0.9   305   23.0 
2025-05-18 00:00 UT   02 16 07.4   +33 47 16    25.397   24.472   23.3    0.9   303   23.0 
2025-05-19 00:00 UT   02 16 16.7   +33 48 07    25.398   24.477   23.8    1.0   301   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.