C/2013 UQ4 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	4 Jul 2014	11.8	1.099 AU	0.387 AU	23h16m	+40°30'	91.7°	67.6°	237°
Nearest approach	9 Jul 2014	11.5	1.102 AU	0.332 AU	20h37m	+59°49'	96.0°	66.6°	199°
Today	25 Dec 2025	34.7	26.085 AU	25.362 AU	09h15m	+14°10'	136.5°	1.5°	289°

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. The light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (13.5 + 5 log[∆] + 10.0 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 UQ4 (Catalina) are:

    e (Eccentricity)                : 0.9812680
    q (Perihelion distance)         : 1.0987550
    i (Inclination)                 : 145.21210
    Ω (Longitude of ascending node) : 317.80900
    ω (Argument of perihelion)      : 23.74980
    L (Longitude of perihelion)     : 297.94097
    B (Latitude of perihelion)      : 13.28420
    T (Time of perihelion passage)  : 2456842.78700
    P (Orbital period in years)     : 449.24

    Epoch                           : 2020 Sep 26
    Reference                       : MPC102951

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-24 00:00 UT   09 15 49.2   +14 09 29    25.374   26.079  135.0    1.5   289   34.7 
2025-12-25 00:00 UT   09 15 41.9   +14 09 55    25.366   26.084  136.1    1.5   289   34.7 
2025-12-25 10:42 UT   09 15 38.6   +14 10 07    25.362   26.085  136.5    1.5   289   34.7 
2025-12-26 00:00 UT   09 15 34.5   +14 10 21    25.358   26.088  137.1    1.5   289   34.7 
2025-12-27 00:00 UT   09 15 27.0   +14 10 48    25.350   26.092  138.2    1.4   289   34.7 
2025-12-28 00:00 UT   09 15 19.3   +14 11 16    25.343   26.096  139.2    1.4   289   34.7 
2025-12-29 00:00 UT   09 15 11.5   +14 11 44    25.335   26.100  140.3    1.4   289   34.7 
2025-12-30 00:00 UT   09 15 03.7   +14 12 12    25.328   26.104  141.3    1.3   289   34.7 
2025-12-31 00:00 UT   09 14 55.7   +14 12 41    25.322   26.108  142.4    1.3   290   34.7 
2026-01-01 00:00 UT   09 14 47.6   +14 13 11    25.315   26.112  143.4    1.3   290   34.7 
2026-01-02 00:00 UT   09 14 39.4   +14 13 41    25.309   26.116  144.5    1.3   290   34.7 
2026-01-03 00:00 UT   09 14 31.1   +14 14 11    25.303   26.120  145.5    1.2   290   34.7 
2026-01-04 00:00 UT   09 14 22.8   +14 14 42    25.297   26.124  146.6    1.2   290   34.7 

    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.