C/2013 UQ4 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	8 Jul 2014	11.4	1.076 AU	0.335 AU	23h11m	+48°00'	90.9°	70.9°	234°
Nearest approach	11 Jul 2014	11.3	1.077 AU	0.306 AU	20h53m	+62°59'	93.1°	70.4°	201°
Today	16 Sep 2026	35.1	27.164 AU	27.957 AU	09h12m	+14°09'	37.2°	1.3°	285°

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)                : 0.9817550
    q (Perihelion distance)         : 1.0756980
    i (Inclination)                 : 144.79810
    Ω (Longitude of ascending node) : 317.79270
    ω (Argument of perihelion)      : 23.50180
    L (Longitude of perihelion)     : 298.23120
    B (Latitude of perihelion)      : 13.28996
    T (Time of perihelion passage)  : 2456846.66640
    P (Orbital period in years)     : 452.71

    Epoch                           : 2026 May 29
    Reference                       : MPC194135

    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
2026-09-15 00:00 UT   09 12 46.1   +14 10 23    27.968   27.157   35.5    1.2   285   35.1 
2026-09-16 00:00 UT   09 12 52.2   +14 09 49    27.962   27.161   36.5    1.3   285   35.1 
2026-09-16 17:46 UT   09 12 56.7   +14 09 24    27.957   27.164   37.2    1.3   285   35.1 
2026-09-17 00:00 UT   09 12 58.2   +14 09 15    27.956   27.165   37.4    1.3   285   35.1 
2026-09-18 00:00 UT   09 13 04.1   +14 08 42    27.949   27.169   38.4    1.3   285   35.1 
2026-09-19 00:00 UT   09 13 10.0   +14 08 08    27.942   27.173   39.3    1.3   285   35.1 
2026-09-20 00:00 UT   09 13 15.7   +14 07 35    27.935   27.177   40.3    1.4   285   35.1 
2026-09-21 00:00 UT   09 13 21.4   +14 07 03    27.927   27.181   41.2    1.4   285   35.1 
2026-09-22 00:00 UT   09 13 26.9   +14 06 31    27.919   27.185   42.2    1.4   285   35.1 
2026-09-23 00:00 UT   09 13 32.4   +14 05 59    27.912   27.189   43.1    1.4   285   35.1 
2026-09-24 00:00 UT   09 13 37.8   +14 05 27    27.904   27.193   44.1    1.5   285   35.1 
2026-09-25 00:00 UT   09 13 43.0   +14 04 56    27.895   27.197   45.1    1.5   285   35.1 
2026-09-26 00:00 UT   09 13 48.2   +14 04 25    27.887   27.201   46.0    1.5   286   35.1 

    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.