C/2013 UQ4 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	8 Jul 2014	11.4	1.076 AU	0.331 AU	23h08m	+48°39'	91.3°	70.8°	233°
Nearest approach	11 Jul 2014	11.2	1.078 AU	0.304 AU	20h53m	+62°51'	93.3°	70.4°	201°
Today	7 May 2026	34.9	26.635 AU	26.668 AU	09h00m	+15°11'	87.0°	2.2°	106°

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)                : 0.9817730
    q (Perihelion distance)         : 1.0761710
    i (Inclination)                 : 144.80900
    Ω (Longitude of ascending node) : 317.79370
    ω (Argument of perihelion)      : 23.51130
    L (Longitude of perihelion)     : 298.22158
    B (Latitude of perihelion)      : 13.29147
    T (Time of perihelion passage)  : 2456847.06980
    P (Orbital period in years)     : 453.68

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    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
2026-05-06 00:00 UT   09 00 15.7   +15 11 14    26.646   26.631   88.0    2.2   106   34.9 
2026-05-07 00:00 UT   09 00 15.7   +15 11 14    26.667   26.635   87.0    2.2   106   34.9 
2026-05-07 01:15 UT   09 00 15.7   +15 11 14    26.668   26.635   87.0    2.2   106   34.9 
2026-05-08 00:00 UT   09 00 15.7   +15 11 13    26.688   26.639   86.1    2.2   106   34.9 
2026-05-09 00:00 UT   09 00 16.0   +15 11 12    26.709   26.643   85.1    2.2   107   34.9 
2026-05-10 00:00 UT   09 00 16.3   +15 11 10    26.730   26.647   84.1    2.2   107   34.9 
2026-05-11 00:00 UT   09 00 16.9   +15 11 08    26.751   26.651   83.2    2.2   107   34.9 
2026-05-12 00:00 UT   09 00 17.6   +15 11 05    26.772   26.655   82.2    2.2   107   34.9 
2026-05-13 00:00 UT   09 00 18.4   +15 11 01    26.793   26.659   81.2    2.1   107   34.9 
2026-05-14 00:00 UT   09 00 19.3   +15 10 57    26.814   26.663   80.3    2.1   107   34.9 
2026-05-15 00:00 UT   09 00 20.4   +15 10 52    26.835   26.667   79.3    2.1   107   34.9 
2026-05-16 00:00 UT   09 00 21.7   +15 10 47    26.856   26.671   78.4    2.1   107   34.9 
2026-05-17 00:00 UT   09 00 23.1   +15 10 40    26.877   26.675   77.4    2.1   107   34.9 

    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.