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°05'	91.0°	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	21 May 2026	34.9	26.691 AU	26.962 AU	09h00m	+15°10'	73.4°	2.1°	107°

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)                : 0.9817580
    q (Perihelion distance)         : 1.0757310
    i (Inclination)                 : 144.79910
    Ω (Longitude of ascending node) : 317.79280
    ω (Argument of perihelion)      : 23.50270
    L (Longitude of perihelion)     : 298.23031
    B (Latitude of perihelion)      : 13.29012
    T (Time of perihelion passage)  : 2456846.72370
    P (Orbital period in years)     : 452.84

    Epoch                           : 2026 May 20
    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
2026-05-20 00:00 UT   09 00 28.1   +15 10 18    26.938   26.687   74.5    2.1   107   34.9 
2026-05-21 00:00 UT   09 00 30.1   +15 10 10    26.958   26.691   73.6    2.1   107   34.9 
2026-05-21 03:37 UT   09 00 30.4   +15 10 08    26.962   26.691   73.4    2.1   107   34.9 
2026-05-22 00:00 UT   09 00 32.2   +15 10 01    26.979   26.695   72.6    2.1   107   34.9 
2026-05-23 00:00 UT   09 00 34.4   +15 09 51    26.999   26.699   71.7    2.1   107   34.9 
2026-05-24 00:00 UT   09 00 36.8   +15 09 40    27.019   26.703   70.7    2.1   107   34.9 
2026-05-25 00:00 UT   09 00 39.3   +15 09 29    27.039   26.707   69.8    2.0   107   34.9 
2026-05-26 00:00 UT   09 00 41.9   +15 09 18    27.059   26.711   68.8    2.0   107   34.9 
2026-05-27 00:00 UT   09 00 44.7   +15 09 06    27.079   26.715   67.9    2.0   107   34.9 
2026-05-28 00:00 UT   09 00 47.6   +15 08 53    27.099   26.719   66.9    2.0   107   34.9 
2026-05-29 00:00 UT   09 00 50.6   +15 08 39    27.119   26.723   66.0    2.0   107   34.9 
2026-05-30 00:00 UT   09 00 53.7   +15 08 26    27.138   26.727   65.0    2.0   107   34.9 
2026-05-31 00:00 UT   09 00 57.0   +15 08 11    27.157   26.731   64.1    2.0   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.