C/2021 U5 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	27 Jan 2022	17.8	2.360 AU	1.622 AU	10h19m	-27°12'	128.1°	19.2°	329°
Nearest approach	3 Mar 2022	17.6	2.393 AU	1.461 AU	10h15m	-16°58'	154.2°	10.4°	24°
Today	4 Jul 2026	29.6	13.104 AU	12.336 AU	18h13m	+18°34'	137.5°	3.0°	167°

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. (13.0 + 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/2021 U5 (Catalina) are:

    e (Eccentricity)                : 0.9896440
    q (Perihelion distance)         : 2.3597390
    i (Inclination)                 : 39.03940
    Ω (Longitude of ascending node) : 182.61560
    ω (Argument of perihelion)      : 321.53100
    L (Longitude of perihelion)     : 150.93522
    B (Latitude of perihelion)      : -23.06823
    T (Time of perihelion passage)  : 2459606.78800
    P (Orbital period in years)     : 3439.60

    Epoch                           : 2026 May 29
    Reference                       : MPC194177

    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
2026-07-03 00:00 UT   18 14 04.1   +18 35 17    12.327   13.097  137.7    3.0   169   29.6 
2026-07-04 00:00 UT   18 13 47.8   +18 34 41    12.334   13.103  137.5    3.0   167   29.6 
2026-07-04 04:25 UT   18 13 44.8   +18 34 34    12.336   13.104  137.5    3.0   167   29.6 
2026-07-05 00:00 UT   18 13 31.6   +18 34 02    12.342   13.108  137.4    3.0   166   29.6 
2026-07-06 00:00 UT   18 13 15.5   +18 33 20    12.350   13.114  137.2    3.0   164   29.6 
2026-07-07 00:00 UT   18 12 59.5   +18 32 35    12.358   13.120  137.0    3.0   163   29.6 
2026-07-08 00:00 UT   18 12 43.5   +18 31 46    12.366   13.126  136.8    3.0   161   29.6 
2026-07-09 00:00 UT   18 12 27.6   +18 30 55    12.375   13.132  136.6    3.0   160   29.6 
2026-07-10 00:00 UT   18 12 11.9   +18 29 60    12.383   13.138  136.4    3.1   159   29.6 
2026-07-11 00:00 UT   18 11 56.2   +18 29 02    12.392   13.144  136.1    3.1   157   29.7 
2026-07-12 00:00 UT   18 11 40.7   +18 28 01    12.402   13.150  135.8    3.1   156   29.7 
2026-07-13 00:00 UT   18 11 25.3   +18 26 58    12.411   13.156  135.5    3.1   154   29.7 
2026-07-14 00:00 UT   18 11 10.0   +18 25 51    12.421   13.162  135.2    3.1   153   29.7 

    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.