C/2021 U5 (Catalina)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	27 Jan 2022	17.8	2.359 AU	1.623 AU	10h19m	-27°15'	127.8°	19.3°	329°
Nearest approach	3 Mar 2022	17.6	2.392 AU	1.460 AU	10h16m	-16°58'	154.3°	10.4°	24°
Today	18 Sep 2025	28.8	11.329 AU	11.317 AU	17h38m	+15°44'	88.1°	5.1°	91°

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.)

The orbital elements of C/2021 U5 (Catalina) are:

            e (Eccentricity)                : 0.9894510
            q (Perihelion distance)         : 2.3589390
            i (Inclination)                 : 39.03960
            Ω (Longitude of ascending node) : 182.66230
            ω (Argument of perihelion)      : 321.47350
            L (Longitude of perihelion)     : 150.92922
            B (Latitude of perihelion)      : -23.09914
            T (Time of perihelion passage)  : 2459606.57360
            P (Orbital period in years)     : 3343.94

            Epoch                           : 2025 Sep 17
            Reference                       : MPEC 2022-WQ9

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. 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. (13.00 + 5 log[∆] + 10.00 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-09-18 00:00 UT   17 38 09.7   +15 46 41    11.304   11.325   88.6    5.1    92   28.8 
2025-09-18 16:08 UT   17 38 13.3   +15 44 30    11.317   11.329   88.1    5.1    91   28.8 
2025-09-19 00:00 UT   17 38 15.1   +15 43 27    11.323   11.331   87.9    5.1    91   28.8 
2025-09-20 00:00 UT   17 38 20.8   +15 40 13    11.342   11.337   87.2    5.1    90   28.8 
2025-09-21 00:00 UT   17 38 26.9   +15 37 00    11.362   11.344   86.4    5.1    90   28.8 
2025-09-22 00:00 UT   17 38 33.3   +15 33 48    11.381   11.350   85.7    5.1    89   28.8 
2025-09-23 00:00 UT   17 38 40.0   +15 30 37    11.400   11.356   85.0    5.1    89   28.8 
2025-09-24 00:00 UT   17 38 47.1   +15 27 26    11.419   11.363   84.2    5.0    88   28.8 
2025-09-25 00:00 UT   17 38 54.5   +15 24 16    11.439   11.369   83.5    5.0    87   28.8 
2025-09-26 00:00 UT   17 39 02.3   +15 21 07    11.458   11.375   82.8    5.0    87   28.9 
2025-09-27 00:00 UT   17 39 10.4   +15 17 59    11.477   11.382   82.0    5.0    86   28.9 
2025-09-28 00:00 UT   17 39 18.8   +15 14 52    11.496   11.388   81.3    5.0    86   28.9 

    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.