C/2020 U4 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	30 Nov 2021	17.1	5.451 AU	4.487 AU	04h00m	+33°53'	166.5°	2.4°	154°
Perihelion	10 Apr 2022	17.7	5.363 AU	6.233 AU	02h40m	+26°37'	27.4°	4.9°	51°
Today	29 Sep 2026	22.6	12.160 AU	11.585 AU	20h43m	-14°59'	123.0°	4.0°	77°

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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 6.5 + 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/2020 U4 (PANSTARRS) are:

    e (Eccentricity)                : 1.0020800
    q (Perihelion distance)         : 5.3629850
    i (Inclination)                 : 167.00330
    Ω (Longitude of ascending node) : 120.40550
    ω (Argument of perihelion)      : 70.21170
    L (Longitude of perihelion)     : 50.67220
    B (Latitude of perihelion)      : 12.21700
    T (Time of perihelion passage)  : 2459680.24600

    Epoch                           : 2026 Sep 28
    Reference                       : MPC194171

    Classification(s):              : Nearly isotropic; New (a > 10000 AU)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-09-28 00:00 UT   20 43 37.3   -14 57 15    11.552   12.151  124.7    3.9    77   22.6 
2026-09-29 00:00 UT   20 43 21.8   -14 58 49    11.572   12.156  123.7    3.9    77   22.6 
2026-09-29 16:14 UT   20 43 11.5   -14 59 53    11.585   12.160  123.0    4.0    77   22.6 
2026-09-30 00:00 UT   20 43 06.6   -15 00 22    11.592   12.162  122.6    4.0    77   22.6 
2026-10-01 00:00 UT   20 42 51.7   -15 01 54    11.612   12.167  121.6    4.0    77   22.6 
2026-10-02 00:00 UT   20 42 37.2   -15 03 24    11.632   12.172  120.6    4.1    77   22.6 
2026-10-03 00:00 UT   20 42 23.0   -15 04 53    11.653   12.177  119.5    4.1    77   22.6 
2026-10-04 00:00 UT   20 42 09.1   -15 06 21    11.673   12.183  118.5    4.1    77   22.7 
2026-10-05 00:00 UT   20 41 55.7   -15 07 47    11.694   12.188  117.4    4.2    77   22.7 
2026-10-06 00:00 UT   20 41 42.5   -15 09 12    11.715   12.193  116.4    4.2    77   22.7 
2026-10-07 00:00 UT   20 41 29.8   -15 10 35    11.736   12.198  115.3    4.2    76   22.7 
2026-10-08 00:00 UT   20 41 17.4   -15 11 57    11.758   12.203  114.3    4.3    76   22.7 
2026-10-09 00:00 UT   20 41 05.3   -15 13 17    11.779   12.209  113.3    4.3    76   22.7 

    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.