C/2020 S4 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	6 Feb 2023	15.0	3.374 AU	2.398 AU	09h29m	+25°12'	170.1°	2.9°	198°
Perihelion	9 Feb 2023	15.0	3.373 AU	2.400 AU	09h28m	+25°42'	168.9°	3.2°	176°
Today	24 Sep 2026	26.2	10.897 AU	11.243 AU	16h33m	-07°28'	67.4°	4.9°	93°

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 5.1 + 5 log[∆] + 15.3 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 S4 (PANSTARRS) are:

    e (Eccentricity)                : 1.0034100
    q (Perihelion distance)         : 3.3734290
    i (Inclination)                 : 20.57170
    Ω (Longitude of ascending node) : 117.67560
    ω (Argument of perihelion)      : 21.12870
    L (Longitude of perihelion)     : 137.56579
    B (Latitude of perihelion)      : 7.27661
    T (Time of perihelion passage)  : 2459985.43510

    Epoch                           : 2026 Sep 24
    Reference                       : MPC194170

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-09-23 00:00 UT   16 33 24.7   -07 24 42    11.206   10.886   68.9    4.9    93   26.1 
2026-09-24 00:00 UT   16 33 37.5   -07 26 41    11.228   10.892   68.0    4.9    93   26.2 
2026-09-24 17:34 UT   16 33 47.1   -07 28 07    11.243   10.897   67.4    4.9    93   26.2 
2026-09-25 00:00 UT   16 33 50.7   -07 28 39    11.248   10.898   67.1    4.9    92   26.2 
2026-09-26 00:00 UT   16 34 04.1   -07 30 37    11.269   10.904   66.2    4.8    92   26.2 
2026-09-27 00:00 UT   16 34 17.9   -07 32 34    11.290   10.911   65.4    4.8    92   26.2 
2026-09-28 00:00 UT   16 34 31.9   -07 34 32    11.311   10.917   64.5    4.8    92   26.2 
2026-09-29 00:00 UT   16 34 46.1   -07 36 29    11.331   10.923   63.6    4.7    91   26.2 
2026-09-30 00:00 UT   16 35 00.7   -07 38 25    11.352   10.929   62.7    4.7    91   26.2 
2026-10-01 00:00 UT   16 35 15.5   -07 40 22    11.372   10.935   61.8    4.6    91   26.2 
2026-10-02 00:00 UT   16 35 30.6   -07 42 18    11.392   10.941   60.9    4.6    90   26.2 
2026-10-03 00:00 UT   16 35 45.9   -07 44 13    11.412   10.947   60.1    4.5    90   26.2 
2026-10-04 00:00 UT   16 36 01.5   -07 46 08    11.432   10.954   59.2    4.5    90   26.2 

    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.