C/2021 G3 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	18 Oct 2021	21.4	5.188 AU	5.747 AU	10h36m	+18°52'	51.6°	8.7°	300°
Nearest approach	5 Feb 2022	20.9	5.254 AU	4.368 AU	10h28m	+39°48'	151.3°	5.2°	219°
Today	11 Sep 2026	27.1	12.991 AU	12.593 AU	20h54m	+57°57'	111.2°	4.1°	142°

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. (10.5 + 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/2021 G3 (PANSTARRS) are:

    e (Eccentricity)                : 0.9997920
    q (Perihelion distance)         : 5.1878030
    i (Inclination)                 : 102.88070
    Ω (Longitude of ascending node) : 147.31800
    ω (Argument of perihelion)      : 10.65570
    L (Longitude of perihelion)     : 144.91625
    B (Latitude of perihelion)      : 10.38455
    T (Time of perihelion passage)  : 2459505.62030

    Epoch                           : 2026 Jul 19
    Reference                       : MPC194174

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-09-10 00:00 UT   20 54 47.4   +58 01 51    12.589   12.985  111.1    4.2   143   27.1 
2026-09-11 00:00 UT   20 54 23.3   +57 57 41    12.593   12.991  111.2    4.1   142   27.1 
2026-09-11 00:36 UT   20 54 22.7   +57 57 34    12.593   12.991  111.2    4.1   142   27.1 
2026-09-12 00:00 UT   20 53 59.6   +57 53 26    12.597   12.996  111.2    4.1   141   27.1 
2026-09-13 00:00 UT   20 53 36.3   +57 49 08    12.601   13.001  111.3    4.1   140   27.1 
2026-09-14 00:00 UT   20 53 13.6   +57 44 46    12.605   13.006  111.4    4.1   138   27.1 
2026-09-15 00:00 UT   20 52 51.3   +57 40 21    12.610   13.011  111.4    4.1   137   27.1 
2026-09-16 00:00 UT   20 52 29.5   +57 35 53    12.614   13.017  111.5    4.1   136   27.1 
2026-09-17 00:00 UT   20 52 08.2   +57 31 21    12.619   13.022  111.5    4.1   135   27.2 
2026-09-18 00:00 UT   20 51 47.4   +57 26 47    12.624   13.027  111.6    4.1   134   27.2 
2026-09-19 00:00 UT   20 51 27.1   +57 22 09    12.629   13.032  111.6    4.1   133   27.2 
2026-09-20 00:00 UT   20 51 07.3   +57 17 28    12.634   13.038  111.6    4.1   131   27.2 
2026-09-21 00:00 UT   20 50 48.0   +57 12 44    12.639   13.043  111.6    4.1   130   27.2 

    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.