P/2019 GG21 (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	25 Mar 2019	20.3	3.954 AU	2.959 AU	12h00m	-03°18'	175.9°	1.0°	67°
Perihelion	13 May 2019	20.5	3.943 AU	3.271 AU	11h45m	-02°15'	125.4°	12.1°	111°
Today	29 Aug 2026	27.0	10.355 AU	9.370 AU	23h18m	-03°33'	166.4°	1.3°	243°

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. (12.0 + 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 P/2019 GG21 (PANSTARRS) are:

    e (Eccentricity)                : 0.4731130
    q (Perihelion distance)         : 3.9434990
    i (Inclination)                 : 6.07160
    Ω (Longitude of ascending node) : 340.53210
    ω (Argument of perihelion)      : 209.15060
    L (Longitude of perihelion)     : 9.54579
    B (Latitude of perihelion)      : -2.95329
    T (Time of perihelion passage)  : 2458616.82090
    P (Orbital period in years)     : 20.48

    Epoch                           : 2026 May 29
    Reference                       : MPC194160

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-08-28 00:00 UT   23 18 45.6   -03 31 20     9.373   10.353  165.2    1.4   244   27.0 
2026-08-29 00:00 UT   23 18 28.3   -03 32 59     9.371   10.354  166.2    1.3   244   27.0 
2026-08-29 04:39 UT   23 18 25.0   -03 33 18     9.370   10.355  166.4    1.3   243   27.0 
2026-08-30 00:00 UT   23 18 10.9   -03 34 38     9.368   10.356  167.3    1.2   243   27.0 
2026-08-31 00:00 UT   23 17 53.4   -03 36 19     9.366   10.357  168.3    1.1   243   27.0 
2026-09-01 00:00 UT   23 17 35.8   -03 37 60     9.365   10.358  169.4    1.0   242   27.0 
2026-09-02 00:00 UT   23 17 18.1   -03 39 41     9.363   10.359  170.4    0.9   242   27.0 
2026-09-03 00:00 UT   23 17 00.4   -03 41 23     9.362   10.361  171.4    0.8   241   27.0 
2026-09-04 00:00 UT   23 16 42.6   -03 43 05     9.361   10.362  172.5    0.7   240   27.0 
2026-09-05 00:00 UT   23 16 24.7   -03 44 48     9.361   10.363  173.5    0.6   239   27.0 
2026-09-06 00:00 UT   23 16 06.8   -03 46 31     9.360   10.364  174.6    0.5   238   27.0 
2026-09-07 00:00 UT   23 15 48.8   -03 48 15     9.360   10.366  175.6    0.4   236   27.0 
2026-09-08 00:00 UT   23 15 30.9   -03 49 59     9.361   10.367  176.6    0.3   232   27.0 

    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.