C/2021 D2 (ZTF)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	3 Feb 2022	17.9	2.956 AU	2.542 AU	16h19m	+85°02'	105.0°	18.8°	290°
Nearest approach	7 Feb 2022	17.9	2.956 AU	2.540 AU	15h39m	+87°05'	105.2°	18.8°	275°
Today	3 Oct 2026	28.1	13.371 AU	13.653 AU	08h10m	-48°24'	71.6°	4.1°	254°

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 11.2 + 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 D2 (ZTF) are:

    e (Eccentricity)                : 1.0013490
    q (Perihelion distance)         : 2.9556220
    i (Inclination)                 : 83.76300
    Ω (Longitude of ascending node) : 305.61020
    ω (Argument of perihelion)      : 125.13260
    L (Longitude of perihelion)     : 296.83337
    B (Latitude of perihelion)      : 54.38829
    T (Time of perihelion passage)  : 2459613.53860

    Epoch                           : 2026 Oct 02
    Reference                       : MPC191586

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-10-02 00:00 UT   08 10 14.0   -48 18 48    13.652   13.364   71.2    4.1   253   28.1 
2026-10-03 00:00 UT   08 10 21.7   -48 23 30    13.653   13.370   71.5    4.1   254   28.1 
2026-10-03 06:34 UT   08 10 23.7   -48 24 47    13.653   13.371   71.6    4.1   254   28.1 
2026-10-04 00:00 UT   08 10 29.0   -48 28 13    13.654   13.375   71.8    4.1   255   28.1 
2026-10-05 00:00 UT   08 10 36.0   -48 32 57    13.655   13.381   72.1    4.1   256   28.1 
2026-10-06 00:00 UT   08 10 42.6   -48 37 42    13.656   13.387   72.4    4.1   257   28.1 
2026-10-07 00:00 UT   08 10 48.7   -48 42 28    13.657   13.393   72.7    4.1   258   28.1 
2026-10-08 00:00 UT   08 10 54.5   -48 47 15    13.657   13.399   73.0    4.1   259   28.1 
2026-10-09 00:00 UT   08 10 59.8   -48 52 03    13.658   13.405   73.3    4.1   260   28.1 
2026-10-10 00:00 UT   08 11 04.7   -48 56 52    13.659   13.411   73.6    4.1   261   28.1 
2026-10-11 00:00 UT   08 11 09.2   -49 01 41    13.659   13.417   73.9    4.1   262   28.1 
2026-10-12 00:00 UT   08 11 13.3   -49 06 30    13.660   13.422   74.2    4.1   263   28.1 
2026-10-13 00:00 UT   08 11 17.0   -49 11 21    13.660   13.428   74.5    4.1   264   28.1 

    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.