C/2021 E3 (ZTF)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	31 May 2022	9.7	1.783 AU	1.220 AU	00h44m	-78°48'	105.5°	33.2°	234°
Perihelion	10 Jun 2022	9.8	1.778 AU	1.263 AU	06h18m	-78°34'	102.0°	34.0°	165°
Today	20 Nov 2025	25.8	11.310 AU	10.648 AU	07h17m	+24°20'	130.1°	3.8°	276°

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 5.7 + 5 log[∆] + 14.3 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/2021 E3 (ZTF) are:

    e (Eccentricity)                : 0.9996190
    q (Perihelion distance)         : 1.7776160
    i (Inclination)                 : 112.52100
    Ω (Longitude of ascending node) : 104.48390
    ω (Argument of perihelion)      : 228.78710
    L (Longitude of perihelion)     : 80.86300
    B (Latitude of perihelion)      : -44.01910
    T (Time of perihelion passage)  : 2459741.31170
    P (Orbital period in years)     : 318690.75

    Epoch                           : 2025 Nov 19
    Reference                       : MPEC 2024-GJ3

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-11-19 00:00 UT   07 17 24.0   +24 18 24    10.655   11.303  128.9    3.9   276   25.8 
2025-11-20 00:00 UT   07 17 06.7   +24 19 56    10.648   11.309  130.0    3.8   276   25.8 
2025-11-20 02:01 UT   07 17 05.2   +24 20 04    10.648   11.310  130.1    3.8   276   25.8 
2025-11-21 00:00 UT   07 16 49.0   +24 21 29    10.642   11.316  131.1    3.8   276   25.9 
2025-11-22 00:00 UT   07 16 30.9   +24 23 02    10.635   11.323  132.2    3.7   276   25.9 
2025-11-23 00:00 UT   07 16 12.5   +24 24 36    10.629   11.329  133.2    3.6   275   25.9 
2025-11-24 00:00 UT   07 15 53.7   +24 26 10    10.623   11.336  134.3    3.6   275   25.9 
2025-11-25 00:00 UT   07 15 34.6   +24 27 44    10.618   11.343  135.4    3.5   275   25.9 
2025-11-26 00:00 UT   07 15 15.2   +24 29 19    10.612   11.349  136.5    3.4   275   25.9 
2025-11-27 00:00 UT   07 14 55.5   +24 30 54    10.607   11.356  137.6    3.4   275   25.9 
2025-11-28 00:00 UT   07 14 35.4   +24 32 29    10.602   11.362  138.7    3.3   275   25.9 
2025-11-29 00:00 UT   07 14 15.1   +24 34 05    10.598   11.369  139.8    3.2   275   25.9 
2025-11-30 00:00 UT   07 13 54.4   +24 35 40    10.593   11.376  140.9    3.1   275   25.9 

    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.