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°49'	105.5°	33.2°	234°
Perihelion	10 Jun 2022	9.8	1.778 AU	1.263 AU	06h18m	-78°33'	102.0°	34.0°	165°
Today	29 Oct 2025	25.8	11.167 AU	10.829 AU	07h21m	+23°49'	107.5°	4.9°	277°

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)                : 0.9996520
    q (Perihelion distance)         : 1.7775880
    i (Inclination)                 : 112.52110
    Ω (Longitude of ascending node) : 104.48390
    ω (Argument of perihelion)      : 228.78890
    L (Longitude of perihelion)     : 80.86157
    B (Latitude of perihelion)      : -44.02058
    T (Time of perihelion passage)  : 2459741.36270
    P (Orbital period in years)     : 365071.39

    Epoch                           : 2025 Oct 28
    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
2025-10-28 00:00 UT   07 22 08.3   +23 47 06    10.845   11.156  105.7    4.9   278   25.8 
2025-10-29 00:00 UT   07 21 59.6   +23 48 24    10.835   11.163  106.8    4.9   277   25.8 
2025-10-29 16:11 UT   07 21 53.5   +23 49 17    10.829   11.167  107.5    4.9   277   25.8 
2025-10-30 00:00 UT   07 21 50.5   +23 49 42    10.826   11.170  107.8    4.9   277   25.8 
2025-10-31 00:00 UT   07 21 41.0   +23 51 02    10.816   11.176  108.8    4.8   277   25.8 
2025-11-01 00:00 UT   07 21 31.0   +23 52 22    10.806   11.183  109.9    4.8   277   25.8 
2025-11-02 00:00 UT   07 21 20.7   +23 53 43    10.796   11.190  110.9    4.8   277   25.8 
2025-11-03 00:00 UT   07 21 09.9   +23 55 04    10.787   11.196  112.0    4.7   277   25.8 
2025-11-04 00:00 UT   07 20 58.8   +23 56 27    10.778   11.203  113.0    4.7   277   25.8 
2025-11-05 00:00 UT   07 20 47.2   +23 57 50    10.768   11.210  114.1    4.6   277   25.8 
2025-11-06 00:00 UT   07 20 35.2   +23 59 14    10.759   11.216  115.1    4.6   277   25.8 
2025-11-07 00:00 UT   07 20 22.9   +24 00 39    10.750   11.223  116.2    4.5   277   25.8 
2025-11-08 00:00 UT   07 20 10.1   +24 02 04    10.741   11.230  117.2    4.5   277   25.8 

    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.