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	06h19m	-78°32'	102.0°	34.0°	165°
Today	2 Oct 2025	25.8	10.988 AU	11.109 AU	07h23m	+23°19'	80.5°	5.2°	278°

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.)

The orbital elements of C/2021 E3 (ZTF) are:

            e (Eccentricity)                : 0.9996940
            q (Perihelion distance)         : 1.7775550
            i (Inclination)                 : 112.52140
            Ω (Longitude of ascending node) : 104.48390
            ω (Argument of perihelion)      : 228.79130
            L (Longitude of perihelion)     : 80.85953
            B (Latitude of perihelion)      : -44.02250
            T (Time of perihelion passage)  : 2459741.42610
            P (Orbital period in years)     : 442743.74

            Epoch                           : 2025 Oct 01
            Reference                       : MPEC 2024-GJ3

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. The gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (8.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 5.70 + 5 log[∆] + 14.26 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-10-02 00:00 UT   07 23 29.9   +23 18 36    11.118   10.982   79.6    5.1   278   25.8 
2025-10-02 20:51 UT   07 23 31.6   +23 19 24    11.109   10.988   80.5    5.2   278   25.8 
2025-10-03 00:00 UT   07 23 31.8   +23 19 31    11.108   10.989   80.6    5.2   278   25.8 
2025-10-04 00:00 UT   07 23 33.3   +23 20 26    11.097   10.996   81.6    5.2   278   25.8 
2025-10-05 00:00 UT   07 23 34.3   +23 21 23    11.087   11.002   82.5    5.2   278   25.8 
2025-10-06 00:00 UT   07 23 35.0   +23 22 20    11.076   11.009   83.5    5.2   278   25.8 
2025-10-07 00:00 UT   07 23 35.3   +23 23 18    11.066   11.016   84.5    5.2   278   25.8 
2025-10-08 00:00 UT   07 23 35.3   +23 24 17    11.055   11.022   85.5    5.2   278   25.8 
2025-10-09 00:00 UT   07 23 34.8   +23 25 17    11.045   11.029   86.5    5.2   278   25.8 
2025-10-10 00:00 UT   07 23 33.9   +23 26 18    11.034   11.036   87.5    5.2   278   25.8 
2025-10-11 00:00 UT   07 23 32.6   +23 27 20    11.023   11.043   88.5    5.2   278   25.8 
2025-10-12 00:00 UT   07 23 30.9   +23 28 22    11.013   11.049   89.5    5.2   278   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.