C/2021 E3 (ZTF)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	31 May 2022	9.7	1.783 AU	1.221 AU	00h45m	-78°48'	105.5°	33.2°	234°
Perihelion	10 Jun 2022	9.8	1.778 AU	1.263 AU	06h16m	-78°35'	102.0°	34.0°	165°
Today	7 Jan 2026	26.0	11.631 AU	10.650 AU	06h58m	+25°35'	175.2°	0.4°	131°

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)                : 0.9995520
    q (Perihelion distance)         : 1.7776880
    i (Inclination)                 : 112.52110
    Ω (Longitude of ascending node) : 104.48390
    ω (Argument of perihelion)      : 228.78370
    L (Longitude of perihelion)     : 80.86542
    B (Latitude of perihelion)      : -44.01618
    T (Time of perihelion passage)  : 2459741.20320
    P (Orbital period in years)     : 249957.57

    Epoch                           : 2026 Jan 06
    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
2026-01-06 00:00 UT   06 58 48.3   +25 33 10    10.637   11.620  176.5    0.3   149   26.0 
2026-01-07 00:00 UT   06 58 22.3   +25 34 34    10.645   11.626  175.8    0.4   137   26.0 
2026-01-07 16:46 UT   06 58 04.1   +25 35 33    10.650   11.631  175.2    0.4   131   26.0 
2026-01-08 00:00 UT   06 57 56.3   +25 35 58    10.652   11.633  174.9    0.4   129   26.0 
2026-01-09 00:00 UT   06 57 30.4   +25 37 21    10.660   11.639  173.9    0.5   123   26.1 
2026-01-10 00:00 UT   06 57 04.5   +25 38 43    10.669   11.646  172.9    0.6   119   26.1 
2026-01-11 00:00 UT   06 56 38.7   +25 40 05    10.678   11.652  171.8    0.7   116   26.1 
2026-01-12 00:00 UT   06 56 13.1   +25 41 26    10.687   11.659  170.8    0.8   114   26.1 
2026-01-13 00:00 UT   06 55 47.5   +25 42 46    10.696   11.665  169.7    0.9   112   26.1 
2026-01-14 00:00 UT   06 55 22.0   +25 44 05    10.706   11.672  168.6    1.0   110   26.1 
2026-01-15 00:00 UT   06 54 56.6   +25 45 23    10.716   11.679  167.6    1.0   109   26.1 
2026-01-16 00:00 UT   06 54 31.4   +25 46 41    10.726   11.685  166.5    1.1   108   26.1 
2026-01-17 00:00 UT   06 54 06.3   +25 47 58    10.737   11.692  165.4    1.2   107   26.1 

    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.