A/2021 E4
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	19 Feb 2022	19.7	4.711 AU	3.939 AU	11h41m	+49°49'	137.1°	8.2°	215°
Perihelion	24 Apr 2022	20.2	4.683 AU	4.530 AU	10h02m	+59°28'	92.5°	12.4°	121°
Today	13 Mar 2026	23.7	11.040 AU	11.893 AU	23h34m	+26°32'	29.6°	2.5°	2°

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. The displayed light curve is calculated under the assumption that the object remains inactive. (H=12.80; G=.15).

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 A/2021 E4 are:

    e (Eccentricity)                : 0.9908460
    q (Perihelion distance)         : 4.6827020
    i (Inclination)                 : 116.39930
    Ω (Longitude of ascending node) : 171.12670
    ω (Argument of perihelion)      : 48.31240
    L (Longitude of perihelion)     : 144.59591
    B (Latitude of perihelion)      : 41.98265
    T (Time of perihelion passage)  : 2459694.39020
    P (Orbital period in years)     : 11569.87

    Epoch                           : 2026 Mar 12
    Reference                       : MPEC 2026-E44

    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
2026-03-12 00:00 UT   23 34 33.9   +26 31 37    11.881   11.034   30.1    2.6     4   23.7 
2026-03-13 00:00 UT   23 34 54.1   +26 31 56    11.891   11.039   29.7    2.6     2   23.7 
2026-03-13 06:06 UT   23 34 59.2   +26 32 01    11.893   11.040   29.6    2.5     2   23.7 
2026-03-14 00:00 UT   23 35 14.2   +26 32 17    11.900   11.045   29.3    2.5     0   23.7 
2026-03-15 00:00 UT   23 35 34.4   +26 32 41    11.910   11.050   28.9    2.5   359   23.7 
2026-03-16 00:00 UT   23 35 54.5   +26 33 07    11.919   11.056   28.6    2.5   357   23.7 
2026-03-17 00:00 UT   23 36 14.5   +26 33 36    11.927   11.061   28.2    2.4   355   23.7 
2026-03-18 00:00 UT   23 36 34.5   +26 34 06    11.936   11.067   27.9    2.4   353   23.7 
2026-03-19 00:00 UT   23 36 54.5   +26 34 39    11.944   11.072   27.6    2.4   351   23.7 
2026-03-20 00:00 UT   23 37 14.4   +26 35 14    11.952   11.078   27.4    2.4   350   23.7 
2026-03-21 00:00 UT   23 37 34.3   +26 35 51    11.960   11.083   27.1    2.3   348   23.7 
2026-03-22 00:00 UT   23 37 54.1   +26 36 31    11.967   11.089   26.9    2.3   346   23.7 
2026-03-23 00:00 UT   23 38 13.8   +26 37 12    11.975   11.094   26.8    2.3   344   23.7 

    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.