A/2021 E4
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	19 Feb 2022	19.7	4.712 AU	3.940 AU	11h41m	+49°49'	137.1°	8.2°	215°
Perihelion	24 Apr 2022	20.2	4.684 AU	4.532 AU	10h02m	+59°28'	92.4°	12.4°	121°
Today	19 Jun 2026	23.9	11.579 AU	11.749 AU	23h55m	+28°34'	77.9°	4.9°	250°

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)                : 0.9909700
    q (Perihelion distance)         : 4.6840240
    i (Inclination)                 : 116.40580
    Ω (Longitude of ascending node) : 171.12230
    ω (Argument of perihelion)      : 48.32840
    L (Longitude of perihelion)     : 144.57340
    B (Latitude of perihelion)      : 41.99257
    T (Time of perihelion passage)  : 2459694.46980
    P (Orbital period in years)     : 11814.00

    Epoch                           : 2026 Jun 18
    Reference                       : MPC194173

    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
2026-06-18 00:00 UT   23 55 21.9   +28 33 19    11.761   11.572   76.8    4.9   250   23.9 
2026-06-19 00:00 UT   23 55 21.4   +28 34 25    11.752   11.577   77.7    4.9   250   23.9 
2026-06-19 05:32 UT   23 55 21.3   +28 34 40    11.749   11.579   77.9    4.9   250   23.9 
2026-06-20 00:00 UT   23 55 20.6   +28 35 30    11.742   11.583   78.5    4.9   249   23.9 
2026-06-21 00:00 UT   23 55 19.4   +28 36 32    11.733   11.588   79.4    4.9   249   23.9 
2026-06-22 00:00 UT   23 55 17.9   +28 37 34    11.723   11.594   80.2    5.0   249   23.9 
2026-06-23 00:00 UT   23 55 16.0   +28 38 33    11.713   11.599   81.1    5.0   248   23.9 
2026-06-24 00:00 UT   23 55 13.8   +28 39 31    11.704   11.605   81.9    5.0   248   23.9 
2026-06-25 00:00 UT   23 55 11.2   +28 40 26    11.694   11.610   82.8    5.0   247   23.9 
2026-06-26 00:00 UT   23 55 08.3   +28 41 20    11.684   11.616   83.6    5.0   247   23.9 
2026-06-27 00:00 UT   23 55 05.0   +28 42 12    11.675   11.621   84.5    5.0   246   23.9 
2026-06-28 00:00 UT   23 55 01.3   +28 43 02    11.665   11.627   85.3    5.0   246   23.9 
2026-06-29 00:00 UT   23 54 57.3   +28 43 50    11.655   11.632   86.2    5.0   246   23.9 

    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.