A/2021 E4
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	19 Feb 2022	19.7	4.705 AU	3.933 AU	11h42m	+49°44'	137.1°	8.2°	215°
Perihelion	25 Apr 2022	20.2	4.677 AU	4.524 AU	10h03m	+59°25'	92.5°	12.4°	121°
Today	26 Apr 2024	22.0	7.243 AU	7.922 AU	00h13m	+51°01'	44.8°	5.6°	316°

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 A/2021 E4 are:

            e (Eccentricity)                : 0.9912010
            q (Perihelion distance)         : 4.6770960
            i (Inclination)                 : 116.36340
            Ω (Longitude of ascending node) : 171.16320
            ω (Argument of perihelion)      : 48.26660
            L (Longitude of perihelion)     : 144.69813
            B (Latitude of perihelion)      : 41.96195
            T (Time of perihelion passage)  : 2459694.51460
            P (Orbital period in years)     : 12255.03

            Epoch                           : 2024 Apr 25
            Reference                       : MPEC 2023-SQ0

            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 indicates the expected brightness if this object is a comet (13.50 + 5 log[∆] + 55.00 log[r]), whereas the red curve indicates the expected lightcurve for an asteroid (H=12.80; G=.15).

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
2024-04-26 00:00 UT   00 13 30.2   +51 00 56     7.922    7.242   44.8    5.6   316   22.0 
2024-04-26 02:55 UT   00 13 34.2   +51 01 08     7.922    7.243   44.8    5.6   316   22.0 
2024-04-27 00:00 UT   00 14 02.2   +51 02 36     7.926    7.248   44.9    5.6   315   22.0 
2024-04-28 00:00 UT   00 14 33.7   +51 04 20     7.930    7.253   45.0    5.6   314   22.1 
2024-04-29 00:00 UT   00 15 04.9   +51 06 07     7.934    7.258   45.1    5.6   312   22.1 
2024-04-30 00:00 UT   00 15 35.6   +51 07 56     7.938    7.264   45.2    5.7   311   22.1 
2024-05-01 00:00 UT   00 16 05.9   +51 09 49     7.941    7.269   45.4    5.7   310   22.1 
2024-05-02 00:00 UT   00 16 35.8   +51 11 45     7.944    7.274   45.5    5.7   309   22.1 
2024-05-03 00:00 UT   00 17 05.3   +51 13 43     7.947    7.280   45.7    5.7   308   22.1 
2024-05-04 00:00 UT   00 17 34.3   +51 15 44     7.950    7.285   45.9    5.7   307   22.1 
2024-05-05 00:00 UT   00 18 02.9   +51 17 48     7.953    7.290   46.1    5.7   305   22.1 
2024-05-06 00:00 UT   00 18 31.1   +51 19 55     7.956    7.296   46.3    5.7   304   22.1 

    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.