C/2023 E1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	30 Jun 2023	10.6	1.027 AU	0.644 AU	14h47m	+79°55'	72.5°	70.7°	126°
Nearest approach	17 Aug 2023	10.4	1.287 AU	0.376 AU	21h46m	+36°27'	130.1°	37.0°	180°
Today	2 Nov 2025	25.2	8.460 AU	7.685 AU	03h55m	-20°27'	139.0°	4.4°	328°

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 11.5 + 5 log[∆] + 10.0 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/2023 E1 (ATLAS) are:

    e (Eccentricity)                : 0.9465590
    q (Perihelion distance)         : 1.0271900
    i (Inclination)                 : 38.28470
    Ω (Longitude of ascending node) : 164.53290
    ω (Argument of perihelion)      : 105.92490
    L (Longitude of perihelion)     : 94.50917
    B (Latitude of perihelion)      : 36.56909
    T (Time of perihelion passage)  : 2460126.28000
    P (Orbital period in years)     : 84.27

    Epoch                           : 2025 Nov 01
    Reference                       : MPEC 2024-D33

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-11-01 00:00 UT   03 55 53.6   -20 23 56     7.679    8.450  138.6    4.5   325   25.1 
2025-11-02 00:00 UT   03 55 28.3   -20 26 40     7.683    8.457  138.9    4.4   327   25.1 
2025-11-02 11:06 UT   03 55 16.6   -20 27 54     7.685    8.460  139.0    4.4   328   25.2 
2025-11-03 00:00 UT   03 55 02.9   -20 29 19     7.688    8.463  139.1    4.4   329   25.2 
2025-11-04 00:00 UT   03 54 37.2   -20 31 53     7.693    8.470  139.3    4.4   330   25.2 
2025-11-05 00:00 UT   03 54 11.4   -20 34 22     7.698    8.477  139.5    4.4   332   25.2 
2025-11-06 00:00 UT   03 53 45.5   -20 36 46     7.703    8.484  139.7    4.3   334   25.2 
2025-11-07 00:00 UT   03 53 19.4   -20 39 06     7.709    8.491  139.8    4.3   335   25.2 
2025-11-08 00:00 UT   03 52 53.2   -20 41 20     7.715    8.497  140.0    4.3   337   25.2 
2025-11-09 00:00 UT   03 52 26.8   -20 43 28     7.721    8.504  140.0    4.3   339   25.2 
2025-11-10 00:00 UT   03 52 00.4   -20 45 32     7.727    8.511  140.1    4.3   340   25.2 
2025-11-11 00:00 UT   03 51 33.9   -20 47 30     7.734    8.518  140.1    4.3   342   25.2 
2025-11-12 00:00 UT   03 51 07.3   -20 49 23     7.740    8.524  140.2    4.3   344   25.2 

    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.