C/2018 E1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	7 Mar 2018	17.4	2.723 AU	2.740 AU	04h27m	-45°21'	78.6°	20.9°	94°
Perihelion	18 Apr 2018	17.5	2.689 AU	2.868 AU	05h44m	-27°54'	69.7°	20.5°	115°
Today	5 Jan 2026	27.8	18.665 AU	18.737 AU	15h59m	+51°12'	84.3°	3.0°	318°

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 12.0 + 5 log[∆] + 7.5 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/2018 E1 (ATLAS) are:

    e (Eccentricity)                : 0.9501030
    q (Perihelion distance)         : 2.6893810
    i (Inclination)                 : 72.48750
    Ω (Longitude of ascending node) : 146.79020
    ω (Argument of perihelion)      : 299.27380
    L (Longitude of perihelion)     : 118.56342
    B (Latitude of perihelion)      : -56.29063
    T (Time of perihelion passage)  : 2458227.05560
    P (Orbital period in years)     : 395.70

    Epoch                           : 2023 Sep 24
    Reference                       : MPC114602

    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
2026-01-04 00:00 UT   15 59 08.8   +51 09 36    18.740   18.657   83.7    3.0   319   27.8 
2026-01-05 00:00 UT   15 59 26.0   +51 11 27    18.738   18.662   84.0    3.0   318   27.8 
2026-01-05 14:39 UT   15 59 36.4   +51 12 37    18.737   18.665   84.3    3.0   318   27.8 
2026-01-06 00:00 UT   15 59 43.0   +51 13 21    18.737   18.667   84.4    3.0   318   27.8 
2026-01-07 00:00 UT   15 59 59.8   +51 15 18    18.735   18.671   84.7    3.0   317   27.8 
2026-01-08 00:00 UT   16 00 16.3   +51 17 16    18.734   18.676   85.1    3.0   316   27.8 
2026-01-09 00:00 UT   16 00 32.7   +51 19 17    18.732   18.681   85.5    3.0   315   27.8 
2026-01-10 00:00 UT   16 00 48.8   +51 21 20    18.731   18.685   85.8    3.0   314   27.8 
2026-01-11 00:00 UT   16 01 04.6   +51 23 26    18.730   18.690   86.2    3.0   313   27.8 
2026-01-12 00:00 UT   16 01 20.3   +51 25 33    18.728   18.695   86.5    3.0   312   27.8 
2026-01-13 00:00 UT   16 01 35.7   +51 27 43    18.727   18.699   86.9    3.0   311   27.8 
2026-01-14 00:00 UT   16 01 50.9   +51 29 55    18.725   18.704   87.2    3.0   310   27.8 
2026-01-15 00:00 UT   16 02 05.8   +51 32 09    18.724   18.709   87.6    3.0   309   27.8 

    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.