C/2018 E1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	6 Mar 2018	17.4	2.731 AU	2.743 AU	04h27m	-45°29'	78.9°	20.9°	93°
Perihelion	18 Apr 2018	17.5	2.697 AU	2.873 AU	05h44m	-27°51'	69.8°	20.5°	115°
Today	1 May 2026	27.9	19.200 AU	18.884 AU	15h58m	+55°59'	106.8°	2.9°	202°

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)                : 0.9502140
    q (Perihelion distance)         : 2.6965080
    i (Inclination)                 : 72.43640
    Ω (Longitude of ascending node) : 146.58460
    ω (Argument of perihelion)      : 299.41380
    L (Longitude of perihelion)     : 118.42696
    B (Latitude of perihelion)      : -56.14883
    T (Time of perihelion passage)  : 2458226.75260
    P (Orbital period in years)     : 398.60

    Epoch                           : 2026 Mar 16
    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
2026-04-30 00:00 UT   15 58 24.5   +55 58 00    18.878   19.196  106.9    2.9   203   27.9 
2026-05-01 00:00 UT   15 58 07.0   +55 59 13    18.884   19.200  106.8    2.9   202   27.9 
2026-05-01 00:24 UT   15 58 06.7   +55 59 14    18.884   19.200  106.8    2.9   202   27.9 
2026-05-02 00:00 UT   15 57 49.3   +56 00 22    18.890   19.205  106.7    2.9   201   27.9 
2026-05-03 00:00 UT   15 57 31.5   +56 01 29    18.897   19.209  106.6    2.9   200   27.9 
2026-05-04 00:00 UT   15 57 13.5   +56 02 32    18.903   19.214  106.5    2.9   199   27.9 
2026-05-05 00:00 UT   15 56 55.5   +56 03 33    18.910   19.219  106.4    2.9   198   27.9 
2026-05-06 00:00 UT   15 56 37.3   +56 04 30    18.916   19.223  106.2    2.9   196   27.9 
2026-05-07 00:00 UT   15 56 19.0   +56 05 24    18.923   19.228  106.1    2.9   195   27.9 
2026-05-08 00:00 UT   15 56 00.6   +56 06 15    18.930   19.232  106.0    2.9   194   27.9 
2026-05-09 00:00 UT   15 55 42.2   +56 07 03    18.937   19.237  105.8    2.9   193   27.9 
2026-05-10 00:00 UT   15 55 23.6   +56 07 48    18.944   19.242  105.7    2.9   192   27.9 
2026-05-11 00:00 UT   15 55 05.0   +56 08 30    18.951   19.246  105.5    2.9   191   27.9 

    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.