C/2019 Y1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	17 Mar 2020	8.1	0.832 AU	1.481 AU	00h10m	+30°44'	32.3°	39.7°	10°
Nearest approach	3 May 2020	9.9	1.196 AU	1.112 AU	05h51m	+81°34'	68.5°	51.7°	49°
Today	4 Oct 2026	33.9	18.726 AU	19.465 AU	13h40m	-43°31'	41.4°	2.0°	157°

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 8.5 + 5 log[∆] + 14.9 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/2019 Y1 (ATLAS) are:

    e (Eccentricity)                : 0.9966850
    q (Perihelion distance)         : 0.8324550
    i (Inclination)                 : 73.23830
    Ω (Longitude of ascending node) : 31.26290
    ω (Argument of perihelion)      : 57.45150
    L (Longitude of perihelion)     : 55.57825
    B (Latitude of perihelion)      : 53.81569
    T (Time of perihelion passage)  : 2458925.95520
    P (Orbital period in years)     : 3979.38

    Epoch                           : 2026 May 29
    Reference                       : MPC194164

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years); Liller

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-10-03 00:00 UT   13 40 19.0   -43 30 25    19.444   18.717   42.3    2.1   155   33.8 
2026-10-04 00:00 UT   13 40 34.0   -43 31 05    19.457   18.723   41.7    2.0   156   33.9 
2026-10-04 15:04 UT   13 40 43.4   -43 31 30    19.465   18.726   41.4    2.0   157   33.9 
2026-10-05 00:00 UT   13 40 49.0   -43 31 46    19.469   18.728   41.1    2.0   157   33.9 
2026-10-06 00:00 UT   13 41 04.1   -43 32 29    19.482   18.734   40.5    2.0   158   33.9 
2026-10-07 00:00 UT   13 41 19.3   -43 33 14    19.494   18.739   40.0    2.0   160   33.9 
2026-10-08 00:00 UT   13 41 34.5   -43 33 60    19.505   18.744   39.4    1.9   161   33.9 
2026-10-09 00:00 UT   13 41 49.7   -43 34 48    19.517   18.750   38.8    1.9   162   33.9 
2026-10-10 00:00 UT   13 42 05.0   -43 35 38    19.528   18.755   38.3    1.9   163   33.9 
2026-10-11 00:00 UT   13 42 20.4   -43 36 29    19.539   18.760   37.8    1.9   164   33.9 
2026-10-12 00:00 UT   13 42 35.8   -43 37 22    19.550   18.766   37.2    1.8   166   33.9 
2026-10-13 00:00 UT   13 42 51.2   -43 38 17    19.561   18.771   36.7    1.8   167   33.9 
2026-10-14 00:00 UT   13 43 06.6   -43 39 13    19.571   18.777   36.3    1.8   168   33.9 

    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.