C/2019 Y4 (ATLAS) - DISINTEGRATED
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Disintegration	1 Apr 2020	8.1	1.440 AU	1.006 AU	07h54m	+70°03'	91.8°	43.9°	109°
Nearest approach	20 May 2020	-	0.379 AU	0.775 AU	03h37m	+39°04'	19.2°	118.7°	350°
Perihelion	29 May 2020	-	0.257 AU	0.874 AU	03h29m	+19°32'	13.2°	116.0°	258°
Today	1 Jan 2026	-	17.362 AU	16.411 AU	07h17m	+09°57'	164.9°	0.8°	331°

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 6.5 + 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/2019 Y4 (ATLAS) are:

    e (Eccentricity)                : 0.9992050
    q (Perihelion distance)         : 0.2573270
    i (Inclination)                 : 44.90040
    Ω (Longitude of ascending node) : 120.80590
    ω (Argument of perihelion)      : 177.39820
    L (Longitude of perihelion)     : 118.96232
    B (Latitude of perihelion)      : 1.83623
    T (Time of perihelion passage)  : 2458998.82300
    P (Orbital period in years)     : 5823.41

    Epoch                           : 2025 Nov 12
    Reference                       : MPEC 2024-A43

    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
2025-12-31 00:00 UT   07 17 53.6   +09 57 02    16.407   17.355  164.0    0.9   327   24.9 
2026-01-01 00:00 UT   07 17 39.5   +09 57 29    16.410   17.361  164.7    0.9   330   24.9 
2026-01-01 07:04 UT   07 17 35.3   +09 57 38    16.411   17.362  164.9    0.8   331   24.9 
2026-01-02 00:00 UT   07 17 25.3   +09 57 58    16.413   17.367  165.3    0.8   333   24.9 
2026-01-03 00:00 UT   07 17 11.1   +09 58 27    16.416   17.372  165.9    0.8   337   24.9 
2026-01-04 00:00 UT   07 16 56.9   +09 58 57    16.420   17.378  166.4    0.8   341   24.9 
2026-01-05 00:00 UT   07 16 42.7   +09 59 28    16.424   17.384  166.8    0.7   345   24.9 
2026-01-06 00:00 UT   07 16 28.4   +10 00 00    16.429   17.389  167.2    0.7   349   24.9 
2026-01-07 00:00 UT   07 16 14.2   +10 00 32    16.433   17.395  167.5    0.7   354   24.9 
2026-01-08 00:00 UT   07 15 59.9   +10 01 06    16.438   17.401  167.7    0.7   359   24.9 
2026-01-09 00:00 UT   07 15 45.7   +10 01 40    16.443   17.406  167.8    0.7     4   24.9 
2026-01-10 00:00 UT   07 15 31.5   +10 02 15    16.449   17.412  167.8    0.7     9   24.9 
2026-01-11 00:00 UT   07 15 17.3   +10 02 50    16.455   17.418  167.8    0.7    14   25.0 

    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.