C/2019 Y4 (ATLAS) - DISINTEGRATED
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Disintegration	1 Apr 2020	8.1	1.448 AU	1.013 AU	07h56m	+69°48'	92.0°	43.6°	109°
Nearest approach	21 May 2020	-	0.375 AU	0.775 AU	03h39m	+38°53'	18.9°	119.2°	350°
Perihelion	29 May 2020	-	0.257 AU	0.873 AU	03h31m	+19°38'	13.1°	116.5°	258°
Today	29 May 2025	-	16.102 AU	16.871 AU	07h05m	+11°11'	39.4°	2.3°	111°

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.)

The orbital elements of C/2019 Y4 (ATLAS) are:

            e (Eccentricity)                : 0.9992260
            q (Perihelion distance)         : 0.2571930
            i (Inclination)                 : 44.94440
            Ω (Longitude of ascending node) : 120.78720
            ω (Argument of perihelion)      : 177.41230
            L (Longitude of perihelion)     : 118.95502
            B (Latitude of perihelion)      : 1.82769
            T (Time of perihelion passage)  : 2458999.23210
            P (Orbital period in years)     : 6057.27

            Epoch                           : 2025 May 27
            Reference                       : MPEC 2024-A43

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. The gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (11.80 + 5 log[∆] + 15.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 6.51 + 5 log[∆] + 10.00 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.50. (See Marcus 2007)

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-05-29 00:00 UT   07 05 13.5   +11 11 18    16.858   16.097   40.1    2.3   110   24.7 
2025-05-29 19:13 UT   07 05 23.0   +11 11 28    16.871   16.102   39.4    2.3   111   24.7 
2025-05-30 00:00 UT   07 05 25.4   +11 11 30    16.874   16.103   39.3    2.3   111   24.7 
2025-05-31 00:00 UT   07 05 37.3   +11 11 41    16.890   16.109   38.4    2.2   111   24.7 
2025-06-01 00:00 UT   07 05 49.3   +11 11 51    16.906   16.115   37.5    2.2   112   24.7 
2025-06-02 00:00 UT   07 06 01.5   +11 11 60    16.922   16.121   36.7    2.2   112   24.7 
2025-06-03 00:00 UT   07 06 13.7   +11 12 08    16.937   16.126   35.8    2.1   113   24.7 
2025-06-04 00:00 UT   07 06 26.1   +11 12 15    16.953   16.132   35.0    2.1   113   24.7 
2025-06-05 00:00 UT   07 06 38.6   +11 12 22    16.968   16.138   34.1    2.0   114   24.7 
2025-06-06 00:00 UT   07 06 51.2   +11 12 27    16.983   16.144   33.3    2.0   114   24.7 
2025-06-07 00:00 UT   07 07 03.8   +11 12 32    16.997   16.150   32.4    1.9   115   24.7 
2025-06-08 00:00 UT   07 07 16.6   +11 12 36    17.011   16.156   31.6    1.9   116   24.7 

    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.