C/2019 Y4-B (ATLAS) - DISINTEGRATED
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Disintegration	12 May 2020	8.6	0.573 AU	0.805 AU	04h06m	+51°12'	34.5°	92.8°	21°
Nearest approach	20 May 2020	8.1	0.384 AU	0.773 AU	03h35m	+39°21'	19.6°	118.1°	351°
Perihelion	28 May 2020	7.2	0.258 AU	0.875 AU	03h27m	+19°22'	13.3°	115.5°	258°
Today	20 Sep 2026	-	18.624 AU	19.023 AU	07h29m	+11°06'	65.2°	2.8°	274°

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 11.6 + 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-B (ATLAS) are:

    e (Eccentricity)                : 0.9977730
    q (Perihelion distance)         : 0.2580420
    i (Inclination)                 : 44.68940
    Ω (Longitude of ascending node) : 120.67790
    ω (Argument of perihelion)      : 177.45640
    L (Longitude of perihelion)     : 118.86899
    B (Latitude of perihelion)      : 1.78852
    T (Time of perihelion passage)  : 2458998.29190
    P (Orbital period in years)     : 1247.26

    Epoch                           : 2026 May 29
    Reference                       : MPC194165

    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
2026-09-19 00:00 UT   07 29 28.8   +11 07 15    19.037   18.617   63.9    2.8   274   30.6 
2026-09-20 00:00 UT   07 29 34.0   +11 06 37    19.027   18.622   64.8    2.8   274   30.6 
2026-09-20 09:39 UT   07 29 36.0   +11 06 22    19.023   18.624   65.2    2.8   274   30.6 
2026-09-21 00:00 UT   07 29 39.0   +11 05 59    19.017   18.627   65.7    2.8   274   30.6 
2026-09-22 00:00 UT   07 29 43.8   +11 05 21    19.007   18.633   66.7    2.8   274   30.6 
2026-09-23 00:00 UT   07 29 48.4   +11 04 43    18.997   18.638   67.6    2.9   274   30.6 
2026-09-24 00:00 UT   07 29 52.8   +11 04 05    18.986   18.644   68.6    2.9   275   30.6 
2026-09-25 00:00 UT   07 29 57.0   +11 03 28    18.976   18.649   69.5    2.9   275   30.6 
2026-09-26 00:00 UT   07 30 01.0   +11 02 50    18.965   18.654   70.4    2.9   275   30.6 
2026-09-27 00:00 UT   07 30 04.9   +11 02 13    18.955   18.660   71.4    2.9   275   30.6 
2026-09-28 00:00 UT   07 30 08.5   +11 01 37    18.944   18.665   72.3    2.9   275   30.6 
2026-09-29 00:00 UT   07 30 11.9   +11 00 60    18.933   18.670   73.3    2.9   276   30.6 
2026-09-30 00:00 UT   07 30 15.1   +11 00 24    18.922   18.676   74.2    3.0   276   30.6 

    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.