C/2019 T3 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	5 Mar 2021	16.6	5.950 AU	6.551 AU	22h50m	+43°02'	49.1°	7.2°	356°
Nearest approach	11 Sep 2021	16.3	6.098 AU	5.371 AU	22h03m	+39°33'	132.7°	7.0°	155°
Today	18 Sep 2026	22.0	14.042 AU	13.535 AU	20h30m	-47°04'	118.5°	3.6°	58°

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 4.8 + 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 T3 (ATLAS) are:

    e (Eccentricity)                : 0.9992220
    q (Perihelion distance)         : 5.9501510
    i (Inclination)                 : 121.89440
    Ω (Longitude of ascending node) : 139.55490
    ω (Argument of perihelion)      : 112.48130
    L (Longitude of perihelion)     : 191.48529
    B (Latitude of perihelion)      : 51.67458
    T (Time of perihelion passage)  : 2459278.85730
    P (Orbital period in years)     : 668840.53

    Epoch                           : 2026 Sep 18
    Reference                       : MPC194163

    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
2026-09-17 00:00 UT   20 31 10.0   -47 04 28    13.504   14.034  120.0    3.6    57   21.9 
2026-09-18 00:00 UT   20 30 52.1   -47 04 27    13.522   14.039  119.1    3.6    57   21.9 
2026-09-18 17:51 UT   20 30 38.9   -47 04 25    13.535   14.042  118.5    3.6    58   22.0 
2026-09-19 00:00 UT   20 30 34.5   -47 04 24    13.540   14.044  118.3    3.6    58   22.0 
2026-09-20 00:00 UT   20 30 17.2   -47 04 19    13.558   14.049  117.4    3.6    59   22.0 
2026-09-21 00:00 UT   20 30 00.4   -47 04 12    13.576   14.054  116.5    3.7    59   22.0 
2026-09-22 00:00 UT   20 29 43.9   -47 04 02    13.595   14.058  115.6    3.7    60   22.0 
2026-09-23 00:00 UT   20 29 27.8   -47 03 51    13.613   14.063  114.7    3.7    61   22.0 
2026-09-24 00:00 UT   20 29 12.2   -47 03 37    13.632   14.068  113.9    3.7    61   22.0 
2026-09-25 00:00 UT   20 28 56.9   -47 03 21    13.651   14.073  113.0    3.8    62   22.0 
2026-09-26 00:00 UT   20 28 42.0   -47 03 04    13.670   14.078  112.1    3.8    62   22.0 
2026-09-27 00:00 UT   20 28 27.5   -47 02 44    13.689   14.083  111.2    3.8    63   22.0 
2026-09-28 00:00 UT   20 28 13.4   -47 02 22    13.708   14.088  110.3    3.8    63   22.0 

    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.