C/2019 T4 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	4 Apr 2022	11.9	4.271 AU	3.325 AU	11h49m	-20°41'	158.5°	4.9°	48°
Perihelion	8 Jun 2022	12.2	4.236 AU	3.889 AU	11h51m	-07°31'	103.1°	13.5°	112°
Today	18 May 2026	19.3	11.271 AU	11.032 AU	19h40m	+34°43'	101.1°	5.1°	237°

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 2.0 + 5 log[∆] + 11.5 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 T4 (ATLAS) are:

    e (Eccentricity)                : 0.9953490
    q (Perihelion distance)         : 4.2364040
    i (Inclination)                 : 53.62550
    Ω (Longitude of ascending node) : 199.86450
    ω (Argument of perihelion)      : 351.12340
    L (Longitude of perihelion)     : 194.57271
    B (Latitude of perihelion)      : -7.13695
    T (Time of perihelion passage)  : 2459739.33660
    P (Orbital period in years)     : 27490.11

    Epoch                           : 2026 May 17
    Reference                       : MPEC 2026-E44

    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
2026-05-17 00:00 UT   19 40 52.4   +34 39 02    11.036   11.263  100.4    5.1   238   19.3 
2026-05-18 00:00 UT   19 40 44.9   +34 42 29    11.033   11.269  100.9    5.1   237   19.3 
2026-05-18 09:53 UT   19 40 41.7   +34 43 53    11.032   11.271  101.1    5.1   237   19.3 
2026-05-19 00:00 UT   19 40 37.0   +34 45 52    11.030   11.274  101.4    5.0   236   19.3 
2026-05-20 00:00 UT   19 40 28.8   +34 49 13    11.027   11.280  102.0    5.0   235   19.3 
2026-05-21 00:00 UT   19 40 20.2   +34 52 31    11.023   11.286  102.5    5.0   234   19.3 
2026-05-22 00:00 UT   19 40 11.3   +34 55 45    11.020   11.291  103.0    5.0   234   19.3 
2026-05-23 00:00 UT   19 40 01.9   +34 58 57    11.018   11.297  103.5    5.0   233   19.3 
2026-05-24 00:00 UT   19 39 52.2   +35 02 05    11.015   11.303  104.0    5.0   232   19.3 
2026-05-25 00:00 UT   19 39 42.2   +35 05 10    11.012   11.308  104.5    5.0   231   19.3 
2026-05-26 00:00 UT   19 39 31.8   +35 08 12    11.009   11.314  105.0    5.0   230   19.3 
2026-05-27 00:00 UT   19 39 21.1   +35 11 11    11.007   11.320  105.5    4.9   229   19.3 
2026-05-28 00:00 UT   19 39 10.1   +35 14 06    11.004   11.326  106.0    4.9   228   19.3 

    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.