C/2025 W2 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	27 Nov 2025	19.4	1.460 AU	0.933 AU	12h09m	+67°00'	99.0°	41.9°	304°
Perihelion	7 Dec 2025	19.5	1.453 AU	0.979 AU	15h34m	+71°42'	95.5°	42.4°	341°
Today	19 Mar 2026	22.7	1.997 AU	2.309 AU	20h51m	+42°17'	59.5°	25.4°	303°

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. The light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (17.9 + 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/2025 W2 (ATLAS) are:

    e (Eccentricity)                : 0.9460410
    q (Perihelion distance)         : 1.4533000
    i (Inclination)                 : 94.71040
    Ω (Longitude of ascending node) : 90.84480
    ω (Argument of perihelion)      : 41.03630
    L (Longitude of perihelion)     : 86.75644
    B (Latitude of perihelion)      : 40.86808
    T (Time of perihelion passage)  : 2461017.33630
    P (Orbital period in years)     : 139.78

    Epoch                           : 2026 Mar 19
    Reference                       : MPC191592

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-03-18 00:00 UT   20 51 19.1   +42 10 36     2.300    1.980   59.0   25.5   305   22.7 
2026-03-19 00:00 UT   20 51 23.6   +42 14 01     2.304    1.989   59.3   25.5   304   22.7 
2026-03-19 22:37 UT   20 51 26.4   +42 17 24     2.309    1.997   59.5   25.4   303   22.7 
2026-03-20 00:00 UT   20 51 26.5   +42 17 37     2.309    1.998   59.5   25.4   303   22.7 
2026-03-21 00:00 UT   20 51 27.9   +42 21 23     2.313    2.007   59.8   25.4   302   22.7 
2026-03-22 00:00 UT   20 51 27.8   +42 25 19     2.317    2.015   60.1   25.4   301   22.8 
2026-03-23 00:00 UT   20 51 26.1   +42 29 25     2.320    2.024   60.4   25.4   300   22.8 
2026-03-24 00:00 UT   20 51 22.7   +42 33 40     2.324    2.033   60.8   25.3   299   22.8 
2026-03-25 00:00 UT   20 51 17.8   +42 38 04     2.327    2.042   61.1   25.3   298   22.8 
2026-03-26 00:00 UT   20 51 11.2   +42 42 36     2.330    2.051   61.5   25.3   297   22.9 
2026-03-27 00:00 UT   20 51 02.9   +42 47 17     2.333    2.059   61.8   25.3   296   22.9 
2026-03-28 00:00 UT   20 50 53.0   +42 52 06     2.336    2.068   62.2   25.3   295   22.9 
2026-03-29 00:00 UT   20 50 41.3   +42 57 02     2.338    2.077   62.6   25.3   293   22.9 

    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.