C/2023 C2 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	20 Jul 2024	13.7	2.708 AU	2.072 AU	15h33m	-63°29'	118.5°	19.3°	79°
Perihelion	16 Nov 2024	14.1	2.368 AU	2.930 AU	18h50m	-24°29'	47.0°	17.8°	86°
Today	19 Oct 2025	16.3	4.242 AU	3.653 AU	22h19m	+56°06'	120.2°	11.7°	120°

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 9.1 + 5 log[∆] + 7.1 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/2023 C2 (ATLAS) are:

    e (Eccentricity)                : 0.9988710
    q (Perihelion distance)         : 2.3684280
    i (Inclination)                 : 48.32230
    Ω (Longitude of ascending node) : 301.00580
    ω (Argument of perihelion)      : 357.43840
    L (Longitude of perihelion)     : 299.30186
    B (Latitude of perihelion)      : -1.91297
    T (Time of perihelion passage)  : 2460631.25350
    P (Orbital period in years)     : 96083.62

    Epoch                           : 2025 Oct 18
    Reference                       : MPC188410

    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
2025-10-18 00:00 UT   22 19 53.2   +56 18 18     3.636    4.228  120.4   11.7   122   16.3 
2025-10-19 00:00 UT   22 19 28.3   +56 11 15     3.646    4.236  120.2   11.7   121   16.3 
2025-10-19 17:19 UT   22 19 11.4   +56 06 06     3.653    4.242  120.2   11.7   120   16.3 
2025-10-20 00:00 UT   22 19 05.1   +56 04 06     3.656    4.244  120.1   11.7   120   16.3 
2025-10-21 00:00 UT   22 18 43.7   +55 56 52     3.666    4.252  120.0   11.7   118   16.3 
2025-10-22 00:00 UT   22 18 24.0   +55 49 34     3.676    4.259  119.8   11.7   117   16.4 
2025-10-23 00:00 UT   22 18 06.1   +55 42 11     3.686    4.267  119.7   11.7   116   16.4 
2025-10-24 00:00 UT   22 17 49.9   +55 34 44     3.696    4.275  119.5   11.7   115   16.4 
2025-10-25 00:00 UT   22 17 35.5   +55 27 14     3.707    4.283  119.3   11.7   113   16.4 
2025-10-26 00:00 UT   22 17 22.7   +55 19 40     3.718    4.291  119.1   11.7   112   16.4 
2025-10-27 00:00 UT   22 17 11.7   +55 12 04     3.729    4.299  118.9   11.7   111   16.4 
2025-10-28 00:00 UT   22 17 02.4   +55 04 25     3.740    4.307  118.7   11.7   110   16.4 
2025-10-29 00:00 UT   22 16 54.7   +54 56 45     3.751    4.314  118.5   11.7   108   16.4 

    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.