C/2025 Q1 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	12 Jun 2024	18.8	10.101 AU	9.710 AU	09h10m	-84°09'	109.9°	5.4°	125°
Perihelion	11 Jul 2024	18.8	10.100 AU	9.757 AU	10h15m	-83°14'	106.9°	5.5°	139°
Today	20 Dec 2025	19.2	10.488 AU	11.078 AU	20h40m	-67°26'	51.1°	4.2°	128°

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. (3.8 + 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/2025 Q1 (ATLAS) are:

    e (Eccentricity)                : 0.9920000
    q (Perihelion distance)         : 10.0996480
    i (Inclination)                 : 66.16080
    Ω (Longitude of ascending node) : 326.94660
    ω (Argument of perihelion)      : 280.23300
    L (Longitude of perihelion)     : 261.01453
    B (Latitude of perihelion)      : -64.17567
    T (Time of perihelion passage)  : 2460503.39710
    P (Orbital period in years)     : 44856.40

    Epoch                           : 2025 Dec 19
    Reference                       : MPEC 2025-XC7

    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
2025-12-19 00:00 UT   20 39 24.0   -67 33 05    11.071   10.486   51.5    4.2   127   19.2 
2025-12-20 00:00 UT   20 40 14.6   -67 27 38    11.077   10.488   51.1    4.2   128   19.2 
2025-12-20 04:03 UT   20 40 23.1   -67 26 43    11.078   10.488   51.1    4.2   128   19.2 
2025-12-21 00:00 UT   20 41 05.4   -67 22 13    11.083   10.489   50.8    4.2   129   19.2 
2025-12-22 00:00 UT   20 41 56.3   -67 16 51    11.089   10.491   50.5    4.1   129   19.2 
2025-12-23 00:00 UT   20 42 47.4   -67 11 30    11.095   10.492   50.2    4.1   130   19.2 
2025-12-24 00:00 UT   20 43 38.6   -67 06 11    11.101   10.494   49.8    4.1   131   19.2 
2025-12-25 00:00 UT   20 44 30.0   -67 00 55    11.107   10.495   49.5    4.1   132   19.2 
2025-12-26 00:00 UT   20 45 21.5   -66 55 41    11.112   10.497   49.3    4.1   133   19.2 
2025-12-27 00:00 UT   20 46 13.1   -66 50 29    11.117   10.498   49.0    4.1   134   19.2 
2025-12-28 00:00 UT   20 47 04.8   -66 45 19    11.122   10.499   48.7    4.0   135   19.2 
2025-12-29 00:00 UT   20 47 56.6   -66 40 12    11.127   10.501   48.4    4.0   136   19.2 
2025-12-30 00:00 UT   20 48 48.5   -66 35 07    11.132   10.502   48.2    4.0   137   19.2 

    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.