C/2023 B2 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	10 Mar 2023	15.4	1.739 AU	0.999 AU	11h35m	-54°13'	121.6°	29.1°	356°
Nearest approach	12 Apr 2023	15.2	1.791 AU	0.862 AU	12h05m	-36°05'	147.5°	17.5°	37°
Today	11 Sep 2026	28.7	11.457 AU	10.884 AU	19h50m	+23°19'	122.5°	4.2°	112°

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 13.0 + 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/2023 B2 (ATLAS) are:

    e (Eccentricity)                : 0.9971680
    q (Perihelion distance)         : 1.7392530
    i (Inclination)                 : 40.76500
    Ω (Longitude of ascending node) : 218.03660
    ω (Argument of perihelion)      : 317.38800
    L (Longitude of perihelion)     : 183.16965
    B (Latitude of perihelion)      : -26.23618
    T (Time of perihelion passage)  : 2460014.34210
    P (Orbital period in years)     : 15219.64

    Epoch                           : 2026 May 29
    Reference                       : MPC194183

    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
2026-09-10 00:00 UT   19 50 34.5   +23 23 29    10.867   11.450  123.2    4.2   114   28.7 
2026-09-11 00:00 UT   19 50 24.7   +23 20 14    10.881   11.456  122.6    4.2   113   28.7 
2026-09-11 04:39 UT   19 50 22.9   +23 19 36    10.884   11.457  122.5    4.2   112   28.7 
2026-09-12 00:00 UT   19 50 15.4   +23 16 58    10.896   11.463  122.1    4.3   112   28.7 
2026-09-13 00:00 UT   19 50 06.3   +23 13 41    10.911   11.469  121.5    4.3   111   28.8 
2026-09-14 00:00 UT   19 49 57.7   +23 10 22    10.927   11.476  120.9    4.3   110   28.8 
2026-09-15 00:00 UT   19 49 49.3   +23 07 02    10.942   11.482  120.3    4.3   109   28.8 
2026-09-16 00:00 UT   19 49 41.4   +23 03 42    10.958   11.489  119.7    4.4   108   28.8 
2026-09-17 00:00 UT   19 49 33.8   +23 00 20    10.974   11.496  119.0    4.4   107   28.8 
2026-09-18 00:00 UT   19 49 26.6   +22 56 58    10.989   11.502  118.4    4.4   106   28.8 
2026-09-19 00:00 UT   19 49 19.7   +22 53 35    11.005   11.509  117.8    4.4   105   28.8 
2026-09-20 00:00 UT   19 49 13.2   +22 50 11    11.022   11.515  117.2    4.5   104   28.8 
2026-09-21 00:00 UT   19 49 07.0   +22 46 47    11.038   11.522  116.5    4.5   103   28.8 

    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.