13P/Olbers
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	30 Jun 2024	6.5	1.175 AU	1.938 AU	08h28m	+42°23'	30.1°	25.7°	59°
Nearest approach	20 Jul 2024	6.7	1.214 AU	1.896 AU	10h17m	+39°21'	35.1°	28.8°	68°
Today	7 Dec 2025	24.6	5.867 AU	6.777 AU	18h18m	-32°49'	20.8°	3.4°	114°

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 estimated manually by the author. (3.5 + 5 log[∆] + 22.0 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 13P/Olbers are:

    e (Eccentricity)                : 0.9305670
    q (Perihelion distance)         : 1.1753380
    i (Inclination)                 : 44.66360
    Ω (Longitude of ascending node) : 85.84600
    ω (Argument of perihelion)      : 64.42520
    L (Longitude of perihelion)     : 141.91042
    B (Latitude of perihelion)      : 39.35107
    T (Time of perihelion passage)  : 2460491.62290
    P (Orbital period in years)     : 69.65

    Epoch                           : 2025 Dec 06
    Reference                       : MPEC 2025-W75

    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
2025-12-06 00:00 UT   18 17 24.7   -32 47 50     6.756    5.854   22.0    3.6   113   24.5 
2025-12-07 00:00 UT   18 18 13.5   -32 48 43     6.769    5.862   21.2    3.5   113   24.6 
2025-12-07 14:18 UT   18 18 42.6   -32 49 14     6.777    5.867   20.8    3.4   114   24.6 
2025-12-08 00:00 UT   18 19 02.4   -32 49 35     6.783    5.870   20.5    3.4   115   24.6 
2025-12-09 00:00 UT   18 19 51.3   -32 50 28     6.795    5.878   19.8    3.2   116   24.6 
2025-12-10 00:00 UT   18 20 40.3   -32 51 20     6.808    5.886   19.0    3.1   117   24.6 
2025-12-11 00:00 UT   18 21 29.3   -32 52 12     6.820    5.894   18.3    3.0   118   24.6 
2025-12-12 00:00 UT   18 22 18.4   -32 53 05     6.833    5.902   17.6    2.9   120   24.6 
2025-12-13 00:00 UT   18 23 07.5   -32 53 57     6.845    5.910   16.9    2.8   121   24.7 
2025-12-14 00:00 UT   18 23 56.7   -32 54 49     6.856    5.918   16.3    2.7   123   24.7 
2025-12-15 00:00 UT   18 24 45.8   -32 55 41     6.868    5.926   15.6    2.6   125   24.7 
2025-12-16 00:00 UT   18 25 35.0   -32 56 34     6.879    5.934   15.0    2.5   127   24.7 
2025-12-17 00:00 UT   18 26 24.2   -32 57 26     6.890    5.942   14.4    2.4   129   24.7 

    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.