C/2021 L3 (Borisov)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	24 Nov 2021	19.9	8.476 AU	8.329 AU	18h33m	+70°47'	95.2°	6.7°	36°
Perihelion	14 Feb 2022	19.9	8.462 AU	8.428 AU	19h37m	+72°55'	88.6°	6.7°	327°
Today	6 Feb 2026	22.0	11.868 AU	11.041 AU	11h37m	+29°50'	145.5°	2.7°	253°

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. (6.0 + 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/2021 L3 (Borisov) are:

    e (Eccentricity)                : 1.0042360
    q (Perihelion distance)         : 8.4616840
    i (Inclination)                 : 78.52290
    Ω (Longitude of ascending node) : 345.02500
    ω (Argument of perihelion)      : 91.66010
    L (Longitude of perihelion)     : 263.31226
    B (Latitude of perihelion)      : 78.40505
    T (Time of perihelion passage)  : 2459625.44840

    Epoch                           : 2026 Feb 06
    Reference                       : MPEC 2024-H50

    Classification(s):              : Nearly isotropic; New (a > 10000 AU)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-02-05 00:00 UT   11 37 47.2   +29 48 19    11.047   11.861  144.2    2.8   256   22.0 
2026-02-06 00:00 UT   11 37 26.7   +29 49 33    11.044   11.865  144.9    2.7   254   22.0 
2026-02-06 19:39 UT   11 37 09.8   +29 50 32    11.041   11.868  145.5    2.7   253   22.0 
2026-02-07 00:00 UT   11 37 06.0   +29 50 45    11.041   11.869  145.7    2.7   253   22.0 
2026-02-08 00:00 UT   11 36 45.1   +29 51 57    11.038   11.872  146.4    2.6   251   22.0 
2026-02-09 00:00 UT   11 36 23.8   +29 53 07    11.035   11.876  147.1    2.6   250   22.0 
2026-02-10 00:00 UT   11 36 02.4   +29 54 16    11.033   11.880  147.8    2.5   248   22.0 
2026-02-11 00:00 UT   11 35 40.7   +29 55 24    11.031   11.884  148.5    2.5   247   22.0 
2026-02-12 00:00 UT   11 35 18.8   +29 56 30    11.029   11.888  149.1    2.4   245   22.0 
2026-02-13 00:00 UT   11 34 56.6   +29 57 35    11.028   11.891  149.8    2.4   243   22.0 
2026-02-14 00:00 UT   11 34 34.3   +29 58 39    11.026   11.895  150.4    2.4   241   22.0 
2026-02-15 00:00 UT   11 34 11.7   +29 59 41    11.026   11.899  151.0    2.3   239   22.0 
2026-02-16 00:00 UT   11 33 49.0   +30 00 41    11.025   11.903  151.5    2.3   237   22.0 

    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.