C/2021 L3 (Borisov)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	24 Nov 2021	19.9	8.475 AU	8.328 AU	18h33m	+70°46'	95.2°	6.7°	36°
Perihelion	15 Feb 2022	19.9	8.460 AU	8.427 AU	19h37m	+72°55'	88.6°	6.7°	327°
Today	19 Jul 2025	21.8	11.120 AU	11.802 AU	11h13m	+34°55'	46.0°	3.8°	86°

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.)

The orbital elements of C/2021 L3 (Borisov) are:

            e (Eccentricity)                : 1.0045370
            q (Perihelion distance)         : 8.4603860
            i (Inclination)                 : 78.53690
            Ω (Longitude of ascending node) : 345.01780
            ω (Argument of perihelion)      : 91.65200
            L (Longitude of perihelion)     : 263.27496
            B (Latitude of perihelion)      : 78.42005
            T (Time of perihelion passage)  : 2459625.50110

            Epoch                           : 2025 Jul 17
            Reference                       : MPEC 2024-H50

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

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. 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. (6.00 + 5 log[∆] + 10.00 log[r]).

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-07-19 00:00 UT   11 13 44.5   +34 55 40    11.801   11.119   46.0    3.8    86   21.8 
2025-07-19 01:11 UT   11 13 45.1   +34 55 26    11.802   11.120   46.0    3.8    86   21.8 
2025-07-20 00:00 UT   11 13 57.1   +34 50 54    11.814   11.123   45.3    3.7    85   21.8 
2025-07-21 00:00 UT   11 14 10.0   +34 46 08    11.827   11.126   44.6    3.7    84   21.8 
2025-07-22 00:00 UT   11 14 23.2   +34 41 24    11.839   11.130   43.9    3.6    84   21.8 
2025-07-23 00:00 UT   11 14 36.5   +34 36 40    11.852   11.134   43.3    3.6    83   21.8 
2025-07-24 00:00 UT   11 14 50.1   +34 31 57    11.864   11.137   42.6    3.5    82   21.8 
2025-07-25 00:00 UT   11 15 03.9   +34 27 15    11.876   11.141   41.9    3.5    81   21.8 
2025-07-26 00:00 UT   11 15 17.9   +34 22 35    11.888   11.144   41.2    3.4    80   21.8 
2025-07-27 00:00 UT   11 15 32.2   +34 17 55    11.899   11.148   40.6    3.4    80   21.8 
2025-07-28 00:00 UT   11 15 46.6   +34 13 16    11.911   11.152   39.9    3.4    79   21.9 
2025-07-29 00:00 UT   11 16 01.2   +34 08 38    11.922   11.155   39.3    3.3    78   21.9 

    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.