2I/Borisov
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	8 Dec 2019	15.6	2.007 AU	1.994 AU	11h28m	-18°19'	76.4°	28.5°	290°
Nearest approach	28 Dec 2019	15.7	2.053 AU	1.937 AU	11h59m	-33°17'	82.4°	28.3°	293°
Today	26 Apr 2025	34.9	38.721 AU	38.222 AU	18h08m	-54°44'	118.8°	1.3°	289°

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 2I/Borisov are:

            e (Eccentricity)                : 3.3566330
            q (Perihelion distance)         : 2.0065480
            i (Inclination)                 : 44.05270
            Ω (Longitude of ascending node) : 308.14800
            ω (Argument of perihelion)      : 209.12510
            L (Longitude of perihelion)     : 329.97095
            B (Latitude of perihelion)      : -19.78093
            T (Time of perihelion passage)  : 2458826.05480

            Epoch                           : 2019 Dec 23
            Reference                       : MPEC 2023-L37

            Classification(s):              : Interstellar
        

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 gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (11.00 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 11.11 + 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
2025-04-26 00:00 UT   18 08 30.0   -54 44 02    38.221   38.719  118.7    1.3   288   34.9 
2025-04-26 01:38 UT   18 08 29.6   -54 44 04    38.222   38.721  118.8    1.3   289   34.9 
2025-04-27 00:00 UT   18 08 24.6   -54 44 38    38.228   38.738  119.5    1.3   289   34.9 
2025-04-28 00:00 UT   18 08 19.0   -54 45 13    38.235   38.757  120.3    1.3   290   34.9 
2025-04-29 00:00 UT   18 08 13.2   -54 45 48    38.242   38.776  121.1    1.3   291   34.9 
2025-04-30 00:00 UT   18 08 07.4   -54 46 22    38.250   38.795  121.9    1.3   291   34.9 
2025-05-01 00:00 UT   18 08 01.3   -54 46 56    38.257   38.814  122.6    1.3   292   34.9 
2025-05-02 00:00 UT   18 07 55.1   -54 47 30    38.265   38.833  123.4    1.2   293   34.9 
2025-05-03 00:00 UT   18 07 48.8   -54 48 02    38.273   38.852  124.2    1.2   294   34.9 
2025-05-04 00:00 UT   18 07 42.4   -54 48 35    38.281   38.871  124.9    1.2   294   34.9 
2025-05-05 00:00 UT   18 07 35.8   -54 49 06    38.289   38.890  125.7    1.2   295   34.9 
2025-05-06 00:00 UT   18 07 29.1   -54 49 38    38.297   38.909  126.5    1.2   296   34.9 

    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.