C/2023 T2 (Borisov)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	22 Dec 2023	18.4	1.998 AU	1.487 AU	21h58m	+76°26'	106.1°	28.2°	55°
Nearest approach	6 Jan 2024	18.4	2.005 AU	1.474 AU	23h48m	+76°40'	107.7°	27.8°	66°
Today	13 May 2026	28.3	8.447 AU	8.011 AU	10h20m	-32°39'	112.3°	6.4°	98°

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. (14.5 + 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 T2 (Borisov) are:

    e (Eccentricity)                : 0.9910070
    q (Perihelion distance)         : 1.9976140
    i (Inclination)                 : 48.58360
    Ω (Longitude of ascending node) : 317.51660
    ω (Argument of perihelion)      : 111.24330
    L (Longitude of perihelion)     : 257.95710
    B (Latitude of perihelion)      : 44.34400
    T (Time of perihelion passage)  : 2460301.12920
    P (Orbital period in years)     : 3310.63

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    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
2026-05-12 00:00 UT   10 20 43.6   -32 44 53     7.984    8.436  113.4    6.3    97   28.3 
2026-05-13 00:00 UT   10 20 41.4   -32 41 14     8.002    8.444  112.7    6.3    98   28.3 
2026-05-13 10:49 UT   10 20 40.6   -32 39 35     8.011    8.447  112.3    6.4    98   28.3 
2026-05-14 00:00 UT   10 20 39.8   -32 37 36     8.021    8.451  111.9    6.4    99   28.3 
2026-05-15 00:00 UT   10 20 38.7   -32 34 01     8.039    8.458  111.2    6.4    99   28.3 
2026-05-16 00:00 UT   10 20 38.1   -32 30 28     8.058    8.465  110.5    6.4   100   28.3 
2026-05-17 00:00 UT   10 20 38.1   -32 26 57     8.076    8.472  109.8    6.4   101   28.3 
2026-05-18 00:00 UT   10 20 38.7   -32 23 28     8.095    8.480  109.1    6.5   101   28.3 
2026-05-19 00:00 UT   10 20 39.8   -32 20 02     8.114    8.487  108.3    6.5   102   28.3 
2026-05-20 00:00 UT   10 20 41.4   -32 16 38     8.133    8.494  107.6    6.5   103   28.3 
2026-05-21 00:00 UT   10 20 43.5   -32 13 16     8.152    8.501  106.9    6.5   103   28.4 
2026-05-22 00:00 UT   10 20 46.2   -32 09 57     8.171    8.508  106.1    6.6   104   28.4 
2026-05-23 00:00 UT   10 20 49.4   -32 06 41     8.190    8.516  105.4    6.6   105   28.4 

    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.