P/2021 R8 (Sheppard)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	25 Apr 2025	26.1	3.581 AU	2.576 AU	14h21m	-11°36'	177.1°	0.8°	236°
Nearest approach	5 Aug 2026	22.8	2.338 AU	1.335 AU	20h11m	-17°23'	168.6°	4.9°	90°
Perihelion	5 Jan 2027	23.9	2.136 AU	2.599 AU	22h34m	-09°22'	51.8°	21.2°	69°

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 P/2021 R8 (Sheppard) are:

            e (Eccentricity)                : 0.2925860
            q (Perihelion distance)         : 2.1364900
            i (Inclination)                 : 2.20270
            Ω (Longitude of ascending node) : 167.06690
            ω (Argument of perihelion)      : 190.82400
            L (Longitude of perihelion)     : 177.88309
            B (Latitude of perihelion)      : -0.41355
            T (Time of perihelion passage)  : 2461411.27850
            P (Orbital period in years)     : 5.25

            Epoch                           : 2025 Apr 24
            Reference                       : MPEC 2021-Y10

            Classification(s):              : Ecliptic; Active asteroid
            Tisserand (Jupiter)             : 3.179
        

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. (18.50 + 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
2025-04-25 00:00 UT   14 21 37.1   -11 38 51     2.578    3.582  176.8    0.9   243   26.1 
2025-04-25 10:56 UT   14 21 15.9   -11 36 55     2.576    3.581  177.1    0.8   236   26.1 
2025-04-26 00:00 UT   14 20 50.6   -11 34 36     2.575    3.580  177.4    0.7   224   26.1 
2025-04-27 00:00 UT   14 20 04.1   -11 30 20     2.573    3.579  177.7    0.7   197   26.1 
2025-04-28 00:00 UT   14 19 17.5   -11 26 04     2.571    3.577  177.4    0.7   171   26.1 
2025-04-29 00:00 UT   14 18 30.9   -11 21 49     2.569    3.575  176.6    0.9   153   26.1 
2025-04-30 00:00 UT   14 17 44.2   -11 17 34     2.568    3.573  175.7    1.2   142   26.1 
2025-05-01 00:00 UT   14 16 57.7   -11 13 20     2.567    3.571  174.7    1.5   135   26.1 
2025-05-02 00:00 UT   14 16 11.2   -11 09 06     2.566    3.569  173.6    1.8   131   26.1 
2025-05-03 00:00 UT   14 15 24.9   -11 04 54     2.565    3.567  172.5    2.1   127   26.1 
2025-05-04 00:00 UT   14 14 38.7   -11 00 44     2.565    3.565  171.4    2.4   125   26.1 
2025-05-05 00:00 UT   14 13 52.8   -10 56 34     2.565    3.563  170.2    2.7   123   26.1 

    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.