Skip Navigation Links

C/2021 O1 (Nishimura)
ephemeris date magn radius delta ra dec elong phase PA
Nearest approach6 Aug 20219.40.800 AU1.687 AU 08h11m+30°57'19.0°24.4°316°
Perihelion15 Aug 20219.30.783 AU1.700 AU 09h07m+28°53'16.4°21.4°333°
Today4 May 202626.815.082 AU14.396 AU 17h55m-44°33'131.4°2.9°290°
C/2021 O1 (Nishimura)- 2026-05-04
astro.vanbuitenen.nl


 
-1 month
-1 week
-1 day
Now
+1 day
+1 week
+1 month

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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 9.2 + 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 O1 (Nishimura) are: 

    e (Eccentricity)                : 1.0002380
    q (Perihelion distance)         : 0.7829610
    i (Inclination)                 : 27.53720
    Ω (Longitude of ascending node) : 41.51090
    ω (Argument of perihelion)      : 74.46710
    L (Longitude of perihelion)     : 114.10709
    B (Latitude of perihelion)      : 26.45142
    T (Time of perihelion passage)  : 2459441.58020

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-05-03 00:00 UT   17 55 30.2   -44 31 39    14.407   15.070  129.6    3.0   289   26.8 
2026-05-04 00:00 UT   17 55 16.1   -44 32 47    14.402   15.076  130.5    2.9   290   26.8 
2026-05-04 23:51 UT   17 55 01.7   -44 33 54    14.396   15.082  131.4    2.9   290   26.8 
2026-05-05 00:00 UT   17 55 01.6   -44 33 54    14.396   15.082  131.4    2.9   290   26.8 
2026-05-06 00:00 UT   17 54 46.9   -44 34 60    14.391   15.088  132.2    2.8   291   26.8 
2026-05-07 00:00 UT   17 54 31.9   -44 36 05    14.386   15.094  133.1    2.8   292   26.8 
2026-05-08 00:00 UT   17 54 16.6   -44 37 08    14.382   15.101  134.0    2.8   293   26.8 
2026-05-09 00:00 UT   17 54 01.0   -44 38 11    14.377   15.107  134.9    2.7   293   26.8 
2026-05-10 00:00 UT   17 53 45.1   -44 39 12    14.373   15.113  135.7    2.7   294   26.8 
2026-05-11 00:00 UT   17 53 29.0   -44 40 11    14.369   15.119  136.6    2.6   295   26.8 
2026-05-12 00:00 UT   17 53 12.6   -44 41 10    14.365   15.125  137.4    2.6   296   26.8 
2026-05-13 00:00 UT   17 52 55.9   -44 42 07    14.361   15.131  138.3    2.5   297   26.8 
2026-05-14 00:00 UT   17 52 39.0   -44 43 03    14.358   15.137  139.1    2.5   298   26.8 




    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.

Privacy policy