C/2023 P1 (Nishimura)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	12 Sep 2023	3.4	0.289 AU	0.839 AU	11h10m	+18°59'	14.7°	117.7°	352°
Perihelion	17 Sep 2023	2.8	0.224 AU	0.926 AU	12h23m	+07°30'	12.4°	104.3°	66°
Today	19 Oct 2026	23.0	11.442 AU	11.773 AU	08h52m	-29°26'	68.3°	4.6°	269°

Please be aware that cometary behaviour is difficult to predict by nature. Predictions on this page are based on standard models and the latest observations available to me, and will gradually improve with time. The ability of comets to either disappoint or pleasantly surprise us, is one of many things that make them so interesting.

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 8.7 + 5 log[∆] + 8.5 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 P1 (Nishimura) are:

    e (Eccentricity)                : 0.9959820
    q (Perihelion distance)         : 0.2235680
    i (Inclination)                 : 132.49070
    Ω (Longitude of ascending node) : 66.73010
    ω (Argument of perihelion)      : 116.14030
    L (Longitude of perihelion)     : 120.72958
    B (Latitude of perihelion)      : 41.44995
    T (Time of perihelion passage)  : 2460204.87660
    P (Orbital period in years)     : 415.05

    Epoch                           : 2026 Oct 18
    Reference                       : MPC194185

    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
2026-10-18 00:00 UT   08 52 36.6   -29 22 01    11.778   11.433   67.4    4.6   268   23.0 
2026-10-19 00:00 UT   08 52 40.4   -29 25 41    11.774   11.440   68.1    4.6   269   23.0 
2026-10-19 08:30 UT   08 52 41.7   -29 26 59    11.773   11.442   68.3    4.6   269   23.0 
2026-10-20 00:00 UT   08 52 44.0   -29 29 21    11.771   11.447   68.7    4.6   270   23.0 
2026-10-21 00:00 UT   08 52 47.1   -29 33 00    11.766   11.454   69.3    4.7   271   23.0 
2026-10-22 00:00 UT   08 52 49.9   -29 36 40    11.762   11.460   70.0    4.7   271   23.0 
2026-10-23 00:00 UT   08 52 52.3   -29 40 20    11.758   11.467   70.6    4.7   272   23.0 
2026-10-24 00:00 UT   08 52 54.3   -29 44 00    11.754   11.474   71.3    4.7   273   23.0 
2026-10-25 00:00 UT   08 52 55.9   -29 47 40    11.749   11.480   71.9    4.7   274   23.0 
2026-10-26 00:00 UT   08 52 57.2   -29 51 19    11.745   11.487   72.6    4.7   274   23.0 
2026-10-27 00:00 UT   08 52 58.1   -29 54 59    11.740   11.494   73.3    4.8   275   23.0 
2026-10-28 00:00 UT   08 52 58.6   -29 58 38    11.736   11.501   73.9    4.8   276   23.0 
2026-10-29 00:00 UT   08 52 58.7   -30 02 17    11.731   11.507   74.6    4.8   277   23.0 

    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.