C/2021 A10 (NEOWISE)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	9 Feb 2021	19.1	1.363 AU	0.577 AU	12h35m	+68°06'	119.1°	39.2°	232°
Perihelion	14 Mar 2021	20.6	1.269 AU	1.310 AU	02h59m	+44°59'	65.1°	45.3°	58°
Today	2 Jun 2026	36.8	15.394 AU	15.099 AU	22h25m	-33°18'	105.0°	3.6°	253°

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. (19.0 + 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 A10 (NEOWISE) are:

    e (Eccentricity)                : 0.9849530
    q (Perihelion distance)         : 1.2687540
    i (Inclination)                 : 152.04810
    Ω (Longitude of ascending node) : 188.93760
    ω (Argument of perihelion)      : 82.70560
    L (Longitude of perihelion)     : 107.18285
    B (Latitude of perihelion)      : 27.70612
    T (Time of perihelion passage)  : 2459288.11480
    P (Orbital period in years)     : 774.27

    Epoch                           : 2026 May 29
    Reference                       : MPC194172

    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
2026-06-01 00:00 UT   22 25 33.0   -33 14 59    15.115   15.385  103.6    3.7   252   36.8 
2026-06-02 00:00 UT   22 25 29.6   -33 16 56    15.105   15.390  104.5    3.7   253   36.8 
2026-06-02 14:51 UT   22 25 27.3   -33 18 09    15.099   15.394  105.0    3.6   253   36.8 
2026-06-03 00:00 UT   22 25 25.8   -33 18 54    15.095   15.396  105.4    3.6   253   36.8 
2026-06-04 00:00 UT   22 25 21.8   -33 20 54    15.086   15.401  106.3    3.6   254   36.8 
2026-06-05 00:00 UT   22 25 17.4   -33 22 55    15.076   15.407  107.2    3.6   254   36.8 
2026-06-06 00:00 UT   22 25 12.8   -33 24 57    15.067   15.413  108.1    3.6   254   36.8 
2026-06-07 00:00 UT   22 25 07.8   -33 26 60    15.058   15.418  109.0    3.6   255   36.8 
2026-06-08 00:00 UT   22 25 02.6   -33 29 04    15.049   15.424  109.9    3.5   255   36.8 
2026-06-09 00:00 UT   22 24 57.0   -33 31 09    15.039   15.430  110.8    3.5   256   36.8 
2026-06-10 00:00 UT   22 24 51.2   -33 33 16    15.030   15.435  111.7    3.5   256   36.8 
2026-06-11 00:00 UT   22 24 45.1   -33 35 23    15.022   15.441  112.6    3.5   257   36.8 
2026-06-12 00:00 UT   22 24 38.6   -33 37 32    15.013   15.446  113.5    3.5   257   36.8 

    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.