C/2021 A2 (NEOWISE)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	21 Jan 2021	11.5	1.419 AU	0.633 AU	09h08m	-37°36'	121.2°	36.4°	345°
Nearest approach	2 Feb 2021	11.1	1.430 AU	0.510 AU	07h29m	-10°29'	144.0°	23.9°	41°
Today	16 Mar 2026	61.1	15.338 AU	15.902 AU	20h54m	+35°16'	53.9°	3.0°	305°

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 6.2 + 5 log[∆] + 41.2 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 A2 (NEOWISE) are:

    e (Eccentricity)                : 0.9938920
    q (Perihelion distance)         : 1.4192810
    i (Inclination)                 : 107.07160
    Ω (Longitude of ascending node) : 125.03430
    ω (Argument of perihelion)      : 338.83800
    L (Longitude of perihelion)     : 131.51775
    B (Latitude of perihelion)      : -20.18788
    T (Time of perihelion passage)  : 2459236.20550
    P (Orbital period in years)     : 3542.04

    Epoch                           : 2026 Mar 15
    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
2026-03-15 00:00 UT   20 54 33.7   +35 14 12    15.900   15.332   53.6    3.0   306   61.1 
2026-03-16 00:00 UT   20 54 46.3   +35 16 18    15.902   15.337   53.9    3.0   305   61.1 
2026-03-16 00:04 UT   20 54 46.3   +35 16 18    15.902   15.338   53.9    3.0   305   61.1 
2026-03-17 00:00 UT   20 54 58.6   +35 18 25    15.903   15.343   54.2    3.0   303   61.1 
2026-03-18 00:00 UT   20 55 10.8   +35 20 35    15.904   15.349   54.6    3.0   302   61.1 
2026-03-19 00:00 UT   20 55 22.7   +35 22 46    15.905   15.355   54.9    3.0   301   61.1 
2026-03-20 00:00 UT   20 55 34.4   +35 24 58    15.906   15.361   55.2    3.1   300   61.1 
2026-03-21 00:00 UT   20 55 45.9   +35 27 12    15.907   15.367   55.6    3.1   299   61.1 
2026-03-22 00:00 UT   20 55 57.2   +35 29 27    15.908   15.372   55.9    3.1   298   61.1 
2026-03-23 00:00 UT   20 56 08.3   +35 31 44    15.908   15.378   56.3    3.1   297   61.1 
2026-03-24 00:00 UT   20 56 19.1   +35 34 02    15.908   15.384   56.7    3.1   296   61.1 
2026-03-25 00:00 UT   20 56 29.7   +35 36 22    15.908   15.390   57.1    3.1   295   61.1 
2026-03-26 00:00 UT   20 56 40.1   +35 38 43    15.908   15.396   57.5    3.1   294   61.1 

    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.