C/2021 A2 (NEOWISE)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	21 Jan 2021	11.4	1.416 AU	0.629 AU	09h07m	-37°53'	121.1°	36.5°	346°
Nearest approach	2 Feb 2021	11.1	1.426 AU	0.507 AU	07h28m	-10°44'	143.6°	24.2°	41°
Today	9 May 2025	58.5	13.479 AU	13.638 AU	21h04m	+40°30'	78.8°	4.2°	257°

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 C/2021 A2 (NEOWISE) are:

            e (Eccentricity)                : 0.9938200
            q (Perihelion distance)         : 1.4157900
            i (Inclination)                 : 107.05040
            Ω (Longitude of ascending node) : 125.06890
            ω (Argument of perihelion)      : 338.79450
            L (Longitude of perihelion)     : 131.55909
            B (Latitude of perihelion)      : -20.23160
            T (Time of perihelion passage)  : 2459236.40980
            P (Orbital period in years)     : 3467.49

            Epoch                           : 2025 May 08
            Reference                       : MPEC 2025-A40

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)
        

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 gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (13.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 6.20 + 5 log[∆] + 41.29 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
2025-05-09 00:00 UT   21 04 27.4   +40 30 01    13.639   13.477   78.7    4.2   257   58.5 
2025-05-09 05:36 UT   21 04 26.9   +40 30 43    13.638   13.479   78.8    4.2   257   58.5 
2025-05-10 00:00 UT   21 04 24.9   +40 33 01    13.635   13.484   79.2    4.2   256   58.5 
2025-05-11 00:00 UT   21 04 21.9   +40 35 59    13.632   13.490   79.8    4.2   255   58.5 
2025-05-12 00:00 UT   21 04 18.6   +40 38 56    13.628   13.496   80.3    4.2   254   58.5 
2025-05-13 00:00 UT   21 04 14.9   +40 41 52    13.625   13.502   80.9    4.2   254   58.5 
2025-05-14 00:00 UT   21 04 10.8   +40 44 47    13.621   13.508   81.4    4.2   253   58.6 
2025-05-15 00:00 UT   21 04 06.4   +40 47 41    13.618   13.514   82.0    4.2   252   58.6 
2025-05-16 00:00 UT   21 04 01.6   +40 50 34    13.614   13.520   82.5    4.3   251   58.6 
2025-05-17 00:00 UT   21 03 56.4   +40 53 25    13.610   13.527   83.1    4.3   250   58.6 
2025-05-18 00:00 UT   21 03 50.9   +40 56 15    13.607   13.533   83.7    4.3   250   58.6 
2025-05-19 00:00 UT   21 03 44.9   +40 59 04    13.603   13.539   84.2    4.3   249   58.6 

    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.