C/2021 A2 (NEOWISE)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	22 Jan 2021	11.4	1.413 AU	0.626 AU	09h06m	-38°07'	121.1°	36.6°	347°
Nearest approach	2 Feb 2021	11.1	1.423 AU	0.506 AU	07h27m	-11°02'	143.2°	24.5°	42°
Today	18 Apr 2024	54.8	10.997 AU	11.345 AU	21h11m	+43°22'	67.3°	4.8°	276°

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)         : 1.4127570
            i (Inclination)                 : 107.01390
            Ω (Longitude of ascending node) : 125.13680
            ω (Argument of perihelion)      : 338.76840
            L (Longitude of perihelion)     : 131.62230
            B (Latitude of perihelion)      : -20.26052
            T (Time of perihelion passage)  : 2459236.70520
            P (Orbital period in years)     : 3456.36

            Epoch                           : 2024 Apr 18
            Reference                       : MPEC 2022-F14

            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[∆] + 41.58 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
2024-04-18 00:00 UT   21 11 14.8   +43 18 44    11.345   10.990   66.9    4.8   277   54.8 
2024-04-18 23:37 UT   21 11 21.4   +43 22 24    11.345   10.997   67.3    4.8   276   54.8 
2024-04-19 00:00 UT   21 11 21.5   +43 22 28    11.345   10.997   67.3    4.8   276   54.8 
2024-04-20 00:00 UT   21 11 27.7   +43 26 12    11.345   11.004   67.7    4.8   275   54.8 
2024-04-21 00:00 UT   21 11 33.5   +43 29 57    11.344   11.010   68.2    4.9   274   54.8 
2024-04-22 00:00 UT   21 11 38.9   +43 33 42    11.344   11.017   68.6    4.9   273   54.8 
2024-04-23 00:00 UT   21 11 43.9   +43 37 28    11.343   11.024   69.0    4.9   273   54.8 
2024-04-24 00:00 UT   21 11 48.3   +43 41 13    11.342   11.031   69.5    4.9   272   54.8 
2024-04-25 00:00 UT   21 11 52.4   +43 44 59    11.342   11.037   69.9    4.9   271   54.8 
2024-04-26 00:00 UT   21 11 56.0   +43 48 45    11.341   11.044   70.4    4.9   270   54.9 
2024-04-27 00:00 UT   21 11 59.1   +43 52 31    11.340   11.051   70.8    4.9   269   54.9 
2024-04-28 00:00 UT   21 12 01.8   +43 56 17    11.339   11.058   71.3    4.9   268   54.9 

    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.