C/2021 J1 (Maury-Attard)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	19 Feb 2021	19.7	1.732 AU	2.322 AU	19h27m	+02°12'	42.8°	22.8°	289°
Nearest approach	27 May 2021	19.3	2.110 AU	1.300 AU	19h35m	-52°31'	131.2°	21.2°	290°
Today	15 Dec 2025	32.4	13.455 AU	13.144 AU	06h15m	-49°41'	106.4°	4.0°	349°

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. (15.5 + 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 J1 (Maury-Attard) are:

    e (Eccentricity)                : 0.9337960
    q (Perihelion distance)         : 1.7320770
    i (Inclination)                 : 92.70810
    Ω (Longitude of ascending node) : 88.43100
    ω (Argument of perihelion)      : 147.16910
    L (Longitude of perihelion)     : 90.17713
    B (Latitude of perihelion)      : 32.78962
    T (Time of perihelion passage)  : 2459264.95170
    P (Orbital period in years)     : 133.82

    Epoch                           : 2025 Nov 12
    Reference                       : MPEC 2022-C56

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-12-14 00:00 UT   06 16 16.6   -49 41 36    13.139   13.448  106.2    4.0   348   32.4 
2025-12-15 00:00 UT   06 15 48.3   -49 41 42    13.143   13.453  106.3    4.0   349   32.4 
2025-12-15 07:45 UT   06 15 39.2   -49 41 42    13.144   13.455  106.4    4.0   349   32.4 
2025-12-16 00:00 UT   06 15 20.0   -49 41 42    13.146   13.458  106.4    4.0   350   32.4 
2025-12-17 00:00 UT   06 14 51.7   -49 41 38    13.150   13.463  106.5    4.0   351   32.4 
2025-12-18 00:00 UT   06 14 23.3   -49 41 29    13.154   13.468  106.6    4.0   352   32.4 
2025-12-19 00:00 UT   06 13 54.8   -49 41 15    13.158   13.474  106.7    4.0   354   32.4 
2025-12-20 00:00 UT   06 13 26.3   -49 40 56    13.162   13.479  106.7    4.0   355   32.4 
2025-12-21 00:00 UT   06 12 57.8   -49 40 31    13.167   13.484  106.8    4.0   356   32.4 
2025-12-22 00:00 UT   06 12 29.3   -49 40 02    13.171   13.489  106.8    4.0   357   32.4 
2025-12-23 00:00 UT   06 12 00.8   -49 39 28    13.175   13.495  106.9    4.0   358   32.4 
2025-12-24 00:00 UT   06 11 32.3   -49 38 49    13.180   13.500  106.9    4.0   359   32.4 
2025-12-25 00:00 UT   06 11 03.8   -49 38 04    13.185   13.505  107.0    4.0     1   32.4 

    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.