C/2021 J1 (Maury-Attard)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	19 Feb 2021	19.7	1.732 AU	2.323 AU	19h27m	+02°12'	42.8°	22.8°	289°
Nearest approach	27 May 2021	19.3	2.111 AU	1.300 AU	19h35m	-52°31'	131.3°	21.2°	290°
Today	20 Oct 2025	32.3	13.164 AU	13.073 AU	06h35m	-47°53'	93.0°	4.3°	289°

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)                : 0.9337990
    q (Perihelion distance)         : 1.7323950
    i (Inclination)                 : 92.70770
    Ω (Longitude of ascending node) : 88.43230
    ω (Argument of perihelion)      : 147.17410
    L (Longitude of perihelion)     : 90.17784
    B (Latitude of perihelion)      : 32.78464
    T (Time of perihelion passage)  : 2459264.94710
    P (Orbital period in years)     : 133.87

    Epoch                           : 2025 Oct 19
    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
2025-10-19 00:00 UT   06 35 35.0   -47 47 03    13.074   13.154   92.4    4.3   288   32.3 
2025-10-20 00:00 UT   06 35 25.2   -47 50 26    13.073   13.159   92.7    4.3   288   32.3 
2025-10-20 22:40 UT   06 35 15.4   -47 53 36    13.073   13.164   93.0    4.3   289   32.3 
2025-10-21 00:00 UT   06 35 14.8   -47 53 47    13.073   13.164   93.1    4.3   289   32.3 
2025-10-22 00:00 UT   06 35 04.0   -47 57 07    13.073   13.169   93.4    4.3   290   32.3 
2025-10-23 00:00 UT   06 34 52.8   -48 00 25    13.072   13.175   93.7    4.3   291   32.3 
2025-10-24 00:00 UT   06 34 41.1   -48 03 42    13.072   13.180   94.0    4.3   292   32.3 
2025-10-25 00:00 UT   06 34 28.9   -48 06 56    13.072   13.185   94.4    4.3   293   32.3 
2025-10-26 00:00 UT   06 34 16.2   -48 10 09    13.071   13.191   94.7    4.3   294   32.3 
2025-10-27 00:00 UT   06 34 03.1   -48 13 19    13.071   13.196   95.0    4.3   295   32.3 
2025-10-28 00:00 UT   06 33 49.6   -48 16 28    13.071   13.201   95.3    4.3   296   32.3 
2025-10-29 00:00 UT   06 33 35.6   -48 19 34    13.071   13.206   95.7    4.3   297   32.3 
2025-10-30 00:00 UT   06 33 21.1   -48 22 37    13.071   13.212   96.0    4.3   298   32.3 

    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.