P/2017 Y3 (Leonard)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	5 Feb 2018	18.8	1.279 AU	1.507 AU	17h27m	-02°06'	57.3°	40.4°	288°
Perihelion	6 Feb 2018	18.8	1.279 AU	1.507 AU	17h33m	-01°58'	57.2°	40.4°	287°
Today	22 Dec 2024	34.2	14.393 AU	14.098 AU	01h37m	-13°03'	105.6°	3.8°	61°

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 P/2017 Y3 (Leonard) are:

            e (Eccentricity)                : 0.8694480
            q (Perihelion distance)         : 1.2791970
            i (Inclination)                 : 27.61630
            Ω (Longitude of ascending node) : 153.98350
            ω (Argument of perihelion)      : 67.38540
            L (Longitude of perihelion)     : 218.80441
            B (Latitude of perihelion)      : 25.33480
            T (Time of perihelion passage)  : 2458155.88490
            P (Orbital period in years)     : 30.67

            Epoch                           : 2024 Dec 21
            Reference                       : MPC111770

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); Halley type (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 (16.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 16.84 + 5 log[∆] + 10.00 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
2024-12-22 00:00 UT   01 37 36.7   -13 04 18    14.090   14.392  106.0    3.8    61   34.2 
2024-12-22 10:18 UT   01 37 34.5   -13 03 54    14.098   14.393  105.6    3.8    61   34.2 
2024-12-23 00:00 UT   01 37 31.7   -13 03 21    14.108   14.395  105.0    3.8    61   34.2 
2024-12-24 00:00 UT   01 37 27.0   -13 02 21    14.127   14.398  104.1    3.8    61   34.2 
2024-12-25 00:00 UT   01 37 22.5   -13 01 20    14.145   14.400  103.1    3.8    62   34.2 
2024-12-26 00:00 UT   01 37 18.4   -13 00 17    14.164   14.403  102.2    3.8    62   34.2 
2024-12-27 00:00 UT   01 37 14.5   -12 59 11    14.182   14.406  101.2    3.8    63   34.2 
2024-12-28 00:00 UT   01 37 10.9   -12 58 04    14.201   14.409  100.3    3.9    63   34.2 
2024-12-29 00:00 UT   01 37 07.5   -12 56 56    14.219   14.411   99.3    3.9    63   34.2 
2024-12-30 00:00 UT   01 37 04.5   -12 55 45    14.238   14.414   98.4    3.9    64   34.2 
2024-12-31 00:00 UT   01 37 01.7   -12 54 33    14.257   14.417   97.4    3.9    64   34.2 
2025-01-01 00:00 UT   01 36 59.2   -12 53 19    14.275   14.419   96.5    3.9    65   34.2 

    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.