45P/Honda-Mrkos-Pajdusakova
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Today	4 Jul 2025	22.0	5.417 AU	4.687 AU	15h27m	-16°36'	131.7°	8.0°	106°
Nearest approach	22 Jul 2027	6.8	0.955 AU	0.532 AU	03h21m	+11°21'	68.1°	80.7°	252°
Perihelion	31 Aug 2027	5.0	0.558 AU	1.049 AU	08h32m	+17°33'	31.4°	70.4°	282°

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 45P/Honda-Mrkos-Pajdusakova are:

            e (Eccentricity)                : 0.8176080
            q (Perihelion distance)         : 0.5575400
            i (Inclination)                 : 4.32400
            Ω (Longitude of ascending node) : 87.68640
            ω (Argument of perihelion)      : 327.95030
            L (Longitude of perihelion)     : 55.71011
            B (Latitude of perihelion)      : -2.29299
            T (Time of perihelion passage)  : 2461649.00390
            P (Orbital period in years)     : 5.34

            Epoch                           : 2025 Jul 03
            Reference                       : MPEC 2022-O01

            Classification(s):              : Ecliptic; Jupiter family
            Tisserand (Jupiter)             : 2.582
        

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[∆] + 20.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 8.42 + 5 log[∆] + 13.91 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.30. (See Marcus 2007)

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
2025-07-04 00:00 UT   15 27 53.9   -16 36 18     4.686    5.417  131.8    8.0   106   22.0 
2025-07-04 01:34 UT   15 27 52.2   -16 36 14     4.687    5.417  131.7    8.0   106   22.0 
2025-07-05 00:00 UT   15 27 29.0   -16 35 18     4.697    5.416  130.8    8.2   106   22.0 
2025-07-06 00:00 UT   15 27 04.9   -16 34 21     4.708    5.414  129.7    8.3   106   22.0 
2025-07-07 00:00 UT   15 26 41.5   -16 33 27     4.719    5.413  128.7    8.4   106   22.0 
2025-07-08 00:00 UT   15 26 18.9   -16 32 35     4.730    5.411  127.6    8.6   106   22.0 
2025-07-09 00:00 UT   15 25 57.1   -16 31 46     4.742    5.410  126.6    8.7   106   22.0 
2025-07-10 00:00 UT   15 25 36.0   -16 30 60     4.754    5.408  125.5    8.8   106   22.0 
2025-07-11 00:00 UT   15 25 15.7   -16 30 17     4.765    5.407  124.5    8.9   106   22.0 
2025-07-12 00:00 UT   15 24 56.2   -16 29 36     4.777    5.405  123.5    9.0   106   22.0 
2025-07-13 00:00 UT   15 24 37.5   -16 28 59     4.790    5.403  122.5    9.1   106   22.0 
2025-07-14 00:00 UT   15 24 19.5   -16 28 24     4.802    5.402  121.4    9.2   106   22.0 

    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.