C/2017 M4 (ATLAS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	17 Jan 2019	14.0	3.237 AU	3.956 AU	17h20m	-13°12'	37.9°	10.8°	287°
Nearest approach	13 May 2019	13.3	3.421 AU	2.469 AU	16h00m	-40°09'	156.7°	6.7°	336°
Today	28 Apr 2025	25.7	16.503 AU	16.788 AU	06h01m	-35°46'	71.8°	3.3°	124°

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/2017 M4 (ATLAS) are:

            e (Eccentricity)                : 1.0002380
            q (Perihelion distance)         : 3.2367680
            i (Inclination)                 : 105.62610
            Ω (Longitude of ascending node) : 66.01460
            ω (Argument of perihelion)      : 167.42180
            L (Longitude of perihelion)     : 69.45401
            B (Latitude of perihelion)      : 12.10612
            T (Time of perihelion passage)  : 2458501.17160

            Epoch                           : 2025 Apr 26
            Reference                       : MPEC 2022-OB6

            Classification(s):              : Nearly isotropic; New (a > 10000 AU)
        

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 (6.00 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 4.82 + 5 log[∆] + 12.13 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
2025-04-28 00:00 UT   06 01 12.1   -35 47 50    16.783   16.500   72.0    3.3   123   25.7 
2025-04-28 09:24 UT   06 01 15.7   -35 46 43    16.788   16.503   71.8    3.3   124   25.7 
2025-04-29 00:00 UT   06 01 21.5   -35 44 60    16.796   16.506   71.6    3.3   124   25.7 
2025-04-30 00:00 UT   06 01 31.0   -35 42 11    16.808   16.511   71.2    3.3   125   25.7 
2025-05-01 00:00 UT   06 01 40.8   -35 39 25    16.820   16.517   70.8    3.3   126   25.7 
2025-05-02 00:00 UT   06 01 50.8   -35 36 41    16.833   16.522   70.4    3.3   127   25.7 
2025-05-03 00:00 UT   06 02 00.9   -35 33 59    16.845   16.527   70.0    3.3   128   25.7 
2025-05-04 00:00 UT   06 02 11.3   -35 31 19    16.857   16.533   69.6    3.3   129   25.7 
2025-05-05 00:00 UT   06 02 21.8   -35 28 42    16.869   16.538   69.2    3.3   130   25.7 
2025-05-06 00:00 UT   06 02 32.5   -35 26 07    16.881   16.543   68.8    3.3   130   25.7 
2025-05-07 00:00 UT   06 02 43.4   -35 23 34    16.893   16.549   68.4    3.3   131   25.7 
2025-05-08 00:00 UT   06 02 54.5   -35 21 04    16.904   16.554   68.0    3.2   132   25.7 

    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.