C/2018 Y1 (Iwamoto)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	3 Feb 2019	7.3	1.294 AU	0.434 AU	12h21m	-04°38'	127.0°	37.4°	295°
Nearest approach	10 Feb 2019	6.6	1.299 AU	0.315 AU	09h58m	+19°55'	172.2°	5.9°	225°
Today	4 Aug 2025	33.4	18.065 AU	17.384 AU	23h44m	+09°53'	130.9°	2.4°	237°

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/2018 Y1 (Iwamoto) are:

            e (Eccentricity)                : 0.9897580
            q (Perihelion distance)         : 1.2941620
            i (Inclination)                 : 160.48730
            Ω (Longitude of ascending node) : 147.32730
            ω (Argument of perihelion)      : 357.86840
            L (Longitude of perihelion)     : 149.33658
            B (Latitude of perihelion)      : -0.71184
            T (Time of perihelion passage)  : 2458517.73600
            P (Orbital period in years)     : 1420.38

            Epoch                           : 2025 Aug 03
            Reference                       : MPEC 2024-A43

            Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (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 (11.50 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 7.37 + 5 log[∆] + 15.75 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
2025-08-04 00:00 UT   23 44 20.3   +09 53 29    17.388   18.062  130.3    2.5   237   33.4 
2025-08-04 15:32 UT   23 44 13.8   +09 53 02    17.384   18.065  130.9    2.4   237   33.4 
2025-08-05 00:00 UT   23 44 10.1   +09 52 47    17.381   18.067  131.3    2.4   237   33.4 
2025-08-06 00:00 UT   23 43 59.8   +09 52 03    17.374   18.072  132.2    2.4   236   33.4 
2025-08-07 00:00 UT   23 43 49.3   +09 51 17    17.367   18.077  133.2    2.3   236   33.4 
2025-08-08 00:00 UT   23 43 38.7   +09 50 31    17.361   18.083  134.2    2.3   236   33.4 
2025-08-09 00:00 UT   23 43 27.9   +09 49 42    17.355   18.088  135.2    2.3   235   33.4 
2025-08-10 00:00 UT   23 43 16.9   +09 48 53    17.349   18.093  136.1    2.2   235   33.4 
2025-08-11 00:00 UT   23 43 05.9   +09 48 02    17.343   18.099  137.1    2.2   235   33.4 
2025-08-12 00:00 UT   23 42 54.7   +09 47 09    17.337   18.104  138.1    2.1   234   33.4 
2025-08-13 00:00 UT   23 42 43.4   +09 46 15    17.332   18.109  139.0    2.1   234   33.4 
2025-08-14 00:00 UT   23 42 31.9   +09 45 20    17.326   18.115  140.0    2.1   233   33.4 

    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.