C/2018 Y1 (Iwamoto)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	2 Feb 2019	7.4	1.299 AU	0.444 AU	12h21m	-04°36'	126.4°	37.6°	295°
Nearest approach	10 Feb 2019	6.7	1.305 AU	0.320 AU	09h58m	+20°08'	172.0°	6.1°	225°
Today	27 May 2026	34.2	19.602 AU	19.973 AU	23h42m	+08°36'	67.1°	2.7°	250°

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. This lightcurve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 7.4 + 5 log[∆] + 15.8 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/2018 Y1 (Iwamoto) are:

    e (Eccentricity)                : 0.9897720
    q (Perihelion distance)         : 1.2992430
    i (Inclination)                 : 160.50880
    Ω (Longitude of ascending node) : 147.28780
    ω (Argument of perihelion)      : 357.89640
    L (Longitude of perihelion)     : 149.27095
    B (Latitude of perihelion)      : -0.70175
    T (Time of perihelion passage)  : 2458517.24290
    P (Orbital period in years)     : 1431.69

    Epoch                           : 2026 May 27
    Reference                       : MPC194158

    Classification(s):              : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-05-26 00:00 UT   23 42 13.3   +08 35 25    19.992   19.593   65.4    2.7   251   34.2 
2026-05-27 00:00 UT   23 42 16.2   +08 36 09    19.981   19.598   66.4    2.7   251   34.2 
2026-05-27 19:57 UT   23 42 18.5   +08 36 45    19.973   19.602   67.1    2.7   250   34.2 
2026-05-28 00:00 UT   23 42 19.0   +08 36 52    19.971   19.603   67.3    2.7   250   34.2 
2026-05-29 00:00 UT   23 42 21.6   +08 37 34    19.961   19.608   68.2    2.8   250   34.2 
2026-05-30 00:00 UT   23 42 24.0   +08 38 16    19.950   19.613   69.1    2.8   250   34.2 
2026-05-31 00:00 UT   23 42 26.3   +08 38 56    19.940   19.618   70.1    2.8   250   34.2 
2026-06-01 00:00 UT   23 42 28.4   +08 39 36    19.929   19.623   71.0    2.8   250   34.2 
2026-06-02 00:00 UT   23 42 30.3   +08 40 14    19.918   19.628   71.9    2.8   249   34.2 
2026-06-03 00:00 UT   23 42 32.1   +08 40 52    19.908   19.633   72.9    2.8   249   34.2 
2026-06-04 00:00 UT   23 42 33.6   +08 41 29    19.897   19.638   73.8    2.8   249   34.2 
2026-06-05 00:00 UT   23 42 35.0   +08 42 04    19.886   19.643   74.7    2.9   249   34.2 
2026-06-06 00:00 UT   23 42 36.2   +08 42 39    19.874   19.649   75.7    2.9   249   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.