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	20 Aug 2026	34.3	20.029 AU	19.167 AU	23h35m	+08°28'	147.6°	1.6°	230°

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)                : 0.9897730
    q (Perihelion distance)         : 1.2992730
    i (Inclination)                 : 160.50890
    Ω (Longitude of ascending node) : 147.28770
    ω (Argument of perihelion)      : 357.89670
    L (Longitude of perihelion)     : 149.27057
    B (Latitude of perihelion)      : -0.70165
    T (Time of perihelion passage)  : 2458517.24240
    P (Orbital period in years)     : 1431.95

    Epoch                           : 2026 May 29
    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
2026-08-19 00:00 UT   23 35 53.9   +08 29 19    19.171   20.023  146.4    1.6   231   34.3 
2026-08-20 00:00 UT   23 35 42.9   +08 28 21    19.168   20.028  147.4    1.6   230   34.3 
2026-08-20 06:04 UT   23 35 40.1   +08 28 06    19.167   20.029  147.6    1.6   230   34.3 
2026-08-21 00:00 UT   23 35 31.8   +08 27 22    19.164   20.033  148.3    1.5   229   34.3 
2026-08-22 00:00 UT   23 35 20.7   +08 26 21    19.161   20.038  149.3    1.5   229   34.3 
2026-08-23 00:00 UT   23 35 09.5   +08 25 19    19.158   20.043  150.2    1.4   228   34.3 
2026-08-24 00:00 UT   23 34 58.2   +08 24 17    19.156   20.048  151.2    1.4   227   34.3 
2026-08-25 00:00 UT   23 34 46.8   +08 23 13    19.153   20.053  152.1    1.4   226   34.3 
2026-08-26 00:00 UT   23 34 35.3   +08 22 08    19.151   20.058  153.0    1.3   226   34.3 
2026-08-27 00:00 UT   23 34 23.8   +08 21 03    19.149   20.063  154.0    1.3   225   34.3 
2026-08-28 00:00 UT   23 34 12.2   +08 19 56    19.148   20.068  154.9    1.2   224   34.3 
2026-08-29 00:00 UT   23 34 00.6   +08 18 48    19.147   20.073  155.8    1.2   223   34.3 
2026-08-30 00:00 UT   23 33 48.9   +08 17 39    19.146   20.078  156.7    1.1   222   34.3 

    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.