C/2018 Y1 (Iwamoto)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	2 Feb 2019	7.4	1.298 AU	0.442 AU	12h22m	-04°38'	126.5°	37.6°	295°
Nearest approach	10 Feb 2019	6.7	1.304 AU	0.319 AU	09h58m	+20°07'	172.0°	6.1°	225°
Today	24 Mar 2026	34.2	19.274 AU	20.250 AU	23h34m	+07°33'	11.3°	0.6°	302°

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)                : 0.9897610
    q (Perihelion distance)         : 1.2980330
    i (Inclination)                 : 160.50460
    Ω (Longitude of ascending node) : 147.29520
    ω (Argument of perihelion)      : 357.88740
    L (Longitude of perihelion)     : 149.28678
    B (Latitude of perihelion)      : -0.70490
    T (Time of perihelion passage)  : 2458517.31050
    P (Orbital period in years)     : 1427.39

    Epoch                           : 2026 Mar 16
    Reference                       : MPEC 2026-E44

    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
2026-03-23 00:00 UT   23 34 29.2   +07 31 29    20.244   19.266   10.6    0.5   309   34.1 
2026-03-24 00:00 UT   23 34 39.2   +07 32 32    20.248   19.271   11.1    0.6   305   34.2 
2026-03-24 13:39 UT   23 34 44.9   +07 33 08    20.250   19.274   11.3    0.6   302   34.2 
2026-03-25 00:00 UT   23 34 49.1   +07 33 35    20.251   19.276   11.6    0.6   301   34.2 
2026-03-26 00:00 UT   23 34 59.0   +07 34 39    20.254   19.281   12.2    0.6   297   34.2 
2026-03-27 00:00 UT   23 35 08.9   +07 35 43    20.257   19.286   12.8    0.7   294   34.2 
2026-03-28 00:00 UT   23 35 18.7   +07 36 47    20.260   19.291   13.4    0.7   291   34.2 
2026-03-29 00:00 UT   23 35 28.4   +07 37 51    20.263   19.296   14.1    0.7   288   34.2 
2026-03-30 00:00 UT   23 35 38.2   +07 38 56    20.265   19.302   14.8    0.8   285   34.2 
2026-03-31 00:00 UT   23 35 47.8   +07 40 01    20.267   19.307   15.5    0.8   283   34.2 
2026-04-01 00:00 UT   23 35 57.4   +07 41 05    20.268   19.312   16.3    0.8   281   34.2 
2026-04-02 00:00 UT   23 36 07.0   +07 42 10    20.269   19.317   17.1    0.9   279   34.2 
2026-04-03 00:00 UT   23 36 16.5   +07 43 15    20.271   19.322   17.9    0.9   277   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.