C/2017 E4 (Lovejoy)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Nearest approach	27 Mar 2017	9.5	0.736 AU	0.655 AU	21h15m	+07°08'	47.5°	91.6°	273°
Perihelion	19 Apr 2017	9.0	0.506 AU	1.108 AU	00h58m	+35°48'	27.2°	65.0°	332°
Today	4 Jun 2026	32.5	24.178 AU	24.505 AU	04h39m	-47°36'	70.0°	2.3°	182°

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 11.7 + 5 log[∆] + 10.0 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/2017 E4 (Lovejoy) are:

    e (Eccentricity)                : 1.0010600
    q (Perihelion distance)         : 0.5061290
    i (Inclination)                 : 88.03010
    Ω (Longitude of ascending node) : 222.95670
    ω (Argument of perihelion)      : 87.34830
    L (Longitude of perihelion)     : 259.53970
    B (Latitude of perihelion)      : 86.69708
    T (Time of perihelion passage)  : 2457863.01760

    Epoch                           : 2026 May 29
    Reference                       : MPC194151

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

Ephemerides

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2026-06-03 00:00 UT   04 39 31.5   -47 36 01    24.501   24.171   69.8    2.3   181   32.5 
2026-06-04 00:00 UT   04 39 45.8   -47 36 03    24.504   24.176   70.0    2.3   182   32.5 
2026-06-04 09:05 UT   04 39 51.2   -47 36 04    24.505   24.178   70.0    2.3   182   32.5 
2026-06-05 00:00 UT   04 40 00.1   -47 36 06    24.506   24.181   70.1    2.3   183   32.5 
2026-06-06 00:00 UT   04 40 14.3   -47 36 12    24.509   24.186   70.3    2.3   184   32.5 
2026-06-07 00:00 UT   04 40 28.6   -47 36 20    24.511   24.191   70.4    2.3   184   32.5 
2026-06-08 00:00 UT   04 40 42.8   -47 36 30    24.514   24.196   70.6    2.3   185   32.5 
2026-06-09 00:00 UT   04 40 57.0   -47 36 43    24.516   24.201   70.7    2.3   186   32.5 
2026-06-10 00:00 UT   04 41 11.2   -47 36 57    24.518   24.206   70.9    2.3   187   32.5 
2026-06-11 00:00 UT   04 41 25.3   -47 37 14    24.520   24.211   71.1    2.3   188   32.5 
2026-06-12 00:00 UT   04 41 39.4   -47 37 33    24.522   24.216   71.2    2.3   189   32.5 
2026-06-13 00:00 UT   04 41 53.5   -47 37 54    24.524   24.221   71.4    2.3   190   32.5 
2026-06-14 00:00 UT   04 42 07.5   -47 38 17    24.526   24.226   71.6    2.3   191   32.5 

    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.