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	7 Sep 2026	32.6	24.646 AU	24.520 AU	04h54m	-49°57'	96.0°	2.3°	268°

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
2026-09-06 00:00 UT   04 54 20.6   -49 54 04    24.520   24.640   95.6    2.3   266   32.6 
2026-09-07 00:00 UT   04 54 20.9   -49 56 25    24.520   24.645   95.9    2.3   267   32.6 
2026-09-07 07:03 UT   04 54 20.9   -49 57 07    24.520   24.646   96.0    2.3   268   32.6 
2026-09-08 00:00 UT   04 54 20.9   -49 58 48    24.520   24.650   96.2    2.3   268   32.6 
2026-09-09 00:00 UT   04 54 20.7   -50 01 10    24.520   24.655   96.5    2.3   269   32.6 
2026-09-10 00:00 UT   04 54 20.2   -50 03 32    24.520   24.660   96.8    2.3   270   32.6 
2026-09-11 00:00 UT   04 54 19.5   -50 05 54    24.520   24.665   97.1    2.3   271   32.6 
2026-09-12 00:00 UT   04 54 18.5   -50 08 16    24.520   24.669   97.4    2.3   272   32.6 
2026-09-13 00:00 UT   04 54 17.3   -50 10 38    24.520   24.674   97.6    2.3   273   32.6 
2026-09-14 00:00 UT   04 54 15.8   -50 13 00    24.520   24.679   97.9    2.3   274   32.6 
2026-09-15 00:00 UT   04 54 14.0   -50 15 22    24.520   24.684   98.2    2.3   275   32.6 
2026-09-16 00:00 UT   04 54 12.0   -50 17 44    24.520   24.689   98.5    2.3   276   32.6 
2026-09-17 00:00 UT   04 54 09.7   -50 20 05    24.520   24.694   98.7    2.3   277   32.6 

    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.