C/2020 H5 (Robinson)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	10 Dec 2020	19.7	9.334 AU	9.791 AU	12h34m	-36°32'	59.8°	5.2°	277°
Nearest approach	11 Apr 2021	19.4	9.360 AU	8.470 AU	12h24m	-34°27'	151.0°	3.0°	29°
Today	17 Dec 2025	22.1	13.621 AU	14.264 AU	15h31m	+12°35'	47.7°	3.1°	319°

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. The light curve is based on the absolute magnitude and slope parameter as calculated from an MPEC, or the latest values provided by the minor planet center. (5.0 + 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/2020 H5 (Robinson) are:

    e (Eccentricity)                : 0.9986190
    q (Perihelion distance)         : 9.3343100
    i (Inclination)                 : 70.21650
    Ω (Longitude of ascending node) : 210.60620
    ω (Argument of perihelion)      : 326.26440
    L (Longitude of perihelion)     : 197.86947
    B (Latitude of perihelion)      : -31.50567
    T (Time of perihelion passage)  : 2459193.54540
    P (Orbital period in years)     : 555690.30

    Epoch                           : 2025 Dec 16
    Reference                       : MPC184409

    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
2025-12-16 00:00 UT   15 30 59.0   +12 33 34    14.271   13.616   46.7    3.0   320   22.1 
2025-12-17 00:00 UT   15 31 17.0   +12 34 56    14.265   13.619   47.4    3.1   319   22.1 
2025-12-17 08:10 UT   15 31 23.1   +12 35 24    14.264   13.621   47.7    3.1   319   22.1 
2025-12-18 00:00 UT   15 31 34.9   +12 36 20    14.260   13.623   48.1    3.1   318   22.1 
2025-12-19 00:00 UT   15 31 52.6   +12 37 47    14.254   13.627   48.9    3.1   317   22.1 
2025-12-20 00:00 UT   15 32 10.3   +12 39 16    14.248   13.630   49.6    3.2   317   22.1 
2025-12-21 00:00 UT   15 32 27.7   +12 40 47    14.241   13.634   50.3    3.2   316   22.1 
2025-12-22 00:00 UT   15 32 45.1   +12 42 21    14.235   13.638   51.0    3.2   315   22.1 
2025-12-23 00:00 UT   15 33 02.2   +12 43 58    14.228   13.641   51.8    3.2   314   22.1 
2025-12-24 00:00 UT   15 33 19.3   +12 45 37    14.221   13.645   52.5    3.3   313   22.1 
2025-12-25 00:00 UT   15 33 36.1   +12 47 18    14.214   13.649   53.3    3.3   313   22.1 
2025-12-26 00:00 UT   15 33 52.9   +12 49 02    14.207   13.653   54.0    3.3   312   22.1 
2025-12-27 00:00 UT   15 34 09.4   +12 50 48    14.200   13.656   54.8    3.4   311   22.1 

    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.