P/2021 HS (PANSTARRS)
ephemeris	date	magn	radius	delta	ra	dec	elong	phase	PA
Perihelion	4 Aug 2021	17.1	0.799 AU	0.265 AU	10h44m	+37°35'	30.9°	139.3°	56°
Nearest approach	8 Aug 2021	17.1	0.802 AU	0.262 AU	10h21m	+43°41'	31.2°	139.1°	33°
Today	22 Jun 2025	35.4	7.540 AU	8.395 AU	08h05m	+12°44'	30.9°	4.0°	115°

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.)

The orbital elements of P/2021 HS (PANSTARRS) are:

            e (Eccentricity)                : 0.8094450
            q (Perihelion distance)         : 0.7990730
            i (Inclination)                 : 12.15440
            Ω (Longitude of ascending node) : 262.35810
            ω (Argument of perihelion)      : 46.11860
            L (Longitude of perihelion)     : 307.82748
            B (Latitude of perihelion)      : 8.72877
            T (Time of perihelion passage)  : 2459431.28430
            P (Orbital period in years)     : 8.59

            Epoch                           : 2025 Jun 21
            Reference                       : MPEC 2021-Y10

            Classification(s):              : Ecliptic; Jupiter family
            Tisserand (Jupiter)             : 2.271
        

The light curve chart below shows the estimated development of the comet's magnitude. Blue and black dots are visual and photometric CCD observations respectively from COBS or the MPC. 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. (22.00 + 5 log[∆] + 10.00 log[r]). The additional green curve shows the effect of forward scattering, occurring when the comet is between the earth and the sun, for a gas-to-dust light ratio δ90 of 0.30. (See Marcus 2007)

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.
A more printer-friendly version of the same chart can be found further down this page as well.

The following chart shows the current location of the comet in a smaller, upside-down telescopic field of view.

A printable version of the short-term path of the comet in a field of view that is optimized for (~10x50) binoculars and finderscopes.

Ephemerides:

Date       Time       RA (2000)    DEC (2000)    delta   radius  elong  phase   PA    magn
2025-06-22 00:00 UT   08 05 21.6   +12 44 32     8.392    7.540   31.1    4.0   114   35.4 
2025-06-22 06:52 UT   08 05 29.8   +12 44 11     8.395    7.540   30.9    4.0   115   35.4 
2025-06-23 00:00 UT   08 05 50.4   +12 43 18     8.401    7.541   30.3    3.9   115   35.4 
2025-06-24 00:00 UT   08 06 19.3   +12 42 02     8.410    7.541   29.5    3.8   115   35.4 
2025-06-25 00:00 UT   08 06 48.4   +12 40 45     8.418    7.542   28.7    3.7   116   35.4 
2025-06-26 00:00 UT   08 07 17.6   +12 39 26     8.426    7.543   27.9    3.6   116   35.4 
2025-06-27 00:00 UT   08 07 47.0   +12 38 06     8.434    7.543   27.1    3.5   117   35.4 
2025-06-28 00:00 UT   08 08 16.5   +12 36 45     8.442    7.544   26.3    3.4   118   35.4 
2025-06-29 00:00 UT   08 08 46.1   +12 35 21     8.450    7.544   25.5    3.3   118   35.4 
2025-06-30 00:00 UT   08 09 15.9   +12 33 57     8.457    7.545   24.7    3.2   119   35.4 
2025-07-01 00:00 UT   08 09 45.8   +12 32 31     8.464    7.546   23.9    3.1   119   35.4 
2025-07-02 00:00 UT   08 10 15.8   +12 31 03     8.471    7.546   23.1    3.0   120   35.4 

    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.