C/2021 U4 (Leonard) |
ephemeris |
date |
magn |
radius |
delta |
ra |
dec |
elong |
phase |
PA |
Nearest approach | 31 Oct 2021 | 19.7 | 1.901 AU | 0.960 AU | 02h36m | -11°52' | 153.6° | 13.4° | 353° |
Perihelion | 22 Dec 2021 | 21.0 | 1.788 AU | 1.940 AU | 23h01m | -28°47' | 66.3° | 30.2° | 75° |
Today | 30 Apr 2025 | 32.2 | 10.702 AU | 9.720 AU | 15h26m | -12°39' | 166.4° | 1.3° | 259° |
C/2021 U4 (Leonard)- 2025-04-30
astro.vanbuitenen.nl
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 C/2021 U4 (Leonard) are:
e (Eccentricity) : 0.9598980
q (Perihelion distance) : 1.7881020
i (Inclination) : 152.88620
Ω (Longitude of ascending node) : 241.80460
ω (Argument of perihelion) : 237.34670
L (Longitude of perihelion) : 187.55696
B (Latitude of perihelion) : -22.56473
T (Time of perihelion passage) : 2459570.92200
P (Orbital period in years) : 297.74
Epoch : 2025 Feb 02
Reference : MPEC 2025-AH4
Classification(s): : Nearly isotropic; Returning (a < 10000 AU); External (P > 200 years)
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. (17.00 + 5 log[∆] + 10.00 log[r]).
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
2025-04-30 00:00 UT 15 26 24.3 -12 40 55 9.718 10.698 165.8 1.3 260 32.2
2025-04-30 13:55 UT 15 26 08.9 -12 39 36 9.720 10.702 166.4 1.3 259 32.2
2025-05-01 00:00 UT 15 25 57.6 -12 38 38 9.721 10.705 166.8 1.2 258 32.2
2025-05-02 00:00 UT 15 25 30.9 -12 36 21 9.724 10.711 167.8 1.1 256 32.2
2025-05-03 00:00 UT 15 25 04.0 -12 34 04 9.727 10.717 168.7 1.1 253 32.2
2025-05-04 00:00 UT 15 24 37.2 -12 31 47 9.730 10.723 169.6 1.0 250 32.2
2025-05-05 00:00 UT 15 24 10.2 -12 29 30 9.734 10.730 170.5 0.9 246 32.2
2025-05-06 00:00 UT 15 23 43.3 -12 27 14 9.738 10.736 171.3 0.8 242 32.3
2025-05-07 00:00 UT 15 23 16.3 -12 24 59 9.742 10.742 172.0 0.7 236 32.3
2025-05-08 00:00 UT 15 22 49.3 -12 22 43 9.746 10.749 172.7 0.7 230 32.3
2025-05-09 00:00 UT 15 22 22.3 -12 20 29 9.751 10.755 173.3 0.6 223 32.3
2025-05-10 00:00 UT 15 21 55.3 -12 18 15 9.757 10.761 173.7 0.6 214 32.3
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.