C/2021 A4 (NEOWISE) |
ephemeris |
date |
magn |
radius |
delta |
ra |
dec |
elong |
phase |
PA |
Nearest approach | 12 Feb 2021 | 12.2 | 1.278 AU | 0.430 AU | 06h44m | +59°24' | 123.9° | 39.9° | 125° |
Perihelion | 19 Mar 2021 | 13.9 | 1.150 AU | 1.143 AU | 04h14m | -02°12' | 64.7° | 51.5° | 91° |
Today | 14 Jul 2025 | 29.7 | 13.314 AU | 12.353 AU | 21h01m | -23°57' | 160.1° | 1.5° | 273° |
C/2021 A4 (NEOWISE)- 2025-07-14
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 A4 (NEOWISE) are:
e (Eccentricity) : 0.9729520
q (Perihelion distance) : 1.1503890
i (Inclination) : 111.64910
Ω (Longitude of ascending node) : 307.08930
ω (Argument of perihelion) : 204.75480
L (Longitude of perihelion) : 297.43499
B (Latitude of perihelion) : -22.90464
T (Time of perihelion passage) : 2459293.08190
P (Orbital period in years) : 277.37
Epoch : 2025 Jul 13
Reference : MPEC 2022-ED3
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 gray curve is based on the absolute magnitude and slope parameter as calculated from the original MPEC, or the latest values provided by the MPC (16.00 + 5 log[∆] + 10.00 log[r]), whereas the red curve is being recalculated every 6 hours based on the available COBS/MPC observations (currently 13.01 + 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
2025-07-14 00:00 UT 21 02 11.8 -23 56 57 12.353 13.309 159.3 1.5 272 29.7
2025-07-14 20:38 UT 21 01 54.5 -23 57 50 12.353 13.314 160.1 1.5 273 29.7
2025-07-15 00:00 UT 21 01 51.6 -23 57 58 12.353 13.315 160.3 1.5 273 29.7
2025-07-16 00:00 UT 21 01 31.4 -23 58 59 12.354 13.321 161.3 1.4 274 29.7
2025-07-17 00:00 UT 21 01 11.0 -23 59 60 12.355 13.327 162.2 1.3 275 29.7
2025-07-18 00:00 UT 21 00 50.6 -24 01 00 12.356 13.332 163.2 1.3 277 29.7
2025-07-19 00:00 UT 21 00 30.0 -24 02 00 12.357 13.338 164.1 1.2 278 29.7
2025-07-20 00:00 UT 21 00 09.3 -24 02 60 12.359 13.344 165.0 1.1 280 29.7
2025-07-21 00:00 UT 20 59 48.6 -24 03 59 12.361 13.350 166.0 1.1 282 29.7
2025-07-22 00:00 UT 20 59 27.8 -24 04 58 12.364 13.356 166.9 1.0 284 29.7
2025-07-23 00:00 UT 20 59 06.8 -24 05 56 12.366 13.361 167.7 0.9 286 29.7
2025-07-24 00:00 UT 20 58 45.9 -24 06 54 12.369 13.367 168.6 0.9 289 29.7
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.