Astro Corner
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Celestial object
C/2021 C4 (ATLAS)
2021 C4, ATLAS, C/2021 C4 (ATLAS)
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Reference data
RADate-dependentMoving object · use an ephemeris
DecDate-dependentMoving object · use an ephemeris
Magnitude—
Angular size—
Position angle—
Distance—
Constellation—
Solar System catalogue
JPL SBDBMoving-object reference
Comets and minor planets move against the background sky. Astro Corner therefore keeps their orbital catalogue record separately and does not pretend a single RA/Dec is permanently correct.
Primary designation2021 C4
JPL SPK-ID1003768
Orbit classCOM
Orbit IDJPL 16
Near-Earth objectNo
Potentially hazardousNo
Epoch · JD2459377.5
Eccentricity0.999196818566
Semi-major axis5607.929825322 AU
Perihelion distance4.504185117 AU
Orbital period153,391,849.0 days
Earth MOID3.618200000 AU
Jupiter Tisserand-1.788000
Inclination132.84262601°
Absolute magnitude · H—
Comet total magnitude · M16.9000 · K1 13.5000
Diameter—
Albedo—
Last catalogue sync2026-09-18 12:30:02
Planning coordinates are intentionally separate.A later Horizons ephemeris layer can calculate the object's apparent position for a specific date, time and observing location. Until then, static-sky tools are hidden for this record rather than showing misleading coordinates.
Open JPL Small-Body Database 
Reference transparencySources & data provenanceSee where catalogue identities and imported reference fields came from.4 records
Community observations
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Guides & knowledge
Published Guides that reference this canonical object.
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Images of this object
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