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C/2009 UG89

C/2009 UG89 (Lemmon)

CometClass Ecatalogued
Unknown

Not currently visible. Last report 5510 days ago at mag 31.6. Historic peak was mag 18.1. Typical backyard telescopes will not show it. HST, JWST, or an 8–10 m class telescope might recover it with a good ephemeris.

Active comet in COBS

JSONCSV

Right ascension

—

J2000

Declination

—

J2000

Estimated magnitude

31.6

Professional survey · COBS consensus

Confidence

33

Class E · priority 60

Observations

12

Arc unknown

Last observation

5510d ago

Tue, 16 Aug 2011 20:52:48 GMT · COBS consensus

Perihelion

2010-12-16

3.950 au

Peak window

2010-10-05 → 2010-12-19

COBS peak mag 18.1 on 2010-10-08 · perihelion 2010-12-16. Window is those dates ±3 days — not a light-curve fit.

Historic peak

18.1

COBS / analyzed peak 2010-10-08

Catalog ingest

11h ago

Venator last wrote this row 2026-09-16 13:20:16 UTC

Light curve

Brightness over time (V mag)

Gold = reported observations. Steel dashed family = ensemble (nominal / outburst / fade / disruption).

Tail length

Converted to degrees from COBS (d / arcmin / arcsec). Empty until analysis has pulled the archive.

Ensemble is a first-pass H0/n photometric model plus observed samples — not a trained ML forecast yet. The background analyzer walks the catalog one object at a time so COBS is not flooded. Disruption track rises after perihelion to stand in for solar-wind stripping.

Orbital elements

q

3.950 au

e

1.0100

i

130.00°

Ω

321.00°

ω

60.70°

a

—

MOID

—

H

—

H0 / n

—

NEO score

—

PHA score

—

RMS

—

Elongation

—

Reporting sources

  • COBS comet list

    ok

    Comet Observation Database magnitudes and perihelion data for the full COBS list (active and inactive).

Name history

  • C/2009 UG89 (Lemmon)

    Informal: Lemmon

    C/2009 UG89 · 2026-09-14 18:27:53 UTC → current

Discoverers

  • Lemmon

    Discoverer · parsed-name · 2026-09-14 18:27:53 UTC → current

Contributors

Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.