C/2009 A9
C/2009 A9 (STEREO)
Not visible to typical instruments. Current estimate mag 32.7. Historic peak was mag -16.3. Visual and most CCD amateur setups will not see it. Space telescopes or large ground telescopes are the remaining path.
Right ascension
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J2000
Declination
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J2000
Estimated magnitude
32.7
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
0
Arc unknown
Last observation
Not in feed
COBS consensus does not publish an observer timestamp. Catalog ingested 2d ago.
Perihelion
2009-01-11
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Peak window
2009-01-08 → 2009-01-14
COBS peak mag -16.3 on 2009-01-11 · perihelion 2009-01-11. Window is those dates ±3 days — not a light-curve fit.
Historic peak
-16.3
COBS / analyzed peak 2009-01-11
Catalog ingest
2d ago
Venator last wrote this row 2026-09-14 20:00:20 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.
No tail measures stored yet for this object.
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
—
e
—
i
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Ω
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ω
—
a
—
MOID
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H
—
H0 / n
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NEO score
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PHA score
—
RMS
—
Elongation
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Reporting sources
COBS comet list
okComet Observation Database magnitudes and perihelion data for the full COBS list (active and inactive).
Name history
C/2009 A9 (STEREO)
Informal: STEREO
C/2009 A9 · 2026-09-14 18:28:00 UTC → current
Discoverers
Discoverer · parsed-name · 2026-09-14 18:28:00 UTC → current
Contributors
- No recent COBS visual or CCD reports linked yet.
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.