C/2003 H1
Not currently visible. Last report 8218 days ago at mag 30.9. Historic peak was mag 10.8. Typical backyard telescopes will not show it. HST, JWST, or an 8–10 m class telescope might recover it with a good ephemeris.
Right ascension
—
J2000
Declination
—
J2000
Estimated magnitude
30.9
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
134
Arc unknown
Last observation
8218d ago
Fri, 07 May 2004 21:36:00 GMT · COBS consensus
Perihelion
2004-02-12
2.220 au
Peak window
2004-02-09 → 2004-02-29
COBS peak mag 10.8 on 2004-02-26 · perihelion 2004-02-12. Window is those dates ±3 days — not a light-curve fit.
Historic peak
10.8
COBS / analyzed peak 2004-02-26
Catalog ingest
13h ago
Venator last wrote this row 2026-11-06 14:20:19 UTC
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.
q
2.220 au
e
0.9990
i
139.00°
Ω
19.10°
ω
196.00°
a
—
MOID
—
H
—
H0 / n
—
NEO score
—
PHA score
—
RMS
—
Elongation
—
COBS comet list
okComet Observation Database magnitudes and perihelion data for the full COBS list (active and inactive).
C/2003 H1 (LINEAR)
Informal: LINEAR
C/2003 H1 · 2026-09-14 18:27:54 UTC → current
Discoverer · parsed-name · 2026-09-14 18:27:54 UTC → current
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Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.