C/2004 C1
C/2004 C1 (Larsen)
Not currently visible. Last report 8245 days ago at mag 26.2. Historic peak was mag 19.4. 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
26.2
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
7
Arc unknown
Last observation
8245d ago
Sun, 11 Apr 2004 12:43:11 GMT · COBS consensus
Perihelion
2043-06-12
4.350 au
Peak window
2003-01-05 → 2043-06-15
COBS peak mag 19.4 on 2003-01-08 · perihelion 2043-06-12. Window is those dates ±3 days — not a light-curve fit.
Historic peak
19.4
COBS / analyzed peak 2003-01-08
Catalog ingest
14h ago
Venator last wrote this row 2026-11-06 14:20:22 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
4.350 au
e
0.6300
i
28.60°
Ω
151.00°
ω
317.00°
a
—
MOID
—
H
—
H0 / n
—
NEO score
—
PHA score
—
RMS
—
Elongation
—
Reporting sources
COBS comet list
okComet Observation Database magnitudes and perihelion data for the full COBS list (active and inactive).
Name history
C/2004 C1 (Larsen)
Informal: Larsen
C/2004 C1 · 2026-09-14 18:27:58 UTC → current
Discoverers
Discoverer · parsed-name · 2026-09-14 18:27:58 UTC → current
Contributors
CCD Observer · NAK01 · 7 reports · last 8245d ago
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.