C/1984 W2
C/1984 W2 (Hartley)
Not currently visible. Last report 14776 days ago at mag 37.5. Historic peak was mag 19.5. 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
37.5
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
15
Arc unknown
Last observation
14776d ago
Fri, 04 Apr 1986 11:02:24 GMT · COBS consensus
Perihelion
1985-10-05
3.980 au
Peak window
1985-10-02 → 1985-10-13
COBS peak mag 19.5 on 1985-10-10 · perihelion 1985-10-05. Window is those dates ±3 days — not a light-curve fit.
Historic peak
19.5
COBS / analyzed peak 1985-10-10
Catalog ingest
10h ago
Venator last wrote this row 2026-09-16 13:20:18 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
3.980 au
e
1.0000
i
89.60°
Ω
251.00°
ω
255.00°
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/1984 W2 (Hartley)
Informal: Hartley
C/1984 W2 · 2026-09-14 18:28:00 UTC → current
Discoverers
Discoverer · parsed-name · 2026-09-14 18:28:00 UTC → current
Contributors
CCD Observer · PEA · 15 reports · last 14776d ago
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.