427P
427P/ATLAS
Not currently visible. Last report 3275 days ago at mag 23.5. Historic peak was mag 18.5. 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
23.5
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
1
Arc unknown
Last observation
3275d ago
Fri, 29 Sep 2017 01:26:23 GMT · COBS consensus
Perihelion
2028-11-01
2.170 au
Peak window
2028-10-29 → 2028-11-04
COBS peak mag 18.5 on 2028-11-01 · perihelion 2028-11-01. Window is those dates ±3 days — not a light-curve fit.
Historic peak
18.5
COBS / analyzed peak 2028-11-01
Catalog ingest
11h ago
Venator last wrote this row 2026-09-16 13:20:19 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
2.170 au
e
0.3150
i
11.90°
Ω
252.00°
ω
99.60°
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
427P/ATLAS
427P · 2026-09-14 18:28:01 UTC → current
Discoverers
Discoverer · parsed-name · 2026-09-14 18:28:01 UTC → current
Contributors
CCD Observer · HIL04 · 1 reports · last 3275d ago
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.