C/2017 T3
Not currently visible. Last report 2926 days ago at mag 30.2. Historic peak was mag 9.8. 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
30.2
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
52
Arc unknown
Last observation
2926d ago
Thu, 13 Sep 2018 09:36:00 GMT · COBS consensus
Perihelion
2018-07-21
0.814 au
Peak window
2018-07-18 → 2018-07-27
COBS peak mag 9.8 on 2018-07-24 · perihelion 2018-07-21. Window is those dates ±3 days — not a light-curve fit.
Historic peak
9.8
COBS / analyzed peak 2018-07-24
Catalog ingest
11h ago
Venator last wrote this row 2026-09-16 13:20:18 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
0.814 au
e
0.9990
i
88.20°
Ω
230.00°
ω
247.00°
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/2017 T3 (ATLAS)
Informal: ATLAS
C/2017 T3 · 2026-09-14 18:27:59 UTC → current
Discoverer · parsed-name · 2026-09-14 18:27:59 UTC → current
Visual Observer · WYA · 12 reports · last 2941d ago
Visual Observer · WOL01 · 8 reports · last 2963d ago
CCD Observer · MAT08 · 7 reports · last 2926d ago
CCD Observer · HIL04 · 5 reports · last 3136d ago
CCD Observer · RAM02 · 4 reports · last 2994d ago
CCD Observer · WAR01 · 2 reports · last 3102d ago
CCD Observer · YOS02 · 2 reports · last 3251d ago
Visual Observer · GOI · 2 reports · last 2975d ago
Visual Observer · MAT08 · 2 reports · last 2982d ago
Visual Observer · CAM03 · 2 reports · last 2979d ago
CCD Observer · DEK01 · 2 reports · last 3126d ago
Visual Observer · FER07 · 1 reports · last 2986d ago
Visual Observer · AMO01 · 1 reports · last 2990d ago
CCD Observer · BAM · 1 reports · last 3251d ago
CCD Observer · FRI02 · 1 reports · last 3220d ago
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.