C/2021 B3
C/2021 B3 (NEOWISE)
Not currently visible. Last report 2038 days ago at mag 30.9. Historic peak was mag 18.3. 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
1
Arc unknown
Last observation
2038d ago
Tue, 16 Feb 2021 20:09:35 GMT · COBS consensus
Perihelion
2021-03-09
2.170 au
Peak window
2021-02-14 → 2021-03-12
COBS peak mag 18.3 on 2021-02-17 · perihelion 2021-03-09. Window is those dates ±3 days — not a light-curve fit.
Historic peak
18.3
COBS / analyzed peak 2021-02-17
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
0.9370
i
119.00°
Ω
67.30°
ω
294.00°
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/2021 B3 (NEOWISE)
Informal: NEOWISE
C/2021 B3 · 2026-09-14 18:28:01 UTC → current
Discoverers
Discoverer · parsed-name · 2026-09-14 18:28:01 UTC → current
Contributors
CCD Observer · PAP04 · 1 reports · last 2038d ago
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.