C/2025 A3
C/2025 A3 (Tsuchinshan)
Not currently visible. Last report 590 days ago at mag 24.6. 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
24.6
Professional survey · COBS consensus
Confidence
33
Class E · priority 60
Observations
1
Arc unknown
Last observation
590d ago
Tue, 04 Feb 2025 03:02:00 GMT · COBS consensus
Perihelion
2026-03-15
5.790 au
Peak window
2026-03-12 → 2026-04-01
COBS peak mag 23.8 on 2026-03-29 · perihelion 2026-03-15. Window is those dates ±3 days — not a light-curve fit.
Historic peak
23.8
COBS / analyzed peak 2026-03-29
Catalog ingest
12h ago
Venator last wrote this row 2026-09-16 13:20:20 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
5.790 au
e
0.4320
i
9.98°
Ω
322.00°
ω
222.00°
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/2025 A3 (Tsuchinshan)
Informal: Tsuchinshan
C/2025 A3 · 2026-09-14 18:28:02 UTC → current
Discoverers
Discoverer · parsed-name · 2026-09-14 18:28:02 UTC → current
Contributors
CCD Observer · CAR06 · 1 reports · last 590d ago
Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.