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Early warning for newly discovered comets and unconfirmed objects.

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C/2025 B2

C/2025 B2 (Borisov)

CometClass Ecatalogued
Unknown

Not visible to typical instruments. Current estimate mag 19.9. Visual and most CCD amateur setups will not see it. Space telescopes or large ground telescopes are the remaining path.

Active comet in COBS

JSONCSV

Right ascension

—

J2000

Declination

—

J2000

Estimated magnitude

19.9

Professional survey · COBS consensus

Confidence

33

Class E · priority 60

Observations

9

Arc unknown

Last observation

4d ago

Sun, 13 Sep 2026 01:40:48 GMT · COBS consensus

Perihelion

2026-09-12

8.240 au

Peak window

2026-09-09 → 2026-11-05

COBS peak mag 19.9 on 2026-11-02 · perihelion 2026-09-12. Window is those dates ±3 days — not a light-curve fit.

Historic peak

19.9

COBS / analyzed peak 2026-11-02

Catalog ingest

4m ago

Venator last wrote this row 2026-09-17 01:25:22 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

8.240 au

e

1.0000

i

91.70°

Ω

84.90°

ω

78.90°

a

—

MOID

—

H

—

H0 / n

—

NEO score

—

PHA score

—

RMS

—

Elongation

—

Reporting sources

  • COBS comet list

    ok

    Comet Observation Database magnitudes and perihelion data for the full COBS list (active and inactive).

Name history

  • C/2025 B2 (Borisov)

    Informal: Borisov

    C/2025 B2 · 2026-09-13 22:21:23 UTC → current

Discoverers

  • Borisov

    Discoverer · parsed-name · 2026-09-13 22:21:23 UTC → current

Contributors

Pips are observation weight on this object (log of report count). Hover for catalog-wide weight.