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Early warning for newly discovered comets and unconfirmed objects.

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139P

139P/Vaisala-Oterma

CometClass Ecatalogued
Both hemispheres

Difficult — CCD / large telescope. Around mag 17.4. A large amateur CCD or a professional telescope is required.

Active comet in COBS

JSONCSV

Right ascension

23h 24m 32s

J2000

Declination

−01° 09′ 25″

J2000

Estimated magnitude

17.4

CCD / citizen telescope · COBS consensus

Confidence

33

Class E · priority 66

Observations

24

Arc unknown

Last observation

21d ago

Fri, 16 Oct 2026 22:05:42 GMT · COBS consensus

Perihelion

2027-07-23

3.390 au

Peak window

2027-07-20 → 2027-11-30

COBS peak mag 16.8 on 2027-11-27 · perihelion 2027-07-23. Window is those dates ±3 days — not a light-curve fit.

Historic peak

16.8

COBS / analyzed peak 2027-11-27

Catalog ingest

2h ago

Venator last wrote this row 2026-11-07 01:30:03 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.

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

3.390 au

e

0.2480

i

2.34°

Ω

242.00°

ω

166.00°

a

4.510 au

MOID

—

H

—

H0 / n

9.5 / 4

NEO score

—

PHA score

—

RMS

—

Elongation

127°

Reporting sources

  • COBS comet list

    ok

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

  • COBS orbits

    ok

    Osculating elements and photometric parameters (H0, n) for active comets.

Name history

  • 139P/Vaisala-Oterma

    139P · 2026-09-14 18:27:52 UTC → current

Discoverers

  • Vaisala-Oterma

    Discoverer · parsed-name · 2026-09-14 18:27:52 UTC → current

Contributors

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