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P/2009 Q4

P/2009 Q4 (Boattini)

CometClass Ecatalogued
Both hemispheres

Visible to modest telescopes (mag 12.7). Last report 8 days ago.

Active comet in COBS

Right ascension

10h 18m 32s

J2000

Declination

+11° 58′ 07″

J2000

Estimated magnitude

12.7

Small telescope · COBS consensus

Confidence

33

Class E · priority 76

Observations

149

80.00 d arc

Last observation

8d ago

Tue, 08 Sep 2026 19:57:21 GMT · COBS consensus

Perihelion

2020-12-26

1.310 au

Peak window

2020-12-21 → 2020-12-29

COBS peak mag 8.1 on 2020-12-24 · perihelion 2020-12-26. Window is those dates ±3 days — not a light-curve fit.

Historic peak

8.1

COBS / analyzed peak 2020-12-24

Catalog ingest

14m ago

Venator last wrote this row 2026-09-16 22:00:03 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

1.310 au

e

0.5830

i

11.00°

Ω

127.00°

ω

320.00°

a

3.130 au

MOID

H

H0 / n

9.0 / 4

NEO score

PHA score

RMS

Elongation

22°

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

  • P/2009 Q4 (Boattini)

    Informal: Boattini

    P/2009 Q4 · 2026-09-08 02:09:56 UTC → current

Discoverers

  • Boattini

    Discoverer · parsed-name · 2026-09-08 17:27:23 UTC → current

Contributors

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