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C/1991 A2

C/1991 A2 (Arai)

CometClass Ecatalogued
Unknown

Not currently visible. Last report 12973 days ago at mag 36.9. Historic peak was mag 8.9. Typical backyard telescopes will not show it. HST, JWST, or an 8–10 m class telescope might recover it with a good ephemeris.

Active comet in COBS

JSONCSV

Right ascension

—

J2000

Declination

—

J2000

Estimated magnitude

36.9

Professional survey · COBS consensus

Confidence

33

Class E · priority 60

Observations

117

Arc unknown

Last observation

12973d ago

Tue, 12 Mar 1991 04:47:59 GMT · COBS consensus

Perihelion

1990-12-10

1.410 au

Peak window

1990-12-07 → 1991-01-08

COBS peak mag 8.9 on 1991-01-05 · perihelion 1990-12-10. Window is those dates ±3 days — not a light-curve fit.

Historic peak

8.9

COBS / analyzed peak 1991-01-05

Catalog ingest

2d ago

Venator last wrote this row 2026-09-14 20:00:17 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

1.410 au

e

0.9900

i

71.60°

Ω

115.00°

ω

338.00°

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/1991 A2 (Arai)

    Informal: Arai

    C/1991 A2 · 2026-09-14 18:27:56 UTC → current

Discoverers

  • Arai

    Discoverer · parsed-name · 2026-09-14 18:27:56 UTC → current

Contributors

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