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Early warning for newly discovered comets and unconfirmed objects.

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P/2005 XA54

P/2005 XA54 (LONEOS-Hill)

CometClass Ecatalogued
Unknown

Not currently visible. Last report 1934 days ago at mag 28.7. Historic peak was mag 17.8. 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

28.7

Professional survey · COBS consensus

Confidence

33

Class E · priority 60

Observations

107

Arc unknown

Last observation

1934d ago

Mon, 31 May 2021 22:19:11 GMT · COBS consensus

Perihelion

2035-12-02

1.760 au

Peak window

2035-11-29 → 2036-01-23

COBS peak mag 17.8 on 2036-01-20 · perihelion 2035-12-02. Window is those dates ±3 days — not a light-curve fit.

Historic peak

17.8

COBS / analyzed peak 2036-01-20

Catalog ingest

12h ago

Venator last wrote this row 2026-09-16 13:20:17 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.

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

1.760 au

e

0.7100

i

17.10°

Ω

143.00°

ω

15.20°

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

  • P/2005 XA54 (LONEOS-Hill)

    Informal: LONEOS-Hill

    P/2005 XA54 · 2026-09-14 18:27:55 UTC → current

Discoverers

  • Hill

    Discoverer · parsed-name · 2026-09-16 13:20:17 UTC → current

  • LONEOS

    Discoverer · parsed-name · 2026-09-16 13:20:17 UTC → current

  • LONEOS-Hill

    Discoverer · parsed-name · 2026-09-16 13:20:17 UTC → current

  • LONEOS-Hill

    Discoverer · parsed-name · 2026-09-14 18:27:55 UTC → 2026-09-16 13:20:17 UTC

Contributors

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