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C/1999 S2

C/1999 S2 (McNaught-Watson)

CometClass Ecatalogued
Unknown

Not currently visible. Last report 9154 days ago at mag 27.1. Historic peak was mag 13.9. 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

27.1

Professional survey · COBS consensus

Confidence

33

Class E · priority 60

Observations

15

Arc unknown

Last observation

9154d ago

Sun, 14 Oct 2001 17:31:12 GMT · COBS consensus

Perihelion

1997-11-09

6.500 au

Peak window

1997-06-25 → 1997-11-12

COBS peak mag 13.9 on 1997-06-28 · perihelion 1997-11-09. Window is those dates ±3 days — not a light-curve fit.

Historic peak

13.9

COBS / analyzed peak 1997-06-28

Catalog ingest

14h ago

Venator last wrote this row 2026-11-06 14:20:21 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

6.500 au

e

1.0000

i

65.60°

Ω

74.40°

ω

224.00°

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/1999 S2 (McNaught-Watson)

    Informal: McNaught-Watson

    C/1999 S2 · 2026-09-14 18:27:58 UTC → current

Discoverers

  • McNaught-Watson

    Discoverer · parsed-name · 2026-09-14 18:27:58 UTC → current

Contributors

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