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Venator

Early warning for newly discovered comets and unconfirmed objects.

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C/2021 G2

C/2021 G2 (ATLAS)

CometClass Ecatalogued
Northern hemisphere

Difficult — CCD / large telescope. Around mag 16.1. A large amateur CCD or a professional telescope is required. Historic peak was mag 14.6.

Active comet in COBS

JSONCSV

Right ascension

01h 33m 39s

J2000

Declination

+27° 03′ 35″

J2000

Estimated magnitude

16.1

CCD / citizen telescope · COBS consensus

Confidence

33

Class E · priority 66

Observations

0

Arc unknown

Last observation

28h ago

Tue, 15 Sep 2026 18:43:11 GMT · COBS consensus

Perihelion

2024-09-09

4.980 au

Peak window

2024-05-15 → 2024-09-12

COBS peak mag 14.6 on 2024-05-18 · perihelion 2024-09-09. Window is those dates ±3 days — not a light-curve fit.

Historic peak

14.6

COBS / analyzed peak 2024-05-18

Catalog ingest

14m ago

Venator last wrote this row 2026-09-16 22:00:04 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

4.980 au

e

1.0000

i

48.50°

Ω

221.00°

ω

343.00°

a

-3800.000 au

MOID

—

H

—

H0 / n

9.6 / 1

NEO score

—

PHA score

—

RMS

—

Elongation

139°

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

  • C/2021 G2 (ATLAS)

    Informal: ATLAS

    C/2021 G2 · 2026-09-13 22:21:23 UTC → current

Discoverers

  • ATLAS

    Discoverer · parsed-name · 2026-09-13 22:21:23 UTC → current

Contributors

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