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Venator

Early warning for newly discovered comets and unconfirmed objects.

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C/2025 Y1

C/2025 Y1 (ATLAS)

CometClass Ecatalogued
Both hemispheres

Difficult — CCD / large telescope. Around mag 16.1. A large amateur CCD or a professional telescope is required. Historic peak was mag 11.0.

Active comet in COBS

JSONCSV

Right ascension

08h 07m 58s

J2000

Declination

+09° 15′ 51″

J2000

Estimated magnitude

16.1

CCD / citizen telescope · COBS consensus

Confidence

33

Class E · priority 66

Observations

203

Arc unknown

Last observation

43d ago

Tue, 04 Aug 2026 18:00:00 GMT · COBS consensus

Perihelion

2027-10-13

2.600 au

Peak window

2027-07-18 → 2027-10-16

COBS peak mag 11.0 on 2027-07-21 · perihelion 2027-10-13. Window is those dates ±3 days — not a light-curve fit.

Historic peak

11.0

COBS / analyzed peak 2027-07-21

Catalog ingest

1m ago

Venator last wrote this row 2026-09-17 00:00:08 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

2.600 au

e

1.0000

i

14.60°

Ω

167.00°

ω

124.00°

a

11700.000 au

MOID

—

H

—

H0 / n

3.8 / 5.1

NEO score

—

PHA score

—

RMS

—

Elongation

52°

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/2025 Y1 (ATLAS)

    Informal: ATLAS

    C/2025 Y1 · 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.