Observation by Robin Leadbeater: Comet 2025 K1 (ATLAS) Spectrum

Uploaded by

Robin Leadbeater

Observer

Robin Leadbeater

Observed

2025 Nov 16 - 01:54

Uploaded

2025 Nov 21 - 10:34

Objects

Spectrum
C/2025 K1

Equipment

ALPY 200 Spectrograph
ALPY 600 Spectrograph
ATIK 428 Camera
Celestron C11 SCT 280mm aperture f5.5

Exposure

12x300s, 20x300s

Location

Wigton, Cumbria, UK

Target name

C/2025 K1 (ATLAS)

Title

Comet 2025 K1 (ATLAS) Spectrum

About this image

This comet (currently fragmenting) shows a rare, unusual spectrum of a carbon chain depleted comet, devoid of the usual carbon-based emissions of CN C2 but with strong NH2 emission bands in the red. The graphic shows a 15 second exposure from the spectrograph guider with the fragmenting coma on the slit, raw uncalibrated spectrum images taken using ALPY200 and ALPY 600 spectrographs (using a wider than usual 35 micron slit to maximise the captured light) and the final spectra (red and grey) compared with a typical solar system comet 2020 F3 (NEOWISE) in blue. The NH2 band wavelengths are marked in green.

Spectra downloadable from the BAA spectroscopy database

Files associated with this observation

2025_K1_RL_THO_20251115-16.png (461.7 kB)

Like this image

Dominic Ford, Alun Halsey, Mike Harlow, Andres Kriete, Oliver Hext

Comments

Nick James, 2025 Nov 22 - 08:59 UTC

Fascinating comparison which shows the carbon depletion very well. A low resolution colour image I took a few days later here shows no sign of the normal green comet coma. For comparison, an image taken with the same equipment, same morning and same processing of 24P here does show the normal green coma although that comet is much fainter.

If anything, C/2025 K1 is the outlier and 3I looks quite normal!

Robin Leadbeater

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