Comet C/2025 A6 (Lemmon) · ATR2600C · 2025-10-07

Comet C/2025 A6 (Lemmon) is a long-period comet discovered on January 3, 2025 by David C. Fuls as part of the Mount Lemmon Survey at the University of Arizona's Steward Observatory, when it appeared as a faint asteroidal object roughly 4.5 AU from the Sun before follow-up observations revealed cometary activity. It brightened substantially as it approached the Sun, becoming visible to the naked eye around its closest approach to Earth on October 21, 2025. Its orbit suggests it won't return to the inner solar system for a very long time, if ever.

[Source: Wikipedia, en.wikipedia.org/wiki/C/2025_A6_(Lemmon); BBC Sky at Night, skyatnightmagazine.com]

Annotated Image

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Sky Location

The chart above shows where this image sits on the night sky. The yellow outline is its field of view, with the picture itself drawn at its true orientation; north is up and east is left. Click the chart to zoom in, and use "open full resolution" for the full-size chart.

Image Details

PixInsight Processing

1. Image Integration (x2)

Comet C/2025 A6 (Lemmon) is a long-period comet discovered on January 3, 2025 by David C. Fuls as part of the Mount Lemmon Survey at the University of Arizona's Steward Observatory, when it appeared as a faint asteroidal object roughly 4.5 AU from the Sun before follow-up observations revealed cometary activity. It brightened substantially as it approached the Sun, becoming visible to the naked eye around its closest approach to Earth on October 21, 2025. Its orbit suggests it won't return to the inner solar system for a very long time, if ever.

[Source: Wikipedia, en.wikipedia.org/wiki/C/2025_A6_(Lemmon); BBC Sky at Night, skyatnightmagazine.com]

Sky Location

The chart above shows where this image sits on the night sky. The yellow outline is its field of view, with the picture itself drawn at its true orientation; north is up and east is left. Click the chart to zoom in, and use "open full resolution" for the full-size chart.

Image Details

PixInsight Processing

1. Channel Combination (x2)
2. Image Integration (x2)
3. Image Calibration
4. Debayer
5. BlurXTerminator (AI deconvolution)
6. GraXpert (gradient removal)
7. NoiseXTerminator (AI denoise)
8. Generalized Hyperbolic Stretch (x5)
9. Curves Transformation

Comet C/2025 A6 (Lemmon) is a long-period comet discovered on January 3, 2025 by David C. Fuls as part of the Mount Lemmon Survey at the University of Arizona's Steward Observatory, when it appeared as a faint asteroidal object roughly 4.5 AU from the Sun before follow-up observations revealed cometary activity. It brightened substantially as it approached the Sun, becoming visible to the naked eye around its closest approach to Earth on October 21, 2025. Its orbit suggests it won't return to the inner solar system for a very long time, if ever.

[Source: Wikipedia, en.wikipedia.org/wiki/C/2025_A6_(Lemmon); BBC Sky at Night, skyatnightmagazine.com]

Annotated Image

The annotated version is shown above - click it to zoom. Open the annotated image at full resolution.

Sky Location

The chart above shows where this image sits on the night sky. The yellow outline is its field of view, with the picture itself drawn at its true orientation; north is up and east is left. Click the chart to zoom in, and use "open full resolution" for the full-size chart.

Image Details

PixInsight Processing

1. Channel Combination (x2)
2. Image Integration (x2)
3. Image Calibration
4. Debayer
5. BlurXTerminator (AI deconvolution)
6. GraXpert (gradient removal)
7. NoiseXTerminator (AI denoise)
8. Generalized Hyperbolic Stretch (x5)
9. Curves Transformation