On the night of September 22, 2025, I captured this image of Comet C/2025 A6 (Lemmon) as it glided across the starry sky. This comet, discovered earlier in 2025 by the Mount Lemmon Survey in Arizona, has been steadily brightening and is now becoming a fascinating target for both amateur and professional astronomers.
In the image, you can clearly see the comet’s greenish coma, a result of diatomic carbon (C₂) fluorescing in sunlight, and its developing tail extending away from the Sun. These features make “Lemmon” a striking reminder of the icy wanderers that visit the inner Solar System from the distant Oort Cloud.
Observing comets like Lemmon requires a dark sky, and September nights provide excellent opportunities to follow its evolution. Over the coming weeks, the comet will continue to shift position against the background stars, gradually changing in brightness and appearance.
Image taken on September 22, 2025 – Prades (Catalonia, Spain).
The full image covers an area of 2º03′ x 1º39′ at a resolution of 1.46″/pixel.
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Image Details
FSQ 106 EDX4:
L: 36×120″ (1h12′)
FSQ 85:
RGB: (6, 6, 6) x 120″ (36′)
Calibrated with darks, flats, dark-flats.
Total exposure: 1h48′
Average Moon phase at 0%
Image resolution: 1.46”/pixel
FOV: 2º03′ x 1º39′
Equipment
FSQ106 + ASI2600MM + LRGB ASTRODON filters + ZWO EFW 7 pos + Primaluce Sesto Sento 2
FSQ85 + ASI2600MM + LRGB Baader filters + ZWO EFW 7 pos + Seletek
Mesu 200 Mount
SGP
Guiding with ASI120MM and ZWO Mini Guide Scope
Software
SGP, APP, PIX, TPZ, PS.
Aleix Roig, September 2025.
Prades (Tarragona, Catalonia – Spain).