Comet 2025A6 Lemmon on early morning of Oct 18, 2025

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Date & Time: Oct 17 2025, 28:26 JST(+0900), 4min. exposed
Optical: TAKAHASHI 16cm(6.3") epsilon (f=530mm, F3.3)
with IDAS LPS-D1 Light-pollution suppression filter
Auto-guided with TAKAHASHI EM-200 Equatorial & Lacerta M-GEN
CMOS Camera: ZWO ASI2600MC Pro (Cooled temp.: -15°C)
Location: Furudono town, Fukushima pref.

Camera Settings: Recording format...16bit FITS, converted to 16bit TIFF(6248×4176)
Device Size...23.5×15.7mm, Gain...100


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Date & Time: Oct 17 2025, from 27:38 to 27:48 JST(+0900)
Composed 6 shots with 2 minutes exposed
Optical: BORG 60ED with conversion lens (f=245mm, F4.1)
with IDAS NGS1-DRT Light-pollution suppression filter
Auto-guided with Kenko SKYMEMO S Equatorial
Digital Camera: Canon EOS R6 (Remodeled)
Location: Furudono town, Fukushima pref.

Camera Settings: Recording format...14bit CCD-RAW, converted to 16bit TIFF(5472×3648)
Device Size...35×24mm, Sensitivity...ISO3200


This image shows comet 2025A6 Lemmon captured three days before its closest approach to Earth, low in the northeastern sky before dawn. It was located about 5 degrees east-southeast of α Canum Venaticorum (Cor Caroli). The coma had brightened to around 4th magnitude, and the ion tail extending northward can be seen reaching nearly 6 degrees in length in the photograph. The region of the ion tail near the coma displays a complex structure, indicating that the comet's nucleus was highly active. Comet Lemmon will soon move into the northwestern evening sky and is expected to begin fading after November.
The second image is cropped to an effective focal length of 300 mm.
1st image: View angle: 1.7×2.5°
2nd image: View angle: 4.6×6.8°


2025R2 SWAN on Oct 17, 2025
2025A6 Lemmon on Oct 9, 2025

Copyright(c) 2025 by Naoyuki Kurita, All rights reserved.
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