Comet C/2025 A6 (Lemmon)
Fig. 1 - Discovered by the Mount Lemmon Survey in images obtained on January 3, 2025: Comet C/2025 A6 (Lemmon), photographed with a Teleskop-Service (TS) 65mm Quadruplet Astrograph on a ZWO AM5 mount. The stars appear as streaks because the comet moved relative to the stars during the exposure stack. The images were aligned on the comet, so its motion against the stellar background creates trails.
| Object name: | Perihelion: | Aphelion: | Eccentricity: | Inclination: | Orbital period: |
|---|---|---|---|---|---|
| C/2025 A6 (Lemmon) | 0.5299 AU | ≈122 AU (inbound) | 0.9957 (inbound) | 143.66° | ≈1,346 years (inbound) |
The non-periodic comet C/2025 A6 (Lemmon), discovered by the Mount Lemmon Survey in images obtained on 3 January 2025. The 1.52 m (60 in) cassegrain reflector telescope used for the discovery is located in Tucson, Arizona. C/2025 A6 (Lemmon) made its closest approach to Earth on October 21, 2025 and was visible to the naked eye in some regions. The comet was expected to only brighten to apparent magnitude 10, but brightened to apparent magnitude of about 3.5.
On November 8, 2025 occurred the perihelion (closest approach to the Sun) of the comet when it was 0.53 AU (79 million km; 49 million mi) from the Sun (source: Wikipedia).
Exposure time: 34min 30s (138x15s) at gain 100 and -10°C, taken on October 18, 2025. Processing with Astro Pixel Processor (APP) and Photoshop. Darks, flats, and bias were used. During the imaging session, the comet was in the constellation Canes Venatici. The brightest white startrail near image center is 25 Canum Venaticorum A (mag 4.84), the second brightest white trail further to the left is BH Canum Venaticorum (mag 5).
Equipment: Cooled ASI 2600MC Pro camera, Teleskop-Service (TS) 65mm f/6.5 Quadruplet Astrograph riding on a ZWO AM5 Strain Wave Mount, ZWO OAG-L off axis system, ASI 174MM Mini guide camera, ASIAIR Plus.