More than astrophotography, an astronomical exploration.
Comet C/2025 A6 (Lemmon) - 25 Sep. 2025
David Cruz · Astromidnight
In Lynx, Comet Lemmon on its way to the Sun, with a green head and a long gas tail that crosses the whole frame. Behind it, galaxies more than 600 million light-years away.
| Catalogue | Comet C/2025 A6 · discovered by the Mount Lemmon Survey on 3 Jan 2025 |
| Type | Long-period comet |
| Distance | ≈ 186 million km (1.24 AU, 25 Sep 2025) |
| Field | 80.0′ × 51.4′ |
| Scale | 0.81″ / pixel |
| Orientation | −3° · north up |
| RA (centre) | 09h 02m 03s |
| DEC (centre) | +37° 54′ 16″ |
| Constellation | Lynx |
| Objects in field | C/2025 A6 · 2 galaxies · 1 quasar · 2 stars |
Distance and orbit of the comet calculated by JPL (Horizons and Small-Body Database) for the early hours of 25 September 2025 (04:30 to 06:00, Portuguese time; 03:30 to 05:00 UT). The period of about 1,300 years is that of JPL's osculating orbit and changes as the comet passes the planets. The position of the comet's head was measured by us on the image and falls on the path predicted by JPL for that night (the comet moved about 3 arcminutes during the session). Distances to the galaxies and the quasar calculated from redshift (NED), with H0 = 70 km/s/Mpc; position of IC 2427 from SIMBAD, because the AstroBin label is slightly off to one side. No real width: the field mixes a comet in the Solar System with distant stars and galaxies.
1 h 20 min of light
Each tick is a 120-second exposure. 40 in total, with the camera at −10 °C and gain 100. Calibrated with 50 darks, 30 flats and 50 bias. The Moon stayed below 15 % illumination throughout.
Carbon Newton 10' f/4
ZWO ASI2600MC Pro
Sky-Watcher CQ350 Pro
Askar M54 OAG · ZWO ASI120MM Mini
TS-Optics Maxfield .95X Coma Corrector
Adobe Photoshop · Pleiades Astrophoto PixInsight · Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
São Pedro da Gafanhoeira, Évora · 358 m
Bortle 3