{"id":25820,"date":"2025-10-01T13:51:55","date_gmt":"2025-10-01T12:51:55","guid":{"rendered":"https:\/\/www.petrhoralek.com\/?p=25820"},"modified":"2026-01-29T19:16:31","modified_gmt":"2026-01-29T18:16:31","slug":"autumn-comet-lemmon","status":"publish","type":"post","link":"https:\/\/www.petrhoralek.com\/?p=25820","title":{"rendered":"Autumn Comet Lemmon"},"content":{"rendered":"

Discovered in January 2025, the comet C\/2025 A6 (Lemmon)<\/a> seems to be promising a nice comet of October 2025. I was also lucky to see this one beauty. Its path nearby the Sun (with perihelion of 8th November 2025) and the Earth then (with perigee on 21st October 2025) brought several truly unusual moments in the sky.<\/p>\n

24th October 2025<\/strong><\/p>\n

\"Aurora<\/a>

Aurora Comet Lemmon<\/p><\/div>\n

Last night was incredible. I have just moved to Sweden, where I organize astrophotography workshop for a group, and this is the view of nature offered over Suotoj\u00e4rvi Lake<\/a>. The comet C\/2025 A6 Lemmon was seemingly swimming in bright Aurora Borealis. The comet was so bright that we could see it with our naked eyes, even very low over the horizon. Captured after 20:30 UTC, Used Nikon Z6III, Nikkor 135mm, f1.8, ISO 3200, 4s exposure foreground, 15x4s comet from tripod (stacked).\u00a8<\/p>\n

\"Aurora<\/a>

Aurora Comet Lemmon<\/p><\/div>\n

\"Aurora<\/a>

Aurora Comet Lemmon<\/p><\/div>\n

Used Canon Ra, Sigma 50mm, f1.4, ISO 2500, 20×3.2s exposure from tripod.<\/p>\n

20th October 2025<\/strong><\/p>\n

\"Shadow<\/a>

Shadow Selfie with the Comet Lemmon – nice cut<\/p><\/div>\n

On 20th October 2025, the sky was truly cloudy over the Czech Republic. Just after I finished a public talk in the library of Nov\u00fd Ji\u010d\u00edn, Czech Republic, I tried to find a good spot before the cirrus cloud completely cover the sky. So I moved up north, after a minutes I spontaneously found a spot where the view was perfect, however, the light pollution made the field in front of me too much illuminated. I did not have much time, so I took this chance. Eventually, I made sort of a “shadow selfie” with view to the Bo\u0159 forest and Vl\u010denec village. To see the comet, I only have some 20 minutes. Then the clouds won and comet dissapeared. Captured after 18:00 UTC, panorama from Canon Ra, Sigma 50mm, f1.4, ISO 2500, panorama 19 single 8s exposures from tripod. for comet used Nikon Z6III, Nikkor 135mm, f1.8, ISO 1000, 15x20s from Vixen Polarie U.<\/p>\n

\"Shadow<\/a>

Shadow Selfie with the Comet Lemmon<\/p><\/div>\n

18th October 2025<\/strong><\/p>\n

\"Solar<\/a>

Solar Wind in Comet’s Tail and the Earth’s Sky<\/p><\/div>\n

\"Solar<\/a>

Solar Wind in Comet’s Tail and the Earth’s Sky – cut<\/p><\/div>\n

That evening, a truly unusual view was possible to capture from Se\u010d Lake, Czech Republic. CME from the Sun hit the Earth, producing a G2 geomagnetic storm, including faint auroras and SAR even in mid-latitudes. As the comet C\/2025 A6 Lemmon approaches Earth (in 2 days), the same cloud from the sun affected even the complicated ion tail of the comet. I succeeded with deeper imaging to reveal that moment in the tail as well as the aurora itself. It doesn’t happen every day to capture the invisible solar wind in two sky phenomena at the same moment. Pano: Canon Ra, Sigma Art 50mm, f 1.4, ISO 4000, 43x8s (pano of single shots from tripod). Around 17:40 UTC on 18 October. Comet’s tail registered into the panorama. Comet’s Tail: Nikon Z6III, Nikkor 135mm, ISO 1000, f1.8, stack of 40x20s, tracked on Vixen Polarie U.<\/p>\n

\"Solar<\/a>

Solar Wind in Comet’s Tail<\/p><\/div>\n

13th October 2025<\/strong><\/p>\n

\"Big<\/a>

Big Dipper Comet Lemmon 2025<\/p><\/div>\n

Another relatively successful night, this time with cloudy weather over Kop\u0159\u00edvn\u00e1, Czech Republic (with view over Kralick\u00fd Sn\u011b\u017en\u00edk Park<\/a>. It was pretty challenging shooting as the cirrus clouds made it almost impossible to capture many details in the complicated comet’s tail. I made the observation just during astronomical twilight, when the sky was still not that cloudy like an hour after. Used Canon Ra, Sigma 50mm, f1.4, ISO 3200, panoramas single 10s exposures. Comet’s tail was enhanced from stacked image taken with Nikon Z6III, Nikor 135mm, f1.8, ISO 1000 and 44x20s from Vixen Polarie U.<\/p>\n

\"Big<\/a>

Big Dipper Comet Lemmon 2025 – wide (annotaterd)<\/p><\/div>\n

\"Big<\/a>

Big Dipper Comet Lemmon 2025 – wide<\/p><\/div>\n

9th October 2025<\/strong><\/p>\n

\"Comet<\/a>

Comet Lemmon over moonlit Lake – square cut<\/p><\/div>\n

After many cloudy nights, I was finally lucky again to shoot the brightening comet C\/2025 A6 Lemmon, which is currently well found south of the Big Dipper asterism. I took the chance from the shore of Se\u010d Lake, Czech Republic, just shortly before a fog completely covered the lake valley. Despite the strong moonlight, the tail of the comet seems to be significant and most likely will show even nicer structures when dark evenings come again. Used Canon Ra, Sigma 50mm, f1.4, ISO 2500, panorama of 37 single 6s exposures. Comet’s tail was enhanced from stacked image taken with Nikon Z6III, Nikor 50mm, f1.2, ISO 800 and 109x8s from Vixen Polarie U.<\/p>\n

\"Comet<\/a>

Comet Lemmon over moonlit Lake – nice cut<\/p><\/div>\n

\"Comet<\/a>

Comet Lemmon over moonlit Lake – detail<\/p><\/div>\n

\"Comet<\/a>

Comet Lemmon over moonlit Lake<\/p><\/div>\n

1st October 2025<\/strong><\/p>\n

This morning, on 1st October, 2025 (around midnight UTC), I was finally lucky with the comet C\/2025 A6 Lemmon from Prose\u010d u Chrudimi, Czech Republic. The beautiful comet is now located in the Ursa Major constellation and starts to be circumpolar from northern mid-latitudes. My observation was truly dramatic as the approaching fog made the view and photography increasingly challenging. Eventually, here is the result, showing a truly significant ion tail of the comet, visible even in small binoculars. Small, but lovely comet, indeed!<\/p>\n

\"Foggy<\/a>

Foggy Comet Lemmon<\/p><\/div>\n

\"Foggy<\/a>

Foggy Comet Lemmon (detail)<\/p><\/div>\n

Used Nikon Z6III, Nikkor 135mm, f2.0, ISO 800, 59x30s from Vixen Polarie U (for ground one of the exposure with stopped mount)<\/p>\n

20th August 2025<\/strong><\/p>\n

On 20 August 2025, a beautiful conjunction of Venus, Jupiter, the Moon, Castor, and Pollux appeared over Se\u010d Lake around 3:30 CEST in the morning. From my place, the Se\u010d Lake, Czech Republic, it looked like a large butterfly in the sky<\/a>. In the scene, also the comet C\/2025 A6 Lemmon was located. Very faint, of course. Used Nikon Z6III, Nikkor 50mm, f1.8, ISO 1000, panorama of five vertical 2s exposures.<\/p>\n

\"Comet<\/a>

Comet C\/2025 A6 Lemmon in the “butterfly conjunction” of 20 August 2025<\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

Discovered in January 2025, the comet C\/2025 A6 (Lemmon) seems to be promising a nice comet of October 2025. I was also lucky to see this one beauty. Its path nearby the Sun (with perihelion of 8th November 2025) and the Earth then (with perigee on 21st October 2025) brought several truly unusual moments in…
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