Translation. Region: Russian Federal
Source: Novosibirsk State University –
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Mikhail Maslov, an engineer at the Vega Observatory at Novosibirsk State University, captured this image of Comet C/2025 A6 Lemmon, which is currently only visible through amateur telescopes early in the morning. It will be one of the most striking astronomical events of the fall: its peak brightness will occur in late October and early November.
The comet was discovered relatively recently: on January 3, 2025, at the Mount Lemmon Observatory (USA), hence its name. It is a long-period comet: its orbital period is currently 1,369 years. Its perihelion (the comet's closest orbital distance to the Sun) is November 8, 2025, at a perihelion distance of 0.53 astronomical units.
"Brightness estimates for this comet have now been revised upward: in late October – early November, a brightness of approximately magnitude 4 is expected; previously, magnitude 6 was expected. This comet's brightening, ahead of the initial baseline forecast, was expected, as this is not the comet's first pass near the Sun, meaning, as astronomers say, it is not 'dynamically new.' In such comets, the most volatile substances from the surface of the nucleus have already largely evaporated during previous returns. Therefore, such comets, as they approach the Sun, exhibit a comparatively low brightness for their size (since the most volatile substances are relatively few in number). Then, closer to the Sun, when the more refractory components of the nucleus, such as water ice, begin to melt and evaporate, they increase their brightness quite sharply," explained Mikhail Maslov.
The comet was photographed around 4 a.m. on September 19, approximately 70 km from Novosibirsk, using a telescope with a focal length of 854 mm and an aperture of 2.8 f/2.0. The total shooting time was 31 minutes. The weather conditions were favorable: despite the presence of clouds, they nevertheless passed by and did not obscure the comet.
Another comet that will be observable from Russia this fall is C/2025 K1 ATLAS. This comet's brightness has also been revised upwards; in October-November, it is expected to reach magnitude 7 or 8 (previously, it was predicted to reach magnitude 9 or 10). It will be visible in amateur telescopes.
"The discovery of another bright autumn comet, C/2025 R2 SWAN, was recently officially announced. It's currently near its peak brightness—magnitude 7—but it's not yet visible at our latitudes. It will become visible around October 5-10, and by the end of the month and into November, it will be at a good altitude, although its brightness is waning," said Mikhail Maslov.
NSU astronomers advise astrophotographers to prepare in advance for the exciting autumn events.
"As they approach the Sun, comets' tails typically become more extended, and this tail may split into ionic (bluish-green gas) and dust (yellowish-white) components. Astrophotographers will have the opportunity to capture these beautiful hues of comet tails with their cameras," added Alfiya Nesterenko, head of the Vega Observatory at NSU.
Photo: Mikhail Maslov, engineer at the Vega Observatory at NSU
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