Translation. Region: Russian Federation –
Source: Novosibirsk State University –
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Mikhail Maslov, an engineer at Novosibirsk State University's Vega Observatory, captured one of this fall's brightest comets yesterday—C/2025 A6 Lemmon. The image was taken in the Iskitim district of the Novosibirsk region; the comet was not very high above the horizon and was obscured by light. A 12-inch Newtonian telescope and a Pentax KP camera were used for the image. The comet will reach its peak brightness in late October or 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.
"The comet's brightness is currently changing in accordance with new estimates, which were revised upward in September: in late October – early November, a brightness of around magnitude 4 is expected, while earlier estimates suggested magnitude 6. This increase in brightness, 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 they contain relatively few of the most volatile substances). 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.
Photo: Mikhail Maslov, engineer at the Vega Observatory at NSU
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