Double Cluster in Perseus (h Persei)

About the object

The Double Cluster in Perseus, h and χ Persei, two young open clusters visible to the eye as a hazy patch between Perseus and Cassiopeia. Both were born from the same cloud only a few million years ago, lie at almost the same distance and move together. Each holds hundreds of hot blue stars and a few red supergiants whose colour stands out even in a city sky.

Distance: about 7,500 light-years, apparent size in the sky: 2 × 30′, constellation Perseus.

How it was shot

Everything here was shot with a DWARF Mini smart telescope from a balcony in a city in Ukraine: light-polluted sky, only the eastern half of it visible, and a roof overhang that cuts off the south. 3 nights (1 night in August and 2 in September), 3 sessions, 177 frames with exposures of 30 s, without a filter, in broadband. The stack holds 1 h 29 min of light; the longest night, 31 August, gave 39 min. The goal for this object is 1 h, and it is reached. First night 1 September 2026, last one 3 September 2026.

Double Cluster in Perseus (h Persei) in the night log: 31 August, 1 September, 2 September.

How it went

Both clusters fit into the DWARF Mini field at once, so this was a quick and rewarding object: three nights of thirty-second frames without a filter. The goal for bright clusters is modest and was reached in one go. The red supergiants among the blue stars showed up right away, with no colour boost.