M103 — midnight transit date and best time to observe

Object data

An open cluster in Cassiopeia, one of the last objects Messier himself discovered.

Location: Tokyo (change)

🗓️

Around Oct 10, 2026

The date it transits around midnight (transit altitude about 65°)

This date has already passed this year. Next year (2027) it will be around Oct 11.

For about 2–3 weeks either side of this date, the object stays high from evening to dawn — its observing season.

Tonight (Oct 11 evening – Oct 12 dawn) · Location: Tokyo (full darkness = end of astronomical dusk to start of dawn, altitude ≥ 15°)

🌑 Moon tonight: New moon (age 29.2 days, 0% illuminated) — Little moonlight — a good time for faint objects

🔭

Oct 11 18:36 – Oct 12 4:19

Hours of full darkness (end of astronomical dusk to start of dawn) when it is above 15° — the darkest sky, mostly clear of buildings and trees.

Night (sunset – sunrise) Full darkness (dusk – dawn) Moon up (darker = brighter moon) Best time to observe (thick line) Now

Sunset 17:11 → Dusk 18:36 → Dawn 4:19 → Sunrise 5:44

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