Southern delta-Aquariids from Hanoi in 2026

Southern delta-Aquariids from Hanoi: the short answer

The Southern delta-Aquariids peaks at 20:23 local time on 31 July 2026 over Hanoi. Culmination is 02:04 at 53.0° — 80% of the rate a zenith radiant would give — so the ceiling here is 0.6 an hour, not worth the sleep.

That ranks it 12th of twelve from Hanoi this year, behind the Geminids (35.1/h) and the Perseids (23.0/h).

The radiant track over this city

The radiant rises at 20:30 bearing ESE, culminates 53.0° up at 02:04 towards south (180°), and sets at 07:39. It lies inside Aquarius. The rate scales with the sine of that altitude, so 53.0° buys you 80% of a zenith radiant.

When it gets dark here

The dark hours here run 19:56 to 04:09 — 8 h 14 min of astronomical night, bracketed by sunset at 18:35 and sunrise at 05:30. Civil twilight ends at 18:59; anything earlier than that is wasted effort.

Local solar midnight, the true middle of the night, falls at 00:03 here rather than at 00:00: Asia/Bangkok runs 3 minutes behind mean solar time at 105.84°E. That offset is why the best hour on this page is not the hour you would guess from the clock.

What the Moon does here

Moonlight is the limiting factor on this night from Hanoi. The Moon is 96% lit and only 1 of 11 sampled hours are moon-free. Moonrise 19:47. Moonset 07:36. At the best hour it stands 53.3° above the horizon, 8° from the radiant, pulling the limiting magnitude down to 3.47.

Why 1 an hour and not 25

The published ZHR of 25 assumes the radiant overhead and a sky at limiting magnitude 6.5. Here the radiant reaches 53.0° inside the dark window and the limiting magnitude at the best hour is 3.47, which with r = 3.2 gives 0.6 an hour. Entry speed is 40.6 km/s.

Hour by hour the modelled rate runs from 0.0 at 19:00 (radiant -20.5°) to 0.0 at 05:00 (radiant 33.3°), peaking at 0.6. That spread across 11 hours is why a "what time" answer beats a "how many" answer.

The stream comes from Comet 96P/Machholz and is listed as active 12 July to 23 August, so 31 July 2026 is the best night from Hanoi rather than the only one.

Watching from around Hanoi

Hanoi is the 32nd largest of the 300 cities covered here, with a population of 8.05 million at 10 m above sea level. The nearest other cities on the site are Haiphong (89 km ESE), Nanning (324 km NE), Haikou (482 km ESE) — close enough that the radiant altitudes barely change, far enough that sunset and moonrise do.

What this page does not know

Rates on this page are computed against this city's own measured sky brightness, derived from satellite night-lights data. That is a calculated brightness for the point directly overhead, not a survey of your street: a park on the edge of town and a lit car park in the centre share the same figure here and will not look the same. It is also zenith-only, while the Bortle scale describes the whole sky from horizon to horizon.

Cloud cover is a forecast, not a constant, so it is resolved when you load the tonight card and is deliberately absent from this prerendered page — the hourly table shows "unavailable" rather than assuming clear skies. Meteor outbursts, local terrain and building horizons are not modelled.

A single observer with an unobstructed horizon typically records 30–50% below the ideal-sky figure. Give your eyes twenty minutes to adapt, keep bright screens away, look about halfway up the sky rather than straight at the radiant, and count for a full hour before judging a shower.