GoodSeeing
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Cheung Chau

22.211° N   114.028° E  ·  4 M
44 /100
PEAK
Marginal, but there is a 4 hours gap from 01:00.
BEST WINDOW 01:00–05:00 · ASTRO DARK 01:00–05:00 · MOON 0%
Transparency
0.37
Seeing
0.42
Cloud
33%
Moon
0%

Fair tonight

Hour by hour, local to Cheung Chau. Colour encodes the score and nothing else; every other measurement is luminance.

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
01
02
03
04
05
06
44
43
43
36
20
0
BEST WINDOW
Low cloud
23%
19%
12%
11%
14%
17%
Mid cloud
2%
6%
11%
13%
20%
26%
High cloud
11%
24%
29%
31%
45%
48%
Transparency
0.34
0.37
0.37
0.12
0.12
0.11
Seeing
0.40
0.40
0.42
0.42
0.42
0.47
Moon clear
down
down
down
down
down
down
Inspect

Cloud tracks show clear sky — a longer bar is better. The figure inside each track is the raw measurement.

Why this hour scored what it did
01 Fair · 44/100
Starting from
100
Cloud
−29
Transparency
−19
Seeing
−8
Moonlight
−0
Darkness
−0
Score
44
CLOUD 33% LOW 23% MID 2% HIGH 11% SUN -52.1° MOON -51.4° / 0% WIND 8 TEMP 30°
Excellent 75+ Good 55+ Fair 35+ Poor 15+ Not worth it Seeing is estimated from surface wind — see how we score.
Tonight's limiting factor
What the GoodSeeing score actually measures

One number from 0 to 100 per hour, combining cloud, transparency, seeing, moonlight and darkness. Cloud gates everything else — no amount of steady, dark air rescues an overcast sky.

What are you doing tonight?

The same forecast, weighted for the target. Planetary work barely cares about moonlight; long exposures die on high cloud a visual observer would never notice.

SET UP 00:30 · OBSERVE 01:00–05:00 · 4H · MEAN 45

Darkness and moonlight dominate. Faint fuzzies need a genuinely dark sky more than they need steady air.

010305
TWILIGHT BEGINS 05:00
SET UP 00:30 · OBSERVE 01:00–05:00 · 4H · MEAN 41

Seeing is everything and moonlight is irrelevant. Bright targets punch through twilight, so darkness barely counts.

010305
TWILIGHT BEGINS 05:00SEEING STAYS SOFT THROUGHOUTMOONLIGHT IGNORED FOR THIS TARGET
SET UP 00:30 · OBSERVE 01:00–04:00 · 3H · MEAN 43

Tolerates soft seeing, but high cloud wrecks a wide frame and moonlight raises the background everywhere.

010305
NO USABLE WINDOW FOR THIS TARGET TONIGHT

Needs conditions to hold still for hours. Sustained transparency matters more than any single good hour.

010305
CONDITIONS STAY BELOW THE USABLE THRESHOLD
SET UP 00:30 · OBSERVE 01:00–05:00 · 4H · MEAN 47

Naked eye, whole sky. Total cloud and moonlight are the only things that count.

010305
TWILIGHT BEGINS 05:00
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The next week of nights

Tonight · 12 Aug
44
Fair
MOON 0%
01:00–05:00
Tomorrow · 13 Aug
30
Poor
MOON 1%
Friday · 14 Aug
27
Poor
MOON 5%
Saturday · 15 Aug
31
Poor
MOON 10%
Sunday · 16 Aug
8
Clouded out
MOON 19%
Monday · 17 Aug
47
Fair
MOON 28%
02:00–03:00
Tuesday · 18 Aug
13
Clouded out
MOON 37%
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Nearby locations

About this forecast

Conditions for Cheung Chau, Hong Kong are computed from the MET Norway forecast model for these exact coordinates, combined with sun and moon positions we calculate directly. The score weighs cloud cover by layer, atmospheric transparency, estimated seeing, moonlight and how dark the sky actually gets. Read the full method →