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Tsukubamirai

35.984° N   140.009° E  ·  10 M
36 /100
PEAK
Marginal, but there is a 1 hour gap from 03:00.
BEST WINDOW 03:00–04:00 · ASTRO DARK 01:00–04:00 · MOON 0%
Transparency
0.10
Seeing
0.97
Cloud
52%
Moon
0%

Fair tonight

Hour by hour, local to Tsukubamirai. 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
0
0
36
14
0
BEST WINDOW
Low cloud
100%
100%
11%
48%
81%
Mid cloud
9%
16%
10%
2%
23%
High cloud
65%
84%
53%
8%
69%
Transparency
0.10
0.10
0.10
0.10
0.10
Seeing
0.97
0.79
0.95
0.93
0.90
Moon clear
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 Clouded out · 0/100
Starting from
100
Cloud
−100
Transparency
−0
Seeing
−0
Moonlight
−0
Darkness
−0
Score
0
CLOUD 100% LOW 100% MID 9% HIGH 65% SUN -36.1° MOON -35.2° / 0% WIND 2 TEMP 23°
Excellent 75+ Good 55+ Fair 35+ Poor 15+ Not worth it Seeing is estimated from surface wind — see how we score.

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 02:30 · OBSERVE 03:00–04:00 · 1H · MEAN 35

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

010305
HIGH CLOUD CLEARS 03:00TWILIGHT BEGINS 04:00
SET UP 02:30 · OBSERVE 03:00–04:00 · 1H · MEAN 45

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

010305
HIGH CLOUD CLEARS 03:00TWILIGHT BEGINS 04:00MOONLIGHT IGNORED FOR THIS TARGET
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

010305
CLOUD NEVER DROPS BELOW 52%
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

010305
CLOUD NEVER DROPS BELOW 52%
NO USABLE WINDOW FOR THIS TARGET TONIGHT

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

010305
CLOUD NEVER DROPS BELOW 52%
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The next week of nights

Tonight · 12 Aug
36
Fair
MOON 0%
03:00–04:00
Tomorrow · 13 Aug
17
Poor
MOON 1%
Friday · 14 Aug
37
Fair
MOON 5%
20:00–21:00
Saturday · 15 Aug
50
Fair
MOON 8%
03:00–04:00
Sunday · 16 Aug
39
Fair
MOON 19%
03:00–04:00
Monday · 17 Aug
61
Good
MOON 28%
21:00–22:00
Tuesday · 18 Aug
48
Fair
MOON 37%
21:00–22:00
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Nearby locations

About this forecast

Conditions for Tsukubamirai, Japan 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 →