GoodSeeing
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Cataño

18.441° N   66.118° W  ·  1 M
53 /100
PEAK
Marginal, but there is a 7 hours gap from 21:00.
BEST WINDOW 21:00–04:00 · ASTRO DARK 21:00–05:00 · MOON 0%
Transparency
0.39
Seeing
0.61
Cloud
23%
Moon
0%

Fair tonight

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

Sky state
Lighter = daylight and twilight  ·  unshaded = astronomical dark
Score
19
20
21
22
23
00
01
02
03
04
05
06
0
46
53
47
46
46
40
45
43
26
24
0
BEST WINDOW
Low cloud
8%
6%
9%
11%
13%
15%
16%
14%
14%
35%
27%
29%
Mid cloud
6%
1%
2%
8%
13%
13%
11%
2%
2%
8%
13%
12%
High cloud
47%
18%
20%
21%
15%
9%
6%
27%
39%
54%
50%
32%
Transparency
0.43
0.39
0.37
0.37
0.37
0.34
0.10
0.32
0.29
0.29
0.31
0.30
Seeing
0.53
0.54
0.54
0.44
0.47
0.47
0.46
0.46
0.61
0.49
0.48
0.41
Moon clear
0%
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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
19 Clouded out · 0/100
Starting from
100
Cloud
−35
Transparency
−15
Seeing
−6
Moonlight
−0
Darkness
−44
Score
0
CLOUD 53% LOW 8% MID 6% HIGH 47% SUN -2.2° MOON 1.9° / 0% WIND 7 TEMP 28°
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 19:30 · OBSERVE 20:00–04:00 · 8H · MEAN 48

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

192123010305
HIGH CLOUD CLEARS 20:00CLOUD RETURNS 04:00
SET UP 19:30 · OBSERVE 20:00–04:00 · 8H · MEAN 47

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

192123010305
HIGH CLOUD CLEARS 20:00CLOUD RETURNS 04:00SEEING STAYS SOFT THROUGHOUT
SET UP 19:30 · OBSERVE 20:00–04:00 · 8H · MEAN 45

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

192123010305
HIGH CLOUD CLEARS 20:00CLOUD RETURNS 04:00
SET UP 20:30 · OBSERVE 21:00–23:00 · 2H · MEAN 38

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

192123010305
ASTRONOMICAL DARK FROM 21:00
SET UP 19:30 · OBSERVE 20:00–04:00 · 8H · MEAN 51

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

192123010305
HIGH CLOUD CLEARS 20:00CLOUD RETURNS 04:00
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The next week of nights

Tonight · 12 Aug
53
Fair
MOON 0%
21:00–04:00
Tomorrow · 13 Aug
54
Fair
MOON 3%
01:00–05:00
Friday · 14 Aug
65
Good
MOON 7%
21:00–03:00
Saturday · 15 Aug
6
Clouded out
MOON 15%
Sunday · 16 Aug
19
Poor
MOON 23%
Monday · 17 Aug
56
Good
MOON 32%
02:00–03:00
Tuesday · 18 Aug
57
Good
MOON 42%
02:00–03:00
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Nearby locations

About this forecast

Conditions for Cataño, Puerto Rico 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 →