Orbit Jet Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Orbit Jet Observatory clear sky chart from 2005-11-06 to 2024-01-31.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
24%
23024
11%
75083
7%
22972
29%
22972
12%
57583

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
6%
757
5%
2649
2%
757
9%
757
3%
2358
January11th to 20thNight
8%
760
3%
2508
2%
760
10%
760
4%
2231
January21st to endNight
10%
835
5%
2711
2%
835
13%
835
4%
2411
February1st to 10thNight
6%
720
4%
2340
1%
720
10%
720
4%
2086
February11th to 20thNight
8%
703
6%
2275
2%
700
13%
700
5%
1944
February21st to endNight
9%
592
7%
1849
2%
592
16%
592
6%
1561
March1st to 10thNight
14%
720
10%
1980
5%
720
19%
720
11%
1608
March11th to 20thNight
17%
720
14%
1980
6%
720
24%
720
13%
1531
March21st to endNight
20%
792
15%
2178
7%
792
26%
792
14%
1682
April1st to 10thNight
18%
720
12%
1811
3%
720
24%
720
16%
1405
April11th to 20thNight
22%
711
14%
1775
5%
711
27%
711
20%
1312
April21st to endNight
26%
558
15%
1638
5%
558
34%
558
17%
1181
May1st to 10thNight
34%
540
13%
1620
8%
540
37%
540
17%
1170
May11th to 20thNight
33%
368
17%
1430
14%
368
42%
368
17%
942
May21st to endNight
42%
388
16%
1551
15%
388
50%
388
22%
918
June1st to 10thNight
39%
360
13%
1440
12%
360
48%
360
18%
920
June11th to 20thNight
40%
360
14%
1440
17%
360
47%
360
19%
893
June21st to endNight
36%
360
12%
1440
11%
360
46%
360
20%
892
July1st to 10thNight
53%
350
16%
1400
20%
350
58%
350
24%
791
July11th to 20thNight
50%
348
17%
1392
20%
348
57%
348
24%
800
July21st to endNight
50%
568
14%
1651
11%
537
52%
537
28%
1037
August1st to 10thNight
54%
537
16%
1600
13%
534
57%
534
30%
995
August11th to 20thNight
51%
534
17%
1598
11%
534
54%
534
24%
1057
August21st to endNight
49%
720
17%
1908
10%
720
51%
720
31%
1258
September1st to 10thNight
45%
720
17%
1800
8%
720
47%
720
28%
1243
September11th to 20thNight
48%
720
24%
1859
14%
720
53%
720
33%
1214
September21st to endNight
39%
720
17%
2042
14%
720
42%
720
21%
1431
October1st to 10thNight
33%
720
14%
2160
12%
720
39%
720
19%
1531
October11th to 20thNight
21%
720
10%
2160
6%
720
28%
720
13%
1650
October21st to endNight
14%
792
12%
2376
6%
792
21%
792
10%
1897
November1st to 10thNight
23%
740
15%
2400
11%
740
29%
740
15%
1739
November11th to 20thNight
15%
760
11%
2660
6%
760
22%
760
9%
2079
November21st to endNight
13%
760
7%
2660
4%
760
18%
760
6%
2218
December1st to 10thNight
8%
760
3%
2660
1%
760
11%
760
3%
2372
December11th to 20thNight
7%
760
3%
3281
0%
759
10%
759
3%
2898
December21st to endNight
6%
831
2%
4861
1%
817
10%
817
2%
4328

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
18%13%5%8%6%3445%6%28%
74828
Night
18%15%6%9%6%34445%26%
75294
TransparencyDay
57%6%11%17%8%1
74543
Night
60%6%10%15%8%1
75113
SeeingDay
27%18%28%17%8%2
13480
Night
27%17%27%20%8%1
23033

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
15%23%9%16%11%443339%
1517
11th to 20thDay
17%23%11%15%8%3433311%
1670
21st to endDay
13%20%9%18%11%45%4338%
1872
February1st to 10thDay
17%22%8%17%10%5%432211%
1620
11th to 20thDay
14%19%10%16%9%4433314%
1573
21st to endDay
20%17%7%12%8%34435%17%
1402
March1st to 10thDay
16%16%7%11%8%44345%22%
1977
11th to 20thDay
15%19%8%9%43343427%
1980
21st to endDay
20%16%48%6%34445%26%
2178
April1st to 10thDay
18%17%5%6%6%245%4429%
2148
11th to 20thDay
19%13%36%434446%34%
2134
21st to endDay
21%13%45%6%3434432%
2336
May1st to 10thDay
21%11%36%6%3445%6%31%
2340
11th to 20thDay
20%8%36%5%45%5%47%34%
2464
21st to endDay
15%7%35%5%35%5%6%8%40%
2725
June1st to 10thDay
19%6%36%5%35%5%5%7%37%
2520
11th to 20thDay
17%6%25%5%35%5%6%10%35%
2520
21st to endDay
18%6%345%35%5%5%8%39%
2520
July1st to 10thDay
13%5%35%345%6%5%9%43%
2520
11th to 20thDay
14%6%35%5%45%6%6%9%36%
2520
21st to endDay
13%6%36%7%36%6%7%7%34%
2566
August1st to 10thDay
12%6%35%5%35%5%7%9%40%
2327
11th to 20thDay
14%6%36%7%45%6%8%10%32%
2303
21st to endDay
16%6%35%5%35%46%9%39%
2428
September1st to 10thDay
18%7%35%6%2446%8%36%
2160
11th to 20thDay
18%5%25%435%5%6%8%40%
2098
21st to endDay
20%6%37%6%45%46%7%33%
1917
October1st to 10thDay
26%8%46%43445%7%30%
1800
11th to 20thDay
26%12%37%5%34445%26%
1800
21st to endDay
30%16%38%5%3434419%
1980
November1st to 10thDay
18%17%47%5%34445%27%
1675
11th to 20thDay
17%24%6%7%433346%21%
1520
21st to endDay
21%24%7%8%6%3343416%
1520
December1st to 10thDay
19%28%12%12%4343249%
1520
11th to 20thDay
19%23%9%16%6%3333412%
1906
21st to endDay
23%29%9%10%6%3333210%
2772
January1st to 10thNight
17%24%9%14%9%3433310%
2649
11th to 20thNight
16%25%9%14%9%4433311%
2508
21st to endNight
13%21%10%14%10%5%5%33311%
2711
February1st to 10thNight
18%20%9%16%10%3333411%
2340
11th to 20thNight
16%16%7%17%9%45%335%14%
2273
21st to endNight
18%17%7%14%9%4434416%
1849
March1st to 10thNight
15%16%7%10%8%45%35%5%22%
1970
11th to 20thNight
19%15%7%7%5%3343429%
1979
21st to endNight
17%15%6%8%6%34445%29%
2178
April1st to 10thNight
20%14%6%6%5%34346%29%
1811
11th to 20thNight
21%11%27%5%34446%34%
1775
21st to endNight
20%11%45%5%35%45%7%32%
1638
May1st to 10thNight
22%8%36%5%445%6%6%31%
1620
11th to 20thNight
14%8%36%5%46%5%6%8%36%
1429
21st to endNight
14%6%25%4335%5%7%45%
1550
June1st to 10thNight
15%6%26%7%46%5%6%7%36%
1440
11th to 20thNight
14%6%35%5%35%46%8%41%
1440
21st to endNight
15%6%25%6%345%6%7%40%
1440
July1st to 10thNight
10%6%35%5%25%46%9%46%
1440
11th to 20thNight
12%6%245%345%7%8%44%
1440
21st to endNight
13%5%243346%7%9%43%
1748
August1st to 10thNight
11%6%25%5%345%6%9%44%
1611
11th to 20thNight
13%6%36%6%45%6%6%8%40%
1598
21st to endNight
14%6%25%435%46%9%42%
1908
September1st to 10thNight
17%7%35%4345%5%7%42%
1800
11th to 20thNight
15%5%344245%46%47%
1859
21st to endNight
19%7%35%5%35%5%5%8%35%
2042
October1st to 10thNight
21%6%36%445%46%6%35%
2160
11th to 20thNight
25%12%36%6%345%46%26%
2160
21st to endNight
31%12%46%5%34445%22%
2376
November1st to 10thNight
19%15%48%5%33345%32%
2400
11th to 20thNight
18%19%5%8%6%35%445%22%
2660
21st to endNight
19%21%9%9%5%34445%17%
2660
December1st to 10thNight
22%26%11%9%6%2433311%
2660
11th to 20thNight
18%24%11%15%5%3433311%
3288
21st to endNight
24%26%8%10%6%344348%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
81%46%7%2
1518
11th to 20thDay
80%47%6%3
1670
21st to endDay
82%46%5%2
1872
February1st to 10thDay
82%47%6%2
1620
11th to 20thDay
75%5%7%10%4
1582
21st to endDay
71%5%9%10%41
1402
March1st to 10thDay
65%6%11%14%41
1980
11th to 20thDay
61%5%10%14%8%1
1980
21st to endDay
62%46%16%9%2
2178
April1st to 10thDay
58%5%11%15%10%1
2148
11th to 20thDay
51%6%10%20%11%2
2134
21st to endDay
56%6%9%16%12%1
2336
May1st to 10thDay
53%6%11%20%9%2
2340
11th to 20thDay
50%7%11%19%12%1
2468
21st to endDay
41%8%16%21%12%1
2725
June1st to 10thDay
46%7%12%20%14%1
2520
11th to 20thDay
44%8%14%22%12%1
2520
21st to endDay
43%7%13%24%13%1
2520
July1st to 10thDay
37%8%13%26%14%2
2450
11th to 20thDay
42%8%16%22%12%
2445
21st to endDay
45%9%14%20%12%
2422
August1st to 10thDay
39%9%16%26%10%1
2314
11th to 20thDay
43%10%16%22%8%1
2303
21st to endDay
42%8%14%24%11%1
2428
September1st to 10thDay
45%7%13%23%11%1
2160
11th to 20thDay
40%7%12%26%13%1
2098
21st to endDay
50%7%12%20%10%1
1917
October1st to 10thDay
54%6%12%16%10%2
1800
11th to 20thDay
60%6%13%14%7%1
1800
21st to endDay
69%49%11%6%1
1980
November1st to 10thDay
58%6%9%16%9%2
1675
11th to 20thDay
64%5%12%12%5%2
1520
21st to endDay
72%5%10%9%4
1520
December1st to 10thDay
81%5%6%7%1
1520
11th to 20thDay
77%6%9%6%2
1906
21st to endDay
82%47%6%
2772
January1st to 10thNight
80%46%6%3
2649
11th to 20thNight
80%48%5%21
2508
21st to endNight
80%46%6%31
2711
February1st to 10thNight
79%5%7%6%3
2340
11th to 20thNight
74%5%8%10%4
2275
21st to endNight
71%5%8%10%5%
1849
March1st to 10thNight
63%7%9%15%6%1
1980
11th to 20thNight
59%5%10%16%8%1
1980
21st to endNight
58%6%6%15%12%2
2178
April1st to 10thNight
57%5%10%18%9%
1811
11th to 20thNight
51%5%11%18%13%2
1775
21st to endNight
52%6%10%17%13%2
1638
May1st to 10thNight
52%6%9%19%12%2
1620
11th to 20thNight
45%9%10%21%13%2
1430
21st to endNight
38%7%15%23%15%2
1551
June1st to 10thNight
43%9%13%21%14%1
1440
11th to 20thNight
41%8%12%22%15%2
1440
21st to endNight
41%8%14%23%12%2
1440
July1st to 10thNight
35%8%13%25%17%3
1400
11th to 20thNight
37%6%15%26%15%1
1392
21st to endNight
36%9%17%23%14%2
1651
August1st to 10thNight
35%9%17%29%11%1
1600
11th to 20thNight
41%9%15%25%10%
1598
21st to endNight
38%6%15%27%11%2
1908
September1st to 10thNight
41%7%13%25%12%2
1800
11th to 20thNight
37%6%12%26%16%2
1859
21st to endNight
46%8%13%21%11%1
2042
October1st to 10thNight
49%7%11%18%14%1
2160
11th to 20thNight
58%6%13%14%8%1
2160
21st to endNight
64%5%11%12%6%1
2376
November1st to 10thNight
55%6%10%18%9%3
2400
11th to 20thNight
63%6%10%13%5%2
2660
21st to endNight
70%7%10%10%3
2660
December1st to 10thNight
79%5%8%6%2
2660
11th to 20thNight
78%6%9%5%2
3288
21st to endNight
80%6%8%6%
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
31%29%29%8%31
180
11th to 20thDay
37%35%19%7%2
252
21st to endDay
29%31%27%9%3
294
February1st to 10thDay
39%33%23%5%
240
11th to 20thDay
34%36%27%3
240
21st to endDay
44%24%27%5%
260
March1st to 10thDay
32%25%29%11%3
420
11th to 20thDay
29%25%34%9%3
420
21st to endDay
34%21%27%14%4
462
April1st to 10thDay
34%21%29%11%5%
420
11th to 20thDay
32%23%24%11%7%2
412
21st to endDay
29%20%31%15%22
420
May1st to 10thDay
33%17%28%14%5%2
423
11th to 20thDay
26%14%30%20%8%2
447
21st to endDay
18%14%30%23%11%4
485
June1st to 10thDay
22%15%36%19%7%1
450
11th to 20thDay
21%14%29%24%11%1
450
21st to endDay
20%13%35%22%8%1
450
July1st to 10thDay
13%9%29%29%16%4
445
11th to 20thDay
15%10%32%26%14%4
444
21st to endDay
16%9%36%25%12%3
488
August1st to 10thDay
14%9%26%31%14%6%
446
11th to 20thDay
15%8%31%25%17%4
439
21st to endDay
19%8%30%25%13%5%
495
September1st to 10thDay
18%12%27%24%14%6%
450
11th to 20thDay
16%8%24%27%18%7%
450
21st to endDay
20%19%26%20%11%5%
450
October1st to 10thDay
27%12%26%18%14%3
450
11th to 20thDay
32%20%28%15%5%
450
21st to endDay
43%18%23%14%2
495
November1st to 10thDay
31%21%26%15%6%1
335
11th to 20thDay
43%21%27%7%21
180
21st to endDay
38%26%29%6%2
180
December1st to 10thDay
42%26%24%6%3
180
11th to 20thDay
42%24%24%10%
180
21st to endDay
41%26%27%5%1
198
January1st to 10thNight
33%27%27%9%3
760
11th to 20thNight
34%27%28%10%1
760
21st to endNight
26%27%31%14%2
835
February1st to 10thNight
33%27%28%11%1
720
11th to 20thNight
30%28%31%10%2
703
21st to endNight
34%24%29%12%1
592
March1st to 10thNight
28%21%32%15%4
720
11th to 20thNight
31%20%29%14%41
720
21st to endNight
26%20%31%17%6%1
792
April1st to 10thNight
29%20%30%19%3
720
11th to 20thNight
29%15%30%19%6%1
711
21st to endNight
25%11%32%24%7%1
558
May1st to 10thNight
27%9%25%29%9%1
540
11th to 20thNight
17%9%33%33%7%
368
21st to endNight
17%9%27%34%13%1
389
June1st to 10thNight
16%6%33%33%12%1
360
11th to 20thNight
17%10%27%37%9%
360
21st to endNight
16%8%36%31%9%
360
July1st to 10thNight
12%5%22%42%18%1
350
11th to 20thNight
12%5%28%36%18%1
348
21st to endNight
15%5%26%35%18%1
568
August1st to 10thNight
13%422%39%20%2
537
11th to 20thNight
13%6%22%34%24%2
534
21st to endNight
15%7%26%30%21%2
720
September1st to 10thNight
21%8%22%30%16%3
720
11th to 20thNight
17%7%23%27%24%3
720
21st to endNight
22%11%24%26%14%3
720
October1st to 10thNight
24%11%27%23%15%1
720
11th to 20thNight
33%16%26%19%5%1
720
21st to endNight
39%14%28%16%2
792
November1st to 10thNight
29%14%29%20%6%1
740
11th to 20thNight
32%21%28%13%5%1
760
21st to endNight
34%23%28%12%4
760
December1st to 10thNight
40%25%21%10%3
760
11th to 20thNight
37%26%25%11%2
760
21st to endNight
36%26%27%10%1
836
Page generated at 2024-01-28 05:26:32. Version ac07

Copyright 2024 Attilla Danko


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