CAMSAT Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the CAMSAT Observatory clear sky chart from 2005-11-05 to 2017-04-28.

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
38%
14431
14%
45683
10%
14396
43%
14396
19%
31895

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 15thNight
17%
718
9%
2497
3%
716
24%
716
9%
1981
January16th to endNight
22%
768
11%
2496
5%
768
29%
768
11%
1939
February1st to 15thNight
18%
702
10%
2287
3%
701
27%
701
11%
1773
February16th to endNight
24%
631
13%
2022
6%
631
34%
631
14%
1485
March1st to 15thNight
25%
720
14%
1980
6%
720
32%
720
17%
1485
March16th to endNight
35%
768
20%
2112
10%
768
44%
768
25%
1441
April1st to 15thNight
35%
718
15%
1805
5%
718
40%
718
24%
1310
April16th to endNight
44%
573
20%
1641
9%
573
50%
573
28%
1081
May1st to 15thNight
51%
429
17%
1419
14%
429
56%
429
24%
917
May16th to endNight
59%
342
17%
1369
20%
342
65%
342
28%
737
June1st to 15thNight
51%
330
12%
1320
14%
330
59%
330
20%
801
June16th to endNight
59%
330
11%
1320
17%
330
63%
330
24%
762
July1st to 15thNight
72%
310
17%
1240
26%
310
75%
310
35%
618
July16th to endNight
66%
426
15%
1377
16%
397
67%
397
31%
785
August1st to 15thNight
69%
494
18%
1474
15%
491
71%
491
35%
870
August16th to endNight
64%
583
22%
1633
14%
583
67%
583
36%
983
September1st to 15thNight
55%
660
20%
1650
10%
660
60%
660
33%
1102
September16th to endNight
56%
657
21%
1839
14%
657
59%
657
31%
1156
October1st to 15thNight
42%
660
18%
1980
17%
660
47%
660
22%
1367
October16th to endNight
28%
704
12%
2112
6%
704
35%
704
15%
1580
November1st to 15thNight
38%
700
18%
2382
16%
700
45%
700
19%
1615
November16th to endNight
28%
720
10%
2520
7%
720
33%
720
12%
1886
December1st to 15thNight
17%
720
7%
2520
3%
720
21%
720
9%
2011
December16th to endNight
16%
768
6%
2688
2%
768
22%
768
7%
2210

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
14%7%36%5%35%5%5%7%34%
46016
Night
15%8%36%5%345%5%6%35%
45861
Cloud CoverDay
14%7%36%5%35%5%5%7%34%
46026
Night
15%8%36%5%3445%6%35%
45866
TransparencyDay
46%8%13%20%10%1
45712
Night
48%7%12%19%10%1
45683
SeeingDay
16%5%24%29%18%6%
4802
Night
19%7%27%29%13%1
14436

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 15thDay
17%12%49%5%44346%26%
1438
16th to endDay
13%13%6%10%8%5%5%45%6%19%
1728
February1st to 15thDay
14%12%5%10%8%45%446%22%
1575
16th to endDay
16%11%6%7%6%45%346%28%
1450
March1st to 15thDay
15%9%47%7%36%45%6%29%
1969
16th to endDay
16%7%45%5%24446%38%
2112
April1st to 15thDay
20%7%47%4235%5%7%30%
2142
16th to endDay
17%6%35%425%445%40%
2277
May1st to 15thDay
13%7%35%5%345%5%8%36%
2202
16th to endDay
10%5%25%5%345%6%7%42%
2394
June1st to 15thDay
14%7%26%435%5%7%8%34%
2310
16th to endDay
12%415%426%5%7%10%38%
2310
July1st to 15thDay
7%4245%36%6%6%9%43%
2310
16th to endDay
9%425%5%36%6%6%11%38%
2379
August1st to 15thDay
7%425%6%36%6%7%9%40%
2145
16th to endDay
9%5%25%435%5%7%8%42%
2206
September1st to 15thDay
14%5%24435%5%6%7%40%
1980
16th to endDay
12%5%35%6%2445%7%41%
1790
October1st to 15thDay
18%7%35%6%35%5%45%35%
1650
16th to endDay
23%9%37%5%3445%6%25%
1760
November1st to 15thDay
15%7%36%6%45%45%8%32%
1473
16th to endDay
18%10%48%7%35%448%23%
1440
December1st to 15thDay
19%13%5%8%6%35%6%47%19%
1440
16th to endDay
20%11%6%9%6%35%5%5%6%19%
1536
January1st to 15thNight
20%13%5%8%434445%24%
2497
16th to endNight
15%11%6%8%7%45%446%23%
2496
February1st to 15thNight
14%14%6%7%7%35%45%6%26%
2285
16th to endNight
15%10%37%6%45%45%6%30%
2022
March1st to 15thNight
18%8%46%6%35%335%32%
1968
16th to endNight
14%6%35%5%24335%43%
2112
April1st to 15thNight
19%7%25%5%245%46%36%
1805
16th to endNight
12%6%35%5%2445%5%44%
1641
May1st to 15thNight
14%4245%25%6%5%7%40%
1419
16th to endNight
11%31432445%7%51%
1367
June1st to 15thNight
12%425%5%35%6%6%7%40%
1320
16th to endNight
10%4146%245%5%10%43%
1320
July1st to 15thNight
431442446%8%56%
1320
16th to endNight
8%3134345%7%8%49%
1480
August1st to 15thNight
8%41442447%9%49%
1485
16th to endNight
8%325%5%24446%52%
1633
September1st to 15thNight
12%5%243335%5%6%46%
1650
16th to endNight
13%425%32346%6%46%
1839
October1st to 15thNight
17%7%25%5%3445%6%37%
1980
16th to endNight
21%8%45%5%35%6%5%6%28%
2112
November1st to 15thNight
16%6%25%5%35%447%36%
2382
16th to endNight
21%9%36%435%5%5%7%26%
2520
December1st to 15thNight
20%12%46%7%35%6%45%22%
2520
16th to endNight
21%12%5%8%5%45%5%46%18%
2688

Percentage Cloud Cover SE (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 15thDay
17%12%48%7%3435%5%25%
1438
16th to endDay
14%12%7%10%7%5%7%446%19%
1728
February1st to 15thDay
14%12%6%10%8%45%445%22%
1575
16th to endDay
16%11%5%7%6%44346%28%
1450
March1st to 15thDay
16%9%37%7%36%45%7%28%
1980
16th to endDay
15%7%445%34446%38%
2111
April1st to 15thDay
20%7%36%5%245%5%7%30%
2142
16th to endDay
17%6%35%424446%40%
2277
May1st to 15thDay
12%6%35%5%35%5%5%8%37%
2202
16th to endDay
10%5%25%5%25%5%6%7%43%
2394
June1st to 15thDay
14%5%35%5%36%5%7%9%34%
2310
16th to endDay
11%324425%5%7%11%39%
2310
July1st to 15thDay
7%4135%36%6%7%9%44%
2310
16th to endDay
8%424446%6%7%10%39%
2379
August1st to 15thDay
7%425%5%35%6%7%9%42%
2145
16th to endDay
8%5%24435%5%7%8%43%
2206
September1st to 15thDay
14%424435%5%6%7%40%
1980
16th to endDay
12%5%25%5%345%5%7%42%
1790
October1st to 15thDay
18%7%35%6%345%46%35%
1650
16th to endDay
23%9%46%6%3345%5%26%
1760
November1st to 15thDay
15%7%37%7%35%45%7%32%
1473
16th to endDay
18%10%48%7%35%45%7%23%
1440
December1st to 15thDay
18%13%5%8%6%45%5%5%6%19%
1440
16th to endDay
20%11%5%9%7%35%446%19%
1536
January1st to 15thNight
21%13%5%8%5%34445%23%
2497
16th to endNight
15%11%6%8%6%45%45%6%23%
2496
February1st to 15thNight
14%14%6%7%7%35%45%6%25%
2278
16th to endNight
15%9%37%6%45%45%6%30%
2022
March1st to 15thNight
19%8%46%6%35%335%31%
1980
16th to endNight
14%6%36%5%24335%43%
2112
April1st to 15thNight
19%6%25%5%24446%36%
1805
16th to endNight
12%7%25%42445%6%44%
1641
May1st to 15thNight
14%4246%345%6%7%40%
1419
16th to endNight
11%22432445%8%50%
1367
June1st to 15thNight
12%425%5%35%5%7%7%40%
1320
16th to endNight
10%4145%3445%10%43%
1320
July1st to 15thNight
4314335%45%8%56%
1320
16th to endNight
8%3135%245%7%8%49%
1480
August1st to 15thNight
8%41442446%9%49%
1485
16th to endNight
7%425%5%24446%52%
1633
September1st to 15thNight
12%5%23424447%46%
1650
16th to endNight
13%5%2442345%6%46%
1839
October1st to 15thNight
18%6%25%6%2345%6%37%
1980
16th to endNight
22%8%35%5%35%6%46%29%
2112
November1st to 15thNight
15%7%26%6%35%45%6%36%
2382
16th to endNight
21%9%36%5%35%5%5%6%27%
2520
December1st to 15thNight
20%12%48%6%35%5%5%5%22%
2520
16th to endNight
22%11%5%8%6%45%5%5%6%18%
2688

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 15thDay
60%8%12%13%4
1439
16th to endDay
64%8%10%9%5%
1728
February1st to 15thDay
63%7%9%15%2
1577
16th to endDay
55%7%12%16%6%
1450
March1st to 15thDay
54%7%12%16%7%
1980
16th to endDay
46%6%10%19%15%1
2112
April1st to 15thDay
51%5%12%17%11%
2142
16th to endDay
44%6%10%21%14%2
2277
May1st to 15thDay
43%7%12%22%13%1
2202
16th to endDay
37%7%14%23%14%2
2398
June1st to 15thDay
43%9%12%22%11%
2310
16th to endDay
36%9%18%22%13%
2310
July1st to 15thDay
30%9%13%27%16%1
2161
16th to endDay
36%11%15%24%11%1
2219
August1st to 15thDay
34%10%17%22%14%1
2132
16th to endDay
33%8%16%30%10%1
2206
September1st to 15thDay
39%9%14%25%10%
1980
16th to endDay
39%8%12%28%10%
1790
October1st to 15thDay
49%7%12%20%9%1
1650
16th to endDay
57%8%16%12%4
1760
November1st to 15thDay
48%9%14%17%7%1
1473
16th to endDay
58%7%14%14%4
1440
December1st to 15thDay
62%10%14%10%1
1440
16th to endDay
65%9%10%11%2
1536
January1st to 15thNight
62%7%11%12%5%
2497
16th to endNight
60%7%12%14%4
2496
February1st to 15thNight
59%8%10%17%4
2287
16th to endNight
54%7%12%18%7%
2022
March1st to 15thNight
55%412%19%7%
1980
16th to endNight
44%48%23%16%2
2112
April1st to 15thNight
49%5%10%19%15%
1805
16th to endNight
40%6%11%20%18%3
1641
May1st to 15thNight
41%7%11%21%15%2
1419
16th to endNight
32%6%14%25%18%3
1369
June1st to 15thNight
40%6%11%23%15%1
1320
16th to endNight
36%6%13%24%17%1
1320
July1st to 15thNight
25%6%14%26%24%2
1240
16th to endNight
30%8%14%26%16%3
1377
August1st to 15thNight
30%7%18%27%14%1
1474
16th to endNight
31%6%11%32%15%1
1633
September1st to 15thNight
36%8%13%26%14%
1650
16th to endNight
36%6%13%30%13%
1839
October1st to 15thNight
46%6%10%22%12%
1980
16th to endNight
54%7%13%16%7%
2112
November1st to 15thNight
47%6%12%19%12%1
2382
16th to endNight
55%8%15%15%5%
2520
December1st to 15thNight
62%8%12%12%3
2520
16th to endNight
66%8%11%9%3
2688

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 15thDay
21%19%31%19%6%1
61
16th to endDay
29%12%31%23%3
96
February1st to 15thDay
23%15%44%15%1
90
16th to endDay
22%12%36%22%5%
103
March1st to 15thDay
23%10%34%23%8%
270
16th to endDay
22%6%30%29%8%1
288
April1st to 15thDay
21%5%29%32%9%1
270
16th to endDay
18%5%29%26%15%4
259
May1st to 15thDay
14%124%32%17%8%
228
16th to endDay
12%219%32%26%6%
267
June1st to 15thDay
17%325%30%20%2
255
16th to endDay
12%16%38%26%5%
255
July1st to 15thDay
9%112%31%34%10%
245
16th to endDay
7%21%36%24%10%
270
August1st to 15thDay
8%15%31%32%11%
253
16th to endDay
13%112%24%29%18%
268
September1st to 15thDay
11%314%27%28%14%
255
16th to endDay
15%317%31%18%12%
254
October1st to 15thDay
18%327%28%16%5%
255
16th to endDay
26%9%31%23%8%
272
November1st to 15thDay
14%6%26%34%15%1
104
16th to endDay
21%10%31%25%10%1
60
December1st to 15thDay
13%18%38%23%5%1
60
16th to endDay
28%14%45%12%
64
January1st to 15thNight
27%14%34%18%4
720
16th to endNight
20%9%35%27%5%
768
February1st to 15thNight
20%13%38%22%4
704
16th to endNight
21%9%36%25%7%
631
March1st to 15thNight
24%8%33%28%4
720
16th to endNight
18%6%32%28%13%1
768
April1st to 15thNight
21%6%31%32%8%
718
16th to endNight
15%5%29%34%12%1
573
May1st to 15thNight
16%125%34%21%1
429
16th to endNight
12%20%40%23%2
343
June1st to 15thNight
14%323%38%18%2
330
16th to endNight
10%216%42%26%1
330
July1st to 15thNight
5%113%48%27%3
310
16th to endNight
8%115%42%28%3
426
August1st to 15thNight
8%11%41%31%5%
494
16th to endNight
9%115%36%31%5%
583
September1st to 15thNight
13%419%28%26%6%
660
16th to endNight
15%417%28%27%6%
657
October1st to 15thNight
21%5%23%30%16%2
660
16th to endNight
25%8%30%27%7%
704
November1st to 15thNight
19%7%27%31%11%2
700
16th to endNight
24%11%27%25%9%1
720
December1st to 15thNight
30%11%34%19%4
720
16th to endNight
26%9%37%22%2
768
Page generated at 2017-04-29 09:45:07. Version ac04

Copyright 2017 A. Danko


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