Bartole Observing Platform
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bartole Observing Platform clear sky chart from 2005-11-05 to 2017-09-24.

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
37%
14803
13%
46698
10%
14768
42%
14768
19%
32881

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
8%
2488
3%
716
24%
716
9%
2007
January16th to endNight
24%
768
9%
2496
5%
768
29%
768
9%
2042
February1st to 15thNight
21%
701
9%
2287
4%
701
27%
701
10%
1789
February16th to endNight
27%
631
12%
2022
6%
631
35%
631
15%
1494
March1st to 15thNight
27%
720
13%
1980
7%
720
32%
720
18%
1474
March16th to endNight
38%
768
20%
2112
12%
768
44%
768
26%
1426
April1st to 15thNight
32%
718
15%
1818
6%
718
36%
718
24%
1320
April16th to endNight
43%
552
19%
1632
12%
552
48%
552
25%
1096
May1st to 15thNight
49%
480
16%
1560
12%
480
55%
480
25%
987
May16th to endNight
54%
374
16%
1497
16%
374
63%
374
27%
811
June1st to 15thNight
51%
360
12%
1440
13%
360
58%
360
21%
850
June16th to endNight
58%
360
13%
1260
17%
360
61%
360
26%
741
July1st to 15thNight
65%
340
17%
1266
23%
340
69%
340
33%
665
July16th to endNight
62%
473
16%
1507
18%
443
64%
443
31%
868
August1st to 15thNight
68%
539
17%
1609
13%
536
71%
536
37%
916
August16th to endNight
63%
616
21%
1762
13%
616
67%
616
36%
1049
September1st to 15thNight
55%
720
19%
1811
11%
720
58%
720
34%
1167
September16th to endNight
57%
693
22%
1936
17%
693
59%
693
32%
1220
October1st to 15thNight
39%
660
16%
1980
14%
660
44%
660
20%
1372
October16th to endNight
23%
704
10%
2112
5%
704
29%
704
13%
1649
November1st to 15thNight
32%
700
16%
2395
14%
700
39%
700
17%
1660
November16th to endNight
25%
720
10%
2520
7%
720
30%
720
11%
1934
December1st to 15thNight
14%
720
5%
2520
1%
720
18%
720
7%
2066
December16th to endNight
12%
768
5%
2688
1%
768
17%
768
6%
2278

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
15%8%36%6%35%5%5%6%32%
48220
Night
15%9%47%6%35%45%6%32%
46873
Cloud CoverDay
14%8%37%6%35%5%5%7%32%
48230
Night
15%9%47%6%3445%6%32%
46877
TransparencyDay
50%5%12%20%10%
47914
Night
51%412%19%9%
46698
SeeingDay
18%322%27%19%7%
5614
Night
19%6%27%31%13%1
14809

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
16%13%6%9%8%5%5%46%5%18%
1447
16th to endDay
13%14%6%11%9%5%5%5%5%5%16%
1728
February1st to 15thDay
12%13%6%12%8%46%6%45%18%
1575
16th to endDay
15%13%5%10%7%45%5%45%23%
1446
March1st to 15thDay
14%9%47%8%36%5%45%29%
1969
16th to endDay
14%7%47%43435%5%38%
2112
April1st to 15thDay
19%9%35%6%25%5%5%5%32%
2129
16th to endDay
17%7%245%34347%40%
2340
May1st to 15thDay
16%6%26%5%345%5%6%37%
2391
16th to endDay
12%4245%35%46%8%42%
2618
June1st to 15thDay
17%5%2442446%8%37%
2520
16th to endDay
14%424435%5%6%8%38%
2694
July1st to 15thDay
9%4245%35%5%6%8%42%
2613
16th to endDay
10%426%5%35%5%7%9%38%
2555
August1st to 15thDay
9%425%5%36%5%5%8%41%
2340
16th to endDay
11%5%24435%5%7%8%40%
2427
September1st to 15thDay
16%6%35%43445%6%38%
2148
16th to endDay
15%416%445%446%41%
1883
October1st to 15thDay
20%6%37%7%35%445%31%
1650
16th to endDay
27%11%48%6%3445%420%
1760
November1st to 15thDay
16%11%36%6%35%5%6%6%28%
1459
16th to endDay
18%16%5%8%8%46%446%17%
1440
December1st to 15thDay
17%15%7%11%7%45%6%45%13%
1440
16th to endDay
20%13%8%10%8%45%45%5%13%
1536
January1st to 15thNight
17%15%5%9%8%46%45%417%
2488
16th to endNight
13%13%6%12%9%5%6%6%45%15%
2496
February1st to 15thNight
12%14%6%10%8%5%5%6%5%419%
2285
16th to endNight
14%11%5%10%6%35%45%7%24%
2022
March1st to 15thNight
16%10%47%8%44335%31%
1968
16th to endNight
14%7%36%425%345%41%
2112
April1st to 15thNight
19%8%36%5%34447%33%
1818
16th to endNight
15%6%36%5%23436%40%
1632
May1st to 15thNight
16%425%5%3446%8%38%
1560
16th to endNight
11%4143245%47%49%
1495
June1st to 15thNight
14%4244345%5%8%40%
1440
16th to endNight
9%425%5%35%5%5%7%44%
1260
July1st to 15thNight
6%4244145%46%54%
1342
16th to endNight
8%324436%46%8%47%
1611
August1st to 15thNight
7%3133345%7%10%49%
1620
16th to endNight
9%424425%45%6%50%
1762
September1st to 15thNight
15%41442346%6%46%
1811
16th to endNight
14%5%245%23446%46%
1936
October1st to 15thNight
19%6%36%6%34445%35%
1980
16th to endNight
22%10%46%8%3445%5%22%
2112
November1st to 15thNight
17%8%46%5%3445%6%32%
2395
16th to endNight
19%13%5%7%6%35%45%6%22%
2520
December1st to 15thNight
19%15%6%12%7%35%445%16%
2520
16th to endNight
20%14%7%13%8%34445%12%
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
16%12%6%9%8%45%5%5%5%18%
1447
16th to endDay
12%14%6%11%10%5%5%5%5%6%16%
1728
February1st to 15thDay
11%13%6%13%8%47%5%5%5%18%
1575
16th to endDay
15%13%410%7%45%45%6%23%
1446
March1st to 15thDay
14%8%48%8%36%5%5%5%29%
1980
16th to endDay
14%7%47%5%34445%38%
2111
April1st to 15thDay
18%9%35%5%345%5%6%31%
2129
16th to endDay
16%7%245%33447%39%
2340
May1st to 15thDay
15%5%36%5%3445%6%37%
2391
16th to endDay
12%5%25%5%35%5%6%7%42%
2618
June1st to 15thDay
16%5%25%425%46%7%37%
2520
16th to endDay
13%425%5%35%5%6%8%38%
2694
July1st to 15thDay
9%4146%45%6%7%7%42%
2613
16th to endDay
9%5%26%5%36%5%7%9%38%
2555
August1st to 15thDay
9%5%25%5%45%5%5%9%40%
2340
16th to endDay
10%5%245%35%6%7%9%40%
2427
September1st to 15thDay
16%6%35%43445%7%37%
2148
16th to endDay
14%5%25%5%45%446%41%
1883
October1st to 15thDay
19%8%37%7%34446%31%
1650
16th to endDay
26%11%5%8%5%43445%20%
1760
November1st to 15thDay
15%12%47%5%345%6%6%28%
1459
16th to endDay
18%15%5%9%7%5%5%446%17%
1440
December1st to 15thDay
17%15%7%12%7%45%45%5%13%
1440
16th to endDay
19%13%7%11%8%45%5%45%13%
1536
January1st to 15thNight
17%14%6%9%8%46%5%5%5%17%
2488
16th to endNight
13%13%6%11%10%5%6%6%45%16%
2496
February1st to 15thNight
12%14%6%9%9%45%5%5%5%20%
2278
16th to endNight
14%11%5%10%7%35%45%7%24%
2022
March1st to 15thNight
15%10%5%7%8%3433431%
1980
16th to endNight
14%7%46%424336%41%
2112
April1st to 15thNight
19%8%45%5%34436%34%
1818
16th to endNight
14%7%36%6%34346%40%
1632
May1st to 15thNight
15%5%25%6%3445%9%37%
1559
16th to endNight
10%5%243245%5%6%49%
1495
June1st to 15thNight
13%425%5%345%7%7%40%
1440
16th to endNight
9%5%25%5%35%5%5%8%43%
1260
July1st to 15thNight
6%325%42445%6%53%
1342
16th to endNight
8%3244346%6%8%46%
1611
August1st to 15thNight
6%3134345%7%10%49%
1620
16th to endNight
8%42443445%7%50%
1762
September1st to 15thNight
14%5%2442435%7%45%
1811
16th to endNight
14%6%24423446%46%
1936
October1st to 15thNight
17%7%37%5%34446%35%
1980
16th to endNight
22%9%5%7%7%3446%5%22%
2112
November1st to 15thNight
17%9%47%5%3445%7%31%
2395
16th to endNight
19%13%5%8%6%345%46%22%
2520
December1st to 15thNight
18%15%6%11%8%36%445%15%
2520
16th to endNight
20%14%7%13%9%34445%12%
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
64%6%11%12%4
1448
16th to endDay
67%5%9%10%6%
1728
February1st to 15thDay
65%5%10%14%4
1577
16th to endDay
61%311%15%7%
1446
March1st to 15thDay
55%5%13%18%6%
1980
16th to endDay
47%39%19%17%1
2112
April1st to 15thDay
52%5%9%20%11%
2129
16th to endDay
44%410%23%15%2
2340
May1st to 15thDay
45%5%10%23%14%1
2391
16th to endDay
38%6%13%25%14%2
2622
June1st to 15thDay
43%413%25%12%
2520
16th to endDay
41%6%14%23%13%
2694
July1st to 15thDay
36%6%13%26%16%1
2461
16th to endDay
40%7%13%25%11%1
2396
August1st to 15thDay
38%6%16%23%13%1
2327
16th to endDay
37%6%16%27%10%1
2427
September1st to 15thDay
44%5%13%24%10%
2148
16th to endDay
43%412%28%9%
1883
October1st to 15thDay
53%311%20%9%
1650
16th to endDay
65%414%11%3
1760
November1st to 15thDay
54%6%13%17%7%
1459
16th to endDay
66%6%12%11%2
1440
December1st to 15thDay
70%413%9%1
1440
16th to endDay
71%411%9%2
1536
January1st to 15thNight
67%5%10%11%4
2488
16th to endNight
68%49%12%3
2496
February1st to 15thNight
63%5%11%15%3
2287
16th to endNight
58%313%16%6%
2022
March1st to 15thNight
57%212%19%6%
1980
16th to endNight
44%410%22%16%1
2112
April1st to 15thNight
51%310%19%14%
1818
16th to endNight
45%410%19%18%2
1632
May1st to 15thNight
42%412%20%17%2
1560
16th to endNight
33%5%15%28%15%2
1497
June1st to 15thNight
40%5%11%26%15%
1440
16th to endNight
37%5%14%26%15%
1260
July1st to 15thNight
29%410%31%21%1
1266
16th to endNight
33%5%12%31%15%1
1507
August1st to 15thNight
28%6%20%28%14%
1609
16th to endNight
31%5%15%28%16%1
1762
September1st to 15thNight
37%316%27%12%1
1811
16th to endNight
38%412%31%13%
1936
October1st to 15thNight
49%5%11%22%11%
1980
16th to endNight
60%6%12%14%6%
2112
November1st to 15thNight
51%5%14%19%8%1
2395
16th to endNight
61%5%14%14%2
2520
December1st to 15thNight
70%413%9%2
2520
16th to endNight
74%49%9%1
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
15%6%46%19%11%1
63
16th to endDay
28%5%32%33%1
96
February1st to 15thDay
20%8%41%28%1
90
16th to endDay
22%7%34%30%4
84
March1st to 15thDay
20%8%32%28%10%
270
16th to endDay
23%229%25%15%3
288
April1st to 15thDay
23%7%29%24%11%4
270
16th to endDay
20%424%25%17%6%
270
May1st to 15thDay
20%219%30%19%7%
288
16th to endDay
15%120%35%19%7%
331
June1st to 15thDay
20%416%27%26%4
315
16th to endDay
16%222%33%21%4
489
July1st to 15thDay
12%116%33%27%9%
395
16th to endDay
8%115%35%25%13%
326
August1st to 15thDay
10%15%26%29%17%
313
16th to endDay
13%115%21%30%16%
332
September1st to 15thDay
15%115%21%27%17%
315
16th to endDay
13%213%27%26%16%
287
October1st to 15thDay
20%5%25%25%16%7%
255
16th to endDay
29%9%29%22%8%
272
November1st to 15thDay
22%7%24%24%17%3
81
16th to endDay
33%8%30%21%6%
60
December1st to 15thDay
18%13%41%15%10%1
60
16th to endDay
29%9%53%7%
64
January1st to 15thNight
23%8%39%21%5%
720
16th to endNight
20%5%33%30%8%
768
February1st to 15thNight
19%7%38%27%6%
704
16th to endNight
21%6%32%32%6%
631
March1st to 15thNight
19%8%34%30%6%
720
16th to endNight
18%5%29%31%13%
768
April1st to 15thNight
23%6%31%31%7%
718
16th to endNight
17%5%25%36%13%1
552
May1st to 15thNight
18%122%37%17%2
480
16th to endNight
11%222%42%19%1
375
June1st to 15thNight
15%5%19%43%15%1
360
16th to endNight
10%118%46%21%1
360
July1st to 15thNight
6%416%47%22%2
340
16th to endNight
10%217%42%25%1
473
August1st to 15thNight
7%113%43%31%2
539
16th to endNight
10%117%35%31%3
616
September1st to 15thNight
16%317%31%22%7%
720
16th to endNight
17%316%31%23%7%
693
October1st to 15thNight
20%5%27%30%14%2
660
16th to endNight
27%9%31%23%7%
704
November1st to 15thNight
22%8%28%25%13%1
700
16th to endNight
25%12%29%25%7%
720
December1st to 15thNight
28%11%37%18%4
720
16th to endNight
26%9%35%22%41
768
Page generated at 2017-09-25 09:02:24. Version ac04

Copyright 2017 A. Danko


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