Burg Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burg Observatory clear sky chart from 2005-11-06 to 2024-01-16.

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
40%
23883
19%
74592
13%
23831
47%
23831
22%
49492

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
19%
760
14%
2459
6%
757
28%
757
12%
1840
January11th to 20thNight
16%
744
13%
2417
6%
744
25%
744
10%
1837
January21st to endNight
19%
792
15%
2574
7%
792
29%
792
14%
1833
February1st to 10thNight
21%
720
12%
2318
6%
720
28%
720
13%
1739
February11th to 20thNight
16%
702
14%
2099
6%
700
24%
700
14%
1541
February21st to endNight
16%
592
15%
1776
6%
592
25%
592
13%
1330
March1st to 10thNight
24%
720
19%
2075
10%
720
33%
720
19%
1435
March11th to 20thNight
25%
720
17%
1980
9%
720
32%
720
20%
1402
March21st to endNight
27%
792
16%
2178
9%
792
34%
792
20%
1537
April1st to 10thNight
29%
707
19%
1967
10%
707
38%
707
25%
1297
April11th to 20thNight
35%
533
23%
1661
13%
533
45%
533
24%
1050
April21st to endNight
32%
540
19%
1620
8%
540
41%
540
22%
1093
May1st to 10thNight
36%
540
15%
1620
8%
540
42%
540
22%
1097
May11th to 20thNight
43%
531
16%
1593
9%
531
48%
531
23%
1072
May21st to endNight
58%
583
18%
1745
14%
582
62%
582
30%
1070
June1st to 10thNight
58%
540
18%
1620
15%
540
62%
540
35%
958
June11th to 20thNight
62%
540
17%
1620
14%
540
66%
540
33%
969
June21st to endNight
58%
540
18%
1620
16%
540
61%
540
35%
960
July1st to 10thNight
63%
525
15%
1575
15%
525
64%
525
30%
988
July11th to 20thNight
69%
522
18%
1566
15%
522
71%
522
38%
889
July21st to endNight
66%
591
20%
1672
17%
558
69%
558
33%
999
August1st to 10thNight
68%
537
22%
1600
20%
534
69%
534
34%
950
August11th to 20thNight
67%
534
24%
1598
21%
534
69%
534
32%
971
August21st to endNight
71%
594
26%
1854
23%
594
73%
594
37%
1038
September1st to 10thNight
64%
706
24%
1966
17%
706
67%
706
37%
1166
September11th to 20thNight
64%
720
29%
1980
22%
720
68%
720
39%
1169
September21st to endNight
54%
720
27%
1980
21%
720
60%
720
32%
1249
October1st to 10thNight
56%
720
27%
2016
23%
720
61%
720
36%
1188
October11th to 20thNight
41%
720
25%
2160
18%
720
51%
720
29%
1306
October21st to endNight
36%
792
24%
2398
19%
792
45%
792
23%
1578
November1st to 10thNight
46%
740
26%
2406
21%
740
55%
740
29%
1391
November11th to 20thNight
32%
760
24%
2470
15%
760
45%
760
21%
1582
November21st to endNight
35%
760
21%
2470
15%
760
43%
760
20%
1644
December1st to 10thNight
25%
760
14%
2470
8%
760
32%
760
13%
1815
December11th to 20thNight
25%
759
17%
2983
10%
759
34%
759
13%
2102
December21st to endNight
22%
827
9%
4486
7%
817
30%
817
7%
3407

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%5%35%5%5%7%36%
74919
Night
15%8%36%6%345%5%7%38%
74903
TransparencyDay
47%411%23%14%2
74642
Night
46%310%22%15%3
74699
SeeingDay
21%12%26%22%14%6%
13754
Night
20%10%24%28%16%2
23895

By Month

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 10thDay
17%12%5%10%7%4445%5%27%
1706
11th to 20thDay
21%14%6%9%8%34345%23%
1671
21st to endDay
19%13%6%7%6%35%45%5%27%
1782
February1st to 10thDay
21%13%6%8%6%24446%27%
1638
11th to 20thDay
20%12%48%6%345%45%28%
1748
21st to endDay
21%13%46%435%445%31%
1480
March1st to 10thDay
18%10%45%5%2445%6%35%
1883
11th to 20thDay
19%9%48%6%45%445%32%
1980
21st to endDay
20%9%46%6%36%446%31%
2178
April1st to 10thDay
14%8%46%6%345%47%39%
2006
11th to 20thDay
17%8%36%5%34447%39%
2247
21st to endDay
18%8%37%6%445%5%7%34%
2340
May1st to 10thDay
18%8%47%5%445%6%6%34%
2340
11th to 20thDay
18%7%47%6%35%5%5%7%32%
2301
21st to endDay
10%6%36%5%37%6%6%9%38%
2531
June1st to 10thDay
11%6%245%46%6%7%10%39%
2340
11th to 20thDay
9%5%36%7%45%6%7%8%40%
2340
21st to endDay
10%5%26%6%36%6%6%10%39%
2340
July1st to 10thDay
12%5%27%5%46%6%7%9%38%
2340
11th to 20thDay
8%6%36%6%46%6%8%9%38%
2340
21st to endDay
11%5%35%6%36%6%6%9%39%
2547
August1st to 10thDay
9%5%25%6%46%7%8%11%37%
2327
11th to 20thDay
9%6%36%6%47%6%7%10%36%
2303
21st to endDay
8%5%25%435%6%7%9%45%
2494
September1st to 10thDay
14%6%25%4345%5%7%46%
1980
11th to 20thDay
10%5%25%5%45%45%7%48%
1980
21st to endDay
16%5%35%5%33446%46%
1980
October1st to 10thDay
13%5%245%345%6%8%46%
1944
11th to 20thDay
15%7%25%5%3446%6%46%
1800
21st to endDay
20%7%46%5%33346%40%
1954
November1st to 10thDay
12%5%344345%45%51%
1672
11th to 20thDay
15%10%36%5%25%5%47%38%
1710
21st to endDay
17%9%36%5%35%346%39%
1710
December1st to 10thDay
23%14%5%7%5%34446%25%
1710
11th to 20thDay
18%13%5%9%5%35%445%29%
2153
21st to endDay
20%17%5%10%6%45%446%18%
3124
January1st to 10thNight
16%13%5%9%7%35%5%5%5%26%
2459
11th to 20thNight
21%14%6%9%7%34445%25%
2417
21st to endNight
17%13%6%8%6%2445%5%30%
2574
February1st to 10thNight
23%12%48%6%34435%27%
2318
11th to 20thNight
21%11%48%7%35%445%30%
2098
21st to endNight
22%14%5%6%5%23445%29%
1776
March1st to 10thNight
17%8%36%6%35%445%38%
2075
11th to 20thNight
19%8%46%6%345%48%33%
1980
21st to endNight
18%9%47%6%25%446%35%
2178
April1st to 10thNight
14%8%36%5%35%46%7%40%
1967
11th to 20thNight
14%6%35%5%35%6%5%7%41%
1661
21st to endNight
17%8%35%5%245%5%6%38%
1620
May1st to 10thNight
17%6%36%6%335%7%7%37%
1620
11th to 20thNight
14%7%36%6%35%5%6%8%36%
1592
21st to endNight
7%5%25%6%45%6%7%12%41%
1744
June1st to 10thNight
7%4246%35%5%7%10%47%
1620
11th to 20thNight
6%5%25%5%45%5%7%11%45%
1620
21st to endNight
8%4146%35%6%7%11%45%
1620
July1st to 10thNight
10%6%35%5%346%6%9%45%
1620
11th to 20thNight
6%415%5%445%8%12%47%
1620
21st to endNight
8%425%5%45%6%8%10%43%
1771
August1st to 10thNight
6%5%25%5%35%6%7%9%47%
1611
11th to 20thNight
8%416%6%45%6%8%7%44%
1598
21st to endNight
7%4245%346%6%9%50%
1854
September1st to 10thNight
11%4244345%5%7%50%
1966
11th to 20thNight
10%5%24435%5%47%53%
1980
21st to endNight
12%5%25%5%34446%48%
1980
October1st to 10thNight
11%5%25%43345%7%52%
2016
11th to 20thNight
14%5%25%5%345%5%8%44%
2160
21st to endNight
19%8%35%4245%46%40%
2398
November1st to 10thNight
13%7%25%5%33446%50%
2406
11th to 20thNight
15%8%46%5%34446%41%
2470
21st to endNight
19%10%47%5%24446%37%
2470
December1st to 10thNight
22%11%5%8%6%34446%27%
2470
11th to 20thNight
16%11%6%9%6%3445%5%31%
3042
21st to endNight
19%15%5%9%8%45%446%20%
4532

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
60%38%18%11%1
1707
11th to 20thDay
64%310%18%5%
1671
21st to endDay
59%310%19%8%1
1782
February1st to 10thDay
61%310%17%8%1
1638
11th to 20thDay
59%28%20%10%1
1758
21st to endDay
56%37%22%10%2
1480
March1st to 10thDay
50%28%29%10%1
1883
11th to 20thDay
55%39%19%12%2
1980
21st to endDay
54%39%22%10%2
2178
April1st to 10thDay
46%210%25%14%3
2006
11th to 20thDay
46%29%21%18%4
2247
21st to endDay
50%311%22%11%3
2340
May1st to 10thDay
50%410%24%10%2
2340
11th to 20thDay
53%411%19%11%1
2305
21st to endDay
41%7%14%23%14%1
2531
June1st to 10thDay
40%6%12%24%17%1
2340
11th to 20thDay
40%5%13%23%15%2
2340
21st to endDay
39%6%13%24%14%3
2340
July1st to 10thDay
42%6%13%21%16%2
2275
11th to 20thDay
40%6%13%22%17%2
2271
21st to endDay
39%5%14%26%14%2
2405
August1st to 10thDay
39%6%15%26%13%1
2314
11th to 20thDay
42%6%11%28%13%1
2303
21st to endDay
35%415%24%17%4
2494
September1st to 10thDay
37%412%22%19%6%
1980
11th to 20thDay
36%310%26%23%2
1980
21st to endDay
41%28%27%21%2
1980
October1st to 10thDay
36%310%26%23%2
1944
11th to 20thDay
40%38%28%19%2
1800
21st to endDay
47%210%24%16%2
1954
November1st to 10thDay
36%38%28%21%3
1672
11th to 20thDay
47%28%22%19%3
1710
21st to endDay
48%29%23%16%1
1710
December1st to 10thDay
62%29%20%6%1
1710
11th to 20thDay
58%28%19%12%1
2150
21st to endDay
68%28%15%6%1
3124
January1st to 10thNight
61%28%18%10%1
2459
11th to 20thNight
63%29%17%7%1
2417
21st to endNight
56%29%22%8%2
2574
February1st to 10thNight
61%38%20%8%1
2318
11th to 20thNight
58%27%21%11%1
2099
21st to endNight
60%29%16%9%3
1776
March1st to 10thNight
50%36%23%16%2
2075
11th to 20thNight
51%410%22%12%2
1980
21st to endNight
51%310%22%13%2
2178
April1st to 10thNight
44%39%25%17%2
1967
11th to 20thNight
43%39%20%17%7%
1661
21st to endNight
47%411%21%16%2
1620
May1st to 10thNight
47%5%13%21%12%3
1620
11th to 20thNight
44%7%14%20%14%2
1593
21st to endNight
35%7%16%23%16%2
1745
June1st to 10thNight
33%5%15%25%18%4
1620
11th to 20thNight
33%6%15%20%22%3
1620
21st to endNight
31%7%15%27%17%3
1620
July1st to 10thNight
37%7%13%23%17%4
1575
11th to 20thNight
30%5%18%24%20%3
1566
21st to endNight
34%6%15%30%14%2
1672
August1st to 10thNight
34%5%15%28%16%2
1600
11th to 20thNight
36%5%12%27%19%1
1598
21st to endNight
30%5%12%28%19%6%
1854
September1st to 10thNight
34%313%24%18%8%
1966
11th to 20thNight
32%310%25%26%3
1980
21st to endNight
38%48%22%26%2
1980
October1st to 10thNight
33%410%28%21%4
2016
11th to 20thNight
39%29%26%21%3
2160
21st to endNight
46%38%24%17%3
2398
November1st to 10thNight
37%29%25%23%4
2406
11th to 20thNight
45%27%21%20%4
2470
21st to endNight
50%29%24%15%1
2470
December1st to 10thNight
59%39%20%8%1
2470
11th to 20thNight
57%29%23%9%1
3044
21st to endNight
67%27%17%7%
4532

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
27%20%35%13%41
270
11th to 20thDay
35%21%33%10%
257
21st to endDay
31%26%28%13%2
264
February1st to 10thDay
35%24%27%10%4
240
11th to 20thDay
43%25%28%4
240
21st to endDay
37%18%38%6%1
198
March1st to 10thDay
32%21%30%15%2
323
11th to 20thDay
27%19%35%15%5%
420
21st to endDay
33%18%28%17%5%
462
April1st to 10thDay
27%18%26%18%10%1
420
11th to 20thDay
27%15%28%17%10%3
412
21st to endDay
26%16%32%18%5%3
420
May1st to 10thDay
27%15%31%15%9%3
423
11th to 20thDay
21%13%29%23%9%4
447
21st to endDay
15%8%24%27%16%8%
485
June1st to 10thDay
13%7%23%30%19%7%
450
11th to 20thDay
12%9%24%31%16%8%
450
21st to endDay
13%7%28%24%19%9%
450
July1st to 10thDay
15%415%22%22%21%
445
11th to 20thDay
8%7%20%30%23%12%
444
21st to endDay
14%318%30%22%13%
488
August1st to 10thDay
11%418%28%26%13%
446
11th to 20thDay
14%5%17%31%22%11%
439
21st to endDay
9%417%30%26%14%
495
September1st to 10thDay
16%415%25%26%12%
450
11th to 20thDay
10%415%28%30%14%
450
21st to endDay
18%7%21%26%23%5%
450
October1st to 10thDay
15%6%23%28%20%7%
450
11th to 20thDay
15%12%34%24%12%3
450
21st to endDay
23%14%31%22%9%1
469
November1st to 10thDay
19%14%33%24%9%2
270
11th to 20thDay
27%16%28%20%8%1
270
21st to endDay
23%21%31%18%6%1
270
December1st to 10thDay
29%20%32%11%7%
270
11th to 20thDay
26%20%36%13%41
270
21st to endDay
34%18%31%12%41
297
January1st to 10thNight
29%17%31%19%4
760
11th to 20thNight
32%16%31%19%3
744
21st to endNight
26%19%30%22%3
792
February1st to 10thNight
32%14%29%23%2
720
11th to 20thNight
31%19%30%19%1
703
21st to endNight
32%17%30%20%1
592
March1st to 10thNight
24%16%30%25%5%
720
11th to 20thNight
26%15%30%20%8%1
720
21st to endNight
22%13%31%26%8%
792
April1st to 10thNight
21%14%31%25%8%
707
11th to 20thNight
19%10%31%27%12%2
533
21st to endNight
21%7%35%29%8%
540
May1st to 10thNight
20%9%29%28%11%2
540
11th to 20thNight
19%5%26%32%17%1
531
21st to endNight
12%418%33%29%5%
584
June1st to 10thNight
9%222%39%25%3
540
11th to 20thNight
8%417%37%29%5%
540
21st to endNight
9%421%33%29%4
540
July1st to 10thNight
12%211%33%32%11%
525
11th to 20thNight
7%112%38%37%5%
522
21st to endNight
11%312%35%35%5%
591
August1st to 10thNight
9%29%37%38%4
537
11th to 20thNight
8%411%35%35%8%
534
21st to endNight
9%113%32%37%8%
594
September1st to 10thNight
13%212%33%34%7%
706
11th to 20thNight
13%312%29%35%8%
720
21st to endNight
16%5%17%32%27%3
720
October1st to 10thNight
14%5%20%32%25%4
720
11th to 20thNight
18%9%27%29%16%1
720
21st to endNight
24%10%25%27%13%1
792
November1st to 10thNight
17%9%24%31%18%1
740
11th to 20thNight
19%16%27%26%11%1
760
21st to endNight
25%12%22%31%10%1
760
December1st to 10thNight
30%16%25%25%5%
760
11th to 20thNight
23%13%32%25%6%1
760
21st to endNight
29%15%27%24%5%
836
Page generated at 2024-01-13 19:28:27. Version ac07

Copyright 2024 Attilla Danko


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