Bojarzin Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bojarzin Observatory clear sky chart from 2005-11-05 to 2017-12-04.

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
41%
16206
21%
47829
13%
16162
48%
16162
27%
30534

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
23%
899
18%
2506
7%
895
32%
895
22%
1736
January16th to endNight
21%
960
16%
2541
4%
960
30%
960
19%
1849
February1st to 15thNight
24%
826
13%
2235
4%
824
30%
824
19%
1604
February16th to endNight
26%
631
20%
1893
9%
631
35%
631
23%
1243
March1st to 15thNight
28%
690
17%
2130
9%
690
35%
690
19%
1459
March16th to endNight
32%
576
14%
2013
9%
576
40%
576
18%
1352
April1st to 15thNight
32%
539
21%
1797
12%
539
45%
539
25%
1097
April16th to endNight
35%
540
21%
1800
15%
540
46%
540
24%
1154
May1st to 15thNight
41%
540
18%
1608
11%
540
48%
540
23%
1092
May16th to endNight
51%
563
20%
1497
13%
561
56%
561
33%
975
June1st to 15thNight
62%
540
20%
1440
13%
540
66%
540
41%
849
June16th to endNight
57%
540
21%
1440
14%
540
61%
540
39%
869
July1st to 15thNight
69%
510
19%
1360
15%
510
70%
510
40%
814
July16th to endNight
73%
564
25%
1426
20%
531
75%
531
47%
797
August1st to 15thNight
77%
539
23%
1679
24%
536
79%
536
41%
895
August16th to endNight
74%
573
23%
1910
25%
573
78%
573
36%
1048
September1st to 15thNight
65%
540
29%
1800
30%
540
68%
540
35%
976
September16th to endNight
62%
678
33%
1941
25%
678
68%
678
39%
1108
October1st to 15thNight
51%
720
28%
2133
19%
720
58%
720
34%
1252
October16th to endNight
34%
768
26%
2361
16%
768
45%
768
28%
1407
November1st to 15thNight
35%
760
26%
2471
17%
760
48%
760
29%
1422
November16th to endNight
29%
830
24%
2585
13%
830
42%
830
26%
1606
December1st to 15thNight
25%
920
14%
2575
6%
920
32%
920
19%
1873
December16th to endNight
21%
960
13%
2688
5%
960
29%
960
15%
2057

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
12%7%35%5%3445%7%39%
48671
Night
13%7%35%424446%43%
47999
Cloud CoverDay
12%7%35%5%3445%7%39%
48679
Night
13%7%35%424446%43%
48004
TransparencyDay
42%5%12%23%13%2
48359
Night
40%411%24%16%2
47830
SeeingDay
13%5%23%28%20%7%
6162
Night
16%7%27%31%14%1
16208

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
15%11%49%7%45%435%27%
1432
16th to endDay
13%12%7%7%6%35%336%30%
1683
February1st to 15thDay
13%10%6%8%5%35%446%30%
1626
16th to endDay
11%11%5%8%6%3445%6%33%
1580
March1st to 15thDay
14%10%5%7%6%33346%33%
1829
16th to endDay
16%10%48%6%34447%29%
2211
April1st to 15thDay
15%7%36%42445%6%37%
2151
16th to endDay
18%6%25%5%35%45%6%35%
2160
May1st to 15thDay
17%7%35%43446%6%33%
2339
16th to endDay
11%6%36%5%35%5%6%8%37%
2617
June1st to 15thDay
8%425%435%5%6%8%45%
2520
16th to endDay
8%435%6%35%5%5%8%43%
2520
July1st to 15thDay
7%3245%25%6%7%9%44%
2520
16th to endDay
5%2145%35%6%8%11%44%
2643
August1st to 15thDay
6%425%5%36%6%6%11%43%
2271
16th to endDay
7%425%6%345%6%8%45%
2292
September1st to 15thDay
12%424435%446%46%
2160
16th to endDay
7%5%25%43445%7%50%
2006
October1st to 15thDay
16%6%24424346%44%
1825
16th to endDay
15%6%34423345%45%
1863
November1st to 15thDay
15%5%25%314447%45%
1717
16th to endDay
16%8%44422335%41%
1703
December1st to 15thDay
17%9%7%6%5%245%5%6%28%
1467
16th to endDay
18%11%5%6%5%245%5%6%27%
1536
January1st to 15thNight
13%8%46%6%34345%38%
2506
16th to endNight
13%11%6%7%5%34335%34%
2541
February1st to 15thNight
14%10%6%7%6%24345%34%
2233
16th to endNight
14%8%36%5%23345%41%
1893
March1st to 15thNight
18%9%25%424445%37%
2117
16th to endNight
17%9%35%5%2445%6%34%
2013
April1st to 15thNight
13%6%25%433447%43%
1797
16th to endNight
17%6%25%424345%41%
1800
May1st to 15thNight
16%7%35%435%45%7%37%
1608
16th to endNight
9%5%25%5%245%6%9%43%
1496
June1st to 15thNight
8%4233245%5%9%51%
1440
16th to endNight
7%42442436%10%47%
1440
July1st to 15thNight
7%3234345%5%9%48%
1440
16th to endNight
32134245%7%10%53%
1522
August1st to 15thNight
6%2133245%6%9%54%
1689
16th to endNight
5%313435%5%6%7%52%
1910
September1st to 15thNight
9%424423346%54%
1800
16th to endNight
7%5%1342445%8%53%
1941
October1st to 15thNight
12%424323346%51%
2133
16th to endNight
16%5%25%313345%49%
2361
November1st to 15thNight
11%5%24423336%50%
2471
16th to endNight
15%7%23423346%44%
2585
December1st to 15thNight
20%10%45%5%24436%32%
2575
16th to endNight
19%12%47%5%35%44427%
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
14%11%5%9%7%36%436%27%
1432
16th to endDay
13%12%7%7%6%34346%30%
1683
February1st to 15thDay
13%11%5%8%5%35%346%30%
1626
16th to endDay
11%11%5%7%6%34446%33%
1580
March1st to 15thDay
15%10%5%7%5%33345%33%
1839
16th to endDay
15%10%47%6%24448%29%
2209
April1st to 15thDay
15%7%46%32445%6%37%
2151
16th to endDay
18%6%25%5%35%45%6%35%
2160
May1st to 15thDay
17%8%35%4345%6%6%33%
2339
16th to endDay
11%6%36%5%35%5%5%8%37%
2617
June1st to 15thDay
8%4245%35%6%5%8%45%
2520
16th to endDay
7%435%6%45%5%6%8%43%
2520
July1st to 15thDay
8%3245%25%6%8%9%44%
2520
16th to endDay
5%2245%26%6%8%12%43%
2643
August1st to 15thDay
6%4245%35%5%6%10%43%
2271
16th to endDay
7%425%5%345%6%9%44%
2292
September1st to 15thDay
12%5%24435%447%46%
2160
16th to endDay
7%5%25%42435%7%50%
2006
October1st to 15thDay
16%5%24423446%45%
1825
16th to endDay
15%7%25%323345%45%
1863
November1st to 15thDay
15%5%24314446%45%
1717
16th to endDay
16%8%45%423336%41%
1703
December1st to 15thDay
18%9%6%6%5%25%45%6%28%
1467
16th to endDay
18%11%5%6%5%235%5%6%27%
1536
January1st to 15thNight
13%8%46%6%34445%38%
2506
16th to endNight
13%11%5%7%6%34335%34%
2541
February1st to 15thNight
14%9%6%6%5%25%345%34%
2226
16th to endNight
14%7%36%5%24346%41%
1893
March1st to 15thNight
18%9%25%424445%37%
2130
16th to endNight
18%9%35%5%2446%6%34%
2013
April1st to 15thNight
13%6%25%443447%43%
1797
16th to endNight
17%6%35%5%24445%41%
1800
May1st to 15thNight
16%7%25%425%46%7%37%
1607
16th to endNight
9%5%25%5%245%5%9%43%
1496
June1st to 15thNight
7%42332445%8%51%
1440
16th to endNight
8%42442436%10%47%
1440
July1st to 15thNight
7%314425%5%6%9%49%
1440
16th to endNight
3314425%47%10%53%
1522
August1st to 15thNight
5%213325%5%6%9%54%
1689
16th to endNight
5%313435%5%5%7%52%
1910
September1st to 15thNight
9%424413346%54%
1800
16th to endNight
7%41432445%8%53%
1941
October1st to 15thNight
12%423423346%51%
2133
16th to endNight
16%5%25%323345%49%
2361
November1st to 15thNight
11%5%25%423336%50%
2471
16th to endNight
15%7%23423336%45%
2585
December1st to 15thNight
20%10%35%5%24435%33%
2575
16th to endNight
19%12%47%5%35%34428%
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
58%38%18%10%
1433
16th to endDay
55%314%19%7%
1683
February1st to 15thDay
53%412%21%6%
1628
16th to endDay
51%313%21%9%
1580
March1st to 15thDay
52%413%22%7%
1839
16th to endDay
53%5%13%20%7%
2211
April1st to 15thDay
45%411%24%12%1
2151
16th to endDay
47%5%11%20%12%1
2160
May1st to 15thDay
48%5%14%22%9%
2339
16th to endDay
42%6%13%19%15%2
2621
June1st to 15thDay
33%7%13%25%18%2
2520
16th to endDay
36%6%12%23%17%3
2520
July1st to 15thDay
35%6%12%28%14%3
2371
16th to endDay
29%7%16%29%16%
2477
August1st to 15thDay
33%6%13%28%15%1
2257
16th to endDay
33%6%13%23%16%5%
2292
September1st to 15thDay
38%46%25%19%6%
2160
16th to endDay
32%47%31%20%2
2006
October1st to 15thDay
40%39%24%18%3
1825
16th to endDay
39%49%26%17%2
1863
November1st to 15thDay
38%411%23%18%3
1717
16th to endDay
45%310%28%11%1
1703
December1st to 15thDay
54%5%13%17%8%
1467
16th to endDay
55%410%19%7%1
1536
January1st to 15thNight
47%411%22%13%
2506
16th to endNight
52%412%21%9%
2541
February1st to 15thNight
52%311%19%11%1
2235
16th to endNight
45%313%25%11%
1893
March1st to 15thNight
49%410%22%11%1
2130
16th to endNight
49%412%21%9%1
2013
April1st to 15thNight
40%39%27%16%2
1797
16th to endNight
44%39%22%16%3
1800
May1st to 15thNight
45%5%10%22%15%
1608
16th to endNight
36%6%15%19%18%3
1498
June1st to 15thNight
28%5%13%29%19%3
1440
16th to endNight
31%5%12%25%20%5%
1440
July1st to 15thNight
30%5%12%28%18%5%
1360
16th to endNight
23%5%17%30%19%2
1426
August1st to 15thNight
24%6%14%28%22%2
1679
16th to endNight
28%6%12%25%21%6%
1910
September1st to 15thNight
31%38%25%23%8%
1800
16th to endNight
28%49%26%25%4
1941
October1st to 15thNight
33%48%26%21%5%
2133
16th to endNight
37%38%26%20%3
2361
November1st to 15thNight
35%310%24%19%6%
2471
16th to endNight
40%39%28%16%
2585
December1st to 15thNight
53%312%18%10%
2575
16th to endNight
58%410%16%8%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
32%8%36%13%8%
90
16th to endDay
11%21%38%23%4
96
February1st to 15thDay
18%17%36%22%4
90
16th to endDay
13%18%32%30%31
81
March1st to 15thDay
28%10%37%18%4
90
16th to endDay
22%13%33%22%7%
195
April1st to 15thDay
18%11%31%26%11%
270
16th to endDay
20%5%31%27%13%2
270
May1st to 15thDay
19%9%28%28%10%3
328
16th to endDay
15%6%30%29%13%5%
517
June1st to 15thDay
10%221%31%25%7%
495
16th to endDay
9%5%28%30%19%6%
495
July1st to 15thDay
11%216%32%25%12%
475
16th to endDay
6%111%33%32%14%
515
August1st to 15thDay
8%11%32%31%15%
424
16th to endDay
8%112%25%36%15%
332
September1st to 15thDay
13%39%30%29%13%
315
16th to endDay
8%314%27%32%12%
314
October1st to 15thDay
20%6%18%30%20%3
160
16th to endDay
19%8%29%29%10%2
144
November1st to 15thDay
11%8%25%25%17%11%
135
16th to endDay
27%8%37%20%6%
135
December1st to 15thDay
12%13%35%26%10%4
100
16th to endDay
29%13%43%13%
96
January1st to 15thNight
18%13%38%24%5%
900
16th to endNight
18%14%36%26%4
960
February1st to 15thNight
20%12%35%28%3
827
16th to endNight
20%10%36%29%2
631
March1st to 15thNight
24%9%33%27%5%
690
16th to endNight
22%8%30%28%10%
576
April1st to 15thNight
17%13%33%28%8%
539
16th to endNight
21%433%29%10%
540
May1st to 15thNight
19%5%27%35%10%1
540
16th to endNight
10%227%36%20%2
563
June1st to 15thNight
9%219%48%18%1
540
16th to endNight
10%121%41%22%1
540
July1st to 15thNight
10%10%41%32%3
510
16th to endNight
4112%39%37%4
564
August1st to 15thNight
7%16%41%36%5%
539
16th to endNight
5%110%38%38%5%
573
September1st to 15thNight
10%312%37%30%5%
540
16th to endNight
8%416%33%32%4
678
October1st to 15thNight
14%425%32%21%2
720
16th to endNight
19%9%33%26%10%
768
November1st to 15thNight
15%8%36%28%10%1
760
16th to endNight
20%10%35%24%8%
830
December1st to 15thNight
26%10%31%24%6%
920
16th to endNight
26%11%31%24%4
960
Page generated at 2017-12-05 09:18:58. Version ac04

Copyright 2017 A. Danko


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