The Dead Gekko Society Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Dead Gekko Society Observatory clear sky chart from 2005-11-05 to 2019-06-24.

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
41%
18151
24%
54267
15%
18104
51%
18104
30%
32526

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%
1050
25%
2717
8%
1045
36%
1045
26%
1774
January16th to endNight
25%
1120
27%
2912
8%
1120
38%
1120
32%
1785
February1st to 15thNight
21%
1030
19%
2678
4%
1026
30%
1026
26%
1757
February16th to endNight
19%
720
23%
2190
7%
720
33%
720
23%
1372
March1st to 15thNight
26%
630
23%
2310
11%
630
40%
630
19%
1471
March16th to endNight
29%
672
16%
2464
11%
672
38%
672
19%
1592
April1st to 15thNight
31%
629
24%
2139
13%
629
48%
629
27%
1227
April16th to endNight
33%
624
21%
2078
12%
624
47%
624
26%
1276
May1st to 15thNight
43%
630
21%
1912
17%
630
51%
630
28%
1193
May16th to endNight
52%
659
18%
1973
16%
657
57%
657
32%
1200
June1st to 15thNight
69%
630
24%
1780
20%
630
74%
630
47%
953
June16th to endNight
70%
609
22%
1793
18%
609
75%
609
46%
948
July1st to 15thNight
70%
555
19%
1665
18%
555
72%
555
40%
940
July16th to endNight
79%
612
25%
1738
27%
579
81%
579
43%
938
August1st to 15thNight
76%
575
25%
1717
30%
572
77%
572
40%
955
August16th to endNight
74%
621
24%
2040
27%
621
77%
621
36%
1112
September1st to 15thNight
66%
585
28%
1959
30%
585
69%
585
35%
1071
September16th to endNight
60%
604
31%
2167
29%
604
65%
604
33%
1152
October1st to 15thNight
51%
780
28%
2340
20%
780
56%
780
36%
1345
October16th to endNight
41%
832
30%
2496
16%
832
52%
832
36%
1395
November1st to 15thNight
38%
820
30%
2460
15%
820
51%
820
33%
1419
November16th to endNight
32%
994
27%
2814
13%
994
43%
994
30%
1707
December1st to 15thNight
26%
1050
22%
2940
7%
1050
38%
1050
27%
1887
December16th to endNight
24%
1120
23%
2985
7%
1120
35%
1120
23%
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%6%25%5%2445%7%43%
54507
Night
11%5%24423346%49%
54462
TransparencyDay
39%5%11%23%15%3
54207
Night
34%5%11%25%19%3
54267
SeeingDay
14%9%24%27%19%5%
8099
Night
14%10%28%29%15%1
18151

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 15thDay
15%8%25%313236%47%
1881
16th to endDay
11%7%25%423345%49%
2016
February1st to 15thDay
14%8%36%424345%41%
1845
16th to endDay
14%9%46%5%2344440%
1866
March1st to 15thDay
14%9%36%423345%42%
2310
16th to endDay
18%6%36%5%24345%36%
2462
April1st to 15thDay
14%7%25%5%24445%42%
2467
16th to endDay
17%7%36%5%3433439%
2487
May1st to 15thDay
16%6%35%5%34446%37%
2696
16th to endDay
10%425%6%36%5%6%8%39%
2846
June1st to 15thDay
7%425%5%35%6%6%9%43%
2824
16th to endDay
5%3245%35%6%6%9%46%
2657
July1st to 15thDay
8%425%6%46%6%7%9%38%
2535
16th to endDay
6%3145%36%5%7%11%43%
2674
August1st to 15thDay
8%4245%346%7%8%42%
2486
16th to endDay
7%5%246%36%6%6%8%43%
2512
September1st to 15thDay
14%5%245%24447%44%
2328
16th to endDay
9%5%2443445%7%48%
2109
October1st to 15thDay
14%5%23323445%48%
1950
16th to endDay
12%5%1342333456%
2080
November1st to 15thDay
12%6%24423346%49%
2058
16th to endDay
15%6%34313345%48%
1800
December1st to 15thDay
15%7%25%5%13345%44%
1680
16th to endDay
14%10%35%424346%40%
1938
January1st to 15thNight
14%7%24423345%47%
2717
16th to endNight
10%6%34423335%53%
2912
February1st to 15thNight
12%8%24423346%45%
2668
16th to endNight
15%6%36%323335%46%
2190
March1st to 15thNight
13%9%35%5%23445%42%
2310
16th to endNight
16%8%35%5%24346%40%
2464
April1st to 15thNight
11%42442445%7%48%
2139
16th to endNight
16%5%1442345%7%45%
2078
May1st to 15thNight
11%5%2442445%6%47%
1911
16th to endNight
9%42443446%9%46%
1971
June1st to 15thNight
421332345%9%58%
1780
16th to endNight
221232447%9%57%
1793
July1st to 15thNight
5%224425%5%6%10%50%
1755
16th to endNight
332343445%8%56%
1846
August1st to 15thNight
5%3134245%6%11%51%
1727
16th to endNight
4224435%5%7%10%49%
2040
September1st to 15thNight
11%412423347%52%
1959
16th to endNight
8%41442335%5%54%
2167
October1st to 15thNight
11%41332335%7%52%
2340
16th to endNight
10%5%2332235%457%
2496
November1st to 15thNight
11%5%24312335%55%
2460
16th to endNight
13%6%2441333452%
2814
December1st to 15thNight
15%7%35%313346%46%
2940
16th to endNight
14%10%46%424345%40%
2985

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
39%29%26%18%2
1882
16th to endDay
36%311%27%16%3
2016
February1st to 15thDay
45%411%24%12%2
1846
16th to endDay
46%48%21%14%4
1866
March1st to 15thDay
44%48%18%16%6%
2310
16th to endDay
49%49%22%12%1
2464
April1st to 15thDay
43%411%23%15%1
2467
16th to endDay
48%5%9%19%15%2
2487
May1st to 15thDay
47%6%11%20%13%
2696
16th to endDay
40%8%13%23%13%
2850
June1st to 15thDay
34%8%14%25%14%1
2824
16th to endDay
30%8%17%25%15%1
2657
July1st to 15thDay
37%9%14%26%10%1
2396
16th to endDay
31%8%17%29%12%1
2519
August1st to 15thDay
34%9%14%22%17%1
2472
16th to endDay
35%8%13%23%14%4
2512
September1st to 15thDay
39%5%10%21%16%7%
2328
16th to endDay
33%5%9%27%20%2
2109
October1st to 15thDay
36%5%9%23%19%5%
1950
16th to endDay
32%37%28%21%7%
2080
November1st to 15thDay
36%38%25%18%7%
2058
16th to endDay
38%39%20%26%2
1800
December1st to 15thDay
42%39%23%18%2
1680
16th to endDay
45%410%22%14%3
1938
January1st to 15thNight
39%39%24%20%2
2717
16th to endNight
34%211%27%20%3
2912
February1st to 15thNight
40%412%25%14%2
2678
16th to endNight
40%310%23%18%3
2190
March1st to 15thNight
44%5%7%17%20%5%
2310
16th to endNight
45%5%8%23%15%1
2464
April1st to 15thNight
34%411%26%19%3
2139
16th to endNight
38%5%10%25%17%2
2078
May1st to 15thNight
36%7%12%24%16%2
1912
16th to endNight
33%7%18%24%14%1
1973
June1st to 15thNight
21%6%15%33%21%2
1780
16th to endNight
20%8%14%32%20%4
1793
July1st to 15thNight
25%7%16%29%17%2
1665
16th to endNight
23%6%14%34%19%1
1738
August1st to 15thNight
25%6%14%29%21%2
1717
16th to endNight
26%7%15%25%19%5%
2040
September1st to 15thNight
31%410%27%16%9%
1959
16th to endNight
30%49%25%25%4
2167
October1st to 15thNight
30%5%11%24%20%8%
2340
16th to endNight
30%38%25%24%8%
2496
November1st to 15thNight
31%48%24%21%7%
2460
16th to endNight
36%37%24%24%4
2814
December1st to 15thNight
40%311%22%19%2
2940
16th to endNight
46%49%21%14%3
2985

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
26%13%34%21%3
180
16th to endDay
13%26%38%15%6%
192
February1st to 15thDay
15%28%41%11%2
180
16th to endDay
30%23%27%15%3
159
March1st to 15thDay
25%25%31%16%1
180
16th to endDay
17%22%39%16%4
192
April1st to 15thDay
15%20%35%20%6%
346
16th to endDay
24%13%31%20%9%
379
May1st to 15thDay
18%11%34%23%10%1
593
16th to endDay
12%8%33%25%14%5%
677
June1st to 15thDay
9%318%36%27%5%
645
16th to endDay
7%226%37%21%4
611
July1st to 15thDay
8%216%34%28%9%
550
16th to endDay
7%9%32%36%13%
595
August1st to 15thDay
12%8%33%36%8%
549
16th to endDay
10%12%33%34%8%
424
September1st to 15thDay
12%211%25%36%11%
363
16th to endDay
8%15%35%25%15%
180
October1st to 15thDay
16%7%27%30%16%2
180
16th to endDay
14%8%37%28%9%1
192
November1st to 15thDay
20%16%30%22%8%2
180
16th to endDay
20%18%24%27%7%1
180
December1st to 15thDay
19%18%35%19%5%2
180
16th to endDay
16%19%39%21%3
192
January1st to 15thNight
20%19%32%21%5%
1050
16th to endNight
14%19%37%24%3
1120
February1st to 15thNight
17%17%41%20%3
1030
16th to endNight
20%19%38%19%1
720
March1st to 15thNight
20%14%36%25%2
630
16th to endNight
19%11%37%24%6%
672
April1st to 15thNight
13%14%37%27%6%
629
16th to endNight
18%10%35%26%8%
624
May1st to 15thNight
13%7%30%36%11%
630
16th to endNight
11%5%24%36%19%3
659
June1st to 15thNight
5%117%43%28%1
630
16th to endNight
320%48%26%1
609
July1st to 15thNight
5%14%37%36%4
555
16th to endNight
5%5%37%43%7%
612
August1st to 15thNight
8%8%34%43%5%
575
16th to endNight
5%110%42%34%4
621
September1st to 15thNight
14%111%32%36%3
585
16th to endNight
12%217%31%32%4
604
October1st to 15thNight
13%325%31%20%3
780
16th to endNight
13%9%31%31%13%
832
November1st to 15thNight
15%11%32%27%12%
820
16th to endNight
18%14%32%25%8%
994
December1st to 15thNight
20%13%36%23%5%
1050
16th to endNight
21%14%37%22%4
1120
Page generated at 2019-06-24 19:41:32. Version ac04

Copyright 2019 A. Danko


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