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 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
41%
15775
24%
47194
15%
15728
50%
15728
31%
28153

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
22%
900
26%
2327
8%
895
35%
895
27%
1490
January16th to endNight
23%
960
27%
2496
7%
960
36%
960
31%
1533
February1st to 15thNight
21%
880
19%
2288
4%
876
30%
876
27%
1492
February16th to endNight
20%
618
25%
1880
7%
618
35%
618
25%
1130
March1st to 15thNight
27%
540
22%
1980
12%
540
40%
540
19%
1268
March16th to endNight
29%
576
17%
2112
11%
576
38%
576
19%
1363
April1st to 15thNight
29%
539
23%
1833
11%
539
47%
539
27%
1048
April16th to endNight
31%
540
22%
1800
12%
540
46%
540
25%
1109
May1st to 15thNight
40%
540
21%
1638
16%
540
49%
540
28%
1023
May16th to endNight
50%
563
19%
1685
17%
561
55%
561
30%
1050
June1st to 15thNight
69%
540
23%
1525
19%
540
73%
540
46%
823
June16th to endNight
70%
540
23%
1591
18%
540
75%
540
45%
846
July1st to 15thNight
68%
510
17%
1530
17%
510
70%
510
38%
882
July16th to endNight
79%
564
26%
1594
29%
531
81%
531
43%
859
August1st to 15thNight
76%
539
25%
1610
30%
536
78%
536
41%
890
August16th to endNight
74%
573
25%
1882
28%
573
76%
573
35%
1035
September1st to 15thNight
65%
540
27%
1808
28%
540
69%
540
34%
988
September16th to endNight
60%
537
32%
1932
29%
537
67%
537
34%
1008
October1st to 15thNight
51%
660
30%
1980
22%
660
56%
660
38%
1113
October16th to endNight
39%
704
30%
2112
16%
704
51%
704
35%
1187
November1st to 15thNight
39%
700
31%
2100
16%
700
53%
700
36%
1159
November16th to endNight
29%
852
26%
2412
13%
852
40%
852
28%
1494
December1st to 15thNight
25%
900
21%
2520
6%
900
37%
900
27%
1619
December16th to endNight
22%
960
24%
2559
8%
960
35%
960
23%
1744

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%44%
47694
Night
10%5%24423346%50%
47389
TransparencyDay
39%5%11%24%16%3
47394
Night
34%5%11%25%19%4
47194
SeeingDay
12%7%23%28%21%5%
5810
Night
14%10%29%28%15%1
15775

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
14%7%25%313236%49%
1611
16th to endDay
11%7%34423345%49%
1728
February1st to 15thDay
13%8%35%414345%44%
1575
16th to endDay
11%8%45%5%23445%43%
1603
March1st to 15thDay
14%9%36%423345%41%
1980
16th to endDay
18%6%36%5%24346%37%
2110
April1st to 15thDay
14%7%246%24445%43%
2113
16th to endDay
17%8%36%5%34435%37%
2160
May1st to 15thDay
17%6%35%5%34445%38%
2310
16th to endDay
11%435%7%46%5%5%7%38%
2430
June1st to 15thDay
7%425%5%35%6%5%9%43%
2421
16th to endDay
5%3245%35%6%6%10%45%
2355
July1st to 15thDay
9%425%6%45%6%7%10%37%
2340
16th to endDay
6%3145%36%5%7%11%43%
2466
August1st to 15thDay
8%4245%35%6%7%9%42%
2340
16th to endDay
7%4246%36%5%6%8%44%
2318
September1st to 15thDay
13%5%24423347%45%
2149
16th to endDay
8%5%2443435%7%49%
1874
October1st to 15thDay
13%5%23324446%50%
1650
16th to endDay
12%5%1342222457%
1760
November1st to 15thDay
10%5%23423346%53%
1758
16th to endDay
15%6%35%313345%47%
1542
December1st to 15thDay
15%8%25%5%14345%43%
1440
16th to endDay
15%10%34414345%41%
1661
January1st to 15thNight
13%6%25%422235%49%
2327
16th to endNight
9%6%34422335%52%
2496
February1st to 15thNight
11%9%25%323346%46%
2278
16th to endNight
11%6%25%323346%49%
1880
March1st to 15thNight
13%8%35%5%24445%41%
1980
16th to endNight
16%8%345%23345%40%
2112
April1st to 15thNight
11%424424447%49%
1833
16th to endNight
16%5%1442345%7%44%
1800
May1st to 15thNight
12%5%3342445%6%47%
1637
16th to endNight
11%4244345%6%8%44%
1683
June1st to 15thNight
421332345%9%59%
1525
16th to endNight
221232448%9%57%
1591
July1st to 15thNight
5%2245%25%5%6%10%49%
1620
16th to endNight
322333445%9%56%
1702
August1st to 15thNight
5%3133245%6%11%51%
1620
16th to endNight
4224435%5%7%9%49%
1882
September1st to 15thNight
10%412424347%52%
1808
16th to endNight
8%41442335%5%55%
1932
October1st to 15thNight
11%41332335%7%55%
1980
16th to endNight
11%5%2431224457%
2112
November1st to 15thNight
9%5%13313345%58%
2100
16th to endNight
15%6%2442323450%
2412
December1st to 15thNight
15%7%35%313346%45%
2520
16th to endNight
13%10%46%424235%42%
2559

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
37%29%27%19%3
1612
16th to endDay
37%311%27%16%3
1728
February1st to 15thDay
43%311%26%12%2
1576
16th to endDay
42%48%24%14%4
1603
March1st to 15thDay
44%49%19%16%5%
1980
16th to endDay
49%410%22%11%1
2112
April1st to 15thDay
42%411%21%17%1
2113
16th to endDay
49%5%8%18%15%2
2160
May1st to 15thDay
47%5%10%21%14%
2310
16th to endDay
43%7%13%22%12%
2434
June1st to 15thDay
35%7%13%26%15%
2421
16th to endDay
30%8%18%25%15%2
2355
July1st to 15thDay
38%8%13%26%10%1
2201
16th to endDay
30%8%17%29%12%1
2311
August1st to 15thDay
34%9%14%23%16%1
2326
16th to endDay
35%7%12%22%15%5%
2318
September1st to 15thDay
38%5%9%22%16%7%
2149
16th to endDay
33%5%9%28%20%2
1874
October1st to 15thDay
34%49%25%20%5%
1650
16th to endDay
32%27%29%20%6%
1760
November1st to 15thDay
32%38%26%20%8%
1758
16th to endDay
39%39%19%25%2
1542
December1st to 15thDay
43%310%23%16%2
1440
16th to endDay
45%39%22%14%3
1661
January1st to 15thNight
38%29%26%20%2
2327
16th to endNight
34%211%27%20%3
2496
February1st to 15thNight
39%311%25%15%3
2288
16th to endNight
36%311%26%18%3
1880
March1st to 15thNight
44%5%7%19%19%4
1980
16th to endNight
45%5%8%22%15%1
2112
April1st to 15thNight
34%410%25%20%4
1833
16th to endNight
39%5%10%25%16%2
1800
May1st to 15thNight
36%7%12%22%18%2
1638
16th to endNight
35%7%17%24%13%1
1685
June1st to 15thNight
21%6%15%32%21%2
1525
16th to endNight
20%8%14%31%20%4
1591
July1st to 15thNight
27%7%15%28%18%1
1530
16th to endNight
23%6%13%34%20%1
1594
August1st to 15thNight
25%6%15%29%20%2
1610
16th to endNight
27%7%14%24%20%5%
1882
September1st to 15thNight
31%410%27%16%9%
1808
16th to endNight
29%49%25%26%4
1932
October1st to 15thNight
28%5%10%24%22%8%
1980
16th to endNight
30%37%26%23%7%
2112
November1st to 15thNight
28%49%26%23%8%
2100
16th to endNight
38%37%23%23%4
2412
December1st to 15thNight
40%311%23%18%2
2520
16th to endNight
45%38%21%15%4
2559

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
27%18%27%21%4
90
16th to endDay
13%31%38%11%5%
96
February1st to 15thDay
7%30%46%11%4
90
16th to endDay
20%24%28%22%3
81
March1st to 15thDay
20%27%36%13%2
90
16th to endDay
11%28%33%21%5%
96
April1st to 15thDay
14%21%33%21%9%
232
16th to endDay
25%15%29%18%9%1
270
May1st to 15thDay
18%12%35%21%10%1
447
16th to endDay
14%8%34%25%13%3
517
June1st to 15thDay
10%319%35%27%4
495
16th to endDay
7%224%37%22%5%
495
July1st to 15thDay
9%318%37%25%5%
475
16th to endDay
7%7%31%37%15%
515
August1st to 15thDay
11%8%33%38%8%
493
16th to endDay
9%12%31%37%8%
358
September1st to 15thDay
10%213%25%36%10%
304
16th to endDay
319%30%28%17%
114
October1st to 15thDay
11%5%32%27%17%5%
90
16th to endDay
12%437%30%12%3
96
November1st to 15thDay
8%11%27%33%13%5%
90
16th to endDay
26%23%25%16%7%
90
December1st to 15thDay
23%11%35%20%5%4
90
16th to endDay
20%16%40%19%2
96
January1st to 15thNight
19%21%33%20%4
900
16th to endNight
13%20%39%22%3
960
February1st to 15thNight
16%18%40%21%2
880
16th to endNight
16%19%41%20%2
618
March1st to 15thNight
20%13%37%26%2
540
16th to endNight
20%11%35%24%7%
576
April1st to 15thNight
13%14%39%25%5%
539
16th to endNight
18%10%36%25%8%
540
May1st to 15thNight
14%7%32%32%12%
540
16th to endNight
12%425%36%18%1
563
June1st to 15thNight
5%217%44%28%1
540
16th to endNight
319%46%27%1
540
July1st to 15thNight
6%15%39%35%2
510
16th to endNight
5%436%44%7%
564
August1st to 15thNight
7%8%33%44%5%
539
16th to endNight
5%110%41%35%4
573
September1st to 15thNight
13%112%32%36%3
540
16th to endNight
11%217%32%31%4
537
October1st to 15thNight
13%326%29%22%4
660
16th to endNight
14%10%31%28%14%
704
November1st to 15thNight
13%12%32%27%14%
700
16th to endNight
20%15%32%23%8%
852
December1st to 15thNight
21%13%36%22%5%
900
16th to endNight
20%15%38%21%4
960
Page generated at 2017-09-25 08:02:16. Version ac04

Copyright 2017 A. Danko


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