Galaxy Quest Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Galaxy Quest Observatory clear sky chart from 2005-11-05 to 2019-06-10.

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
31%
17118
18%
53895
8%
17087
42%
17087
20%
35700

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
20%
840
20%
2926
6%
836
38%
836
16%
1846
January16th to endNight
15%
896
16%
3119
3%
896
31%
896
14%
2070
February1st to 15thNight
18%
822
17%
2654
5%
821
33%
821
15%
1801
February16th to endNight
19%
735
19%
2205
5%
735
36%
735
20%
1486
March1st to 15thNight
21%
840
18%
2449
6%
840
34%
840
19%
1732
March16th to endNight
28%
896
20%
2464
7%
896
39%
896
24%
1636
April1st to 15thNight
22%
796
19%
2058
4%
796
31%
796
21%
1478
April16th to endNight
30%
623
14%
1869
6%
623
36%
623
18%
1329
May1st to 15thNight
34%
630
13%
1890
8%
630
39%
630
20%
1345
May16th to endNight
35%
530
11%
1825
10%
530
41%
530
16%
1284
June1st to 15thNight
41%
408
12%
1428
11%
408
47%
408
15%
1011
June16th to endNight
50%
390
11%
1365
12%
390
53%
390
20%
915
July1st to 15thNight
57%
370
12%
1467
18%
370
59%
370
21%
899
July16th to endNight
53%
418
12%
1556
14%
396
56%
396
19%
1007
August1st to 15thNight
54%
574
12%
1713
9%
570
56%
570
23%
1142
August16th to endNight
58%
640
21%
1882
14%
640
61%
640
33%
1132
September1st to 15thNight
51%
780
19%
2073
11%
780
56%
780
34%
1308
September16th to endNight
48%
777
26%
2145
16%
777
56%
777
35%
1286
October1st to 15thNight
38%
780
20%
2236
10%
780
48%
780
26%
1465
October16th to endNight
26%
832
18%
2654
7%
832
39%
832
21%
1725
November1st to 15thNight
31%
820
22%
2667
11%
820
45%
820
21%
1710
November16th to endNight
25%
877
20%
2859
8%
877
40%
877
18%
1852
December1st to 15thNight
18%
900
19%
3087
4%
900
35%
900
17%
2050
December16th to endNight
16%
944
17%
3304
2%
944
34%
944
15%
2191

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
17%6%25%43445%7%38%
54607
Night
18%7%25%424446%38%
54067
TransparencyDay
45%411%22%14%1
54297
Night
46%310%22%14%1
53895
SeeingDay
22%7%28%26%11%2
8496
Night
23%9%28%26%10%1
17121

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%6%35%423447%40%
1672
16th to endDay
17%7%35%42345%6%39%
1809
February1st to 15thDay
16%9%25%5%34446%36%
1864
16th to endDay
13%10%36%5%35%5%5%6%36%
1840
March1st to 15thDay
20%9%35%5%34446%34%
2160
16th to endDay
15%7%24434345%43%
2464
April1st to 15thDay
19%7%36%433446%37%
2548
16th to endDay
21%7%36%424346%35%
2696
May1st to 15thDay
23%7%25%424446%32%
2722
16th to endDay
21%6%25%42445%8%33%
3000
June1st to 15thDay
23%7%345%34447%31%
3060
16th to endDay
20%5%26%5%245%6%7%33%
2925
July1st to 15thDay
13%5%245%35%5%6%8%40%
2739
16th to endDay
14%6%25%5%35%5%6%10%34%
2854
August1st to 15thDay
14%5%35%425%5%7%9%35%
2488
16th to endDay
12%31443447%9%45%
2670
September1st to 15thDay
10%424434447%48%
2217
16th to endDay
14%41432335%6%50%
2145
October1st to 15thDay
18%5%34423335%43%
2054
16th to endDay
20%5%24424445%41%
1921
November1st to 15thDay
20%6%24324447%39%
1851
16th to endDay
19%8%34322345%41%
1758
December1st to 15thDay
20%8%34433337%37%
1529
16th to endDay
22%10%3442333436%
1621
January1st to 15thNight
15%7%245%2445%7%40%
2926
16th to endNight
14%10%36%5%34446%36%
3119
February1st to 15thNight
15%8%36%5%46%445%35%
2653
16th to endNight
15%9%35%434345%39%
2205
March1st to 15thNight
19%10%36%434445%34%
2436
16th to endNight
15%6%25%5%24446%42%
2464
April1st to 15thNight
20%9%35%5%34346%33%
2058
16th to endNight
23%8%35%5%23446%31%
1869
May1st to 15thNight
23%7%35%434447%31%
1890
16th to endNight
21%7%37%5%35%45%8%28%
1823
June1st to 15thNight
24%8%25%5%2445%6%28%
1428
16th to endNight
19%6%25%5%26%446%35%
1365
July1st to 15thNight
15%5%35%435%5%5%9%37%
1547
16th to endNight
16%7%36%335%5%5%7%34%
1652
August1st to 15thNight
14%7%25%5%35%5%5%7%37%
1725
16th to endNight
12%42342445%8%46%
1882
September1st to 15thNight
14%5%2432345%6%48%
2073
16th to endNight
13%413323447%51%
2145
October1st to 15thNight
19%5%24324446%42%
2236
16th to endNight
20%6%24423346%40%
2654
November1st to 15thNight
19%6%25%323346%41%
2667
16th to endNight
19%5%24424346%41%
2859
December1st to 15thNight
20%8%245%33345%38%
3087
16th to endNight
21%9%34323345%38%
3304

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
45%411%21%15%2
1673
16th to endDay
46%111%24%14%1
1809
February1st to 15thDay
49%313%20%13%
1867
16th to endDay
48%311%19%14%3
1840
March1st to 15thDay
49%311%20%12%2
2170
16th to endDay
41%310%18%20%5%
2464
April1st to 15thDay
48%27%21%16%3
2548
16th to endDay
49%39%19%14%3
2696
May1st to 15thDay
52%28%20%13%2
2722
16th to endDay
49%413%20%10%1
3004
June1st to 15thDay
51%410%20%11%1
3060
16th to endDay
49%5%10%20%12%1
2925
July1st to 15thDay
39%5%14%26%13%
2590
16th to endDay
45%5%14%23%10%1
2688
August1st to 15thDay
41%6%15%27%8%
2475
16th to endDay
33%5%13%27%18%
2670
September1st to 15thDay
34%412%27%18%1
2217
16th to endDay
36%39%28%20%1
2145
October1st to 15thDay
42%311%26%14%1
2054
16th to endDay
44%212%24%15%
1921
November1st to 15thDay
45%312%23%14%1
1851
16th to endDay
46%313%19%16%1
1758
December1st to 15thDay
47%311%24%12%
1529
16th to endDay
53%38%17%15%1
1621
January1st to 15thNight
43%412%23%13%1
2926
16th to endNight
49%310%20%13%1
3119
February1st to 15thNight
50%311%20%13%1
2654
16th to endNight
47%39%22%14%2
2205
March1st to 15thNight
52%28%20%13%2
2449
16th to endNight
43%39%17%21%4
2464
April1st to 15thNight
51%36%17%18%2
2058
16th to endNight
53%38%17%13%3
1869
May1st to 15thNight
52%310%17%14%1
1890
16th to endNight
55%311%18%11%1
1825
June1st to 15thNight
54%411%18%7%2
1428
16th to endNight
49%311%22%11%1
1365
July1st to 15thNight
43%5%14%23%13%
1467
16th to endNight
47%414%23%8%1
1556
August1st to 15thNight
46%415%23%9%
1713
16th to endNight
35%413%27%17%
1882
September1st to 15thNight
37%313%27%17%1
2073
16th to endNight
34%39%31%19%1
2145
October1st to 15thNight
43%310%26%14%1
2236
16th to endNight
45%310%25%14%1
2654
November1st to 15thNight
44%311%22%15%1
2667
16th to endNight
46%311%21%15%1
2859
December1st to 15thNight
49%29%24%13%
3087
16th to endNight
49%210%21%13%1
3304

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
18%22%30%21%6%
120
16th to endDay
22%13%43%19%1
145
February1st to 15thDay
28%11%38%16%4
332
16th to endDay
19%14%37%23%4
343
March1st to 15thDay
26%11%37%20%3
390
16th to endDay
20%14%33%23%6%1
416
April1st to 15thDay
26%11%34%21%5%
390
16th to endDay
26%6%35%21%8%2
379
May1st to 15thDay
29%5%29%25%6%2
408
16th to endDay
22%6%31%27%10%1
476
June1st to 15thDay
25%227%29%13%1
615
16th to endDay
24%222%32%15%2
570
July1st to 15thDay
16%120%40%16%4
374
16th to endDay
19%219%33%20%5%
390
August1st to 15thDay
17%220%34%22%2
358
16th to endDay
16%217%34%23%4
396
September1st to 15thDay
14%322%33%21%4
375
16th to endDay
18%425%28%15%8%
374
October1st to 15thDay
21%7%23%27%15%5%
347
16th to endDay
24%11%33%23%6%
336
November1st to 15thDay
25%12%26%26%7%3
325
16th to endDay
27%12%29%21%7%
330
December1st to 15thDay
24%9%39%17%8%
179
16th to endDay
28%21%34%14%1
128
January1st to 15thNight
20%18%35%21%3
840
16th to endNight
22%18%36%18%3
896
February1st to 15thNight
21%16%37%21%2
824
16th to endNight
23%12%36%21%6%
735
March1st to 15thNight
26%10%35%23%3
840
16th to endNight
19%11%32%26%9%1
896
April1st to 15thNight
26%7%35%23%6%
796
16th to endNight
30%7%23%28%9%1
623
May1st to 15thNight
27%226%28%12%2
630
16th to endNight
25%322%33%13%1
531
June1st to 15thNight
29%216%34%15%1
408
16th to endNight
24%215%41%16%
390
July1st to 15thNight
20%12%40%22%2
370
16th to endNight
20%12%36%27%1
418
August1st to 15thNight
17%211%42%23%2
574
16th to endNight
15%215%37%26%4
640
September1st to 15thNight
16%220%35%22%3
780
16th to endNight
17%424%28%18%6%
777
October1st to 15thNight
23%5%25%28%14%2
780
16th to endNight
23%11%33%22%7%
832
November1st to 15thNight
23%10%28%25%10%2
820
16th to endNight
21%14%31%22%8%1
877
December1st to 15thNight
27%13%36%18%5%
900
16th to endNight
27%16%34%18%3
944
Page generated at 2019-06-10 19:29:47. Version ac04

Copyright 2019 A. Danko


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