Heavens Gate Farm Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Heavens Gate Farm Observatory clear sky chart from 2005-11-05 to 2017-10-06.

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%
15972
20%
47093
13%
15926
48%
15926
27%
30069

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
25%
900
19%
2497
8%
895
35%
895
24%
1687
January16th to endNight
21%
960
18%
2496
4%
960
30%
960
22%
1761
February1st to 15thNight
23%
872
12%
2281
3%
869
28%
869
20%
1657
February16th to endNight
25%
631
22%
1893
8%
631
38%
631
25%
1219
March1st to 15thNight
28%
636
19%
2076
10%
636
37%
636
20%
1382
March16th to endNight
30%
576
14%
2049
10%
576
37%
576
15%
1434
April1st to 15thNight
31%
539
19%
1797
12%
539
42%
539
24%
1110
April16th to endNight
39%
540
20%
1800
17%
540
48%
540
23%
1173
May1st to 15thNight
41%
539
18%
1601
13%
539
48%
539
25%
1072
May16th to endNight
49%
563
22%
1497
13%
561
55%
561
32%
983
June1st to 15thNight
59%
540
19%
1440
13%
540
63%
540
40%
859
June16th to endNight
58%
540
19%
1440
12%
540
62%
540
36%
891
July1st to 15thNight
66%
510
17%
1360
12%
510
68%
510
37%
828
July16th to endNight
75%
564
24%
1488
22%
531
77%
531
45%
822
August1st to 15thNight
77%
539
23%
1634
26%
536
77%
536
39%
901
August16th to endNight
72%
573
23%
1910
26%
573
75%
573
35%
1059
September1st to 15thNight
64%
540
28%
1800
29%
540
68%
540
35%
987
September16th to endNight
61%
643
32%
1939
23%
643
68%
643
37%
1084
October1st to 15thNight
47%
684
28%
2052
20%
684
54%
684
34%
1187
October16th to endNight
35%
704
24%
2120
14%
704
45%
704
30%
1258
November1st to 15thNight
37%
700
26%
2276
16%
700
50%
700
30%
1295
November16th to endNight
28%
819
20%
2439
11%
819
38%
819
26%
1558
December1st to 15thNight
26%
900
15%
2520
6%
900
33%
900
20%
1824
December16th to endNight
21%
960
14%
2688
5%
960
30%
960
16%
2038

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%35%5%3445%7%40%
48115
Night
12%6%35%424446%44%
47274
TransparencyDay
42%6%12%23%13%2
47799
Night
39%5%11%24%16%2
47095
SeeingDay
13%7%23%29%19%6%
5994
Night
15%8%29%30%14%1
15973

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
12%8%49%6%24346%36%
1439
16th to endDay
12%11%48%6%3435%5%33%
1728
February1st to 15thDay
13%9%48%435%447%33%
1582
16th to endDay
11%10%37%5%3445%6%36%
1580
March1st to 15thDay
13%10%5%6%6%35%345%35%
1895
16th to endDay
17%9%47%5%3445%7%32%
2173
April1st to 15thDay
16%9%37%5%23335%39%
2151
16th to endDay
20%5%27%5%2445%6%35%
2160
May1st to 15thDay
19%6%36%5%35%45%7%33%
2346
16th to endDay
13%6%36%5%35%447%39%
2617
June1st to 15thDay
7%426%5%35%6%7%9%41%
2520
16th to endDay
8%4245%35%5%7%9%43%
2520
July1st to 15thDay
7%3145%35%6%7%10%43%
2520
16th to endDay
6%314436%6%5%11%46%
2577
August1st to 15thDay
7%425%5%36%6%6%8%43%
2316
16th to endDay
9%4245%25%5%6%8%45%
2292
September1st to 15thDay
12%42332345%8%48%
2160
16th to endDay
8%5%145%2446%7%48%
2005
October1st to 15thDay
16%5%14422336%48%
1706
16th to endDay
14%6%24423345%49%
1752
November1st to 15thDay
15%6%13323446%47%
1582
16th to endDay
16%8%45%423346%40%
1518
December1st to 15thDay
16%11%47%434436%33%
1440
16th to endDay
17%11%5%5%425%45%5%32%
1536
January1st to 15thNight
12%9%36%5%34446%40%
2497
16th to endNight
11%9%6%6%5%34446%37%
2496
February1st to 15thNight
14%9%5%6%5%35%346%35%
2271
16th to endNight
14%8%35%5%23435%44%
1893
March1st to 15thNight
16%8%345%25%345%39%
2076
16th to endNight
17%9%45%5%36%5%5%6%31%
2049
April1st to 15thNight
12%6%25%5%24447%43%
1797
16th to endNight
16%7%35%423346%41%
1800
May1st to 15thNight
15%5%35%5%2445%7%39%
1601
16th to endNight
9%6%26%424448%45%
1496
June1st to 15thNight
6%425%33245%9%51%
1440
16th to endNight
8%324425%46%11%46%
1440
July1st to 15thNight
7%425%425%46%7%49%
1440
16th to endNight
6%2143235%5%9%54%
1590
August1st to 15thNight
5%2134245%5%10%53%
1644
16th to endNight
6%3144245%5%8%52%
1910
September1st to 15thNight
11%41332235%6%53%
1800
16th to endNight
6%325%32435%8%54%
1939
October1st to 15thNight
9%5%14323337%52%
2052
16th to endNight
15%5%23323435%51%
2120
November1st to 15thNight
11%5%24422336%51%
2276
16th to endNight
16%7%24323446%44%
2439
December1st to 15thNight
18%10%36%42346%6%33%
2520
16th to endNight
18%11%5%8%5%3433430%
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
49%49%23%13%
1440
16th to endDay
52%5%13%20%8%
1728
February1st to 15thDay
50%5%13%21%8%
1583
16th to endDay
48%5%12%22%10%
1580
March1st to 15thDay
49%5%11%23%8%1
1895
16th to endDay
52%6%13%18%8%
2175
April1st to 15thDay
47%39%22%14%1
2151
16th to endDay
48%411%20%12%1
2160
May1st to 15thDay
49%6%10%24%8%
2346
16th to endDay
44%7%12%19%14%2
2621
June1st to 15thDay
35%7%14%23%16%2
2520
16th to endDay
34%7%14%24%16%3
2520
July1st to 15thDay
33%8%15%26%12%3
2371
16th to endDay
30%7%16%29%15%
2416
August1st to 15thDay
34%8%13%25%16%1
2302
16th to endDay
33%7%12%22%17%5%
2292
September1st to 15thDay
33%5%9%26%19%5%
2160
16th to endDay
32%5%9%31%19%1
2005
October1st to 15thDay
37%49%25%19%3
1706
16th to endDay
37%411%26%17%3
1752
November1st to 15thDay
38%310%21%21%3
1582
16th to endDay
45%411%25%11%
1518
December1st to 15thDay
52%5%13%19%9%
1440
16th to endDay
52%411%20%8%1
1536
January1st to 15thNight
44%411%25%13%
2497
16th to endNight
47%5%13%22%10%
2496
February1st to 15thNight
50%5%12%19%10%1
2281
16th to endNight
42%412%26%12%1
1893
March1st to 15thNight
47%49%24%11%2
2076
16th to endNight
51%6%11%20%8%
2049
April1st to 15thNight
39%5%11%24%15%3
1797
16th to endNight
43%5%9%22%15%3
1800
May1st to 15thNight
43%6%11%22%16%
1602
16th to endNight
36%7%12%20%19%3
1498
June1st to 15thNight
29%5%14%27%20%2
1440
16th to endNight
31%7%13%22%20%4
1440
July1st to 15thNight
32%5%12%26%18%4
1360
16th to endNight
24%5%16%31%19%2
1488
August1st to 15thNight
25%7%12%30%20%3
1634
16th to endNight
27%7%11%24%21%6%
1910
September1st to 15thNight
30%49%23%25%7%
1800
16th to endNight
29%49%27%26%3
1939
October1st to 15thNight
32%48%26%22%5%
2052
16th to endNight
35%49%25%20%3
2120
November1st to 15thNight
34%311%23%19%7%
2276
16th to endNight
41%411%27%14%
2439
December1st to 15thNight
51%5%12%19%10%
2520
16th to endNight
57%410%16%9%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
27%14%36%16%22
90
16th to endDay
12%22%39%18%6%
96
February1st to 15thDay
17%18%36%21%5%
90
16th to endDay
12%24%24%29%8%
81
March1st to 15thDay
21%16%47%11%21
90
16th to endDay
22%15%33%20%7%
159
April1st to 15thDay
18%12%30%23%13%
270
16th to endDay
21%9%27%27%12%1
270
May1st to 15thDay
19%12%29%24%12%2
387
16th to endDay
17%7%29%29%10%5%
517
June1st to 15thDay
7%5%23%33%22%8%
495
16th to endDay
10%426%33%17%6%
495
July1st to 15thDay
9%119%38%23%8%
475
16th to endDay
6%115%31%34%10%
515
August1st to 15thDay
6%112%37%32%10%
469
16th to endDay
8%12%31%36%11%
332
September1st to 15thDay
13%112%29%30%12%
315
16th to endDay
8%5%16%34%25%10%
279
October1st to 15thDay
14%9%24%31%12%8%
107
16th to endDay
15%7%38%31%7%
96
November1st to 15thDay
35%28%31%23%7%
90
16th to endDay
36%18%22%14%7%
90
December1st to 15thDay
18%14%43%14%44
90
16th to endDay
30%16%40%11%1
96
January1st to 15thNight
15%15%39%22%6%
900
16th to endNight
18%14%39%25%3
960
February1st to 15thNight
18%13%39%24%4
872
16th to endNight
18%12%39%26%2
631
March1st to 15thNight
20%11%36%26%5%
636
16th to endNight
20%10%32%29%6%
576
April1st to 15thNight
15%11%37%27%7%
539
16th to endNight
19%5%30%35%7%
540
May1st to 15thNight
17%429%36%11%1
540
16th to endNight
12%327%34%19%1
563
June1st to 15thNight
6%321%47%19%1
540
16th to endNight
9%122%41%21%2
540
July1st to 15thNight
9%113%43%29%2
510
16th to endNight
6%10%40%39%2
564
August1st to 15thNight
7%6%42%38%3
539
16th to endNight
5%12%35%40%4
573
September1st to 15thNight
14%212%35%27%7%
540
16th to endNight
7%5%18%34%28%6%
643
October1st to 15thNight
12%428%31%20%2
684
16th to endNight
19%7%34%28%9%
704
November1st to 15thNight
14%8%36%29%10%1
700
16th to endNight
19%12%36%24%7%
819
December1st to 15thNight
23%11%35%23%5%
900
16th to endNight
23%11%35%24%3
960
Page generated at 2017-10-07 13:07:48. Version ac04

Copyright 2017 A. Danko


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