Homestake Dry Camp
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Homestake Dry Camp clear sky chart from 2005-11-05 to 2017-09-22.

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
67%
15514
36%
46874
28%
15480
76%
15480
58%
20983

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
62%
716
30%
2506
24%
716
74%
716
52%
1068
January16th to endNight
56%
768
35%
2487
26%
768
71%
768
46%
1195
February1st to 15thNight
61%
700
34%
2103
27%
697
71%
697
51%
1019
February16th to endNight
56%
632
34%
1895
28%
632
68%
632
51%
921
March1st to 15thNight
56%
720
33%
2160
23%
720
73%
720
55%
1003
March16th to endNight
57%
768
36%
2019
21%
768
69%
768
53%
1032
April1st to 15thNight
51%
719
35%
1799
15%
719
61%
719
57%
933
April16th to endNight
58%
720
37%
1800
16%
720
67%
720
64%
874
May1st to 15thNight
64%
539
36%
1619
22%
539
73%
539
57%
708
May16th to endNight
65%
561
33%
1684
23%
561
72%
561
59%
739
June1st to 15thNight
74%
374
35%
1454
36%
374
82%
374
61%
506
June16th to endNight
83%
360
39%
1440
43%
360
91%
360
73%
446
July1st to 15thNight
88%
340
34%
1360
41%
340
90%
340
59%
490
July16th to endNight
83%
456
38%
1490
38%
428
85%
428
57%
613
August1st to 15thNight
80%
702
37%
1776
24%
699
81%
699
73%
826
August16th to endNight
88%
764
43%
1910
28%
764
88%
764
78%
868
September1st to 15thNight
83%
720
41%
1839
28%
720
87%
720
74%
849
September16th to endNight
82%
683
47%
1890
40%
683
89%
683
80%
772
October1st to 15thNight
70%
660
40%
1829
33%
660
78%
660
63%
854
October16th to endNight
75%
704
42%
2192
41%
704
83%
704
62%
927
November1st to 15thNight
71%
700
38%
2275
35%
700
81%
700
62%
939
November16th to endNight
71%
720
39%
2340
36%
720
79%
720
58%
992
December1st to 15thNight
63%
720
34%
2340
26%
720
74%
720
48%
1093
December16th to endNight
51%
768
31%
2667
23%
768
66%
768
37%
1316

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
1112212346%72%
48005
Night
1212212346%71%
47063
TransparencyDay
12%25%16%27%33%
47683
Night
14%36%18%28%28%
46885
SeeingDay
411%37%30%12%2
5766
Night
2420%41%27%3
15525

By Month

Percentage Cloud Cover SW (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
11321226%9%67%
1432
16th to endDay
3323313347%61%
1731
February1st to 15thDay
1211413449%65%
1751
16th to endDay
2413322347%64%
1579
March1st to 15thDay
11231236%8%67%
1800
16th to endDay
111322335%8%66%
2201
April1st to 15thDay
121331335%7%68%
2149
16th to endDay
11212246%74%
2160
May1st to 15thDay
11213346%73%
2331
16th to endDay
1212213347%68%
2429
June1st to 15thDay
11112335%78%
2502
16th to endDay
11113385%
2520
July1st to 15thDay
1112323345%71%
2520
16th to endDay
111222345%6%70%
2575
August1st to 15thDay
111122382%
2172
16th to endDay
111123482%
2292
September1st to 15thDay
121223380%
2121
16th to endDay
111112386%
1882
October1st to 15thDay
211212345%74%
1800
16th to endDay
1112212335%74%
1680
November1st to 15thDay
1112112235%76%
1584
16th to endDay
2121335%6%71%
1620
December1st to 15thDay
121331335%8%64%
1620
16th to endDay
2313323349%60%
1554
January1st to 15thNight
123313247%68%
2506
16th to endNight
3313323336%64%
2487
February1st to 15thNight
121341335%9%62%
2101
16th to endNight
3323313347%64%
1895
March1st to 15thNight
11321445%8%66%
2160
16th to endNight
131222345%7%65%
2019
April1st to 15thNight
2212223345%69%
1799
16th to endNight
11131233476%
1800
May1st to 15thNight
111222246%73%
1619
16th to endNight
2111212347%71%
1684
June1st to 15thNight
11121233478%
1454
16th to endNight
1112386%
1440
July1st to 15thNight
111213335%75%
1440
16th to endNight
22223445%71%
1592
August1st to 15thNight
11111213381%
1785
16th to endNight
111222482%
1910
September1st to 15thNight
1212235%79%
1839
16th to endNight
1111125%83%
1890
October1st to 15thNight
1112213245%72%
1829
16th to endNight
112112245%75%
2192
November1st to 15thNight
121212236%74%
2275
16th to endNight
2211212237%71%
2340
December1st to 15thNight
133323346%65%
2340
16th to endNight
2414324347%60%
2667

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
13%411%30%31%7%
1432
16th to endDay
22%49%25%25%12%
1731
February1st to 15thDay
16%48%27%28%13%
1751
16th to endDay
19%47%25%31%10%
1579
March1st to 15thDay
12%39%25%31%17%
1800
16th to endDay
16%39%26%27%17%
2201
April1st to 15thDay
15%37%21%32%19%
2149
16th to endDay
11%26%20%35%23%
2160
May1st to 15thDay
10%3416%35%29%
2331
16th to endDay
15%2415%36%25%
2432
June1st to 15thDay
8%2410%24%50%
2502
16th to endDay
6%11316%70%
2520
July1st to 15thDay
13%237%14%57%
2371
16th to endDay
13%35%9%17%50%
2414
August1st to 15thDay
7%127%17%63%
2157
16th to endDay
7%126%23%58%
2292
September1st to 15thDay
9%239%19%57%
2121
16th to endDay
6%119%35%45%
1882
October1st to 15thDay
12%2314%36%30%
1800
16th to endDay
12%3314%36%29%
1680
November1st to 15thDay
11%25%26%37%16%
1584
16th to endDay
12%38%25%34%17%
1620
December1st to 15thDay
18%5%12%24%30%9%
1620
16th to endDay
22%5%11%27%23%10%
1554
January1st to 15thNight
15%410%27%33%9%
2506
16th to endNight
21%38%23%26%16%
2487
February1st to 15thNight
18%310%26%26%14%
2112
16th to endNight
20%29%25%31%10%
1895
March1st to 15thNight
15%36%25%30%18%
2160
16th to endNight
16%46%26%31%13%
2019
April1st to 15thNight
16%27%19%36%16%
1799
16th to endNight
11%2420%37%22%
1800
May1st to 15thNight
12%3315%37%27%
1620
16th to endNight
12%36%15%34%27%
1685
June1st to 15thNight
9%2310%26%46%
1454
16th to endNight
6%11418%67%
1440
July1st to 15thNight
11%338%13%60%
1360
16th to endNight
14%3410%16%51%
1490
August1st to 15thNight
9%226%18%61%
1776
16th to endNight
7%236%21%59%
1910
September1st to 15thNight
9%238%20%55%
1839
16th to endNight
6%128%32%48%
1890
October1st to 15thNight
14%1314%32%31%
1829
16th to endNight
11%3413%34%32%
2192
November1st to 15thNight
12%26%21%36%20%
2275
16th to endNight
14%27%20%32%22%
2340
December1st to 15thNight
19%310%27%29%8%
2340
16th to endNight
23%5%10%25%24%10%
2667

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
311%55%21%8%
60
16th to endDay
7%8%35%31%14%2
199
February1st to 15thDay
413%38%30%13%
266
16th to endDay
11%18%40%19%10%
238
March1st to 15thDay
5%15%40%25%11%1
270
16th to endDay
6%20%40%26%5%
288
April1st to 15thDay
9%25%33%22%8%1
269
16th to endDay
7%22%48%17%22
270
May1st to 15thDay
5%18%41%23%9%1
288
16th to endDay
5%15%35%29%11%1
330
June1st to 15thDay
314%40%29%11%
315
16th to endDay
211%33%32%16%3
315
July1st to 15thDay
2437%37%15%3
305
16th to endDay
2334%40%14%4
327
August1st to 15thDay
36%46%25%11%6%
315
16th to endDay
1437%34%16%6%
332
September1st to 15thDay
2438%38%13%2
315
16th to endDay
26%30%43%14%1
280
October1st to 15thDay
312%39%31%10%1
255
16th to endDay
411%29%36%15%1
192
November1st to 15thDay
35%14%35%34%6%
90
16th to endDay
2434%41%17%
90
December1st to 15thDay
27%34%46%8%
90
16th to endDay
5%5%38%28%20%
67
January1st to 15thNight
2425%43%20%4
720
16th to endNight
5%327%39%20%2
768
February1st to 15thNight
2326%42%21%3
704
16th to endNight
46%28%39%17%2
632
March1st to 15thNight
15%30%37%21%3
720
16th to endNight
310%25%37%21%2
768
April1st to 15thNight
39%30%35%17%2
719
16th to endNight
17%30%36%22%2
720
May1st to 15thNight
18%20%44%21%2
540
16th to endNight
26%22%39%27%
563
June1st to 15thNight
2415%44%32%
374
16th to endNight
1112%41%38%4
360
July1st to 15thNight
25%46%42%3
340
16th to endNight
19%44%42%2
456
August1st to 15thNight
1113%49%31%1
702
16th to endNight
8%42%43%4
764
September1st to 15thNight
111%43%39%3
720
16th to endNight
113%42%38%3
683
October1st to 15thNight
1320%40%28%6%
660
16th to endNight
2315%40%29%7%
704
November1st to 15thNight
2320%37%30%6%
700
16th to endNight
4217%42%28%3
720
December1st to 15thNight
5%323%43%22%2
720
16th to endNight
5%8%28%39%16%1
768
Page generated at 2017-09-23 03:43:45. Version ac04

Copyright 2017 A. Danko


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