Cargeena 2 Astronomy
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cargeena 2 Astronomy clear sky chart from 2005-11-05 to 2017-09-20.

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
61%
16024
20%
46980
16%
15984
65%
15984
29%
30052

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
51%
717
20%
2327
16%
716
58%
716
26%
1445
January16th to endNight
48%
768
24%
2439
19%
768
56%
768
30%
1459
February1st to 15thNight
47%
701
22%
2103
16%
698
55%
698
31%
1285
February16th to endNight
50%
631
27%
1811
16%
631
60%
631
37%
1047
March1st to 15thNight
52%
720
30%
1980
17%
720
62%
720
41%
1119
March16th to endNight
58%
768
27%
2112
20%
768
63%
768
41%
1195
April1st to 15thNight
62%
718
23%
1976
19%
718
66%
718
43%
1103
April16th to endNight
61%
720
28%
1842
17%
720
67%
720
43%
1080
May1st to 15thNight
70%
614
27%
1694
19%
614
74%
614
41%
978
May16th to endNight
76%
561
21%
1682
17%
561
78%
561
34%
1045
June1st to 15thNight
67%
540
9%
1620
8%
540
67%
540
19%
1201
June16th to endNight
72%
540
7%
1620
6%
540
72%
540
20%
1225
July1st to 15thNight
71%
510
6%
1530
5%
510
71%
510
19%
1182
July16th to endNight
76%
564
7%
1595
7%
531
76%
531
20%
1201
August1st to 15thNight
78%
539
5%
1609
6%
536
78%
536
24%
1130
August16th to endNight
61%
744
6%
2073
5%
744
61%
744
18%
1559
September1st to 15thNight
61%
720
5%
1980
6%
720
61%
720
16%
1522
September16th to endNight
59%
677
10%
1870
10%
677
59%
677
17%
1398
October1st to 15thNight
67%
660
24%
1881
25%
660
69%
660
31%
1187
October16th to endNight
59%
704
26%
2112
24%
704
65%
704
32%
1279
November1st to 15thNight
63%
700
31%
2101
27%
700
69%
700
39%
1188
November16th to endNight
55%
720
30%
2187
25%
720
64%
720
33%
1290
December1st to 15thNight
57%
720
24%
2340
23%
720
62%
720
28%
1434
December16th to endNight
58%
768
22%
2496
22%
768
63%
768
30%
1500

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
8%5%36%7%46%6%6%8%35%
47839
Night
7%425%5%35%5%6%9%43%
47189
TransparencyDay
43%9%13%15%12%5%
47540
Night
35%9%15%19%14%5%
46992
SeeingDay
9%112%20%25%30%
5864
Night
9%216%33%28%9%
16033

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
10%5%36%6%25%6%7%7%37%
1611
16th to endDay
9%4245%3446%8%45%
1783
February1st to 15thDay
10%5%25%5%2446%5%46%
1750
16th to endDay
7%5%25%5%35%45%6%47%
1661
March1st to 15thDay
5%2135%36%6%5%7%51%
1980
16th to endDay
7%3245%35%5%5%8%47%
2111
April1st to 15thDay
6%3246%36%6%6%9%42%
1972
16th to endDay
6%415%436%6%6%8%44%
2115
May1st to 15thDay
5%3245%46%6%6%8%46%
2265
16th to endDay
6%438%8%47%6%6%9%33%
2431
June1st to 15thDay
12%9%48%7%5%7%6%6%8%21%
2340
16th to endDay
9%7%38%9%5%7%7%7%9%23%
2340
July1st to 15thDay
8%7%49%10%5%9%7%7%7%20%
2340
16th to endDay
9%7%48%10%6%8%7%7%9%19%
2465
August1st to 15thDay
6%5%38%10%6%8%8%8%10%22%
2340
16th to endDay
11%7%48%9%6%7%8%7%8%20%
2112
September1st to 15thDay
9%6%47%10%5%8%7%7%9%22%
1980
16th to endDay
11%8%49%9%5%7%6%7%9%20%
1859
October1st to 15thDay
8%6%26%7%47%5%6%8%36%
1749
16th to endDay
8%426%5%445%5%7%43%
1760
November1st to 15thDay
5%425%5%45%6%48%48%
1757
16th to endDay
7%5%36%5%46%45%7%43%
1770
December1st to 15thDay
9%6%35%6%5%5%5%5%7%39%
1620
16th to endDay
7%4346%35%6%5%9%43%
1728
January1st to 15thNight
8%5%26%5%45%45%9%41%
2327
16th to endNight
10%5%24425%45%8%44%
2439
February1st to 15thNight
11%5%25%5%2445%7%47%
2103
16th to endNight
6%41442446%9%50%
1811
March1st to 15thNight
43145%3445%8%55%
1980
16th to endNight
5%41432235%9%55%
2112
April1st to 15thNight
421432446%8%55%
1976
16th to endNight
6%31342446%8%55%
1842
May1st to 15thNight
431342445%8%56%
1694
16th to endNight
6%3145%35%5%7%9%46%
1682
June1st to 15thNight
8%7%38%7%46%7%7%12%27%
1620
16th to endNight
7%5%28%7%47%7%7%10%31%
1620
July1st to 15thNight
7%6%46%7%47%6%7%11%30%
1620
16th to endNight
5%428%7%5%8%7%8%12%28%
1703
August1st to 15thNight
5%426%5%35%7%8%12%35%
1620
16th to endNight
10%6%36%7%36%6%7%11%30%
2073
September1st to 15thNight
8%6%38%7%5%6%7%7%10%27%
1980
16th to endNight
10%7%38%7%5%7%6%7%8%28%
1870
October1st to 15thNight
8%5%25%5%245%5%7%46%
1881
16th to endNight
10%6%2442345%8%47%
2112
November1st to 15thNight
6%4245%2435%8%52%
2101
16th to endNight
8%425%5%2445%8%47%
2187
December1st to 15thNight
8%5%34435%5%6%7%45%
2340
16th to endNight
6%425%5%25%5%7%9%45%
2496

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
41%8%8%19%18%5%
1612
16th to endDay
35%5%9%19%21%9%
1783
February1st to 15thDay
36%5%8%15%20%13%
1752
16th to endDay
36%5%9%15%21%10%
1661
March1st to 15thDay
30%6%11%23%19%8%
1980
16th to endDay
33%6%10%20%21%7%
2112
April1st to 15thDay
33%8%14%19%18%5%
1972
16th to endDay
35%6%10%16%22%7%
2115
May1st to 15thDay
34%6%12%18%19%8%
2265
16th to endDay
43%9%13%18%12%1
2435
June1st to 15thDay
57%10%14%13%3
2340
16th to endDay
55%12%17%12%2
2340
July1st to 15thDay
58%14%17%7%1
2201
16th to endDay
57%12%18%9%1
2310
August1st to 15thDay
50%16%24%8%
2327
16th to endDay
56%16%18%7%1
2112
September1st to 15thDay
52%15%19%9%2
1980
16th to endDay
57%12%15%9%41
1859
October1st to 15thDay
42%8%11%15%15%6%
1749
16th to endDay
39%5%10%12%21%10%
1760
November1st to 15thDay
32%6%10%21%19%10%
1757
16th to endDay
37%7%8%17%16%12%
1770
December1st to 15thDay
43%5%12%16%16%5%
1620
16th to endDay
35%7%11%20%17%7%
1728
January1st to 15thNight
37%7%12%21%15%5%
2327
16th to endNight
35%5%10%22%17%8%
2439
February1st to 15thNight
36%5%7%16%21%12%
2112
16th to endNight
28%7%12%21%21%8%
1811
March1st to 15thNight
26%5%11%29%20%7%
1980
16th to endNight
25%6%13%24%20%8%
2112
April1st to 15thNight
24%6%16%25%20%6%
1976
16th to endNight
25%6%13%24%23%6%
1842
May1st to 15thNight
26%6%12%26%20%6%
1695
16th to endNight
30%9%18%23%16%1
1684
June1st to 15thNight
46%13%20%15%4
1620
16th to endNight
44%16%21%13%4
1620
July1st to 15thNight
45%16%25%10%2
1530
16th to endNight
43%16%26%13%
1595
August1st to 15thNight
36%16%36%10%
1609
16th to endNight
44%16%27%9%1
2073
September1st to 15thNight
46%17%21%12%2
1980
16th to endNight
48%12%17%14%41
1870
October1st to 15thNight
35%7%13%18%19%5%
1881
16th to endNight
34%6%11%15%23%9%
2112
November1st to 15thNight
29%411%23%22%8%
2101
16th to endNight
32%6%8%21%19%11%
2187
December1st to 15thNight
36%6%12%23%14%6%
2340
16th to endNight
33%8%13%19%17%7%
2496

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
22%6%32%20%12%6%
90
16th to endDay
12%12%33%21%16%3
96
February1st to 15thDay
413%30%26%17%7%
90
16th to endDay
12%230%37%16%
162
March1st to 15thDay
5%426%35%23%4
270
16th to endDay
8%322%27%32%6%
288
April1st to 15thDay
2222%31%28%10%
270
16th to endDay
8%113%27%28%20%
270
May1st to 15thDay
5%10%24%34%25%
288
16th to endDay
6%6%18%32%34%
331
June1st to 15thDay
15%111%12%20%39%
315
16th to endDay
7%38%22%57%
315
July1st to 15thDay
6%6%17%69%
305
16th to endDay
11%410%14%58%
326
August1st to 15thDay
7%39%16%62%
313
16th to endDay
11%48%19%55%
332
September1st to 15thDay
10%15%11%22%48%
315
16th to endDay
11%18%36%40%
270
October1st to 15thDay
9%17%29%33%17%
255
16th to endDay
9%118%27%30%11%
272
November1st to 15thDay
6%112%33%33%11%
265
16th to endDay
9%217%36%30%3
240
December1st to 15thDay
11%430%40%14%
90
16th to endDay
8%313%29%37%8%
96
January1st to 15thNight
11%5%22%40%18%1
720
16th to endNight
12%428%39%12%1
768
February1st to 15thNight
13%427%41%12%
704
16th to endNight
8%430%43%13%
631
March1st to 15thNight
5%432%42%14%1
720
16th to endNight
7%325%44%18%
768
April1st to 15thNight
5%224%44%21%1
718
16th to endNight
7%222%44%23%
720
May1st to 15thNight
5%116%48%25%2
615
16th to endNight
6%7%35%42%6%
563
June1st to 15thNight
10%5%24%46%14%
540
16th to endNight
8%213%43%31%
540
July1st to 15thNight
8%19%45%34%
510
16th to endNight
6%29%42%39%
564
August1st to 15thNight
6%16%47%36%
539
16th to endNight
12%6%15%36%28%
744
September1st to 15thNight
11%1418%38%25%
720
16th to endNight
13%6%21%42%15%
677
October1st to 15thNight
12%8%36%35%6%
660
16th to endNight
12%117%33%30%4
704
November1st to 15thNight
7%118%41%27%3
700
16th to endNight
10%124%42%20%1
720
December1st to 15thNight
10%322%38%23%
720
16th to endNight
7%324%38%24%2
768
Page generated at 2017-09-21 07:18:16. Version ac04

Copyright 2017 A. Danko


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