Stardust Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stardust Observatory clear sky chart from 2005-11-06 to 2024-01-13.

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
38%
24503
20%
74680
12%
24443
46%
24443
25%
48640

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 10thNight
21%
950
17%
2648
6%
946
30%
946
19%
1888
January11th to 20thNight
20%
915
14%
2552
5%
915
27%
915
17%
1905
January21st to endNight
19%
990
14%
2574
4%
990
27%
990
18%
1926
February1st to 10thNight
21%
900
12%
2340
3%
900
27%
900
17%
1757
February11th to 20thNight
25%
710
18%
2107
7%
708
34%
708
21%
1425
February21st to endNight
18%
592
19%
1776
6%
592
30%
592
19%
1229
March1st to 10thNight
24%
720
18%
2160
7%
720
33%
720
20%
1464
March11th to 20thNight
31%
592
18%
2032
11%
592
41%
592
21%
1307
March21st to endNight
25%
594
14%
2027
6%
594
34%
594
15%
1448
April1st to 10thNight
29%
540
19%
1800
11%
540
41%
540
23%
1114
April11th to 20thNight
33%
533
22%
1775
17%
533
45%
533
26%
1092
April21st to endNight
29%
540
17%
1800
10%
540
38%
540
19%
1200
May1st to 10thNight
33%
540
16%
1655
9%
540
41%
540
24%
1108
May11th to 20thNight
44%
531
20%
1436
12%
531
50%
531
29%
957
May21st to endNight
49%
584
18%
1551
11%
582
54%
582
29%
1037
June1st to 10thNight
62%
540
20%
1440
13%
540
66%
540
43%
832
June11th to 20thNight
61%
540
24%
1440
15%
540
65%
540
40%
849
June21st to endNight
53%
540
19%
1440
11%
540
58%
540
36%
894
July1st to 10thNight
70%
525
18%
1400
15%
525
71%
525
38%
844
July11th to 20thNight
72%
522
26%
1392
19%
522
75%
522
47%
774
July21st to endNight
70%
591
27%
1487
22%
558
73%
558
44%
860
August1st to 10thNight
73%
537
24%
1605
24%
534
75%
534
42%
854
August11th to 20thNight
70%
534
24%
1776
26%
534
73%
534
36%
960
August21st to endNight
72%
594
24%
1980
27%
594
75%
594
40%
1036
September1st to 10thNight
62%
540
26%
1800
26%
540
67%
540
34%
993
September11th to 20thNight
65%
575
35%
1835
34%
575
69%
575
39%
997
September21st to endNight
55%
720
29%
1980
18%
720
62%
720
38%
1168
October1st to 10thNight
51%
720
25%
2114
18%
720
56%
720
36%
1225
October11th to 20thNight
37%
720
28%
2160
16%
720
49%
720
31%
1273
October21st to endNight
28%
792
20%
2470
11%
792
38%
792
22%
1618
November1st to 10thNight
34%
740
27%
2406
17%
740
47%
740
31%
1340
November11th to 20thNight
29%
760
24%
2470
11%
760
45%
760
25%
1466
November21st to endNight
26%
842
21%
2552
11%
842
37%
842
22%
1697
December1st to 10thNight
23%
950
15%
2660
7%
950
31%
950
20%
1897
December11th to 20thNight
26%
950
17%
3173
7%
948
35%
948
18%
2168
December21st to endNight
17%
1040
8%
4867
4%
1026
27%
1026
7%
4038

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
13%8%36%6%35%5%5%7%39%
74778
Night
13%8%36%5%3445%7%41%
74986
TransparencyDay
44%5%12%23%14%2
74479
Night
43%411%23%15%3
74806
SeeingDay
16%9%26%26%17%6%
14549
Night
17%9%29%31%13%1
24509

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 10thDay
14%13%6%9%8%45%5%5%6%27%
1517
11th to 20thDay
15%15%7%10%8%4435%6%24%
1465
21st to endDay
13%14%7%10%7%4435%5%27%
1782
February1st to 10thDay
16%13%5%11%7%35%336%29%
1620
11th to 20thDay
14%10%46%7%5%5%5%5%8%30%
1739
21st to endDay
17%12%5%10%5%33446%29%
1480
March1st to 10thDay
16%11%47%7%35%445%35%
1800
11th to 20thDay
14%11%5%6%6%445%6%8%33%
1943
21st to endDay
21%11%49%6%35%446%25%
2328
April1st to 10thDay
15%7%46%6%35%46%8%37%
2160
11th to 20thDay
15%9%45%6%345%5%6%39%
2134
21st to endDay
19%8%36%6%35%45%6%36%
2160
May1st to 10thDay
16%8%36%6%45%5%6%8%32%
2304
11th to 20thDay
17%7%35%6%45%5%5%7%36%
2456
21st to endDay
12%6%36%7%46%6%6%9%35%
2725
June1st to 10thDay
8%425%6%35%5%7%9%46%
2520
11th to 20thDay
8%5%25%435%5%6%8%49%
2520
21st to endDay
8%426%6%46%6%7%10%42%
2520
July1st to 10thDay
8%3145%45%6%7%11%45%
2520
11th to 20thDay
6%425%5%35%6%7%10%48%
2520
21st to endDay
8%424435%5%8%10%47%
2743
August1st to 10thDay
8%5%25%5%35%6%8%11%42%
2320
11th to 20thDay
8%425%5%35%6%6%9%47%
2125
21st to endDay
7%425%5%346%7%9%48%
2376
September1st to 10thDay
12%5%25%5%345%6%8%47%
2160
11th to 20thDay
9%425%425%5%47%52%
2106
21st to endDay
8%5%25%43446%8%51%
1980
October1st to 10thDay
11%5%345%2445%7%50%
1841
11th to 20thDay
17%8%35%5%34436%44%
1800
21st to endDay
19%10%36%42345%6%39%
1886
November1st to 10thDay
11%6%25%5%2345%7%51%
1672
11th to 20thDay
16%8%5%6%42335%7%41%
1710
21st to endDay
16%10%47%6%3344438%
1625
December1st to 10thDay
14%10%6%7%6%3446%6%33%
1520
11th to 20thDay
14%10%5%8%6%35%45%8%31%
1918
21st to endDay
22%17%8%11%5%3444418%
2783
January1st to 10thNight
11%12%5%8%7%45%45%6%35%
2648
11th to 20thNight
15%12%5%9%7%34335%32%
2552
21st to endNight
14%11%5%9%7%45%446%30%
2574
February1st to 10thNight
17%11%6%8%6%35%447%31%
2340
11th to 20thNight
14%9%5%7%7%2346%6%37%
2106
21st to endNight
18%10%37%7%24345%36%
1776
March1st to 10thNight
15%10%46%5%3445%5%39%
2160
11th to 20thNight
16%8%36%5%3445%7%39%
2032
21st to endNight
20%10%47%7%3445%6%30%
2027
April1st to 10thNight
12%6%45%5%35%5%5%6%42%
1800
11th to 20thNight
14%7%26%5%35%35%7%44%
1775
21st to endNight
20%7%37%5%34446%38%
1800
May1st to 10thNight
16%5%36%5%36%5%6%9%38%
1655
11th to 20thNight
16%6%35%44446%7%42%
1435
21st to endNight
10%6%35%7%35%5%7%10%39%
1551
June1st to 10thNight
9%42443346%10%52%
1440
11th to 20thNight
8%424335%5%6%8%51%
1440
21st to endNight
7%426%6%26%47%10%45%
1440
July1st to 10thNight
8%415%435%46%10%49%
1440
11th to 20thNight
5%3243345%6%9%56%
1440
21st to endNight
4315%5%36%5%6%9%53%
1575
August1st to 10thNight
6%32443346%12%53%
1614
11th to 20thNight
7%425%5%245%5%8%54%
1776
21st to endNight
5%3234346%6%8%55%
1980
September1st to 10thNight
11%5%245%24337%54%
1800
11th to 20thNight
8%5%2443345%8%54%
1835
21st to endNight
7%5%245%25%45%8%52%
1980
October1st to 10thNight
11%425%424446%54%
2114
11th to 20thNight
15%6%23424347%50%
2160
21st to endNight
19%9%25%5%34345%42%
2470
November1st to 10thNight
9%6%25%5%33346%53%
2406
11th to 20thNight
13%6%36%424447%46%
2470
21st to endNight
17%9%36%424436%41%
2552
December1st to 10thNight
15%11%37%6%35%447%33%
2660
11th to 20thNight
16%9%48%6%34335%38%
3279
21st to endNight
22%19%7%10%6%3443418%
4884

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 10thDay
59%48%18%11%1
1518
11th to 20thDay
63%411%16%6%
1465
21st to endDay
59%411%17%7%
1782
February1st to 10thDay
59%411%18%7%1
1620
11th to 20thDay
53%411%21%11%1
1749
21st to endDay
56%48%21%9%2
1480
March1st to 10thDay
53%411%22%10%1
1800
11th to 20thDay
49%5%13%22%8%2
1943
21st to endDay
60%49%19%6%1
2328
April1st to 10thDay
45%5%12%24%13%
2160
11th to 20thDay
46%49%25%14%2
2134
21st to endDay
49%5%12%20%12%2
2160
May1st to 10thDay
49%6%15%21%9%1
2304
11th to 20thDay
48%5%13%21%13%1
2460
21st to endDay
43%8%13%19%15%2
2725
June1st to 10thDay
34%5%14%28%16%3
2520
11th to 20thDay
34%5%11%24%23%3
2520
21st to endDay
36%7%14%23%17%3
2520
July1st to 10thDay
32%7%15%29%14%3
2451
11th to 20thDay
30%7%16%31%14%2
2445
21st to endDay
30%7%15%31%17%1
2591
August1st to 10thDay
32%7%19%29%11%2
2305
11th to 20thDay
33%7%12%31%16%1
2125
21st to endDay
31%7%13%24%20%5%
2376
September1st to 10thDay
35%5%10%26%17%6%
2160
11th to 20thDay
32%49%27%22%6%
2106
21st to endDay
31%49%31%22%3
1980
October1st to 10thDay
34%412%24%22%3
1841
11th to 20thDay
43%49%22%21%2
1800
21st to endDay
47%410%24%14%2
1886
November1st to 10thDay
34%315%25%18%4
1672
11th to 20thDay
45%310%26%15%2
1710
21st to endDay
52%310%23%12%
1625
December1st to 10thDay
52%5%13%21%9%1
1520
11th to 20thDay
51%5%9%26%6%2
1915
21st to endDay
70%49%12%5%
2783
January1st to 10thNight
51%49%21%14%1
2648
11th to 20thNight
57%311%21%8%
2552
21st to endNight
55%413%18%9%1
2574
February1st to 10thNight
55%5%11%17%10%2
2340
11th to 20thNight
48%311%23%13%2
2107
21st to endNight
51%310%22%11%3
1776
March1st to 10thNight
48%49%24%14%1
2160
11th to 20thNight
46%413%21%14%3
2032
21st to endNight
55%5%11%19%9%1
2027
April1st to 10thNight
41%413%24%15%3
1800
11th to 20thNight
41%310%26%17%3
1775
21st to endNight
49%410%19%15%4
1800
May1st to 10thNight
43%7%13%24%13%1
1655
11th to 20thNight
42%5%13%22%17%1
1436
21st to endNight
39%7%14%20%16%4
1552
June1st to 10thNight
27%5%16%29%18%5%
1440
11th to 20thNight
30%5%12%25%23%5%
1440
21st to endNight
33%7%16%23%19%3
1440
July1st to 10thNight
31%6%14%30%16%4
1400
11th to 20thNight
24%5%14%33%21%3
1392
21st to endNight
27%5%15%30%20%3
1487
August1st to 10thNight
26%5%17%34%16%2
1605
11th to 20thNight
29%6%11%32%21%2
1776
21st to endNight
25%7%14%28%20%7%
1980
September1st to 10thNight
32%410%27%20%8%
1800
11th to 20thNight
29%49%27%26%5%
1835
21st to endNight
31%49%27%23%5%
1980
October1st to 10thNight
33%410%24%24%5%
2114
11th to 20thNight
35%38%28%21%4
2160
21st to endNight
46%39%21%19%2
2470
November1st to 10thNight
33%411%27%20%5%
2406
11th to 20thNight
39%312%26%19%2
2470
21st to endNight
46%310%25%15%1
2552
December1st to 10thNight
52%412%22%10%1
2660
11th to 20thNight
49%412%25%10%1
3281
21st to endNight
71%47%12%5%1
4884

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 10thDay
26%20%29%18%8%
270
11th to 20thDay
29%15%35%17%4
248
21st to endDay
17%20%36%22%5%
264
February1st to 10thDay
25%17%39%15%3
240
11th to 20thDay
25%22%27%22%5%
240
21st to endDay
28%15%41%15%2
198
March1st to 10thDay
24%18%39%16%3
240
11th to 20thDay
28%13%38%15%6%
240
21st to endDay
33%12%32%17%5%1
414
April1st to 10thDay
20%12%33%27%7%
420
11th to 20thDay
20%16%30%23%9%2
412
21st to endDay
25%12%35%19%8%1
420
May1st to 10thDay
22%9%33%23%10%2
423
11th to 20thDay
20%10%26%27%15%2
602
21st to endDay
13%5%32%27%14%8%
679
June1st to 10thDay
9%5%22%31%26%8%
630
11th to 20thDay
10%5%21%33%24%7%
630
21st to endDay
9%5%28%32%21%5%
630
July1st to 10thDay
11%212%30%27%17%
621
11th to 20thDay
8%221%30%28%11%
618
21st to endDay
10%216%33%32%7%
684
August1st to 10thDay
9%112%35%30%12%
617
11th to 20thDay
10%5%15%28%28%15%
439
21st to endDay
7%216%29%34%11%
495
September1st to 10thDay
14%221%27%27%8%
450
11th to 20thDay
8%313%29%33%14%
450
21st to endDay
9%9%22%26%25%8%
450
October1st to 10thDay
12%8%27%31%19%4
311
11th to 20thDay
19%19%31%23%6%1
270
21st to endDay
34%12%32%17%5%
297
November1st to 10thDay
11%12%37%26%10%5%
270
11th to 20thDay
23%15%31%19%10%2
270
21st to endDay
29%9%34%23%5%
270
December1st to 10thDay
16%19%37%18%7%3
270
11th to 20thDay
20%15%41%19%4
270
21st to endDay
27%16%40%14%2
297
January1st to 10thNight
17%15%39%24%5%
950
11th to 20thNight
21%13%38%22%5%
915
21st to endNight
21%14%35%27%3
990
February1st to 10thNight
24%13%35%24%4
900
11th to 20thNight
21%14%35%27%3
711
21st to endNight
24%15%37%21%3
592
March1st to 10thNight
20%14%36%24%5%
720
11th to 20thNight
21%10%34%29%6%
592
21st to endNight
24%10%35%25%6%
594
April1st to 10thNight
16%14%36%28%6%
540
11th to 20thNight
18%11%32%29%9%
533
21st to endNight
24%8%34%27%7%
540
May1st to 10thNight
18%6%36%32%7%1
540
11th to 20thNight
18%426%38%12%2
531
21st to endNight
12%425%34%23%2
584
June1st to 10thNight
10%319%48%20%
540
11th to 20thNight
10%122%44%20%2
540
21st to endNight
9%327%39%21%1
540
July1st to 10thNight
9%210%37%36%6%
525
11th to 20thNight
4215%45%30%3
522
21st to endNight
6%114%45%33%2
591
August1st to 10thNight
7%19%48%31%3
537
11th to 20thNight
8%210%42%32%5%
534
21st to endNight
6%214%35%41%3
594
September1st to 10thNight
12%416%38%26%4
540
11th to 20thNight
8%316%38%30%5%
575
21st to endNight
9%8%22%33%25%3
720
October1st to 10thNight
12%428%33%21%2
720
11th to 20thNight
17%11%30%29%12%1
720
21st to endNight
24%10%33%26%7%
792
November1st to 10thNight
12%9%40%27%11%1
740
11th to 20thNight
18%13%36%27%7%1
760
21st to endNight
22%12%35%25%6%
842
December1st to 10thNight
22%10%38%25%5%
950
11th to 20thNight
23%10%34%28%5%1
950
21st to endNight
28%15%32%23%2
1045
Page generated at 2024-01-10 18:35:25. Version ac07

Copyright 2024 Attilla Danko


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