Starlifter Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Starlifter Observatory clear sky chart from 2005-11-06 to 2024-01-22.

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
29%
22682
11%
74848
8%
22640
34%
22640
12%
56683

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
15%
760
6%
2649
4%
757
18%
757
5%
2268
January11th to 20thNight
15%
760
6%
2660
3%
760
19%
760
5%
2208
January21st to endNight
18%
800
8%
2798
5%
800
24%
800
8%
2204
February1st to 10thNight
14%
720
6%
2408
2%
720
20%
720
6%
2017
February11th to 20thNight
16%
703
8%
2107
3%
700
22%
700
8%
1716
February21st to endNight
21%
592
12%
1776
6%
592
29%
592
10%
1403
March1st to 10thNight
23%
720
12%
2160
9%
720
29%
720
11%
1699
March11th to 20thNight
24%
720
13%
2115
6%
720
31%
720
13%
1613
March21st to endNight
24%
792
17%
1980
6%
792
31%
792
16%
1523
April1st to 10thNight
22%
720
12%
1800
4%
720
27%
720
15%
1420
April11th to 20thNight
27%
711
13%
1775
5%
711
31%
711
18%
1327
April21st to endNight
24%
541
14%
1621
6%
541
31%
541
14%
1210
May1st to 10thNight
27%
515
14%
1595
8%
515
34%
515
16%
1146
May11th to 20thNight
32%
354
16%
1416
15%
354
41%
354
15%
927
May21st to endNight
42%
388
11%
1551
11%
388
49%
388
16%
1019
June1st to 10thNight
34%
360
11%
1440
12%
360
41%
360
13%
1005
June11th to 20thNight
44%
360
10%
1440
13%
360
50%
360
17%
942
June21st to endNight
47%
360
9%
1440
14%
360
50%
360
15%
999
July1st to 10thNight
48%
350
11%
1400
15%
350
53%
350
19%
893
July11th to 20thNight
55%
348
13%
1392
19%
348
58%
348
19%
874
July21st to endNight
52%
394
13%
1486
18%
372
54%
372
19%
934
August1st to 10thNight
57%
358
15%
1422
19%
356
59%
356
21%
868
August11th to 20thNight
49%
564
15%
1628
11%
564
51%
564
25%
1108
August21st to endNight
49%
792
16%
1980
8%
792
50%
792
27%
1383
September1st to 10thNight
46%
720
12%
1800
5%
720
49%
720
28%
1245
September11th to 20thNight
48%
720
20%
1922
12%
720
52%
720
29%
1257
September21st to endNight
42%
720
19%
1980
14%
720
46%
720
25%
1349
October1st to 10thNight
36%
720
13%
2024
9%
720
40%
720
17%
1495
October11th to 20thNight
33%
720
13%
2234
9%
720
39%
720
15%
1653
October21st to endNight
23%
792
9%
2574
6%
792
28%
792
11%
2035
November1st to 10thNight
27%
740
13%
2407
10%
740
32%
740
13%
1773
November11th to 20thNight
23%
760
16%
2470
12%
760
29%
760
12%
1886
November21st to endNight
19%
760
9%
2626
6%
760
23%
760
8%
2120
December1st to 10thNight
13%
760
3%
2660
2%
760
16%
760
4%
2316
December11th to 20thNight
18%
760
6%
3263
4%
759
20%
759
4%
2759
December21st to endNight
13%
828
4%
4849
3%
817
16%
817
2%
4089

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
16%11%5%8%7%45%5%5%6%28%
74849
Night
16%11%5%9%7%45%5%5%6%28%
75079
TransparencyDay
55%7%11%17%8%1
74554
Night
57%8%10%16%8%1
74908
SeeingDay
24%19%29%18%8%2
13627
Night
22%16%26%25%9%1
22691

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 10thDay
11%13%9%16%12%46%6%5%5%14%
1517
11th to 20thDay
13%15%6%13%11%46%5%5%6%17%
1520
21st to endDay
10%12%7%13%9%5%8%5%5%6%21%
1592
February1st to 10thDay
12%14%6%12%12%5%7%45%5%18%
1550
11th to 20thDay
10%14%8%14%11%5%6%5%4419%
1739
21st to endDay
12%13%6%13%10%5%5%5%45%20%
1480
March1st to 10thDay
11%14%7%12%9%46%5%45%23%
1797
11th to 20thDay
15%13%6%10%8%44445%27%
1841
21st to endDay
16%13%6%11%7%34435%28%
2376
April1st to 10thDay
18%14%6%9%7%44436%26%
2160
11th to 20thDay
17%11%5%7%6%35%45%6%33%
2134
21st to endDay
23%11%37%6%35%45%6%26%
2337
May1st to 10thDay
20%11%47%6%3445%5%31%
2380
11th to 20thDay
17%9%36%6%35%45%6%35%
2478
21st to endDay
17%7%37%6%446%7%8%32%
2725
June1st to 10thDay
25%7%36%6%35%5%6%7%27%
2520
11th to 20thDay
17%7%36%6%36%5%6%9%33%
2520
21st to endDay
20%8%37%6%45%5%6%8%27%
2520
July1st to 10thDay
15%8%35%6%35%5%6%8%36%
2520
11th to 20thDay
13%6%28%6%47%6%7%9%32%
2520
21st to endDay
16%7%27%6%36%6%6%8%32%
2744
August1st to 10thDay
15%7%36%7%46%6%6%9%32%
2495
11th to 20thDay
13%7%36%7%46%5%6%9%33%
2261
21st to endDay
14%7%36%6%35%6%7%9%35%
2376
September1st to 10thDay
16%6%35%4345%7%8%40%
2160
11th to 20thDay
16%8%24424448%44%
2037
21st to endDay
15%7%35%6%45%5%5%8%36%
1980
October1st to 10thDay
23%10%37%5%435%5%6%29%
1935
11th to 20thDay
16%11%38%6%45%6%6%6%30%
1725
21st to endDay
22%20%5%6%5%3444323%
1782
November1st to 10thDay
15%14%5%7%7%36%5%5%6%28%
1671
11th to 20thDay
15%15%7%10%7%35%446%22%
1710
21st to endDay
16%14%7%12%6%35%5%6%6%21%
1549
December1st to 10thDay
16%18%9%14%9%45%34415%
1520
11th to 20thDay
18%14%9%9%7%35%35%5%22%
1906
21st to endDay
20%14%7%14%9%45%43315%
2772
January1st to 10thNight
12%14%6%15%12%5%6%6%6%5%12%
2649
11th to 20thNight
14%14%5%13%11%5%7%5%5%5%17%
2660
21st to endNight
9%11%7%13%10%5%7%7%5%6%20%
2798
February1st to 10thNight
12%12%6%14%12%6%7%5%45%16%
2408
11th to 20thNight
10%11%7%12%11%6%7%5%5%6%20%
2105
21st to endNight
11%13%5%12%9%5%5%45%5%24%
1776
March1st to 10thNight
12%12%6%11%10%5%6%5%45%25%
2150
11th to 20thNight
14%14%5%9%8%45%445%29%
2114
21st to endNight
15%12%5%9%7%45%43432%
1980
April1st to 10thNight
19%12%5%8%7%45%5%5%5%27%
1800
11th to 20thNight
17%10%35%8%5%445%5%33%
1775
21st to endNight
20%11%36%6%445%5%7%30%
1621
May1st to 10thNight
22%10%36%6%34447%32%
1595
11th to 20thNight
17%8%36%5%35%5%5%6%37%
1415
21st to endNight
15%6%36%6%35%6%6%8%37%
1550
June1st to 10thNight
24%7%35%6%25%45%8%30%
1440
11th to 20thNight
17%5%26%6%35%46%8%36%
1440
21st to endNight
20%6%35%5%45%5%6%9%32%
1440
July1st to 10thNight
16%6%35%5%35%6%6%7%38%
1440
11th to 20thNight
13%5%25%6%45%5%7%10%38%
1440
21st to endNight
14%5%26%5%35%6%7%8%39%
1574
August1st to 10thNight
12%5%25%5%446%6%9%42%
1432
11th to 20thNight
13%6%36%6%3445%7%42%
1628
21st to endNight
15%6%35%5%336%6%8%41%
1980
September1st to 10thNight
13%6%35%5%35%5%5%7%43%
1800
11th to 20thNight
15%7%34433347%46%
1922
21st to endNight
17%6%345%44447%42%
1980
October1st to 10thNight
21%9%36%5%45%45%7%32%
2024
11th to 20thNight
17%11%38%6%46%5%5%6%30%
2234
21st to endNight
23%14%37%7%36%45%6%22%
2574
November1st to 10thNight
15%13%48%6%45%5%5%5%30%
2407
11th to 20thNight
16%12%7%10%7%3445%5%27%
2470
21st to endNight
15%12%8%12%8%5%5%45%5%21%
2626
December1st to 10thNight
17%17%9%12%10%45%5%4412%
2660
11th to 20thNight
19%15%8%13%8%45%44316%
3288
21st to endNight
20%14%6%16%9%4443415%
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
70%8%8%11%3
1518
11th to 20thDay
68%7%7%11%6%1
1520
21st to endDay
63%7%11%11%6%1
1592
February1st to 10thDay
67%8%7%11%6%1
1550
11th to 20thDay
68%5%9%12%5%1
1748
21st to endDay
65%6%8%10%8%2
1480
March1st to 10thDay
64%5%10%13%6%2
1800
11th to 20thDay
60%5%11%11%11%2
1841
21st to endDay
60%5%6%16%10%3
2376
April1st to 10thDay
60%5%8%16%9%2
2160
11th to 20thDay
53%6%9%18%13%1
2134
21st to endDay
58%7%9%15%8%3
2337
May1st to 10thDay
55%5%8%19%11%2
2380
11th to 20thDay
50%6%9%20%13%2
2482
21st to endDay
48%10%12%19%10%1
2725
June1st to 10thDay
55%8%12%16%8%
2520
11th to 20thDay
48%7%11%21%12%1
2520
21st to endDay
55%8%11%18%8%1
2520
July1st to 10thDay
44%9%14%22%11%
2450
11th to 20thDay
46%9%14%24%7%
2445
21st to endDay
47%10%14%21%8%
2591
August1st to 10thDay
46%10%17%21%7%
2481
11th to 20thDay
46%8%17%20%9%
2261
21st to endDay
43%9%14%22%12%1
2376
September1st to 10thDay
40%8%13%27%12%1
2160
11th to 20thDay
40%6%10%28%15%1
2037
21st to endDay
45%9%13%21%10%2
1980
October1st to 10thDay
57%6%10%18%9%
1935
11th to 20thDay
52%9%15%17%7%
1725
21st to endDay
66%6%8%12%6%2
1782
November1st to 10thDay
54%9%12%17%8%
1671
11th to 20thDay
63%7%9%11%7%2
1710
21st to endDay
62%8%13%12%31
1549
December1st to 10thDay
73%7%8%9%3
1520
11th to 20thDay
65%6%9%14%6%
1906
21st to endDay
74%5%7%9%4
2772
January1st to 10thNight
71%9%9%7%3
2649
11th to 20thNight
69%7%9%10%5%
2660
21st to endNight
63%8%10%11%7%1
2798
February1st to 10thNight
68%9%8%9%5%
2408
11th to 20thNight
65%7%8%12%7%
2107
21st to endNight
62%7%9%13%8%1
1776
March1st to 10thNight
62%6%9%14%7%2
2160
11th to 20thNight
59%5%9%16%10%1
2115
21st to endNight
56%5%8%18%11%2
1980
April1st to 10thNight
58%6%9%15%10%2
1800
11th to 20thNight
52%7%9%20%12%
1775
21st to endNight
53%8%9%15%12%3
1621
May1st to 10thNight
53%5%7%19%13%2
1595
11th to 20thNight
47%8%10%19%15%2
1416
21st to endNight
46%9%13%19%12%1
1551
June1st to 10thNight
53%8%10%22%8%1
1440
11th to 20thNight
45%8%14%20%10%2
1440
21st to endNight
47%11%13%20%9%
1440
July1st to 10thNight
42%9%15%20%13%1
1400
11th to 20thNight
38%12%14%27%9%
1392
21st to endNight
39%11%16%24%9%
1486
August1st to 10thNight
37%10%18%27%8%
1422
11th to 20thNight
42%9%16%22%11%
1628
21st to endNight
40%10%14%24%12%
1980
September1st to 10thNight
39%9%14%27%10%1
1800
11th to 20thNight
39%7%12%30%12%1
1922
21st to endNight
43%7%12%24%12%2
1980
October1st to 10thNight
52%7%12%19%10%
2024
11th to 20thNight
54%8%13%19%6%
2234
21st to endNight
62%7%10%12%7%1
2574
November1st to 10thNight
53%9%13%16%8%1
2407
11th to 20thNight
59%6%10%15%7%2
2470
21st to endNight
64%8%10%13%4
2626
December1st to 10thNight
75%7%8%7%2
2660
11th to 20thNight
72%7%7%9%5%
3288
21st to endNight
74%7%6%10%3
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
20%27%33%16%4
180
11th to 20thDay
29%24%31%11%31
180
21st to endDay
19%29%35%12%4
178
February1st to 10thDay
35%34%23%6%1
210
11th to 20thDay
29%24%34%10%3
407
21st to endDay
29%23%31%14%3
346
March1st to 10thDay
29%20%31%17%3
420
11th to 20thDay
27%27%29%14%4
420
21st to endDay
30%21%26%13%8%2
462
April1st to 10thDay
35%17%26%15%5%1
420
11th to 20thDay
28%25%23%15%6%2
412
21st to endDay
34%18%27%12%7%1
420
May1st to 10thDay
31%20%27%13%6%2
423
11th to 20thDay
19%20%34%19%5%2
447
21st to endDay
20%20%32%20%8%1
485
June1st to 10thDay
28%18%31%15%7%1
450
11th to 20thDay
21%16%29%21%10%2
450
21st to endDay
21%19%34%17%8%1
450
July1st to 10thDay
18%13%31%24%12%2
445
11th to 20thDay
14%12%35%26%11%2
444
21st to endDay
17%11%35%25%10%2
488
August1st to 10thDay
15%12%30%28%12%3
446
11th to 20thDay
16%12%30%23%13%6%
439
21st to endDay
16%17%28%23%12%5%
495
September1st to 10thDay
16%15%29%20%16%6%
450
11th to 20thDay
20%13%24%19%16%8%
450
21st to endDay
16%15%29%22%12%6%
450
October1st to 10thDay
28%14%23%18%13%4
450
11th to 20thDay
23%22%25%21%8%1
412
21st to endDay
36%20%22%18%5%
396
November1st to 10thDay
27%18%24%22%8%1
365
11th to 20thDay
28%25%25%14%7%1
370
21st to endDay
33%15%32%18%11
209
December1st to 10thDay
27%22%31%15%4
180
11th to 20thDay
31%27%29%12%2
180
21st to endDay
33%23%30%12%21
198
January1st to 10thNight
22%24%31%19%4
760
11th to 20thNight
25%23%29%20%4
760
21st to endNight
16%22%34%24%41
800
February1st to 10thNight
20%22%35%20%3
720
11th to 20thNight
22%24%31%21%3
703
21st to endNight
21%22%30%23%4
592
March1st to 10thNight
24%18%29%25%3
720
11th to 20thNight
25%20%27%21%7%
720
21st to endNight
25%20%24%22%7%1
792
April1st to 10thNight
28%18%27%22%5%
720
11th to 20thNight
24%18%26%23%8%1
711
21st to endNight
28%15%28%22%6%
541
May1st to 10thNight
27%14%26%23%8%1
515
11th to 20thNight
19%14%30%28%8%2
354
21st to endNight
17%11%23%37%11%1
389
June1st to 10thNight
26%9%25%28%11%1
360
11th to 20thNight
20%7%23%34%15%1
360
21st to endNight
18%9%18%40%14%1
360
July1st to 10thNight
15%5%23%39%16%1
350
11th to 20thNight
11%422%42%20%1
348
21st to endNight
14%5%20%44%16%
394
August1st to 10thNight
14%6%16%42%23%
358
11th to 20thNight
14%8%22%32%21%3
564
21st to endNight
18%6%21%33%21%2
792
September1st to 10thNight
15%9%23%33%18%2
720
11th to 20thNight
18%8%20%29%21%3
720
21st to endNight
19%11%25%25%18%2
720
October1st to 10thNight
27%12%19%26%14%2
720
11th to 20thNight
23%17%21%27%12%1
720
21st to endNight
28%19%24%23%5%
792
November1st to 10thNight
23%20%24%23%9%1
740
11th to 20thNight
24%20%27%19%8%2
760
21st to endNight
27%20%27%19%7%1
760
December1st to 10thNight
27%23%28%19%4
760
11th to 20thNight
27%21%26%21%5%
760
21st to endNight
28%23%26%19%3
836
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Copyright 2024 Attilla Danko


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