Abraas Stargate Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Abraas Stargate Observatory clear sky chart from 2005-11-05 to 2018-01-12.

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
46%
16406
30%
48375
14%
16361
60%
16361
46%
24888

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
33%
953
32%
2659
10%
948
53%
948
53%
1297
January16th to endNight
25%
768
36%
2496
14%
768
51%
768
51%
1118
February1st to 15thNight
23%
701
28%
2231
7%
698
45%
698
41%
1139
February16th to endNight
23%
632
38%
1894
9%
632
53%
632
49%
932
March1st to 15thNight
35%
720
30%
2101
12%
720
52%
720
51%
1045
March16th to endNight
40%
685
32%
2029
15%
685
56%
685
46%
1018
April1st to 15thNight
36%
539
26%
1798
12%
539
55%
539
40%
873
April16th to endNight
39%
540
25%
1800
14%
540
56%
540
34%
982
May1st to 15thNight
49%
539
22%
1674
15%
539
59%
539
32%
984
May16th to endNight
52%
562
21%
1498
11%
561
61%
561
39%
868
June1st to 15thNight
61%
540
24%
1440
15%
540
67%
540
54%
742
June16th to endNight
69%
540
24%
1440
19%
540
73%
540
51%
769
July1st to 15thNight
70%
510
17%
1360
14%
510
72%
510
35%
847
July16th to endNight
79%
564
17%
1491
16%
531
79%
531
34%
904
August1st to 15thNight
72%
539
16%
1689
15%
536
74%
536
32%
981
August16th to endNight
77%
573
24%
1910
26%
573
78%
573
37%
1033
September1st to 15thNight
67%
540
27%
1800
24%
540
74%
540
36%
976
September16th to endNight
67%
537
37%
1929
32%
537
77%
537
48%
859
October1st to 15thNight
53%
711
32%
2151
19%
711
63%
711
48%
1088
October16th to endNight
49%
773
39%
2309
19%
773
63%
773
54%
1091
November1st to 15thNight
44%
950
36%
2470
15%
950
56%
950
59%
1224
November16th to endNight
38%
975
41%
2564
13%
975
58%
975
62%
1238
December1st to 15thNight
30%
975
28%
2730
7%
975
49%
975
50%
1390
December16th to endNight
28%
1040
33%
2912
9%
1040
49%
1040
48%
1490

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
431332446%8%58%
48974
Night
4313213347%62%
48554
Cloud CoverDay
431332446%8%58%
48972
Night
4313213347%62%
48554
TransparencyDay
22%5%12%24%24%9%
48656
Night
21%5%13%27%24%8%
48375
SeeingDay
7%9%33%31%15%2
6139
Night
5%5%37%36%13%
16411

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
1323322236%69%
1535
16th to endDay
2413312327%68%
1728
February1st to 15thDay
25%2331335%6%62%
1630
16th to endDay
1423312446%64%
1580
March1st to 15thDay
231332335%8%60%
1857
16th to endDay
45%2232346%9%55%
2194
April1st to 15thDay
431332346%9%56%
2150
16th to endDay
9%5%1333445%6%50%
2160
May1st to 15thDay
8%4145%346%7%8%46%
2275
16th to endDay
7%21332446%8%53%
2616
June1st to 15thDay
5%123236%8%9%55%
2520
16th to endDay
2112325%6%5%8%60%
2520
July1st to 15thDay
6%212435%6%7%9%48%
2520
16th to endDay
32145%46%6%10%11%43%
2573
August1st to 15thDay
4213435%6%8%11%46%
2262
16th to endDay
42134346%7%9%54%
2292
September1st to 15thDay
6%3124236%7%7%54%
2160
16th to endDay
6%112313335%67%
2029
October1st to 15thDay
5%212212447%65%
1807
16th to endDay
3312112245%70%
1902
November1st to 15thDay
132112347%70%
1718
16th to endDay
1212112247%72%
1722
December1st to 15thDay
1422212246%67%
1560
16th to endDay
233221235%9%62%
1664
January1st to 15thNight
2313212247%69%
2659
16th to endNight
2322212335%71%
2496
February1st to 15thNight
26%24212347%62%
2221
16th to endNight
25%2323336%67%
1894
March1st to 15thNight
3412212346%66%
2101
16th to endNight
45%22212236%66%
2029
April1st to 15thNight
45%13212346%63%
1798
16th to endNight
10%6%22312347%55%
1800
May1st to 15thNight
12%422314447%50%
1673
16th to endNight
9%31231347%7%55%
1497
June1st to 15thNight
5%1122235%8%66%
1440
16th to endNight
3212325%36%8%62%
1440
July1st to 15thNight
8%2143446%8%9%47%
1440
16th to endNight
4213426%6%9%12%45%
1593
August1st to 15thNight
31145%36%5%7%9%51%
1698
16th to endNight
5%2133246%8%10%51%
1910
September1st to 15thNight
8%3133145%6%9%52%
1800
16th to endNight
6%211213345%67%
1929
October1st to 15thNight
5%32112345%66%
2151
16th to endNight
4312212336%68%
2309
November1st to 15thNight
1312212247%70%
2470
16th to endNight
231212137%72%
2564
December1st to 15thNight
324312347%65%
2730
16th to endNight
15%23212248%64%
2912

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
1323212237%68%
1535
16th to endDay
2313312236%68%
1728
February1st to 15thDay
15%2331335%7%61%
1630
16th to endDay
1423321447%64%
1580
March1st to 15thDay
231432335%9%60%
1857
16th to endDay
35%2322346%10%55%
2192
April1st to 15thDay
431332346%9%56%
2150
16th to endDay
8%6%13335%45%7%50%
2160
May1st to 15thDay
8%4245%346%7%8%45%
2275
16th to endDay
6%223325%5%6%8%53%
2616
June1st to 15thDay
4133236%7%10%54%
2520
16th to endDay
2112225%6%6%8%60%
2520
July1st to 15thDay
6%2125%36%6%7%10%48%
2520
16th to endDay
32145%47%6%9%11%43%
2573
August1st to 15thDay
4213436%6%8%11%46%
2262
16th to endDay
4213425%5%7%9%53%
2292
September1st to 15thDay
5%3133246%7%7%53%
2160
16th to endDay
6%112323335%67%
2029
October1st to 15thDay
422312347%65%
1807
16th to endDay
3312112245%69%
1902
November1st to 15thDay
1311212347%70%
1718
16th to endDay
1311112246%72%
1722
December1st to 15thDay
1413312346%67%
1560
16th to endDay
233321335%9%62%
1664
January1st to 15thNight
1313212246%69%
2659
16th to endNight
2313212335%71%
2496
February1st to 15thNight
26%34212347%62%
2221
16th to endNight
25%23213246%67%
1894
March1st to 15thNight
35%12212337%66%
2101
16th to endNight
35%22212236%66%
2029
April1st to 15thNight
45%13213247%63%
1798
16th to endNight
10%6%13322347%55%
1800
May1st to 15thNight
12%5%22314447%50%
1673
16th to endNight
8%4123135%6%8%55%
1497
June1st to 15thNight
41121235%8%66%
1440
16th to endNight
221232436%8%62%
1440
July1st to 15thNight
8%215%3446%7%9%47%
1440
16th to endNight
3223425%6%9%12%45%
1593
August1st to 15thNight
31235%35%5%7%9%51%
1698
16th to endNight
5%2133346%8%10%50%
1910
September1st to 15thNight
8%3133145%6%9%52%
1800
16th to endNight
6%211213345%67%
1929
October1st to 15thNight
4312113346%66%
2151
16th to endNight
4312212336%68%
2309
November1st to 15thNight
1212112338%70%
2470
16th to endNight
231122137%72%
2564
December1st to 15thNight
324312347%65%
2730
16th to endNight
15%23212348%64%
2912

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
18%210%35%26%5%
1536
16th to endDay
18%38%32%28%8%
1728
February1st to 15thDay
22%313%33%21%6%
1631
16th to endDay
20%28%27%32%8%
1580
March1st to 15thDay
20%310%26%29%9%
1857
16th to endDay
24%5%12%23%25%8%
2194
April1st to 15thDay
22%5%12%25%24%10%
2150
16th to endDay
32%5%11%22%20%7%
2160
May1st to 15thDay
32%8%15%19%19%4
2275
16th to endDay
26%8%16%21%17%9%
2620
June1st to 15thDay
21%7%15%19%19%16%
2520
16th to endDay
18%5%10%20%26%17%
2520
July1st to 15thDay
28%7%15%20%16%10%
2371
16th to endDay
29%9%18%24%14%3
2413
August1st to 15thDay
28%9%17%19%15%9%
2247
16th to endDay
23%6%15%23%24%6%
2292
September1st to 15thDay
25%6%12%24%19%11%
2160
16th to endDay
20%37%22%33%13%
2029
October1st to 15thDay
18%410%20%33%13%
1807
16th to endDay
17%27%25%33%13%
1902
November1st to 15thDay
13%38%26%33%13%
1718
16th to endDay
13%36%28%33%14%
1722
December1st to 15thDay
18%313%31%25%7%
1560
16th to endDay
19%316%30%23%6%
1664
January1st to 15thNight
17%312%34%28%4
2659
16th to endNight
16%311%33%28%6%
2496
February1st to 15thNight
24%411%36%20%3
2231
16th to endNight
19%37%31%29%8%
1894
March1st to 15thNight
19%311%29%30%6%
2101
16th to endNight
20%411%26%31%5%
2029
April1st to 15thNight
21%5%11%28%23%9%
1798
16th to endNight
30%413%23%21%7%
1800
May1st to 15thNight
32%6%14%21%20%5%
1674
16th to endNight
25%8%18%19%17%10%
1498
June1st to 15thNight
15%7%17%25%16%17%
1440
16th to endNight
19%6%13%21%20%18%
1440
July1st to 15thNight
30%9%16%21%14%7%
1360
16th to endNight
26%13%22%23%12%2
1491
August1st to 15thNight
26%12%20%21%11%7%
1689
16th to endNight
24%9%17%26%17%4
1910
September1st to 15thNight
26%7%15%25%16%8%
1800
16th to endNight
18%39%25%31%9%
1929
October1st to 15thNight
18%6%11%20%29%12%
2151
16th to endNight
18%29%23%32%12%
2309
November1st to 15thNight
15%29%28%31%12%
2470
16th to endNight
14%27%32%32%10%
2564
December1st to 15thNight
18%414%32%23%5%
2730
16th to endNight
19%416%29%23%5%
2912

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
9%6%37%36%8%1
123
16th to endDay
6%353%27%10%
96
February1st to 15thDay
6%12%51%27%11
90
16th to endDay
118%38%32%9%
81
March1st to 15thDay
418%44%27%4
147
16th to endDay
9%30%37%19%2
288
April1st to 15thDay
9%25%38%18%6%
269
16th to endDay
17%21%40%15%3
270
May1st to 15thDay
10%10%37%30%9%1
387
16th to endDay
12%7%33%31%12%1
517
June1st to 15thDay
5%8%31%33%18%2
495
16th to endDay
35%28%40%19%2
495
July1st to 15thDay
9%222%35%25%5%
475
16th to endDay
4116%40%29%6%
432
August1st to 15thDay
7%425%36%19%6%
315
16th to endDay
7%131%34%19%4
332
September1st to 15thDay
6%5%34%35%14%2
315
16th to endDay
12%6%32%28%16%3
184
October1st to 15thDay
7%8%31%31%17%2
135
16th to endDay
6%9%26%34%18%4
144
November1st to 15thDay
3434%31%22%3
135
16th to endDay
313%48%26%8%
135
December1st to 15thDay
5%8%57%23%5%
135
16th to endDay
210%52%28%41
144
January1st to 15thNight
37%50%29%8%
953
16th to endNight
25%60%24%5%
768
February1st to 15thNight
46%58%27%2
704
16th to endNight
5%7%60%22%3
632
March1st to 15thNight
5%5%49%32%7%
720
16th to endNight
6%8%40%38%5%
685
April1st to 15thNight
6%8%42%34%6%
539
16th to endNight
14%7%35%34%7%
540
May1st to 15thNight
13%427%41%12%
540
16th to endNight
10%427%41%16%
563
June1st to 15thNight
6%225%47%16%1
540
16th to endNight
418%50%24%
540
July1st to 15thNight
9%19%42%34%2
510
16th to endNight
45%42%43%3
564
August1st to 15thNight
5%10%44%38%
539
16th to endNight
5%19%46%35%1
573
September1st to 15thNight
10%14%43%28%2
540
16th to endNight
7%219%45%22%2
537
October1st to 15thNight
6%332%42%13%1
711
16th to endNight
5%437%37%14%1
773
November1st to 15thNight
26%43%36%10%
950
16th to endNight
45%48%36%5%
975
December1st to 15thNight
26%55%30%4
975
16th to endNight
47%54%27%5%
1040
Page generated at 2018-01-12 20:01:26. Version ac04

Copyright 2018 A. Danko


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