Barathrum I Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barathrum I Observatory clear sky chart from 2005-11-05 to 2017-10-31.

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
37%
16193
18%
47404
10%
16147
44%
16147
26%
30851

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
27%
900
14%
2485
6%
895
34%
895
22%
1721
January16th to endNight
22%
960
16%
2496
5%
960
31%
960
19%
1840
February1st to 15thNight
23%
880
13%
2288
4%
876
29%
876
20%
1669
February16th to endNight
28%
723
19%
1985
6%
723
38%
723
25%
1339
March1st to 15thNight
31%
565
19%
2005
12%
565
42%
565
23%
1241
March16th to endNight
24%
576
11%
2103
6%
576
33%
576
15%
1480
April1st to 15thNight
28%
539
16%
1797
12%
539
38%
539
22%
1169
April16th to endNight
32%
540
18%
1722
11%
540
44%
540
22%
1154
May1st to 15thNight
36%
540
17%
1550
11%
540
43%
540
26%
1039
May16th to endNight
44%
562
16%
1497
7%
561
50%
561
28%
1014
June1st to 15thNight
52%
540
14%
1440
6%
540
55%
540
33%
925
June16th to endNight
55%
540
18%
1440
8%
540
58%
540
38%
874
July1st to 15thNight
64%
510
16%
1360
8%
510
66%
510
42%
800
July16th to endNight
73%
564
24%
1504
18%
531
75%
531
48%
804
August1st to 15thNight
66%
539
20%
1610
21%
536
69%
536
36%
938
August16th to endNight
59%
573
21%
1827
22%
573
64%
573
34%
1044
September1st to 15thNight
59%
540
26%
1800
25%
540
66%
540
35%
976
September16th to endNight
48%
585
25%
1983
19%
585
58%
585
34%
1094
October1st to 15thNight
37%
720
23%
2160
15%
720
44%
720
30%
1322
October16th to endNight
33%
768
22%
2304
11%
768
43%
768
26%
1435
November1st to 15thNight
34%
769
24%
2320
13%
769
44%
769
30%
1377
November16th to endNight
26%
900
15%
2520
7%
900
34%
900
25%
1677
December1st to 15thNight
21%
900
12%
2520
3%
900
29%
900
17%
1868
December16th to endNight
21%
960
14%
2688
5%
960
29%
960
15%
2051

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%7%36%5%3445%7%37%
48343
Night
12%7%35%424347%43%
47582
Cloud CoverDay
13%7%35%5%3445%7%37%
48352
Night
12%7%35%424447%43%
47586
TransparencyDay
44%6%13%21%11%1
48038
Night
40%5%13%23%14%1
47405
SeeingDay
15%7%28%28%15%4
6179
Night
16%8%32%30%11%1
16194

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 15thDay
8%10%6%7%7%46%45%7%30%
1450
16th to endDay
13%10%7%9%7%345%6%6%25%
1728
February1st to 15thDay
12%12%5%8%5%35%5%5%7%29%
1575
16th to endDay
13%9%47%5%3446%5%35%
1487
March1st to 15thDay
13%10%47%4345%5%8%33%
1954
16th to endDay
19%12%47%5%25%35%6%29%
2121
April1st to 15thDay
19%8%35%5%24447%33%
2151
16th to endDay
24%9%36%434446%29%
2235
May1st to 15thDay
19%6%35%6%345%47%32%
2400
16th to endDay
16%6%35%5%3446%6%36%
2617
June1st to 15thDay
14%5%25%5%345%6%7%39%
2520
16th to endDay
9%435%435%5%7%9%41%
2520
July1st to 15thDay
7%325%5%35%5%6%8%47%
2520
16th to endDay
7%4235%25%6%6%9%45%
2557
August1st to 15thDay
8%5%25%5%35%5%6%8%42%
2340
16th to endDay
12%5%245%3446%8%42%
2375
September1st to 15thDay
10%5%2341245%7%51%
2160
16th to endDay
12%5%25%424446%47%
1964
October1st to 15thDay
16%7%25%434335%44%
1800
16th to endDay
16%7%25%5%23437%41%
1919
November1st to 15thDay
12%6%3432345%7%46%
1534
16th to endDay
15%10%36%423347%38%
1440
December1st to 15thDay
16%12%37%7%35%346%27%
1440
16th to endDay
17%15%5%8%7%34436%22%
1536
January1st to 15thNight
9%8%37%5%35%45%7%36%
2485
16th to endNight
11%11%5%9%5%33446%33%
2496
February1st to 15thNight
11%12%5%8%5%3345%7%33%
2285
16th to endNight
12%7%36%5%24346%42%
1985
March1st to 15thNight
14%7%25%5%23347%45%
1993
16th to endNight
16%10%47%5%24446%33%
2103
April1st to 15thNight
14%8%36%5%24347%40%
1797
16th to endNight
20%7%25%5%23336%40%
1722
May1st to 15thNight
15%5%2442446%7%41%
1550
16th to endNight
12%5%25%435%45%6%43%
1496
June1st to 15thNight
9%4244245%6%9%45%
1440
16th to endNight
6%32443446%8%50%
1440
July1st to 15thNight
5%113426%45%8%55%
1440
16th to endNight
321332446%11%56%
1608
August1st to 15thNight
6%3244245%6%7%52%
1620
16th to endNight
10%415%322336%54%
1827
September1st to 15thNight
9%414323245%57%
1800
16th to endNight
10%423323347%54%
1983
October1st to 15thNight
13%5%25%423346%48%
2160
16th to endNight
14%7%24423346%46%
2304
November1st to 15thNight
11%5%24323346%50%
2320
16th to endNight
14%9%35%323347%41%
2520
December1st to 15thNight
15%10%48%5%35%446%30%
2520
16th to endNight
18%11%48%6%34245%29%
2688

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
8%11%5%8%7%46%45%7%30%
1450
16th to endDay
13%9%7%9%7%345%5%6%25%
1728
February1st to 15thDay
12%12%5%8%5%35%45%7%29%
1575
16th to endDay
13%9%47%5%2446%6%34%
1487
March1st to 15thDay
13%10%37%5%345%5%7%33%
1965
16th to endDay
19%11%46%5%24446%28%
2119
April1st to 15thDay
19%8%26%5%24447%33%
2151
16th to endDay
24%9%35%5%3435%5%29%
2235
May1st to 15thDay
19%7%35%6%3445%6%32%
2400
16th to endDay
16%6%35%5%3446%6%36%
2617
June1st to 15thDay
14%425%5%25%5%5%8%39%
2520
16th to endDay
9%5%25%435%5%7%9%41%
2520
July1st to 15thDay
7%4245%36%5%5%8%46%
2520
16th to endDay
6%4245%35%6%7%8%45%
2557
August1st to 15thDay
7%5%25%6%35%5%6%8%42%
2340
16th to endDay
12%5%345%3445%8%42%
2375
September1st to 15thDay
10%5%2441245%7%51%
2160
16th to endDay
11%5%24425%446%47%
1964
October1st to 15thDay
16%6%25%5%2433444%
1800
16th to endDay
16%6%35%5%23446%41%
1919
November1st to 15thDay
12%6%34323447%46%
1534
16th to endDay
15%9%36%423347%37%
1440
December1st to 15thDay
17%12%47%7%34446%27%
1440
16th to endDay
17%14%6%9%6%34436%23%
1536
January1st to 15thNight
10%7%47%5%35%46%7%35%
2485
16th to endNight
12%10%5%9%5%33446%33%
2496
February1st to 15thNight
11%11%49%5%2445%7%33%
2278
16th to endNight
12%7%35%5%24446%41%
1985
March1st to 15thNight
14%7%35%5%23346%45%
2005
16th to endNight
16%10%46%5%24436%33%
2103
April1st to 15thNight
14%7%35%5%23347%40%
1797
16th to endNight
20%7%25%5%23345%40%
1722
May1st to 15thNight
15%5%245%2446%7%40%
1549
16th to endNight
11%5%25%5%25%5%5%6%43%
1496
June1st to 15thNight
9%426%3245%6%10%45%
1440
16th to endNight
6%32443445%8%50%
1440
July1st to 15thNight
4213426%45%8%55%
1440
16th to endNight
3213325%46%11%56%
1608
August1st to 15thNight
6%3244245%5%8%51%
1620
16th to endNight
10%415%413346%54%
1827
September1st to 15thNight
9%424332346%56%
1800
16th to endNight
10%5%13323447%54%
1983
October1st to 15thNight
13%5%24423346%48%
2160
16th to endNight
13%7%24324346%46%
2304
November1st to 15thNight
11%6%24423346%50%
2320
16th to endNight
14%9%35%423346%42%
2520
December1st to 15thNight
15%11%47%5%35%45%6%30%
2520
16th to endNight
18%12%48%6%24245%28%
2688

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
51%6%13%16%11%
1451
16th to endDay
57%6%14%14%6%
1728
February1st to 15thDay
52%5%15%19%6%
1576
16th to endDay
47%6%15%18%9%1
1487
March1st to 15thDay
49%6%16%18%8%1
1965
16th to endDay
56%6%12%17%6%
2121
April1st to 15thDay
49%6%11%23%8%
2151
16th to endDay
56%5%10%17%8%
2235
May1st to 15thDay
51%6%12%20%7%
2400
16th to endDay
46%8%13%18%11%2
2621
June1st to 15thDay
41%8%15%21%13%
2520
16th to endDay
36%8%13%24%15%1
2520
July1st to 15thDay
35%8%14%25%13%3
2371
16th to endDay
31%9%17%24%15%2
2398
August1st to 15thDay
37%8%14%25%12%1
2326
16th to endDay
38%7%11%25%14%2
2375
September1st to 15thDay
31%6%13%28%18%1
2160
16th to endDay
36%6%12%29%13%1
1964
October1st to 15thDay
42%49%23%18%1
1800
16th to endDay
43%5%12%25%12%
1919
November1st to 15thDay
36%5%13%25%17%1
1534
16th to endDay
46%5%18%22%6%
1440
December1st to 15thDay
58%5%14%15%5%1
1440
16th to endDay
64%411%12%7%
1536
January1st to 15thNight
45%6%16%18%12%
2485
16th to endNight
51%5%14%19%9%
2496
February1st to 15thNight
50%5%13%19%9%
2288
16th to endNight
43%413%24%12%2
1985
March1st to 15thNight
41%413%26%13%1
2005
16th to endNight
51%6%13%18%7%
2103
April1st to 15thNight
43%5%12%24%11%2
1797
16th to endNight
46%411%21%12%2
1722
May1st to 15thNight
41%7%13%22%13%
1550
16th to endNight
40%7%12%23%14%2
1498
June1st to 15thNight
33%8%17%23%14%2
1440
16th to endNight
30%6%13%26%19%4
1440
July1st to 15thNight
25%8%15%30%16%4
1360
16th to endNight
20%7%18%31%20%2
1504
August1st to 15thNight
28%9%13%32%14%3
1610
16th to endNight
31%5%13%25%18%5%
1827
September1st to 15thNight
30%48%29%25%2
1800
16th to endNight
29%5%11%31%19%1
1983
October1st to 15thNight
36%5%9%24%20%2
2160
16th to endNight
38%5%13%23%16%2
2304
November1st to 15thNight
35%412%25%18%3
2320
16th to endNight
43%415%25%9%1
2520
December1st to 15thNight
53%5%13%18%8%
2520
16th to endNight
57%412%15%8%
2688

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%10%42%21%22
90
16th to endDay
22%7%39%22%5%2
96
February1st to 15thDay
6%27%41%20%4
90
16th to endDay
27%6%34%20%8%2
81
March1st to 15thDay
17%16%43%20%2
90
16th to endDay
36%10%29%20%2
105
April1st to 15thDay
19%11%32%25%10%
270
16th to endDay
30%9%33%15%8%2
345
May1st to 15thDay
21%14%30%21%9%2
468
16th to endDay
17%9%30%28%11%2
517
June1st to 15thDay
12%5%27%32%17%3
495
16th to endDay
9%6%33%30%15%4
495
July1st to 15thDay
7%227%31%19%10%
475
16th to endDay
8%120%37%25%5%
515
August1st to 15thDay
10%121%35%24%5%
493
16th to endDay
17%218%31%22%7%
415
September1st to 15thDay
10%222%32%23%8%
315
16th to endDay
10%7%31%31%15%2
179
October1st to 15thDay
18%10%31%26%10%2
135
16th to endDay
18%13%33%25%8%
144
November1st to 15thDay
5%6%35%33%13%5%
90
16th to endDay
36%13%32%15%2
90
December1st to 15thDay
24%22%30%16%6%
90
16th to endDay
30%15%40%10%3
96
January1st to 15thNight
14%12%37%27%7%
900
16th to endNight
17%11%39%27%4
960
February1st to 15thNight
18%10%37%25%7%
880
16th to endNight
16%11%38%25%7%
723
March1st to 15thNight
19%9%34%24%10%1
565
16th to endNight
19%10%37%23%6%1
576
April1st to 15thNight
17%12%35%27%6%
539
16th to endNight
24%7%31%27%8%1
540
May1st to 15thNight
18%7%34%31%7%
540
16th to endNight
14%6%28%37%13%
563
June1st to 15thNight
11%427%41%14%
540
16th to endNight
7%330%44%14%
540
July1st to 15thNight
6%120%43%25%2
510
16th to endNight
317%49%26%2
564
August1st to 15thNight
6%117%43%28%2
539
16th to endNight
12%218%36%26%4
573
September1st to 15thNight
12%220%37%23%4
540
16th to endNight
12%5%29%31%19%
585
October1st to 15thNight
17%6%35%26%12%1
720
16th to endNight
19%9%33%27%9%
768
November1st to 15thNight
15%9%37%28%8%
769
16th to endNight
18%13%37%22%8%
900
December1st to 15thNight
21%13%36%23%4
900
16th to endNight
25%9%33%25%6%
960
Page generated at 2017-11-01 16:23:36. Version ac04

Copyright 2017 A. Danko


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