Murillo Family Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Murillo Family Observatory clear sky chart from 2005-11-05 to 2017-09-22.

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
73%
15959
34%
46752
30%
15916
77%
15916
53%
22879

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
61%
717
30%
2327
27%
716
69%
716
41%
1175
January16th to endNight
58%
768
32%
2313
25%
768
67%
768
38%
1274
February1st to 15thNight
62%
698
32%
2107
30%
697
69%
697
44%
1101
February16th to endNight
59%
632
28%
1895
29%
632
63%
632
34%
1106
March1st to 15thNight
63%
720
29%
2160
28%
720
69%
720
43%
1145
March16th to endNight
68%
768
30%
2028
23%
768
73%
768
49%
1112
April1st to 15thNight
61%
719
28%
1799
17%
719
65%
719
46%
1041
April16th to endNight
66%
720
32%
1800
18%
720
69%
720
55%
970
May1st to 15thNight
72%
575
32%
1655
23%
575
74%
575
56%
810
May16th to endNight
72%
561
31%
1685
25%
561
74%
561
55%
800
June1st to 15thNight
82%
540
32%
1620
30%
540
82%
540
66%
702
June16th to endNight
94%
386
41%
1466
47%
386
94%
386
81%
447
July1st to 15thNight
92%
384
35%
1404
39%
384
92%
384
70%
484
July16th to endNight
87%
615
32%
1640
26%
578
88%
578
62%
765
August1st to 15thNight
93%
717
37%
1790
24%
713
93%
713
81%
796
August16th to endNight
94%
764
44%
1910
30%
764
94%
764
82%
852
September1st to 15thNight
90%
720
38%
1857
31%
720
90%
720
71%
869
September16th to endNight
88%
683
46%
1890
43%
683
90%
683
76%
798
October1st to 15thNight
76%
660
38%
1815
34%
660
80%
660
57%
900
October16th to endNight
75%
704
38%
2140
38%
704
79%
704
54%
1005
November1st to 15thNight
76%
700
35%
2275
36%
700
81%
700
55%
997
November16th to endNight
70%
720
36%
2340
38%
720
75%
720
47%
1134
December1st to 15thNight
62%
720
32%
2340
29%
720
69%
720
37%
1239
December16th to endNight
54%
768
32%
2496
28%
768
63%
768
34%
1357

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
4212212236%68%
48116
Night
5%312212235%68%
46951
TransparencyDay
18%27%15%27%29%
47810
Night
19%26%15%26%28%
46758
SeeingDay
7%8%30%36%12%4
5923
Night
6%212%32%35%10%
15971

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
8%312213346%61%
1611
16th to endDay
9%31332335%458%
1908
February1st to 15thDay
8%322312346%61%
1751
16th to endDay
13%6%23313236%51%
1579
March1st to 15thDay
6%31221346%8%60%
1800
16th to endDay
5%31332335%8%58%
2193
April1st to 15thDay
7%423223348%58%
2149
16th to endDay
5%311112236%69%
2160
May1st to 15thDay
4413212236%67%
2293
16th to endDay
4312212336%67%
2429
June1st to 15thDay
33222246%71%
2340
16th to endDay
1111387%
2487
July1st to 15thDay
111213436%73%
2469
16th to endDay
2112213346%70%
2414
August1st to 15thDay
112235%81%
2160
16th to endDay
1111223479%
2292
September1st to 15thDay
11211135%78%
2103
16th to endDay
1121222380%
1882
October1st to 15thDay
5%21231223470%
1815
16th to endDay
431211233372%
1729
November1st to 15thDay
3312214235%69%
1584
16th to endDay
7%212214336%63%
1620
December1st to 15thDay
6%41321325%9%57%
1620
16th to endDay
13%413312335%56%
1728
January1st to 15thNight
8%323322236%61%
2327
16th to endNight
10%424313345%58%
2313
February1st to 15thNight
8%5%13212235%61%
2101
16th to endNight
14%5%23313345%52%
1895
March1st to 15thNight
5%6%23223336%59%
2160
16th to endNight
6%413213347%61%
2028
April1st to 15thNight
8%433313237%57%
1799
16th to endNight
6%412312235%66%
1800
May1st to 15thNight
4313212137%68%
1655
16th to endNight
3412212336%68%
1684
June1st to 15thNight
1311112325%75%
1620
16th to endNight
111290%
1466
July1st to 15thNight
111111135%80%
1488
16th to endNight
3211212236%72%
1752
August1st to 15thNight
111223383%
1800
16th to endNight
11122385%
1910
September1st to 15thNight
11221222378%
1857
16th to endNight
1111112383%
1890
October1st to 15thNight
431221223471%
1815
16th to endNight
43221322371%
2140
November1st to 15thNight
3312113325%71%
2275
16th to endNight
6%43222236%63%
2340
December1st to 15thNight
9%5%12323347%56%
2340
16th to endNight
11%423313345%58%
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
23%36%15%26%23%
1612
16th to endDay
28%37%14%22%24%
1908
February1st to 15thDay
24%35%14%25%25%
1751
16th to endDay
34%45%16%26%13%
1579
March1st to 15thDay
21%310%20%22%22%
1800
16th to endDay
24%410%21%24%15%
2193
April1st to 15thDay
26%48%20%27%13%
2149
16th to endDay
18%29%20%28%19%
2160
May1st to 15thDay
19%28%18%28%21%
2293
16th to endDay
18%29%22%33%14%
2432
June1st to 15thDay
15%16%16%31%28%
2340
16th to endDay
6%146%25%56%
2487
July1st to 15thDay
11%35%9%23%46%
2324
16th to endDay
14%38%19%24%29%
2263
August1st to 15thDay
6%2410%29%46%
2146
16th to endDay
8%25%9%34%38%
2292
September1st to 15thDay
9%25%10%30%41%
2103
16th to endDay
9%1311%32%41%
1882
October1st to 15thDay
19%16%14%29%29%
1815
16th to endDay
17%25%10%22%41%
1729
November1st to 15thDay
18%27%13%27%30%
1584
16th to endDay
22%26%13%23%31%
1620
December1st to 15thDay
23%411%18%20%21%
1620
16th to endDay
29%48%17%22%17%
1728
January1st to 15thNight
25%35%14%25%26%
2327
16th to endNight
29%38%12%18%26%
2313
February1st to 15thNight
25%38%15%22%25%
2112
16th to endNight
33%46%15%24%14%
1895
March1st to 15thNight
25%37%18%24%20%
2160
16th to endNight
22%410%22%24%15%
2028
April1st to 15thNight
27%29%24%21%15%
1799
16th to endNight
20%27%22%28%17%
1800
May1st to 15thNight
18%28%24%27%18%
1656
16th to endNight
17%310%23%31%13%
1685
June1st to 15thNight
12%16%16%31%30%
1620
16th to endNight
4137%25%57%
1466
July1st to 15thNight
8%2410%25%49%
1404
16th to endNight
13%38%17%28%28%
1640
August1st to 15thNight
6%1411%35%40%
1790
16th to endNight
6%1410%35%41%
1910
September1st to 15thNight
11%249%33%38%
1857
16th to endNight
8%1213%32%40%
1890
October1st to 15thNight
18%25%15%33%25%
1815
16th to endNight
18%249%24%41%
2140
November1st to 15thNight
16%26%14%27%32%
2275
16th to endNight
22%25%15%20%32%
2340
December1st to 15thNight
28%47%15%20%23%
2340
16th to endNight
29%48%14%25%18%
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
31%318%37%8%
90
16th to endDay
15%12%30%31%9%1
276
February1st to 15thDay
10%11%37%27%12%1
266
16th to endDay
20%15%28%24%10%
238
March1st to 15thDay
10%14%29%30%11%2
270
16th to endDay
7%13%41%23%11%2
288
April1st to 15thDay
10%21%37%17%9%3
269
16th to endDay
7%24%38%22%42
270
May1st to 15thDay
9%14%34%29%7%3
288
16th to endDay
10%8%40%30%8%3
330
June1st to 15thDay
38%35%37%11%4
315
16th to endDay
1225%46%16%8%
315
July1st to 15thDay
1120%51%18%7%
305
16th to endDay
2114%54%17%9%
327
August1st to 15thDay
1129%46%11%9%
315
16th to endDay
118%53%15%10%
332
September1st to 15thDay
2133%45%13%3
315
16th to endDay
35%29%43%15%2
280
October1st to 15thDay
49%38%35%10%
255
16th to endDay
7%7%28%35%19%
213
November1st to 15thDay
3420%28%28%14%
90
16th to endDay
5%13%31%27%22%
90
December1st to 15thDay
6%5%26%34%24%2
90
16th to endDay
18%5%21%40%13%
96
January1st to 15thNight
9%418%38%21%7%
720
16th to endNight
12%418%34%24%6%
768
February1st to 15thNight
9%316%39%24%6%
704
16th to endNight
16%316%35%21%6%
632
March1st to 15thNight
7%418%38%24%6%
720
16th to endNight
6%316%38%28%5%
768
April1st to 15thNight
8%5%18%37%23%5%
719
16th to endNight
6%5%18%34%27%7%
720
May1st to 15thNight
6%16%36%32%6%
576
16th to endNight
6%115%35%32%7%
563
June1st to 15thNight
310%40%40%4
540
16th to endNight
431%56%6%
386
July1st to 15thNight
2120%61%14%
384
16th to endNight
21223%57%13%
615
August1st to 15thNight
1223%55%17%
717
16th to endNight
115%57%25%
764
September1st to 15thNight
2223%50%21%
720
16th to endNight
25%28%47%16%
683
October1st to 15thNight
7%110%34%35%9%
660
16th to endNight
6%111%31%32%16%
704
November1st to 15thNight
413%35%33%11%
700
16th to endNight
8%113%34%30%11%
720
December1st to 15thNight
12%215%35%26%6%
720
16th to endNight
13%6%20%32%21%4
768
Page generated at 2017-09-23 03:43:41. Version ac04

Copyright 2017 A. Danko


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