Great Neck South High Big Blue Rebel Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Great Neck South High Big Blue Rebel Observatory clear sky chart from 2005-11-06 to 2024-02-15.

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
33%
23252
19%
80233
10%
23160
44%
23160
21%
51107

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
19%
753
24%
4334
8%
737
38%
737
13%
2334
January11th to 20thNight
23%
760
23%
4337
6%
740
38%
740
11%
2501
January21st to endNight
19%
830
14%
4633
8%
814
38%
814
11%
3118
February1st to 10thNight
20%
760
19%
2435
6%
760
36%
760
20%
1582
February11th to 20thNight
16%
722
20%
2155
5%
719
34%
719
19%
1451
February21st to endNight
19%
592
25%
1776
9%
592
39%
592
20%
1160
March1st to 10thNight
23%
720
21%
2160
9%
720
40%
720
25%
1346
March11th to 20thNight
23%
720
20%
2084
9%
720
35%
720
23%
1373
March21st to endNight
24%
792
22%
1984
7%
792
35%
792
25%
1379
April1st to 10thNight
25%
720
19%
1800
6%
720
32%
720
23%
1273
April11th to 20thNight
31%
711
17%
1775
5%
711
37%
711
27%
1250
April21st to endNight
30%
680
19%
1760
6%
680
37%
680
24%
1218
May1st to 10thNight
27%
540
15%
1620
7%
540
34%
540
18%
1154
May11th to 20thNight
30%
418
18%
1480
10%
418
40%
418
17%
988
May21st to endNight
49%
388
14%
1551
15%
388
54%
388
18%
971
June1st to 10thNight
44%
360
17%
1440
17%
360
52%
360
19%
909
June11th to 20thNight
53%
360
15%
1440
16%
360
59%
360
21%
890
June21st to endNight
59%
360
15%
1440
18%
360
65%
360
23%
854
July1st to 10thNight
55%
350
13%
1400
15%
350
58%
350
19%
878
July11th to 20thNight
57%
348
15%
1392
19%
348
60%
348
20%
856
July21st to endNight
58%
394
18%
1486
17%
372
65%
372
24%
859
August1st to 10thNight
57%
471
16%
1535
13%
469
60%
469
27%
945
August11th to 20thNight
56%
710
14%
1774
9%
710
57%
710
28%
1250
August21st to endNight
57%
792
17%
1980
9%
792
59%
792
31%
1340
September1st to 10thNight
49%
720
19%
1800
11%
720
52%
720
29%
1251
September11th to 20thNight
52%
720
25%
1892
16%
720
57%
720
36%
1178
September21st to endNight
45%
720
23%
1980
15%
720
52%
720
27%
1327
October1st to 10thNight
38%
720
16%
2052
11%
720
44%
720
22%
1399
October11th to 20thNight
40%
720
23%
2160
14%
720
51%
720
28%
1315
October21st to endNight
27%
792
19%
2535
9%
792
40%
792
21%
1667
November1st to 10thNight
35%
740
23%
2407
12%
740
51%
740
27%
1425
November11th to 20thNight
28%
760
25%
2470
13%
760
44%
760
23%
1525
November21st to endNight
28%
760
23%
2515
10%
760
44%
760
24%
1506
December1st to 10thNight
22%
760
18%
2660
7%
760
36%
760
17%
1715
December11th to 20thNight
23%
760
19%
3179
6%
759
37%
759
15%
1941
December21st to endNight
20%
829
13%
4812
7%
817
38%
817
11%
2979

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%6%35%5%345%5%7%41%
78236
Night
17%7%35%43445%6%42%
80828
TransparencyDay
41%7%13%22%15%2
77941
Night
42%6%12%22%15%2
80657
SeeingDay
18%11%30%26%12%3
13993
Night
19%10%31%28%10%1
23273

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
16%7%24424346%48%
2517
11th to 20thDay
16%9%35%5%45%45%7%37%
2520
21st to endDay
21%12%5%6%434445%33%
2973
February1st to 10thDay
17%8%35%5%3445%6%40%
1743
11th to 20thDay
15%5%36%5%34446%44%
1788
21st to endDay
21%7%25%5%3445%6%38%
1480
March1st to 10thDay
14%6%36%42445%7%45%
1797
11th to 20thDay
14%6%35%435%5%7%8%39%
1872
21st to endDay
19%8%36%42445%5%40%
2371
April1st to 10thDay
18%7%45%42445%7%40%
2160
11th to 20thDay
17%5%25%435%448%42%
2134
21st to endDay
20%5%24435%46%7%40%
2199
May1st to 10thDay
23%6%35%5%3435%8%36%
2340
11th to 20thDay
19%6%25%5%345%6%9%36%
2428
21st to endDay
16%6%244345%5%9%43%
2725
June1st to 10thDay
16%6%35%5%345%7%9%38%
2520
11th to 20thDay
15%7%35%5%35%6%5%8%38%
2520
21st to endDay
10%5%36%5%35%5%6%9%42%
2520
July1st to 10thDay
11%5%35%6%36%6%6%9%40%
2520
11th to 20thDay
9%5%245%35%6%7%10%43%
2520
21st to endDay
12%5%36%6%46%6%7%8%38%
2744
August1st to 10thDay
10%5%25%5%35%7%8%9%40%
2371
11th to 20thDay
11%6%25%6%45%5%7%8%41%
2126
21st to endDay
12%5%35%5%345%6%9%43%
2376
September1st to 10thDay
14%5%24445%45%8%45%
2160
11th to 20thDay
12%5%2433445%7%50%
2066
21st to endDay
18%5%25%5%245%5%6%42%
1980
October1st to 10thDay
20%7%25%425%45%6%42%
1905
11th to 20thDay
16%5%25%5%345%5%7%45%
1800
21st to endDay
21%5%25%43445%6%41%
1819
November1st to 10thDay
14%6%25%5%2345%5%51%
1671
11th to 20thDay
17%6%24424346%48%
1710
21st to endDay
15%6%25%3345%5%7%45%
1663
December1st to 10thDay
19%7%35%6%24448%39%
1520
11th to 20thDay
22%6%34323336%46%
1906
21st to endDay
18%9%36%7%45%5%6%6%32%
2772
January1st to 10thNight
17%6%2442335%6%47%
4429
11th to 20thNight
17%9%25%434445%43%
4440
21st to endNight
24%10%35%424445%34%
4678
February1st to 10thNight
18%8%25%5%34447%41%
2435
11th to 20thNight
17%7%46%5%34445%41%
2153
21st to endNight
20%7%24433445%42%
1776
March1st to 10thNight
17%6%2442345%8%45%
2150
11th to 20thNight
17%7%35%4345%5%7%41%
2083
21st to endNight
18%8%35%5%24446%41%
1984
April1st to 10thNight
19%6%36%5%25%5%46%38%
1800
11th to 20thNight
19%7%25%435%5%46%40%
1775
21st to endNight
19%6%35%5%23446%41%
1760
May1st to 10thNight
21%7%47%6%34445%35%
1620
11th to 20thNight
19%9%26%43445%6%38%
1479
21st to endNight
17%7%35%5%3445%8%40%
1550
June1st to 10thNight
18%6%24435%5%5%8%40%
1440
11th to 20thNight
14%6%36%5%3446%10%39%
1440
21st to endNight
10%5%25%5%35%5%7%11%41%
1440
July1st to 10thNight
12%6%36%5%45%7%5%9%39%
1440
11th to 20thNight
11%6%25%6%46%6%6%9%40%
1440
21st to endNight
10%5%35%435%6%7%9%43%
1574
August1st to 10thNight
8%6%15%6%35%5%7%8%44%
1545
11th to 20thNight
11%6%36%6%36%7%6%9%37%
1774
21st to endNight
12%6%35%435%47%7%44%
1980
September1st to 10thNight
15%5%26%5%46%5%5%6%42%
1800
11th to 20thNight
13%5%25%423346%52%
1892
21st to endNight
17%5%26%5%3445%7%43%
1980
October1st to 10thNight
20%6%35%5%24445%42%
2052
11th to 20thNight
15%5%25%423446%49%
2160
21st to endNight
22%7%34423445%43%
2535
November1st to 10thNight
13%5%25%433446%50%
2407
11th to 20thNight
20%5%24323345%48%
2470
21st to endNight
15%5%244345%5%7%47%
2515
December1st to 10thNight
21%6%35%5%3445%6%39%
2660
11th to 20thNight
20%6%2443445%6%43%
3288
21st to endNight
20%9%35%435%45%6%37%
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
38%410%31%14%3
2518
11th to 20thDay
44%6%12%23%13%2
2520
21st to endDay
53%7%9%22%9%2
2973
February1st to 10thDay
45%5%13%23%13%1
1743
11th to 20thDay
42%5%10%25%15%3
1797
21st to endDay
47%411%20%15%3
1480
March1st to 10thDay
39%6%14%24%14%3
1800
11th to 20thDay
40%7%13%24%14%2
1872
21st to endDay
46%5%8%19%17%5%
2371
April1st to 10thDay
43%6%11%20%16%4
2160
11th to 20thDay
40%5%13%22%17%3
2134
21st to endDay
42%7%11%20%16%4
2199
May1st to 10thDay
47%7%10%19%15%2
2340
11th to 20thDay
43%8%11%21%14%3
2432
21st to endDay
39%9%17%20%13%2
2725
June1st to 10thDay
41%9%14%21%14%2
2520
11th to 20thDay
42%9%13%23%12%2
2520
21st to endDay
36%10%15%23%15%1
2520
July1st to 10thDay
38%11%14%21%16%1
2450
11th to 20thDay
34%9%17%25%13%2
2445
21st to endDay
39%10%13%20%16%2
2591
August1st to 10thDay
35%11%17%24%13%1
2357
11th to 20thDay
38%10%14%23%14%1
2126
21st to endDay
37%9%12%22%18%2
2376
September1st to 10thDay
37%8%14%21%18%2
2160
11th to 20thDay
32%7%13%23%24%2
2066
21st to endDay
42%6%10%18%20%3
1980
October1st to 10thDay
43%6%12%21%16%2
1905
11th to 20thDay
37%6%13%25%18%2
1800
21st to endDay
43%5%11%22%17%2
1819
November1st to 10thDay
35%6%13%23%21%2
1671
11th to 20thDay
39%5%10%22%21%3
1710
21st to endDay
38%5%15%29%11%2
1663
December1st to 10thDay
45%6%15%19%13%1
1520
11th to 20thDay
42%5%14%23%15%2
1906
21st to endDay
48%9%11%23%8%
2772
January1st to 10thNight
38%5%11%29%12%4
4429
11th to 20thNight
44%5%13%24%13%2
4440
21st to endNight
52%5%9%21%12%2
4678
February1st to 10thNight
44%5%13%23%13%2
2435
11th to 20thNight
45%5%9%19%16%5%
2155
21st to endNight
44%48%24%17%3
1776
March1st to 10thNight
39%413%24%15%5%
2160
11th to 20thNight
42%6%12%21%15%4
2084
21st to endNight
44%5%9%18%18%5%
1984
April1st to 10thNight
45%7%10%19%16%4
1800
11th to 20thNight
44%6%10%18%20%2
1775
21st to endNight
43%7%9%19%17%5%
1760
May1st to 10thNight
51%6%10%18%14%2
1620
11th to 20thNight
47%7%11%16%17%2
1480
21st to endNight
44%7%16%20%12%2
1551
June1st to 10thNight
43%7%9%20%19%1
1440
11th to 20thNight
40%9%14%25%11%1
1440
21st to endNight
35%10%15%24%14%1
1440
July1st to 10thNight
41%10%14%21%14%2
1400
11th to 20thNight
39%10%13%25%12%1
1392
21st to endNight
34%9%17%22%15%3
1486
August1st to 10thNight
35%9%17%23%14%1
1535
11th to 20thNight
40%10%15%23%10%1
1774
21st to endNight
37%9%14%20%18%2
1980
September1st to 10thNight
40%9%11%22%17%2
1800
11th to 20thNight
33%6%12%24%23%3
1892
21st to endNight
41%7%8%21%21%3
1980
October1st to 10thNight
45%7%11%20%14%3
2052
11th to 20thNight
36%5%13%28%16%2
2160
21st to endNight
44%5%11%22%17%1
2535
November1st to 10thNight
36%5%12%22%21%4
2407
11th to 20thNight
40%5%8%23%19%4
2470
21st to endNight
37%6%13%28%15%2
2515
December1st to 10thNight
45%6%13%22%13%2
2660
11th to 20thNight
42%5%13%20%17%3
3288
21st to endNight
46%7%13%23%11%
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%26%29%20%41
180
11th to 20thDay
17%29%36%16%3
180
21st to endDay
19%18%41%15%6%2
256
February1st to 10thDay
25%15%39%18%3
303
11th to 20thDay
22%18%40%19%1
432
21st to endDay
25%19%35%17%3
346
March1st to 10thDay
16%23%37%20%5%
420
11th to 20thDay
17%16%43%18%5%1
420
21st to endDay
24%17%35%18%6%1
462
April1st to 10thDay
22%17%37%16%8%1
420
11th to 20thDay
20%13%33%22%10%1
412
21st to endDay
27%15%34%20%5%1
420
May1st to 10thDay
29%13%30%19%6%1
423
11th to 20thDay
20%9%34%28%7%1
447
21st to endDay
19%425%29%19%3
485
June1st to 10thDay
17%8%29%29%14%3
450
11th to 20thDay
15%9%29%34%11%2
450
21st to endDay
13%5%29%32%18%2
450
July1st to 10thDay
13%221%38%20%5%
445
11th to 20thDay
9%321%37%25%4
444
21st to endDay
13%423%39%19%3
488
August1st to 10thDay
11%322%38%20%7%
446
11th to 20thDay
14%318%38%24%3
439
21st to endDay
12%424%36%16%7%
495
September1st to 10thDay
18%426%26%20%6%
450
11th to 20thDay
15%427%28%16%10%
450
21st to endDay
21%8%26%27%14%5%
450
October1st to 10thDay
24%8%23%25%16%4
450
11th to 20thDay
18%11%29%28%13%2
450
21st to endDay
21%11%36%21%10%1
414
November1st to 10thDay
14%11%31%29%12%3
365
11th to 20thDay
19%19%32%24%6%1
370
21st to endDay
18%14%35%26%7%1
323
December1st to 10thDay
19%18%38%18%7%
180
11th to 20thDay
27%21%34%15%3
180
21st to endDay
24%18%37%12%9%1
198
January1st to 10thNight
19%17%41%20%3
760
11th to 20thNight
23%17%33%23%3
760
21st to endNight
19%16%42%21%3
836
February1st to 10thNight
21%14%39%24%2
760
11th to 20thNight
21%18%41%18%2
722
21st to endNight
23%16%37%20%3
592
March1st to 10thNight
22%13%39%21%5%
720
11th to 20thNight
22%13%39%22%41
720
21st to endNight
21%11%39%24%4
792
April1st to 10thNight
22%14%35%23%5%
720
11th to 20thNight
20%11%35%28%6%
711
21st to endNight
21%9%35%28%5%1
680
May1st to 10thNight
24%9%32%26%9%
540
11th to 20thNight
22%8%34%29%6%
418
21st to endNight
21%417%38%18%2
389
June1st to 10thNight
20%326%34%15%1
360
11th to 20thNight
14%323%44%16%
360
21st to endNight
11%220%51%15%1
360
July1st to 10thNight
12%419%43%20%1
350
11th to 20thNight
14%216%46%20%3
348
21st to endNight
11%321%44%20%1
394
August1st to 10thNight
11%220%44%21%1
471
11th to 20thNight
15%317%37%26%2
710
21st to endNight
14%317%38%25%3
792
September1st to 10thNight
16%423%36%18%3
720
11th to 20thNight
16%422%33%20%5%
720
21st to endNight
20%425%31%18%2
720
October1st to 10thNight
23%9%24%25%17%3
720
11th to 20thNight
17%10%28%33%12%
720
21st to endNight
24%10%34%23%8%1
792
November1st to 10thNight
15%10%35%28%12%1
740
11th to 20thNight
22%13%32%24%8%
760
21st to endNight
16%15%36%27%6%1
760
December1st to 10thNight
25%14%36%19%5%1
760
11th to 20thNight
22%15%35%24%4
760
21st to endNight
23%14%39%22%3
836
Page generated at 2024-02-12 06:35:34. Version ac07

Copyright 2024 Attilla Danko


Great Neck South High Big Blue Rebel Observatory Clear Sky Chart |Charts Home