BREIT IDEAS Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the BREIT IDEAS Observatory clear sky chart from 2005-11-06 to 2024-11-08.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	10% 3 1 3 2 2 2 2 3 5% 66%	105236
	Night	12% 4 1 3 2 2 3 2 4 5% 61%	102589
Transparency	Day	23% 3 7% 18% 24% 26%	104990
	Night	27% 4 8% 17% 21% 23%	102425
Seeing	Day	12% 5% 20% 30% 25% 7%	15154
	Night	13% 3 11% 35% 32% 6%	24388

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	29% 7% 2 4 3 3 2 2 4 6% 36%	2539
	11th to 20th	Day	28% 9% 3 6% 4 4 3 2 3 4 35%	2773
	21st to end	Day	29% 7% 3 5% 3 3 3 2 5% 6% 33%	3146
February	1st to 10th	Day	21% 4 1 5% 2 3 4 3 5% 5% 47%	1710
	11th to 20th	Day	18% 6% 2 5% 3 3 3 3 4 6% 48%	1747
	21st to end	Day	20% 4 1 4 2 4 3 2 6% 6% 48%	1570
March	1st to 10th	Day	24% 11% 3 7% 4 4 3 3 4 5% 32%	3279
	11th to 20th	Day	15% 4 1 3 3 2 3 2 3 6% 57%	3490
	21st to end	Day	19% 9% 2 6% 4 3 4 3 5% 7% 38%	3943
April	1st to 10th	Day	15% 5% 2 5% 4 3 4 3 4 7% 48%	2280
	11th to 20th	Day	12% 4 1 4 3 3 3 3 5% 5% 57%	2249
	21st to end	Day	7% 3 1 4 2 3 3 3 4 7% 63%	2280
May	1st to 10th	Day	7% 2 1 2 2 2 3 2 3 5% 71%	3991
	11th to 20th	Day	3 2 1 2 2 2 1 2 3 4 79%	4377
	21st to end	Day	3 1 1 2 2 2 2 2 3 6% 76%	4813
June	1st to 10th	Day	5% 3 1 3 2 2 4 2 5% 7% 65%	2660
	11th to 20th	Day	1 1 1 2 2 2 2 2 3 5% 79%	2660
	21st to end	Day	2 1 1 1 1 1 2 2 3 86%	2660
July	1st to 10th	Day	1 1 1 1 93%	4420
	11th to 20th	Day	1 1 1 1 1 1 1 1 2 3 86%	4420
	21st to end	Day	1 1 1 1 1 1 2 2 90%	4470
August	1st to 10th	Day	2 1 1 2 1 2 2 2 4 6% 77%	4091
	11th to 20th	Day	1 1 1 1 1 1 2 90%	3846
	21st to end	Day	1 1 1 1 1 1 1 1 2 90%	4180
September	1st to 10th	Day	1 1 1 1 1 1 1 2 3 88%	2280
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 78%	2280
	21st to end	Day	3 1 2 1 1 1 2 2 5% 80%	2036
October	1st to 10th	Day	2 2 1 3 2 2 2 2 3 5% 77%	3180
	11th to 20th	Day	6% 3 1 2 1 2 2 2 4 6% 70%	3161
	21st to end	Day	6% 2 1 3 3 3 4 4 5% 7% 60%	3448
November	1st to 10th	Day	13% 3 1 3 3 3 3 3 5% 8% 55%	1785
	11th to 20th	Day	15% 3 1 4 3 3 4 4 5% 6% 51%	1710
	21st to end	Day	14% 3 2 4 4 2 3 3 4 6% 55%	1520
December	1st to 10th	Day	19% 4 2 3 4 3 2 3 4 5% 50%	1520
	11th to 20th	Day	32% 6% 3 7% 3 3 3 3 4 6% 30%	1928
	21st to end	Day	20% 7% 3 6% 4 4 4 4 5% 8% 36%	2794
January	1st to 10th	Night	19% 8% 2 5% 4 3 3 3 5% 7% 40%	4406
	11th to 20th	Night	27% 6% 2 5% 4 4 3 3 5% 5% 36%	4191
	21st to end	Night	29% 7% 3 6% 4 3 3 3 4 5% 32%	4521
February	1st to 10th	Night	19% 5% 2 3 3 3 2 3 4 7% 49%	2470
	11th to 20th	Night	16% 5% 2 5% 3 4 3 3 5% 6% 49%	2318
	21st to end	Night	18% 5% 2 4 3 3 3 3 4 5% 50%	1884
March	1st to 10th	Night	25% 11% 3 6% 4 3 4 3 4 5% 34%	3591
	11th to 20th	Night	19% 4 1 3 2 1 2 2 3 6% 56%	3490
	21st to end	Night	21% 7% 3 6% 4 4 4 3 6% 5% 37%	3709
April	1st to 10th	Night	10% 7% 2 5% 4 2 4 4 5% 6% 51%	1900
	11th to 20th	Night	11% 4 1 3 3 3 3 3 4 7% 57%	1879
	21st to end	Night	7% 4 1 2 2 2 3 3 4 7% 66%	1900
May	1st to 10th	Night	5% 3 1 4 2 3 2 2 4 6% 69%	2979
	11th to 20th	Night	2 2 1 2 2 2 2 3 3 5% 77%	2516
	21st to end	Night	3 2 1 2 2 2 2 2 3 4 77%	2762
June	1st to 10th	Night	5% 3 1 3 2 3 3 4 6% 8% 64%	1520
	11th to 20th	Night	1 1 1 2 2 2 3 4 6% 78%	1520
	21st to end	Night	2 1 1 2 1 2 2 2 3 3 81%	1520
July	1st to 10th	Night	1 1 1 1 1 1 1 93%	2540
	11th to 20th	Night	1 1 2 2 2 2 2 2 2 84%	2540
	21st to end	Night	1 1 1 1 2 1 2 3 87%	3076
August	1st to 10th	Night	3 2 1 2 2 2 2 2 4 4 76%	2848
	11th to 20th	Night	1 1 1 1 1 2 2 91%	2997
	21st to end	Night	2 1 1 1 1 1 1 1 2 88%	3498
September	1st to 10th	Night	1 1 1 1 1 1 1 1 3 88%	1900
	11th to 20th	Night	3 2 1 3 1 1 2 2 3 5% 77%	1900
	21st to end	Night	3 1 2 1 1 2 2 3 5% 81%	2139
October	1st to 10th	Night	3 1 1 2 2 2 2 2 3 3 79%	3800
	11th to 20th	Night	4 2 1 2 2 2 3 2 4 4 76%	3777
	21st to end	Night	9% 2 1 2 2 3 3 3 5% 7% 64%	4121
November	1st to 10th	Night	14% 4 1 4 2 2 3 3 5% 7% 55%	2454
	11th to 20th	Night	13% 3 1 3 3 3 3 3 6% 7% 55%	2470
	21st to end	Night	13% 4 2 3 3 3 3 2 4 6% 56%	2655
December	1st to 10th	Night	21% 4 1 4 2 2 3 2 5% 7% 49%	2660
	11th to 20th	Night	34% 5% 2 4 2 3 3 3 5% 7% 33%	3276
	21st to end	Night	23% 6% 2 6% 4 4 4 4 4 6% 36%	4862

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	51% 4 7% 27% 8% 3	2539
	11th to 20th	Day	56% 4 7% 15% 10% 9%	2773
	21st to end	Day	52% 5% 10% 15% 12% 5%	3146
February	1st to 10th	Day	39% 3 10% 20% 19% 9%	1710
	11th to 20th	Day	38% 5% 9% 19% 22% 7%	1756
	21st to end	Day	37% 3 10% 25% 18% 7%	1570
March	1st to 10th	Day	54% 7% 8% 15% 13% 4	3279
	11th to 20th	Day	32% 3 8% 26% 19% 12%	3490
	21st to end	Day	45% 7% 12% 22% 12% 3	3943
April	1st to 10th	Day	36% 5% 10% 24% 20% 5%	2280
	11th to 20th	Day	30% 4 12% 23% 24% 8%	2252
	21st to end	Day	21% 5% 12% 30% 25% 7%	2280
May	1st to 10th	Day	16% 3 9% 27% 25% 20%	3991
	11th to 20th	Day	11% 2 6% 24% 39% 18%	4380
	21st to end	Day	12% 3 11% 34% 29% 10%	4814
June	1st to 10th	Day	19% 5% 10% 25% 26% 15%	2660
	11th to 20th	Day	10% 3 7% 20% 32% 28%	2660
	21st to end	Day	7% 2 4 13% 35% 40%	2660
July	1st to 10th	Day	3 1 2 5% 16% 74%	4351
	11th to 20th	Day	6% 1 2 7% 17% 66%	4345
	21st to end	Day	4 1 2 5% 27% 61%	4329
August	1st to 10th	Day	10% 2 3 7% 26% 53%	4076
	11th to 20th	Day	4 1 2 7% 41% 45%	3885
	21st to end	Day	5% 1 2 10% 40% 42%	4179
September	1st to 10th	Day	5% 1 2 7% 27% 58%	2280
	11th to 20th	Day	13% 2 5% 20% 38% 22%	2280
	21st to end	Day	10% 2 5% 19% 31% 33%	2036
October	1st to 10th	Day	12% 2 5% 11% 25% 45%	3180
	11th to 20th	Day	16% 4 4 21% 32% 22%	3161
	21st to end	Day	22% 4 6% 22% 29% 17%	3448
November	1st to 10th	Day	29% 4 8% 25% 19% 15%	1785
	11th to 20th	Day	34% 4 10% 22% 20% 9%	1710
	21st to end	Day	31% 5% 9% 21% 22% 13%	1520
December	1st to 10th	Day	36% 5% 9% 20% 21% 10%	1520
	11th to 20th	Day	57% 3 7% 13% 14% 5%	1928
	21st to end	Day	46% 6% 16% 18% 11% 4	2794
January	1st to 10th	Night	44% 6% 15% 23% 9% 4	4406
	11th to 20th	Night	50% 6% 11% 11% 13% 9%	4191
	21st to end	Night	55% 4 10% 12% 12% 6%	4521
February	1st to 10th	Night	37% 4 8% 20% 19% 12%	2470
	11th to 20th	Night	36% 4 9% 20% 22% 9%	2320
	21st to end	Night	37% 4 8% 23% 20% 9%	1884
March	1st to 10th	Night	52% 7% 10% 13% 13% 5%	3591
	11th to 20th	Night	32% 3 6% 24% 21% 13%	3490
	21st to end	Night	47% 7% 10% 21% 11% 4	3709
April	1st to 10th	Night	33% 6% 12% 21% 20% 8%	1900
	11th to 20th	Night	27% 5% 12% 25% 19% 12%	1879
	21st to end	Night	20% 4 13% 28% 25% 8%	1900
May	1st to 10th	Night	17% 4 12% 18% 28% 20%	2979
	11th to 20th	Night	11% 3 7% 22% 36% 20%	2516
	21st to end	Night	12% 3 10% 35% 28% 12%	2762
June	1st to 10th	Night	18% 6% 12% 25% 26% 12%	1520
	11th to 20th	Night	8% 4 8% 18% 31% 30%	1520
	21st to end	Night	10% 2 3 12% 29% 43%	1520
July	1st to 10th	Night	3 1 1 6% 15% 74%	2500
	11th to 20th	Night	8% 1 3 7% 14% 68%	2492
	21st to end	Night	5% 1 2 6% 25% 60%	2980
August	1st to 10th	Night	14% 1 2 7% 24% 52%	2839
	11th to 20th	Night	4 1 2 8% 35% 50%	3024
	21st to end	Night	7% 1 2 11% 33% 47%	3498
September	1st to 10th	Night	6% 1 2 6% 27% 57%	1900
	11th to 20th	Night	12% 2 5% 17% 39% 25%	1900
	21st to end	Night	9% 2 4 16% 30% 39%	2139
October	1st to 10th	Night	13% 2 4 10% 17% 54%	3800
	11th to 20th	Night	13% 3 5% 24% 30% 24%	3777
	21st to end	Night	21% 3 5% 20% 31% 21%	4121
November	1st to 10th	Night	30% 4 9% 23% 18% 16%	2454
	11th to 20th	Night	28% 5% 12% 25% 20% 11%	2470
	21st to end	Night	32% 4 6% 21% 23% 14%	2655
December	1st to 10th	Night	37% 4 10% 20% 16% 14%	2660
	11th to 20th	Night	52% 4 8% 14% 17% 6%	3276
	21st to end	Night	49% 7% 11% 17% 11% 4	4862

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	47% 3 13% 21% 13% 3	180
	11th to 20th	Day	27% 6% 17% 30% 15% 6%	322
	21st to end	Day	23% 5% 19% 29% 19% 5%	407
February	1st to 10th	Day	24% 6% 17% 29% 20% 3	370
	11th to 20th	Day	24% 9% 25% 24% 16% 2	405
	21st to end	Day	20% 8% 25% 32% 11% 3	382
March	1st to 10th	Day	30% 10% 28% 18% 11% 2	460
	11th to 20th	Day	26% 8% 25% 21% 16% 4	460
	21st to end	Day	23% 10% 28% 25% 14% 1	506
April	1st to 10th	Day	19% 9% 28% 24% 16% 4	460
	11th to 20th	Day	17% 11% 28% 23% 16% 6%	452
	21st to end	Day	7% 10% 25% 32% 20% 6%	460
May	1st to 10th	Day	10% 11% 29% 29% 17% 5%	463
	11th to 20th	Day	8% 9% 22% 30% 24% 7%	488
	21st to end	Day	5% 7% 21% 30% 27% 9%	529
June	1st to 10th	Day	6% 8% 20% 28% 29% 10%	490
	11th to 20th	Day	4 6% 25% 37% 22% 7%	490
	21st to end	Day	2 3 18% 39% 29% 9%	490
July	1st to 10th	Day	2 2 14% 42% 33% 7%	486
	11th to 20th	Day	1 1 13% 39% 39% 8%	484
	21st to end	Day	1 1 11% 39% 38% 10%	531
August	1st to 10th	Day	2 1 14% 39% 33% 10%	487
	11th to 20th	Day	1 1 18% 33% 34% 13%	477
	21st to end	Day	1 2 12% 35% 37% 12%	539
September	1st to 10th	Day	1 2 12% 43% 31% 10%	490
	11th to 20th	Day	5% 4 21% 28% 33% 8%	490
	21st to end	Day	3 5% 22% 30% 33% 8%	490
October	1st to 10th	Day	4 5% 23% 24% 32% 10%	490
	11th to 20th	Day	8% 6% 16% 27% 34% 9%	490
	21st to end	Day	13% 5% 18% 31% 25% 9%	539
November	1st to 10th	Day	19% 3 18% 28% 24% 9%	339
	11th to 20th	Day	14% 2 14% 32% 24% 13%	270
	21st to end	Day	13% 5% 19% 35% 19% 8%	180
December	1st to 10th	Day	29% 3 15% 26% 18% 10%	180
	11th to 20th	Day	27% 4 19% 22% 20% 9%	180
	21st to end	Day	24% 5% 22% 25% 21% 4	198
January	1st to 10th	Night	26% 3 10% 32% 23% 6%	760
	11th to 20th	Night	22% 3 13% 36% 22% 5%	760
	21st to end	Night	22% 2 13% 35% 23% 5%	836
February	1st to 10th	Night	21% 3 12% 38% 23% 3	760
	11th to 20th	Night	19% 4 14% 35% 24% 5%	744
	21st to end	Night	21% 5% 15% 39% 18% 4	628
March	1st to 10th	Night	27% 6% 15% 30% 19% 4	760
	11th to 20th	Night	22% 4 14% 31% 26% 3	760
	21st to end	Night	22% 5% 18% 34% 19% 2	836
April	1st to 10th	Night	14% 5% 17% 40% 22% 2	760
	11th to 20th	Night	13% 5% 16% 37% 23% 6%	751
	21st to end	Night	10% 4 15% 37% 29% 5%	760
May	1st to 10th	Night	9% 4 21% 36% 26% 5%	650
	11th to 20th	Night	6% 3 17% 38% 34% 3	374
	21st to end	Night	7% 3 13% 32% 42% 3	411
June	1st to 10th	Night	6% 3 14% 34% 37% 6%	380
	11th to 20th	Night	2 2 16% 41% 36% 4	380
	21st to end	Night	3 1 12% 38% 41% 5%	380
July	1st to 10th	Night	1 1 5% 38% 51% 5%	370
	11th to 20th	Night	1 6% 40% 50% 4	368
	21st to end	Night	1 2 32% 58% 7%	604
August	1st to 10th	Night	3 1 3 35% 52% 7%	567
	11th to 20th	Night	6% 35% 49% 9%	671
	21st to end	Night	1 1 4 31% 56% 7%	836
September	1st to 10th	Night	2 1 6% 32% 51% 8%	760
	11th to 20th	Night	4 1 7% 34% 43% 11%	760
	21st to end	Night	3 2 11% 36% 38% 11%	760
October	1st to 10th	Night	6% 3 10% 39% 33% 9%	760
	11th to 20th	Night	8% 2 11% 33% 38% 8%	760
	21st to end	Night	10% 2 10% 35% 30% 12%	836
November	1st to 10th	Night	18% 3 10% 31% 30% 8%	770
	11th to 20th	Night	15% 2 10% 39% 29% 5%	760
	21st to end	Night	14% 2 12% 36% 30% 6%	760
December	1st to 10th	Night	23% 2 10% 35% 22% 7%	760
	11th to 20th	Night	29% 2 10% 33% 22% 3	760
	21st to end	Night	26% 3 13% 34% 21% 2	836

Page generated at 2024-11-05 05:15:50. Version ac07

Copyright © 2024 Attilla Danko.