The Dead Gekko Society Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the The Dead Gekko Society Observatory clear sky chart from 2005-11-06 to 2024-01-14.

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	12% 7% 3 5% 5% 3 4 5% 5% 7% 44%	74478
	Night	12% 7% 3 5% 4 2 4 4 5% 7% 49%	75255
Transparency	Day	39% 6% 11% 24% 17% 3	74201
	Night	35% 5% 10% 25% 20% 4	75052
Seeing	Day	14% 11% 25% 27% 18% 5%	14324
	Night	15% 10% 28% 30% 15% 1	24282

By Month

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 9% 3 5% 5% 2 3 3 3 7% 47%	1707
	11th to 20th	Day	13% 10% 4 5% 3 3 4 4 4 5% 46%	1647
	21st to end	Day	14% 9% 3 6% 4 2 3 4 4 5% 47%	1782
February	1st to 10th	Day	16% 11% 3 6% 5% 2 4 4 4 5% 40%	1620
	11th to 20th	Day	13% 8% 4 7% 5% 2 5% 3 4 6% 43%	1583
	21st to end	Day	17% 10% 4 6% 5% 2 3 4 4 5% 40%	1594
March	1st to 10th	Day	13% 9% 4 6% 4 3 3 4 5% 6% 44%	1980
	11th to 20th	Day	19% 9% 3 6% 4 2 4 4 5% 4 39%	1980
	21st to end	Day	18% 8% 3 7% 7% 4 4 4 4 6% 35%	2178
April	1st to 10th	Day	11% 7% 2 5% 6% 3 4 5% 5% 7% 45%	2103
	11th to 20th	Day	18% 8% 2 5% 5% 3 5% 5% 4 6% 39%	2134
	21st to end	Day	18% 8% 4 7% 6% 3 4 3 3 4 39%	2160
May	1st to 10th	Day	17% 7% 4 7% 5% 4 4 5% 5% 6% 38%	2308
	11th to 20th	Day	14% 6% 3 5% 6% 3 6% 5% 5% 7% 40%	2302
	21st to end	Day	10% 5% 3 6% 7% 4 6% 6% 6% 9% 37%	2531
June	1st to 10th	Day	8% 5% 2 5% 5% 3 5% 6% 7% 10% 44%	2370
	11th to 20th	Day	6% 4 2 5% 5% 3 6% 7% 6% 10% 45%	2451
	21st to end	Day	4 3 2 4 5% 3 5% 6% 6% 9% 53%	2340
July	1st to 10th	Day	9% 4 3 6% 6% 4 5% 6% 8% 10% 39%	2340
	11th to 20th	Day	5% 3 1 4 5% 4 6% 5% 8% 11% 48%	2340
	21st to end	Day	7% 4 2 5% 5% 3 6% 6% 7% 11% 43%	2546
August	1st to 10th	Day	7% 5% 3 5% 5% 4 5% 7% 7% 9% 42%	2328
	11th to 20th	Day	9% 5% 2 5% 6% 3 5% 6% 7% 7% 46%	2253
	21st to end	Day	6% 5% 2 4 5% 4 5% 5% 5% 8% 50%	2376
September	1st to 10th	Day	11% 5% 2 4 5% 3 4 4 5% 7% 49%	2160
	11th to 20th	Day	11% 6% 2 6% 5% 3 5% 4 5% 7% 47%	2054
	21st to end	Day	8% 4 2 4 5% 3 4 4 5% 7% 55%	1931
October	1st to 10th	Day	9% 5% 2 4 4 3 4 5% 4 7% 53%	1800
	11th to 20th	Day	14% 5% 2 4 4 2 3 3 3 5% 56%	1800
	21st to end	Day	18% 7% 2 4 5% 2 3 2 3 4 49%	1980
November	1st to 10th	Day	11% 6% 2 4 4 2 3 3 4 6% 57%	1858
	11th to 20th	Day	11% 7% 3 5% 4 3 3 4 4 6% 51%	1873
	21st to end	Day	16% 7% 3 5% 3 2 3 3 4 6% 48%	1520
December	1st to 10th	Day	14% 7% 3 6% 5% 2 4 3 5% 7% 46%	1520
	11th to 20th	Day	13% 12% 2 6% 6% 3 4 3 3 4 43%	1918
	21st to end	Day	13% 18% 6% 6% 5% 2 5% 4 4 6% 31%	3111
January	1st to 10th	Night	13% 7% 3 5% 5% 3 3 3 5% 6% 46%	2458
	11th to 20th	Night	13% 8% 3 5% 3 2 3 3 4 6% 49%	2392
	21st to end	Night	13% 8% 3 5% 4 2 3 4 4 5% 50%	2574
February	1st to 10th	Night	14% 11% 3 5% 4 2 4 3 4 7% 42%	2340
	11th to 20th	Night	15% 8% 3 7% 4 2 3 3 3 5% 47%	2262
	21st to end	Night	16% 8% 3 5% 4 2 4 3 4 5% 44%	1678
March	1st to 10th	Night	13% 9% 3 5% 5% 2 3 4 5% 5% 45%	1980
	11th to 20th	Night	17% 10% 3 4 5% 3 4 4 4 6% 41%	1980
	21st to end	Night	17% 10% 4 6% 5% 2 4 4 5% 5% 39%	2178
April	1st to 10th	Night	11% 5% 2 4 4 3 4 4 4 7% 51%	1855
	11th to 20th	Night	13% 7% 2 5% 4 2 3 4 5% 7% 47%	1775
	21st to end	Night	19% 5% 2 5% 5% 3 3 4 5% 7% 42%	1800
May	1st to 10th	Night	12% 6% 3 4 5% 3 4 4 6% 6% 47%	1648
	11th to 20th	Night	13% 6% 2 4 3 3 3 4 5% 7% 49%	1593
	21st to end	Night	9% 5% 3 5% 5% 3 6% 5% 7% 10% 43%	1745
June	1st to 10th	Night	7% 3 1 3 3 2 4 4 6% 10% 56%	1569
	11th to 20th	Night	4 3 1 3 3 3 5% 5% 6% 11% 56%	1486
	21st to end	Night	2 2 1 3 4 3 4 4 7% 8% 63%	1620
July	1st to 10th	Night	4 3 2 5% 6% 3 5% 5% 6% 10% 51%	1620
	11th to 20th	Night	3 2 2 2 4 2 4 5% 5% 9% 61%	1620
	21st to end	Night	5% 3 2 5% 4 4 5% 4 6% 9% 53%	1772
August	1st to 10th	Night	5% 3 1 4 5% 3 5% 6% 8% 12% 49%	1611
	11th to 20th	Night	6% 4 1 3 4 3 5% 5% 6% 10% 51%	1645
	21st to end	Night	4 3 2 4 5% 3 5% 4 6% 9% 55%	1980
September	1st to 10th	Night	9% 4 1 3 3 2 4 4 5% 8% 57%	1800
	11th to 20th	Night	11% 4 2 4 5% 3 3 4 5% 6% 53%	1901
	21st to end	Night	7% 4 2 4 4 2 3 4 5% 7% 59%	2009
October	1st to 10th	Night	7% 4 2 3 3 2 3 4 5% 8% 60%	2160
	11th to 20th	Night	14% 5% 2 4 3 2 3 3 5% 5% 56%	2160
	21st to end	Night	16% 7% 2 4 4 2 3 3 3 4 52%	2376
November	1st to 10th	Night	11% 4 2 4 3 2 3 3 3 5% 60%	2220
	11th to 20th	Night	12% 6% 2 4 3 2 3 4 4 6% 55%	2299
	21st to end	Night	16% 7% 2 4 4 2 3 3 4 5% 49%	2660
December	1st to 10th	Night	14% 9% 3 5% 4 2 3 3 4 6% 47%	2660
	11th to 20th	Night	14% 10% 4 7% 4 3 4 3 4 5% 44%	3279
	21st to end	Night	15% 15% 5% 7% 5% 3 4 3 4 4 34%	4550

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	40% 2 9% 25% 20% 4	1708
	11th to 20th	Day	42% 4 9% 25% 19% 1	1647
	21st to end	Day	40% 3 11% 27% 15% 4	1782
February	1st to 10th	Day	48% 4 9% 23% 12% 3	1620
	11th to 20th	Day	45% 5% 9% 22% 16% 3	1592
	21st to end	Day	47% 4 7% 19% 14% 8%	1594
March	1st to 10th	Day	42% 4 8% 18% 20% 7%	1980
	11th to 20th	Day	48% 6% 7% 22% 14% 5%	1980
	21st to end	Day	51% 5% 10% 21% 12% 1	2178
April	1st to 10th	Day	39% 5% 11% 24% 18% 2	2103
	11th to 20th	Day	46% 6% 11% 18% 16% 3	2134
	21st to end	Day	50% 4 9% 23% 14% 1	2160
May	1st to 10th	Day	47% 6% 11% 21% 15% 1	2308
	11th to 20th	Day	42% 7% 12% 24% 13% 1	2306
	21st to end	Day	42% 9% 14% 23% 12% 1	2531
June	1st to 10th	Day	34% 9% 15% 27% 14% 1	2370
	11th to 20th	Day	32% 9% 15% 28% 15% 2	2451
	21st to end	Day	26% 8% 16% 29% 18% 4	2340
July	1st to 10th	Day	37% 9% 16% 22% 14% 2	2276
	11th to 20th	Day	26% 8% 15% 30% 18% 2	2271
	21st to end	Day	33% 9% 16% 30% 11%	2405
August	1st to 10th	Day	33% 10% 17% 25% 13% 1	2314
	11th to 20th	Day	34% 8% 12% 27% 17% 1	2253
	21st to end	Day	31% 7% 13% 25% 19% 6%	2376
September	1st to 10th	Day	34% 6% 10% 26% 17% 8%	2160
	11th to 20th	Day	35% 6% 10% 22% 24% 3	2054
	21st to end	Day	28% 6% 9% 27% 26% 4	1931
October	1st to 10th	Day	30% 6% 10% 25% 23% 5%	1800
	11th to 20th	Day	32% 3 7% 23% 26% 7%	1800
	21st to end	Day	41% 4 6% 26% 18% 6%	1980
November	1st to 10th	Day	30% 4 9% 27% 23% 7%	1858
	11th to 20th	Day	36% 3 7% 22% 23% 9%	1873
	21st to end	Day	40% 3 9% 19% 25% 3	1520
December	1st to 10th	Day	40% 4 8% 27% 18% 2	1520
	11th to 20th	Day	46% 3 6% 17% 24% 3	1915
	21st to end	Day	54% 6% 8% 17% 13% 2	3111
January	1st to 10th	Night	39% 4 10% 23% 21% 4	2458
	11th to 20th	Night	39% 3 10% 27% 19% 2	2392
	21st to end	Night	37% 3 10% 26% 20% 4	2574
February	1st to 10th	Night	44% 4 11% 22% 15% 3	2340
	11th to 20th	Night	43% 3 8% 25% 18% 3	2263
	21st to end	Night	43% 4 8% 19% 19% 6%	1678
March	1st to 10th	Night	41% 5% 7% 18% 21% 9%	1980
	11th to 20th	Night	47% 4 8% 20% 18% 3	1980
	21st to end	Night	47% 6% 8% 23% 14% 2	2178
April	1st to 10th	Night	34% 4 10% 26% 21% 5%	1855
	11th to 20th	Night	36% 5% 9% 25% 20% 5%	1775
	21st to end	Night	43% 5% 10% 24% 16% 2	1800
May	1st to 10th	Night	36% 7% 12% 25% 17% 2	1648
	11th to 20th	Night	34% 8% 15% 24% 17% 2	1594
	21st to end	Night	36% 8% 16% 26% 12% 1	1746
June	1st to 10th	Night	22% 9% 16% 33% 18% 3	1569
	11th to 20th	Night	21% 8% 15% 34% 20% 3	1486
	21st to end	Night	19% 7% 15% 31% 23% 6%	1620
July	1st to 10th	Night	26% 8% 18% 28% 18% 2	1575
	11th to 20th	Night	18% 7% 15% 30% 26% 3	1566
	21st to end	Night	26% 7% 13% 36% 18%	1673
August	1st to 10th	Night	26% 7% 17% 34% 15%	1601
	11th to 20th	Night	26% 9% 13% 27% 22% 3	1645
	21st to end	Night	25% 7% 14% 26% 24% 5%	1980
September	1st to 10th	Night	26% 5% 12% 30% 19% 8%	1800
	11th to 20th	Night	32% 5% 9% 22% 25% 6%	1901
	21st to end	Night	26% 5% 9% 25% 30% 5%	2009
October	1st to 10th	Night	23% 6% 12% 26% 26% 8%	2160
	11th to 20th	Night	31% 4 7% 22% 27% 9%	2160
	21st to end	Night	38% 4 7% 22% 21% 8%	2376
November	1st to 10th	Night	28% 4 9% 25% 26% 8%	2220
	11th to 20th	Night	32% 4 8% 24% 26% 7%	2299
	21st to end	Night	38% 4 7% 21% 25% 4	2660
December	1st to 10th	Night	40% 4 11% 22% 20% 3	2660
	11th to 20th	Night	44% 4 6% 21% 21% 3	3281
	21st to end	Night	54% 4 8% 18% 12% 3	4550

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	23% 17% 34% 21% 4	270
	11th to 20th	Day	28% 20% 35% 15% 2	249
	21st to end	Day	17% 25% 38% 15% 5%	264
February	1st to 10th	Day	21% 25% 40% 13% 2	240
	11th to 20th	Day	22% 30% 31% 15% 3	240
	21st to end	Day	34% 24% 30% 11% 2	198
March	1st to 10th	Day	21% 26% 33% 17% 3	240
	11th to 20th	Day	30% 18% 31% 20% 2	240
	21st to end	Day	26% 23% 41% 8% 3	264
April	1st to 10th	Day	16% 23% 36% 16% 8% 1	363
	11th to 20th	Day	22% 19% 33% 18% 6%	412
	21st to end	Day	24% 19% 29% 22% 6% 1	420
May	1st to 10th	Day	19% 15% 35% 23% 8%	571
	11th to 20th	Day	16% 11% 30% 27% 14% 2	625
	21st to end	Day	11% 6% 36% 25% 16% 6%	679
June	1st to 10th	Day	10% 3 17% 35% 28% 7%	630
	11th to 20th	Day	8% 3 19% 39% 24% 6%	630
	21st to end	Day	4 3 27% 37% 25% 5%	630
July	1st to 10th	Day	7% 3 15% 30% 33% 11%	621
	11th to 20th	Day	5% 2 16% 35% 32% 11%	618
	21st to end	Day	8% 1 11% 33% 33% 14%	684
August	1st to 10th	Day	9% 3 11% 41% 32% 5%	626
	11th to 20th	Day	13% 1 10% 31% 37% 8%	567
	21st to end	Day	8% 1 11% 31% 36% 13%	495
September	1st to 10th	Day	9% 2 13% 33% 33% 10%	450
	11th to 20th	Day	7% 1 15% 40% 26% 10%	344
	21st to end	Day	9% 4 24% 30% 26% 8%	270
October	1st to 10th	Day	9% 8% 31% 29% 17% 5%	270
	11th to 20th	Day	14% 14% 38% 22% 11%	270
	21st to end	Day	29% 14% 29% 21% 6% 1	297
November	1st to 10th	Day	14% 13% 38% 25% 7% 3	270
	11th to 20th	Day	14% 21% 32% 22% 10% 2	270
	21st to end	Day	24% 19% 25% 26% 5% 2	270
December	1st to 10th	Day	17% 21% 33% 21% 6% 2	270
	11th to 20th	Day	22% 16% 35% 20% 6%	270
	21st to end	Day	21% 23% 37% 16% 2	297
January	1st to 10th	Night	19% 18% 34% 25% 5%	950
	11th to 20th	Night	20% 21% 35% 20% 4	920
	21st to end	Night	17% 18% 39% 23% 3	990
February	1st to 10th	Night	21% 16% 39% 21% 4	900
	11th to 20th	Night	19% 19% 41% 18% 2	868
	21st to end	Night	22% 19% 35% 21% 1	494
March	1st to 10th	Night	20% 14% 36% 27% 3	540
	11th to 20th	Night	24% 13% 33% 25% 5%	540
	21st to end	Night	22% 13% 38% 22% 6%	594
April	1st to 10th	Night	15% 15% 38% 27% 5%	540
	11th to 20th	Night	17% 12% 36% 28% 7%	533
	21st to end	Night	21% 12% 37% 23% 7%	540
May	1st to 10th	Night	13% 8% 33% 36% 9%	540
	11th to 20th	Night	16% 7% 24% 36% 16% 1	531
	21st to end	Night	11% 4 25% 37% 19% 4	584
June	1st to 10th	Night	8% 3 14% 39% 34% 1	540
	11th to 20th	Night	4 2 20% 46% 26% 2	540
	21st to end	Night	2 18% 49% 28% 2	540
July	1st to 10th	Night	5% 1 12% 35% 43% 5%	525
	11th to 20th	Night	4 1 10% 39% 40% 7%	522
	21st to end	Night	6% 2 7% 40% 39% 7%	591
August	1st to 10th	Night	6% 1 9% 42% 38% 4	537
	11th to 20th	Night	8% 1 10% 43% 35% 3	534
	21st to end	Night	5% 1 12% 37% 40% 5%	594
September	1st to 10th	Night	11% 1 11% 38% 37% 2	540
	11th to 20th	Night	14% 1 9% 37% 34% 4	540
	21st to end	Night	9% 3 20% 34% 30% 4	569
October	1st to 10th	Night	8% 3 23% 37% 25% 4	720
	11th to 20th	Night	15% 8% 34% 31% 13%	720
	21st to end	Night	20% 11% 28% 30% 10%	792
November	1st to 10th	Night	14% 8% 34% 31% 13%	740
	11th to 20th	Night	16% 12% 32% 32% 8%	779
	21st to end	Night	20% 14% 31% 26% 8%	950
December	1st to 10th	Night	20% 13% 37% 24% 6%	950
	11th to 20th	Night	23% 15% 33% 26% 4	950
	21st to end	Night	20% 17% 37% 22% 4	1045

Page generated at 2024-01-11 12:32:03. Version ac07

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