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 2024-06-30.

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% 8% 3 6% 4 4 4 4 5% 7% 44%	89239
	Night	12% 7% 3 6% 4 3 4 3 5% 6% 48%	89876
Transparency	Day	39% 6% 11% 24% 17% 3	89012
	Night	37% 5% 10% 24% 19% 4	89708
Seeing	Day	15% 11% 26% 27% 18% 5%	14975
	Night	15% 10% 28% 30% 15% 1	24860

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% 13% 3 5% 4 3 3 2 3 5% 45%	2847
	11th to 20th	Day	9% 9% 3 8% 3 3 3 2 4 5% 50%	2850
	21st to end	Day	21% 9% 3 6% 2 2 3 2 3 4 43%	3135
February	1st to 10th	Day	16% 11% 3 7% 5% 3 3 3 4 5% 39%	1710
	11th to 20th	Day	13% 9% 3 7% 4 3 4 2 4 5% 43%	1673
	21st to end	Day	15% 10% 4 7% 4 3 3 3 5% 5% 41%	1691
March	1st to 10th	Day	15% 9% 3 6% 3 3 3 3 4 4 46%	3436
	11th to 20th	Day	13% 7% 2 5% 3 3 3 3 6% 6% 49%	3480
	21st to end	Day	16% 10% 3 8% 6% 5% 4 3 4 5% 36%	3814
April	1st to 10th	Day	12% 8% 2 6% 5% 4 4 4 5% 7% 45%	2220
	11th to 20th	Day	17% 8% 2 6% 4 4 4 4 5% 6% 39%	2254
	21st to end	Day	18% 9% 3 7% 5% 4 4 3 3 4 39%	2280
May	1st to 10th	Day	17% 8% 3 7% 5% 5% 4 4 6% 6% 34%	4036
	11th to 20th	Day	12% 7% 3 7% 5% 5% 6% 4 5% 6% 40%	4082
	21st to end	Day	13% 6% 2 6% 6% 5% 6% 4 6% 8% 37%	4477
June	1st to 10th	Day	8% 5% 2 6% 5% 4 5% 5% 7% 10% 44%	2502
	11th to 20th	Day	6% 4 2 6% 5% 5% 6% 5% 6% 9% 46%	2586
	21st to end	Day	3 3 2 4 4 4 5% 5% 6% 9% 53%	2458
July	1st to 10th	Day	9% 5% 2 6% 6% 5% 5% 5% 8% 10% 39%	2340
	11th to 20th	Day	5% 3 1 5% 5% 5% 5% 4 8% 11% 48%	2340
	21st to end	Day	7% 4 2 6% 5% 5% 5% 5% 7% 11% 42%	2546
August	1st to 10th	Day	7% 5% 2 5% 5% 5% 5% 5% 7% 9% 42%	2328
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 7% 7% 46%	2253
	21st to end	Day	6% 5% 2 5% 4 5% 5% 4 6% 8% 50%	2376
September	1st to 10th	Day	11% 5% 2 6% 4 4 4 3 6% 7% 49%	2160
	11th to 20th	Day	11% 6% 2 6% 5% 4 4 3 5% 7% 47%	2054
	21st to end	Day	8% 4 2 4 4 4 4 3 5% 7% 55%	1931
October	1st to 10th	Day	9% 5% 2 4 4 4 4 4 4 7% 53%	1800
	11th to 20th	Day	13% 5% 2 5% 3 3 3 2 3 5% 56%	1800
	21st to end	Day	18% 7% 2 5% 4 4 3 2 3 4 49%	1980
November	1st to 10th	Day	11% 6% 2 4 3 2 3 3 4 6% 56%	1858
	11th to 20th	Day	11% 8% 2 5% 3 4 3 3 4 6% 51%	1873
	21st to end	Day	16% 8% 3 6% 4 3 2 3 4 6% 47%	1520
December	1st to 10th	Day	14% 7% 3 6% 4 3 4 3 5% 6% 46%	1520
	11th to 20th	Day	13% 12% 3 7% 5% 4 3 2 3 4 43%	1918
	21st to end	Day	13% 19% 6% 6% 4 4 4 3 4 5% 31%	3111
January	1st to 10th	Night	11% 9% 5% 9% 4 5% 3 3 5% 5% 40%	4108
	11th to 20th	Night	11% 7% 2 7% 4 4 5% 3 4 5% 48%	4120
	21st to end	Night	21% 11% 4 5% 3 2 2 2 3 4 42%	4532
February	1st to 10th	Night	14% 12% 3 6% 4 3 4 3 5% 7% 41%	2470
	11th to 20th	Night	15% 8% 3 8% 4 3 3 3 3 5% 47%	2392
	21st to end	Night	15% 8% 3 5% 4 3 3 3 5% 6% 45%	1780
March	1st to 10th	Night	17% 10% 2 5% 4 3 3 3 4 5% 44%	3419
	11th to 20th	Night	12% 8% 2 5% 4 3 3 3 4 6% 49%	3480
	21st to end	Night	13% 10% 3 7% 5% 4 4 3 5% 6% 39%	3817
April	1st to 10th	Night	12% 6% 2 5% 3 4 4 3 4 7% 51%	1958
	11th to 20th	Night	14% 7% 2 5% 4 3 3 4 5% 7% 47%	1875
	21st to end	Night	19% 5% 2 6% 4 4 3 4 5% 7% 41%	1900
May	1st to 10th	Night	12% 9% 3 5% 4 3 3 3 6% 7% 44%	2864
	11th to 20th	Night	11% 8% 3 7% 4 5% 4 4 6% 7% 42%	2823
	21st to end	Night	12% 7% 2 6% 5% 4 4 3 6% 8% 42%	3090
June	1st to 10th	Night	7% 3 1 4 3 4 3 4 6% 9% 56%	1656
	11th to 20th	Night	4 4 1 3 2 4 4 5% 7% 11% 55%	1569
	21st to end	Night	2 3 1 3 3 4 4 4 7% 8% 63%	1701
July	1st to 10th	Night	4 3 2 5% 5% 4 5% 4 7% 10% 51%	1620
	11th to 20th	Night	3 2 1 2 3 3 4 5% 6% 9% 61%	1620
	21st to end	Night	5% 4 1 5% 4 5% 4 3 6% 9% 53%	1772
August	1st to 10th	Night	5% 3 1 5% 4 4 5% 5% 8% 11% 49%	1611
	11th to 20th	Night	6% 4 1 4 3 4 5% 5% 6% 10% 51%	1645
	21st to end	Night	4 3 2 5% 4 4 5% 3 6% 9% 55%	1980
September	1st to 10th	Night	9% 4 1 3 3 3 4 3 5% 8% 57%	1800
	11th to 20th	Night	11% 4 2 5% 4 4 3 3 5% 6% 52%	1901
	21st to end	Night	7% 4 2 5% 3 3 3 3 5% 7% 58%	2009
October	1st to 10th	Night	7% 4 2 3 3 3 3 3 5% 8% 59%	2160
	11th to 20th	Night	13% 5% 2 4 2 3 3 2 5% 5% 56%	2160
	21st to end	Night	16% 7% 2 5% 3 3 3 2 3 4 51%	2376
November	1st to 10th	Night	11% 5% 2 4 2 3 2 2 3 5% 60%	2220
	11th to 20th	Night	12% 7% 2 5% 3 2 3 3 4 6% 55%	2299
	21st to end	Night	16% 8% 2 5% 4 2 3 2 4 5% 49%	2660
December	1st to 10th	Night	14% 9% 3 6% 3 3 3 2 4 6% 47%	2660
	11th to 20th	Night	14% 11% 4 7% 4 4 3 3 4 5% 44%	3279
	21st to end	Night	15% 15% 5% 8% 4 4 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	43% 2 6% 26% 20% 2	2848
	11th to 20th	Day	38% 4 13% 25% 17% 4	2850
	21st to end	Day	46% 3 8% 20% 18% 5%	3135
February	1st to 10th	Day	48% 4 9% 22% 13% 3	1710
	11th to 20th	Day	44% 5% 8% 22% 18% 3	1682
	21st to end	Day	46% 4 7% 20% 15% 8%	1691
March	1st to 10th	Day	41% 4 7% 19% 20% 10%	3436
	11th to 20th	Day	35% 6% 10% 24% 20% 4	3480
	21st to end	Day	50% 6% 9% 23% 11% 1	3814
April	1st to 10th	Day	39% 5% 11% 23% 19% 3	2220
	11th to 20th	Day	45% 7% 10% 18% 18% 3	2254
	21st to end	Day	49% 4 9% 22% 14% 2	2280
May	1st to 10th	Day	47% 8% 10% 20% 14% 1	4074
	11th to 20th	Day	41% 9% 12% 24% 14%	4086
	21st to end	Day	41% 9% 13% 22% 14% 1	4489
June	1st to 10th	Day	34% 9% 16% 27% 14% 1	2502
	11th to 20th	Day	31% 8% 14% 29% 16% 2	2586
	21st to end	Day	25% 8% 16% 29% 18% 4	2458
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	44% 4 9% 21% 19% 2	4108
	11th to 20th	Night	39% 4 12% 23% 20% 2	4120
	21st to end	Night	48% 3 10% 19% 18% 3	4532
February	1st to 10th	Night	44% 5% 11% 22% 15% 4	2470
	11th to 20th	Night	42% 3 8% 25% 18% 4	2393
	21st to end	Night	41% 4 8% 19% 21% 7%	1780
March	1st to 10th	Night	42% 5% 7% 18% 18% 9%	3419
	11th to 20th	Night	36% 6% 8% 28% 19% 3	3480
	21st to end	Night	45% 7% 10% 25% 13% 1	3817
April	1st to 10th	Night	35% 4 10% 25% 21% 6%	1958
	11th to 20th	Night	36% 5% 8% 25% 21% 5%	1875
	21st to end	Night	43% 5% 10% 24% 16% 2	1900
May	1st to 10th	Night	38% 7% 12% 24% 15% 3	2891
	11th to 20th	Night	38% 10% 13% 25% 14% 1	2824
	21st to end	Night	38% 8% 15% 27% 12%	3099
June	1st to 10th	Night	23% 9% 16% 32% 17% 4	1656
	11th to 20th	Night	20% 8% 14% 34% 21% 3	1569
	21st to end	Night	19% 7% 15% 31% 22% 6%	1701
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	27% 22% 34% 14% 1	270
	21st to end	Day	19% 24% 37% 15% 5%	297
February	1st to 10th	Day	23% 23% 37% 14% 2	270
	11th to 20th	Day	22% 29% 31% 16% 3	270
	21st to end	Day	32% 24% 32% 10% 1	225
March	1st to 10th	Day	20% 24% 34% 18% 4	270
	11th to 20th	Day	27% 20% 34% 18% 2	270
	21st to end	Day	27% 21% 40% 8% 3	297
April	1st to 10th	Day	19% 23% 35% 15% 8% 1	400
	11th to 20th	Day	21% 20% 34% 18% 6%	452
	21st to end	Day	24% 19% 28% 22% 6% 1	460
May	1st to 10th	Day	19% 16% 35% 23% 7%	620
	11th to 20th	Day	16% 11% 29% 27% 15% 2	675
	21st to end	Day	11% 7% 36% 25% 15% 5%	734
June	1st to 10th	Day	10% 4 18% 35% 27% 6%	680
	11th to 20th	Day	8% 3 20% 39% 24% 6%	680
	21st to end	Day	4 3 28% 36% 24% 4	676
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% 36% 20% 4	950
	21st to end	Night	18% 17% 38% 24% 3	1045
February	1st to 10th	Night	21% 16% 38% 22% 3	950
	11th to 20th	Night	19% 19% 41% 19% 2	918
	21st to end	Night	22% 19% 36% 21% 1	524
March	1st to 10th	Night	20% 14% 36% 27% 3	570
	11th to 20th	Night	23% 14% 33% 26% 4	570
	21st to end	Night	22% 13% 38% 22% 6%	627
April	1st to 10th	Night	16% 16% 37% 27% 5%	570
	11th to 20th	Night	17% 13% 36% 27% 7%	563
	21st to end	Night	20% 12% 36% 24% 8%	570
May	1st to 10th	Night	14% 8% 32% 37% 9%	570
	11th to 20th	Night	16% 7% 24% 37% 16% 1	561
	21st to end	Night	12% 5% 25% 37% 18% 3	617
June	1st to 10th	Night	8% 3 15% 41% 33% 1	570
	11th to 20th	Night	4 2 20% 45% 26% 2	570
	21st to end	Night	2 19% 49% 27% 2	567
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 2024-06-26 21:18:45. Version ac07

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