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 2024-11-28.

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	11% 7% 2 6% 4 4 4 4 5% 7% 45%	100912
	Night	11% 7% 2 5% 4 3 4 3 5% 7% 49%	98659
Transparency	Day	37% 5% 11% 25% 18% 4	104562
	Night	34% 5% 10% 25% 20% 5%	103149
Seeing	Day	14% 11% 26% 27% 18% 5%	15553
	Night	15% 10% 28% 30% 15% 1	25382

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 4 2 4 4 5% 5% 5% 6% 9% 52%	2470
July	1st to 10th	Day	10% 5% 2 6% 5% 4 5% 4 7% 10% 43%	4120
	11th to 20th	Day	5% 4 2 5% 4 4 5% 4 7% 11% 49%	4120
	21st to end	Day	6% 4 2 6% 5% 5% 6% 6% 8% 11% 41%	4465
August	1st to 10th	Day	5% 3 2 4 4 4 4 4 6% 8% 57%	4104
	11th to 20th	Day	10% 5% 2 6% 5% 4 4 4 6% 7% 47%	3951
	21st to end	Day	5% 4 1 4 4 4 5% 4 6% 8% 54%	4180
September	1st to 10th	Day	11% 5% 2 5% 4 4 4 3 5% 7% 50%	2280
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 3 5% 7% 46%	2168
	21st to end	Day	7% 4 2 5% 4 4 4 4 5% 7% 54%	2038
October	1st to 10th	Day	9% 5% 2 4 4 4 3 3 4 7% 55%	1900
	11th to 20th	Day	13% 5% 2 5% 3 3 3 2 3 5% 58%	1900
	21st to end	Day	17% 7% 2 5% 4 4 3 2 3 4 50%	2090
November	1st to 10th	Day	12% 6% 2 4 3 2 3 3 4 6% 55%	1958
	11th to 20th	Day	11% 8% 2 5% 3 4 3 3 4 6% 51%	1970
	21st to end	Day	15% 7% 3 6% 4 2 2 3 4 6% 48%	1576
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% 62%	1710
July	1st to 10th	Night	9% 4 2 6% 4 4 4 3 5% 9% 50%	2850
	11th to 20th	Night	4 3 1 3 4 3 4 4 5% 8% 63%	2850
	21st to end	Night	6% 4 2 6% 4 4 5% 4 7% 9% 50%	3098
August	1st to 10th	Night	3 2 1 4 3 4 4 4 6% 10% 59%	2836
	11th to 20th	Night	7% 5% 2 5% 4 4 5% 4 5% 8% 51%	2882
	21st to end	Night	4 3 1 3 3 3 4 3 6% 9% 61%	3476
September	1st to 10th	Night	9% 4 1 3 3 3 4 3 5% 8% 57%	1900
	11th to 20th	Night	10% 4 2 5% 4 4 3 3 5% 6% 52%	2007
	21st to end	Night	7% 5% 2 6% 3 3 3 3 5% 6% 57%	2121
October	1st to 10th	Night	6% 4 2 3 3 3 3 3 5% 8% 61%	2280
	11th to 20th	Night	13% 5% 2 4 2 3 3 2 5% 5% 57%	2280
	21st to end	Night	16% 7% 2 5% 3 3 3 2 4 4 52%	2508
November	1st to 10th	Night	12% 5% 2 4 2 3 2 2 3 5% 59%	2340
	11th to 20th	Night	11% 6% 2 4 3 2 3 3 4 6% 55%	2420
	21st to end	Night	15% 7% 2 4 4 2 3 2 4 5% 50%	2759
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	26% 8% 17% 28% 18% 4	2470
July	1st to 10th	Day	36% 6% 17% 26% 13% 2	4056
	11th to 20th	Day	28% 5% 12% 35% 18% 1	4051
	21st to end	Day	34% 5% 22% 29% 10%	4325
August	1st to 10th	Day	24% 6% 16% 29% 21% 4	4090
	11th to 20th	Day	36% 5% 16% 28% 14%	3990
	21st to end	Day	27% 5% 12% 38% 15% 3	4179
September	1st to 10th	Day	33% 5% 10% 25% 17% 9%	2280
	11th to 20th	Day	36% 5% 10% 23% 23% 3	2168
	21st to end	Day	30% 6% 9% 26% 26% 3	2038
October	1st to 10th	Day	17% 4 6% 17% 40% 16%	3160
	11th to 20th	Day	19% 2 5% 20% 38% 15%	3140
	21st to end	Day	29% 2 7% 32% 25% 5%	3428
November	1st to 10th	Day	32% 4 8% 26% 23% 8%	1958
	11th to 20th	Day	35% 3 7% 22% 23% 10%	1970
	21st to end	Day	40% 3 9% 20% 25% 3	1576
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%	1710
July	1st to 10th	Night	32% 6% 19% 24% 16% 4	2805
	11th to 20th	Night	20% 5% 11% 39% 23% 2	2796
	21st to end	Night	31% 4 19% 33% 14%	2999
August	1st to 10th	Night	21% 5% 15% 35% 23% 1	2826
	11th to 20th	Night	32% 5% 17% 27% 17% 2	2909
	21st to end	Night	21% 4 13% 37% 22% 3	3476
September	1st to 10th	Night	26% 5% 12% 30% 20% 9%	1900
	11th to 20th	Night	32% 5% 10% 23% 25% 5%	2007
	21st to end	Night	28% 4 9% 24% 30% 5%	2121
October	1st to 10th	Night	13% 3 7% 15% 40% 22%	3800
	11th to 20th	Night	20% 3 4 19% 33% 21%	3779
	21st to end	Night	29% 2 6% 33% 23% 7%	4120
November	1st to 10th	Night	29% 4 8% 24% 26% 8%	2340
	11th to 20th	Night	31% 4 8% 24% 26% 8%	2420
	21st to end	Night	37% 4 7% 22% 25% 4	2759
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% 37% 24% 4	680
July	1st to 10th	Day	8% 3 18% 30% 31% 10%	671
	11th to 20th	Day	5% 2 16% 36% 31% 10%	668
	21st to end	Day	8% 1 12% 33% 31% 14%	739
August	1st to 10th	Day	8% 3 13% 40% 30% 5%	676
	11th to 20th	Day	13% 1 12% 31% 36% 7%	614
	21st to end	Day	8% 2 12% 30% 36% 13%	539
September	1st to 10th	Day	9% 2 13% 34% 32% 10%	490
	11th to 20th	Day	9% 2 17% 39% 24% 10%	378
	21st to end	Day	10% 5% 27% 28% 24% 7%	300
October	1st to 10th	Day	8% 7% 30% 29% 19% 6%	300
	11th to 20th	Day	14% 13% 37% 24% 12% 1	300
	21st to end	Day	26% 15% 31% 21% 6% 1	330
November	1st to 10th	Day	18% 13% 37% 23% 7% 2	300
	11th to 20th	Day	15% 20% 33% 21% 9% 2	300
	21st to end	Day	24% 18% 27% 24% 5% 2	291
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	570
July	1st to 10th	Night	6% 1 12% 36% 41% 5%	555
	11th to 20th	Night	4 1 10% 41% 38% 6%	552
	21st to end	Night	5% 2 8% 40% 39% 6%	624
August	1st to 10th	Night	6% 1 10% 42% 38% 4	567
	11th to 20th	Night	8% 1 11% 43% 34% 3	564
	21st to end	Night	5% 1 11% 38% 40% 5%	627
September	1st to 10th	Night	11% 1 11% 38% 37% 2	570
	11th to 20th	Night	15% 1 10% 37% 33% 4	570
	21st to end	Night	10% 3 21% 34% 29% 3	601
October	1st to 10th	Night	8% 3 23% 37% 26% 4	760
	11th to 20th	Night	15% 8% 33% 32% 13%	760
	21st to end	Night	20% 12% 28% 30% 10%	836
November	1st to 10th	Night	15% 8% 33% 31% 12%	780
	11th to 20th	Night	16% 12% 32% 32% 8%	820
	21st to end	Night	20% 15% 32% 26% 8%	986
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 2024-11-24 23:22:21. Version ac07

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