HSV Stargazers Observation Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the HSV Stargazers Observation Site clear sky chart from 2005-11-06 to 2024-12-24.

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	14% 6% 2 6% 4 4 4 3 5% 7% 45%	100971
	Night	13% 6% 2 5% 3 3 3 3 5% 6% 50%	99199
Transparency	Day	38% 6% 10% 22% 19% 6%	104616
	Night	33% 5% 10% 23% 22% 7%	103693
Seeing	Day	17% 11% 25% 26% 17% 5%	15486
	Night	16% 10% 24% 29% 17% 2	25341

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	18% 8% 3 6% 4 3 3 2 4 5% 44%	2847
	11th to 20th	Day	13% 12% 3 6% 3 3 3 2 4 4 49%	2850
	21st to end	Day	25% 6% 2 4 3 2 2 2 3 4 47%	3135
February	1st to 10th	Day	22% 9% 3 5% 3 3 3 2 4 4 41%	1710
	11th to 20th	Day	18% 9% 2 6% 4 3 3 2 5% 5% 42%	1762
	21st to end	Day	23% 8% 3 7% 4 3 3 3 4 5% 37%	1660
March	1st to 10th	Day	23% 10% 3 6% 3 3 3 2 3 5% 38%	3436
	11th to 20th	Day	15% 7% 3 6% 4 4 4 3 4 6% 44%	3480
	21st to end	Day	17% 7% 3 6% 4 4 4 2 4 6% 42%	3814
April	1st to 10th	Day	15% 7% 2 5% 4 4 4 3 4 6% 45%	2251
	11th to 20th	Day	18% 6% 2 5% 4 4 4 2 4 6% 45%	2254
	21st to end	Day	17% 7% 2 7% 5% 4 4 3 5% 6% 41%	2280
May	1st to 10th	Day	20% 7% 2 7% 5% 4 4 3 4 7% 36%	3783
	11th to 20th	Day	14% 5% 2 6% 5% 5% 5% 4 5% 7% 42%	4082
	21st to end	Day	15% 7% 3 8% 6% 5% 6% 4 6% 7% 34%	4477
June	1st to 10th	Day	9% 6% 2 6% 6% 5% 5% 5% 6% 9% 41%	2470
	11th to 20th	Day	5% 4 2 6% 6% 6% 6% 5% 7% 9% 43%	2470
	21st to end	Day	5% 4 2 5% 5% 6% 6% 5% 8% 10% 46%	2470
July	1st to 10th	Day	8% 5% 2 6% 5% 5% 6% 5% 7% 10% 41%	4120
	11th to 20th	Day	7% 3 2 5% 4 4 4 4 6% 9% 54%	4120
	21st to end	Day	11% 9% 3 9% 6% 6% 6% 5% 7% 8% 31%	4465
August	1st to 10th	Day	3 2 1 4 4 4 4 4 6% 8% 59%	4104
	11th to 20th	Day	8% 6% 2 7% 5% 4 5% 4 7% 9% 43%	3793
	21st to end	Day	5% 4 1 5% 5% 5% 5% 4 7% 9% 49%	4180
September	1st to 10th	Day	12% 5% 2 6% 4 4 5% 4 5% 7% 46%	2280
	11th to 20th	Day	15% 5% 2 5% 4 4 5% 5% 5% 8% 43%	2239
	21st to end	Day	11% 5% 2 4 3 4 4 3 5% 6% 53%	2000
October	1st to 10th	Day	8% 4 2 5% 3 3 3 2 5% 6% 58%	1900
	11th to 20th	Day	15% 5% 1 4 3 2 2 2 4 6% 57%	1900
	21st to end	Day	18% 5% 2 4 3 3 3 3 3 5% 52%	2090
November	1st to 10th	Day	14% 6% 2 5% 3 2 3 3 3 5% 55%	1958
	11th to 20th	Day	12% 5% 2 4 3 2 2 2 5% 6% 55%	2000
	21st to end	Day	20% 7% 2 5% 4 3 3 2 3 5% 47%	1750
December	1st to 10th	Day	19% 7% 2 5% 3 2 3 3 4 6% 47%	1600
	11th to 20th	Day	15% 8% 3 7% 5% 3 4 3 4 3 43%	2079
	21st to end	Day	16% 8% 3 7% 4 4 5% 4 5% 5% 39%	3162
January	1st to 10th	Night	16% 8% 2 6% 4 3 4 2 4 5% 45%	4108
	11th to 20th	Night	18% 6% 2 4 3 2 2 2 3 4 54%	4120
	21st to end	Night	24% 8% 2 3 2 2 2 2 3 4 47%	4532
February	1st to 10th	Night	21% 9% 3 5% 4 3 3 3 4 5% 42%	2470
	11th to 20th	Night	18% 7% 2 6% 4 4 3 3 4 5% 46%	2302
	21st to end	Night	20% 8% 2 4 3 3 3 3 3 5% 46%	1808
March	1st to 10th	Night	21% 9% 2 5% 3 3 3 3 5% 5% 41%	3419
	11th to 20th	Night	17% 7% 2 5% 3 3 3 2 4 5% 50%	3480
	21st to end	Night	13% 7% 3 6% 5% 4 4 3 5% 8% 42%	3817
April	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 5% 7% 50%	1929
	11th to 20th	Night	14% 4 2 5% 4 4 4 3 5% 6% 50%	1875
	21st to end	Night	13% 6% 2 5% 3 3 4 3 5% 7% 49%	1900
May	1st to 10th	Night	19% 7% 2 6% 4 4 3 4 5% 7% 38%	3109
	11th to 20th	Night	15% 7% 2 5% 4 4 4 4 5% 7% 44%	2823
	21st to end	Night	16% 7% 2 6% 4 4 4 4 5% 8% 41%	3090
June	1st to 10th	Night	6% 4 2 4 3 4 4 3 7% 10% 54%	1710
	11th to 20th	Night	4 3 2 5% 4 3 4 3 5% 9% 58%	1710
	21st to end	Night	4 3 1 3 3 3 4 4 6% 8% 61%	1710
July	1st to 10th	Night	7% 4 2 5% 4 4 5% 4 6% 11% 48%	2850
	11th to 20th	Night	4 3 1 4 3 3 3 3 6% 10% 60%	2850
	21st to end	Night	9% 6% 2 7% 5% 5% 5% 4 6% 9% 41%	3098
August	1st to 10th	Night	3 2 1 2 2 3 2 3 5% 8% 69%	2836
	11th to 20th	Night	4 2 1 4 3 3 4 4 6% 10% 56%	3037
	21st to end	Night	3 3 1 4 3 4 4 4 7% 9% 57%	3476
September	1st to 10th	Night	7% 4 1 5% 3 4 5% 4 5% 6% 57%	1900
	11th to 20th	Night	10% 5% 2 5% 3 3 4 3 5% 7% 51%	1935
	21st to end	Night	9% 4 1 4 3 3 3 4 5% 6% 59%	2160
October	1st to 10th	Night	9% 3 1 3 2 2 3 3 4 7% 62%	2280
	11th to 20th	Night	12% 3 1 4 3 2 2 2 4 5% 61%	2280
	21st to end	Night	17% 5% 2 4 3 3 3 2 2 3 56%	2508
November	1st to 10th	Night	13% 4 2 4 3 3 3 2 4 5% 57%	2340
	11th to 20th	Night	11% 5% 1 4 4 3 3 3 4 6% 56%	2400
	21st to end	Night	15% 8% 2 5% 3 3 2 2 4 5% 52%	2639
December	1st to 10th	Night	18% 7% 2 5% 3 3 3 3 4 5% 47%	2800
	11th to 20th	Night	18% 7% 2 5% 4 4 3 3 3 4 48%	3320
	21st to end	Night	16% 7% 2 6% 4 4 4 3 4 5% 45%	4578

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	45% 3 5% 22% 21% 4	2848
	11th to 20th	Day	40% 3 10% 22% 21% 3	2850
	21st to end	Day	43% 3 6% 18% 21% 9%	3135
February	1st to 10th	Day	48% 4 8% 19% 17% 4	1710
	11th to 20th	Day	45% 4 6% 20% 19% 6%	1771
	21st to end	Day	51% 4 6% 14% 17% 9%	1660
March	1st to 10th	Day	50% 4 7% 12% 18% 10%	3436
	11th to 20th	Day	41% 5% 8% 22% 18% 5%	3480
	21st to end	Day	45% 4 8% 21% 20% 1	3814
April	1st to 10th	Day	40% 5% 9% 21% 20% 5%	2251
	11th to 20th	Day	43% 4 8% 20% 19% 7%	2254
	21st to end	Day	43% 6% 9% 19% 19% 3	2280
May	1st to 10th	Day	47% 6% 10% 21% 13% 2	3818
	11th to 20th	Day	39% 9% 11% 25% 15% 1	4086
	21st to end	Day	47% 8% 12% 19% 10% 3	4489
June	1st to 10th	Day	37% 8% 13% 24% 15% 2	2470
	11th to 20th	Day	35% 8% 13% 24% 19% 2	2470
	21st to end	Day	30% 9% 13% 27% 19% 3	2470
July	1st to 10th	Day	34% 9% 17% 28% 11% 1	4056
	11th to 20th	Day	26% 6% 10% 34% 22% 2	4051
	21st to end	Day	47% 9% 14% 21% 8%	4325
August	1st to 10th	Day	22% 6% 14% 27% 24% 6%	4090
	11th to 20th	Day	35% 8% 15% 31% 10% 1	3830
	21st to end	Day	28% 9% 13% 29% 19% 3	4179
September	1st to 10th	Day	37% 7% 10% 19% 19% 8%	2280
	11th to 20th	Day	37% 8% 11% 17% 21% 6%	2239
	21st to end	Day	31% 7% 8% 20% 26% 8%	2000
October	1st to 10th	Day	17% 3 6% 12% 33% 30%	3160
	11th to 20th	Day	19% 2 4 19% 37% 19%	3140
	21st to end	Day	31% 5% 5% 27% 25% 7%	3428
November	1st to 10th	Day	33% 3 8% 24% 23% 8%	1958
	11th to 20th	Day	31% 3 8% 19% 28% 11%	2000
	21st to end	Day	43% 2 5% 17% 26% 6%	1750
December	1st to 10th	Day	41% 4 9% 23% 18% 6%	1600
	11th to 20th	Day	45% 4 5% 18% 23% 5%	2076
	21st to end	Day	46% 5% 9% 16% 18% 6%	3162
January	1st to 10th	Night	42% 4 6% 18% 27% 3	4108
	11th to 20th	Night	36% 4 9% 22% 24% 6%	4120
	21st to end	Night	42% 4 9% 18% 23% 5%	4532
February	1st to 10th	Night	46% 4 7% 19% 17% 6%	2470
	11th to 20th	Night	43% 3 7% 20% 21% 6%	2303
	21st to end	Night	42% 3 8% 16% 22% 9%	1808
March	1st to 10th	Night	45% 5% 8% 13% 18% 11%	3419
	11th to 20th	Night	39% 4 7% 25% 18% 7%	3480
	21st to end	Night	40% 5% 9% 23% 21% 2	3817
April	1st to 10th	Night	34% 5% 9% 23% 20% 10%	1929
	11th to 20th	Night	35% 5% 8% 22% 21% 9%	1875
	21st to end	Night	34% 6% 11% 24% 21% 4	1900
May	1st to 10th	Night	45% 7% 10% 22% 13% 3	3139
	11th to 20th	Night	39% 7% 13% 27% 14% 1	2824
	21st to end	Night	41% 7% 14% 22% 13% 2	3099
June	1st to 10th	Night	25% 10% 14% 30% 19% 2	1710
	11th to 20th	Night	24% 5% 12% 33% 23% 3	1710
	21st to end	Night	20% 6% 13% 32% 24% 5%	1710
July	1st to 10th	Night	29% 8% 19% 28% 15% 1	2805
	11th to 20th	Night	18% 6% 13% 35% 26% 2	2796
	21st to end	Night	38% 10% 13% 24% 14%	2999
August	1st to 10th	Night	13% 5% 17% 32% 27% 6%	2826
	11th to 20th	Night	21% 8% 19% 36% 15% 2	3066
	21st to end	Night	22% 8% 12% 29% 27% 2	3476
September	1st to 10th	Night	26% 7% 11% 24% 22% 9%	1900
	11th to 20th	Night	32% 8% 9% 20% 25% 6%	1935
	21st to end	Night	25% 5% 10% 22% 29% 9%	2160
October	1st to 10th	Night	15% 4 7% 14% 27% 33%	3800
	11th to 20th	Night	17% 2 4 16% 37% 24%	3779
	21st to end	Night	27% 4 5% 23% 28% 13%	4120
November	1st to 10th	Night	31% 4 7% 21% 26% 10%	2340
	11th to 20th	Night	31% 3 7% 21% 27% 12%	2400
	21st to end	Night	36% 3 7% 19% 28% 6%	2639
December	1st to 10th	Night	40% 4 8% 20% 21% 7%	2800
	11th to 20th	Night	42% 3 5% 18% 25% 7%	3321
	21st to end	Night	41% 4 8% 22% 21% 4	4578

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	29% 20% 31% 15% 5%	270
	11th to 20th	Day	31% 20% 35% 11% 1 1	270
	21st to end	Day	25% 25% 33% 12% 4	297
February	1st to 10th	Day	33% 19% 32% 12% 4	270
	11th to 20th	Day	31% 27% 30% 9% 2	270
	21st to end	Day	42% 23% 26% 8% 2	225
March	1st to 10th	Day	31% 17% 33% 15% 3	270
	11th to 20th	Day	33% 21% 33% 12% 1	270
	21st to end	Day	31% 25% 32% 10% 1	297
April	1st to 10th	Day	24% 22% 34% 14% 6%	431
	11th to 20th	Day	29% 16% 33% 16% 5% 1	452
	21st to end	Day	23% 19% 33% 17% 7% 2	460
May	1st to 10th	Day	24% 15% 32% 21% 7% 1	468
	11th to 20th	Day	17% 8% 32% 27% 13% 2	675
	21st to end	Day	11% 9% 29% 31% 16% 4	734
June	1st to 10th	Day	11% 6% 18% 34% 24% 7%	680
	11th to 20th	Day	7% 4 21% 38% 24% 7%	680
	21st to end	Day	4 4 24% 37% 23% 8%	680
July	1st to 10th	Day	6% 3 17% 34% 32% 8%	671
	11th to 20th	Day	6% 2 13% 37% 32% 10%	668
	21st to end	Day	7% 3 13% 33% 33% 11%	739
August	1st to 10th	Day	6% 1 16% 37% 31% 9%	676
	11th to 20th	Day	14% 2 10% 35% 30% 8%	519
	21st to end	Day	10% 1 7% 29% 36% 15%	539
September	1st to 10th	Day	11% 3 13% 29% 35% 9%	490
	11th to 20th	Day	12% 3 16% 26% 33% 9%	449
	21st to end	Day	15% 5% 19% 37% 19% 4	300
October	1st to 10th	Day	6% 6% 32% 35% 18% 4	300
	11th to 20th	Day	15% 12% 35% 25% 10% 2	300
	21st to end	Day	26% 14% 33% 18% 7% 1	330
November	1st to 10th	Day	21% 18% 31% 20% 10% 1	300
	11th to 20th	Day	17% 16% 39% 22% 5% 2	300
	21st to end	Day	30% 17% 27% 21% 5% 1	300
December	1st to 10th	Day	27% 23% 27% 17% 6%	300
	11th to 20th	Day	26% 21% 31% 17% 5%	300
	21st to end	Day	28% 16% 40% 12% 2 1	306
January	1st to 10th	Night	24% 18% 29% 26% 4	950
	11th to 20th	Night	25% 19% 29% 22% 4	950
	21st to end	Night	23% 16% 33% 24% 4	1045
February	1st to 10th	Night	27% 17% 29% 23% 4	950
	11th to 20th	Night	24% 18% 36% 20% 2	828
	21st to end	Night	28% 20% 30% 19% 3	552
March	1st to 10th	Night	23% 11% 33% 28% 5%	570
	11th to 20th	Night	24% 14% 30% 27% 4	570
	21st to end	Night	19% 16% 32% 27% 6%	627
April	1st to 10th	Night	17% 17% 33% 26% 7%	570
	11th to 20th	Night	15% 15% 34% 25% 10% 1	563
	21st to end	Night	16% 13% 35% 26% 9%	570
May	1st to 10th	Night	15% 7% 31% 36% 11% 1	570
	11th to 20th	Night	15% 9% 26% 30% 17% 2	561
	21st to end	Night	10% 6% 25% 32% 23% 4	617
June	1st to 10th	Night	8% 2 15% 36% 35% 5%	570
	11th to 20th	Night	5% 2 14% 41% 34% 4	570
	21st to end	Night	5% 1 14% 39% 36% 6%	570
July	1st to 10th	Night	5% 1 12% 32% 43% 7%	555
	11th to 20th	Night	3 11% 34% 41% 10%	552
	21st to end	Night	6% 7% 35% 43% 9%	624
August	1st to 10th	Night	4 1 10% 37% 40% 7%	567
	11th to 20th	Night	8% 1 10% 37% 37% 6%	564
	21st to end	Night	7% 1 8% 32% 44% 7%	627
September	1st to 10th	Night	8% 2 9% 34% 41% 6%	570
	11th to 20th	Night	11% 2 14% 32% 37% 4	570
	21st to end	Night	10% 4 16% 32% 33% 5%	640
October	1st to 10th	Night	11% 3 18% 35% 29% 5%	760
	11th to 20th	Night	13% 8% 26% 36% 17% 1	760
	21st to end	Night	20% 9% 27% 27% 16% 1	836
November	1st to 10th	Night	14% 11% 24% 33% 15% 2	780
	11th to 20th	Night	14% 11% 32% 31% 12%	800
	21st to end	Night	20% 16% 28% 24% 12%	870
December	1st to 10th	Night	23% 10% 32% 28% 6%	1000
	11th to 20th	Night	25% 13% 27% 27% 7%	1000
	21st to end	Night	23% 16% 28% 26% 6%	1063

Page generated at 2024-12-21 03:13:47. Version ac07

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