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Putman Mountain Observatory

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Putman Mountain Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Putman Mountain Observatory clear sky chart from 2005-11-06 to 2024-11-05.

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	9% 5% 2 5% 4 4 4 4 5% 7% 52%	100990
	Night	8% 4 2 4 3 3 3 3 5% 7% 57%	98160
Transparency	Day	31% 5% 10% 22% 22% 11%	104834
	Night	28% 5% 10% 21% 22% 13%	102443
Seeing	Day	11% 8% 23% 31% 20% 5%	14875
	Night	11% 8% 31% 36% 13% 1	24780

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	9% 10% 2 4 2 2 3 2 4 5% 58%	2847
	11th to 20th	Day	12% 6% 1 3 2 3 3 3 4 5% 57%	2850
	21st to end	Day	13% 6% 3 5% 3 3 3 2 4 7% 51%	3432
February	1st to 10th	Day	13% 6% 2 6% 2 3 3 2 4 6% 52%	1900
	11th to 20th	Day	13% 7% 2 4 2 3 4 4 5% 6% 50%	1849
	21st to end	Day	13% 6% 2 4 3 3 3 3 5% 5% 54%	1570
March	1st to 10th	Day	11% 8% 3 6% 4 3 4 3 3 7% 48%	3307
	11th to 20th	Day	17% 6% 3 7% 6% 4 4 4 5% 6% 38%	3480
	21st to end	Day	8% 6% 2 5% 4 4 4 4 6% 7% 50%	3814
April	1st to 10th	Day	10% 5% 2 6% 5% 4 4 4 5% 7% 49%	2090
	11th to 20th	Day	13% 7% 3 6% 3 3 4 3 5% 6% 48%	2168
	21st to end	Day	10% 5% 2 5% 4 4 4 3 5% 6% 53%	2378
May	1st to 10th	Day	12% 6% 2 7% 5% 5% 4 4 6% 8% 39%	4082
	11th to 20th	Day	11% 8% 2 6% 4 4 4 4 5% 6% 46%	4082
	21st to end	Day	8% 5% 2 6% 5% 6% 6% 6% 8% 9% 42%	4477
June	1st to 10th	Day	4 3 1 4 4 4 5% 4 7% 10% 53%	2470
	11th to 20th	Day	3 4 2 4 3 4 4 4 7% 10% 56%	2470
	21st to end	Day	5% 4 1 4 4 5% 5% 6% 7% 9% 50%	2470
July	1st to 10th	Day	5% 4 1 5% 4 5% 5% 5% 7% 8% 51%	4120
	11th to 20th	Day	3 2 1 3 3 4 4 4 6% 9% 60%	4120
	21st to end	Day	7% 4 1 5% 4 4 5% 4 7% 11% 49%	4465
August	1st to 10th	Day	1 1 1 2 2 3 3 3 5% 8% 72%	3963
	11th to 20th	Day	4 2 1 3 3 3 4 3 6% 8% 62%	3726
	21st to end	Day	3 2 2 4 4 4 6% 5% 8% 11% 51%	4098
September	1st to 10th	Day	9% 5% 2 7% 4 4 5% 3 4 7% 49%	2090
	11th to 20th	Day	10% 5% 3 6% 4 5% 4 4 6% 7% 47%	2090
	21st to end	Day	9% 2 1 4 3 4 5% 4 6% 7% 54%	2090
October	1st to 10th	Day	4 4 1 5% 3 3 3 3 5% 7% 62%	2090
	11th to 20th	Day	10% 5% 1 5% 3 3 3 2 5% 5% 59%	2009
	21st to end	Day	9% 4 2 4 2 3 2 2 4 5% 62%	2090
November	1st to 10th	Day	10% 6% 2 4 3 3 4 3 5% 7% 52%	1877
	11th to 20th	Day	8% 3 1 5% 3 3 3 4 5% 7% 57%	1710
	21st to end	Day	13% 7% 2 5% 4 4 3 2 4 5% 52%	1710
December	1st to 10th	Day	13% 5% 2 4 4 3 3 2 5% 6% 53%	1710
	11th to 20th	Day	12% 6% 2 6% 4 3 3 3 6% 6% 50%	2161
	21st to end	Day	10% 7% 1 4 3 3 2 2 3 5% 59%	3135
January	1st to 10th	Night	11% 7% 3 4 3 2 2 2 3 5% 58%	4108
	11th to 20th	Night	11% 3 1 3 2 2 2 2 3 4 67%	4120
	21st to end	Night	15% 8% 2 4 3 3 3 3 4 7% 49%	4262
February	1st to 10th	Night	12% 6% 2 5% 3 3 3 3 5% 6% 53%	2280
	11th to 20th	Night	13% 7% 2 4 2 3 3 2 4 6% 54%	2218
	21st to end	Night	12% 5% 1 5% 3 3 3 3 5% 7% 52%	1884
March	1st to 10th	Night	8% 6% 2 5% 3 4 5% 3 6% 8% 50%	3549
	11th to 20th	Night	16% 6% 2 5% 5% 4 5% 3 6% 6% 41%	3480
	21st to end	Night	7% 6% 2 5% 4 4 4 3 5% 7% 53%	3817
April	1st to 10th	Night	7% 5% 2 4 4 4 4 3 6% 8% 54%	2090
	11th to 20th	Night	9% 5% 2 5% 4 4 3 3 5% 7% 52%	1957
	21st to end	Night	9% 4 2 3 5% 2 3 4 6% 8% 55%	1800
May	1st to 10th	Night	13% 5% 2 5% 4 3 4 3 5% 9% 47%	2823
	11th to 20th	Night	7% 5% 2 5% 3 4 4 4 5% 8% 53%	2823
	21st to end	Night	7% 4 2 5% 4 4 4 4 8% 10% 49%	3090
June	1st to 10th	Night	2 2 1 2 3 4 4 3 7% 10% 63%	1710
	11th to 20th	Night	3 1 1 3 3 2 3 3 6% 9% 66%	1710
	21st to end	Night	3 3 2 3 3 3 3 4 6% 8% 61%	1710
July	1st to 10th	Night	3 3 1 4 3 3 4 3 7% 9% 60%	2850
	11th to 20th	Night	2 2 1 3 3 3 3 3 5% 9% 67%	2850
	21st to end	Night	3 3 1 3 4 4 4 4 8% 12% 55%	3098
August	1st to 10th	Night	1 1 2 2 2 3 2 4 6% 77%	2958
	11th to 20th	Night	3 2 1 3 2 3 4 4 6% 9% 64%	3113
	21st to end	Night	3 2 1 3 3 3 4 4 7% 13% 57%	3566
September	1st to 10th	Night	7% 4 2 4 3 3 5% 3 6% 8% 54%	2090
	11th to 20th	Night	9% 5% 2 4 4 5% 4 4 6% 9% 49%	2090
	21st to end	Night	8% 2 1 3 3 4 4 4 5% 7% 59%	2090
October	1st to 10th	Night	4 2 1 2 2 3 3 2 4 7% 69%	2090
	11th to 20th	Night	10% 3 1 3 3 3 3 3 4 6% 61%	2150
	21st to end	Night	10% 5% 1 3 3 3 2 3 4 4 63%	2508
November	1st to 10th	Night	10% 4 1 4 3 3 3 3 4 7% 60%	2298
	11th to 20th	Night	6% 4 2 4 3 3 3 3 5% 7% 61%	2470
	21st to end	Night	14% 5% 2 4 4 4 4 3 5% 6% 51%	2470
December	1st to 10th	Night	10% 4 2 4 4 2 3 3 6% 6% 56%	2470
	11th to 20th	Night	9% 8% 2 6% 4 4 4 4 5% 5% 50%	3036
	21st to end	Night	9% 5% 2 5% 3 3 3 3 4 5% 59%	4532

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	32% 3 3 16% 27% 19%	2848
	11th to 20th	Day	31% 3 6% 13% 32% 16%	2850
	21st to end	Day	36% 2 6% 12% 30% 13%	3432
February	1st to 10th	Day	36% 3 6% 14% 21% 19%	1900
	11th to 20th	Day	36% 4 5% 19% 20% 17%	1859
	21st to end	Day	35% 3 5% 17% 22% 19%	1570
March	1st to 10th	Day	39% 4 5% 14% 21% 17%	3307
	11th to 20th	Day	48% 4 10% 11% 17% 10%	3480
	21st to end	Day	34% 4 10% 16% 21% 15%	3814
April	1st to 10th	Day	36% 5% 8% 18% 18% 15%	2090
	11th to 20th	Day	40% 3 7% 16% 22% 12%	2168
	21st to end	Day	36% 4 5% 23% 21% 10%	2378
May	1st to 10th	Day	43% 6% 12% 15% 18% 7%	4120
	11th to 20th	Day	40% 5% 8% 16% 22% 10%	4086
	21st to end	Day	38% 6% 12% 27% 13% 4	4489
June	1st to 10th	Day	27% 5% 13% 29% 21% 4	2470
	11th to 20th	Day	26% 6% 12% 27% 22% 6%	2470
	21st to end	Day	30% 8% 13% 23% 20% 6%	2470
July	1st to 10th	Day	29% 8% 16% 38% 9% 1	4056
	11th to 20th	Day	20% 6% 14% 37% 18% 4	4051
	21st to end	Day	27% 7% 18% 32% 14% 1	4325
August	1st to 10th	Day	12% 4 11% 38% 33% 1	3949
	11th to 20th	Day	20% 4 21% 38% 14% 2	3762
	21st to end	Day	27% 10% 17% 24% 19% 3	4097
September	1st to 10th	Day	35% 6% 9% 21% 18% 10%	2090
	11th to 20th	Day	37% 6% 12% 19% 21% 6%	2090
	21st to end	Day	30% 6% 9% 22% 21% 13%	2090
October	1st to 10th	Day	14% 3 6% 12% 28% 36%	3480
	11th to 20th	Day	22% 4 6% 18% 25% 24%	3314
	21st to end	Day	21% 3 5% 19% 39% 14%	3428
November	1st to 10th	Day	34% 5% 7% 20% 22% 11%	1877
	11th to 20th	Day	28% 5% 8% 19% 22% 17%	1710
	21st to end	Day	38% 3 5% 17% 23% 15%	1710
December	1st to 10th	Day	34% 3 7% 21% 25% 11%	1710
	11th to 20th	Day	37% 3 8% 12% 23% 17%	2159
	21st to end	Day	31% 2 4 15% 28% 19%	3135
January	1st to 10th	Night	33% 3 3 14% 28% 21%	4108
	11th to 20th	Night	24% 2 4 17% 28% 25%	4120
	21st to end	Night	39% 3 4 12% 28% 14%	4262
February	1st to 10th	Night	35% 4 6% 13% 23% 20%	2280
	11th to 20th	Night	35% 5% 5% 17% 21% 18%	2218
	21st to end	Night	35% 4 6% 13% 21% 20%	1884
March	1st to 10th	Night	35% 6% 7% 15% 24% 13%	3549
	11th to 20th	Night	44% 5% 10% 14% 16% 11%	3480
	21st to end	Night	34% 4 10% 18% 19% 14%	3817
April	1st to 10th	Night	31% 5% 9% 20% 18% 16%	2090
	11th to 20th	Night	35% 5% 8% 15% 20% 16%	1957
	21st to end	Night	32% 6% 9% 21% 22% 10%	1800
May	1st to 10th	Night	40% 9% 8% 19% 14% 10%	2850
	11th to 20th	Night	32% 5% 12% 23% 18% 11%	2824
	21st to end	Night	33% 5% 15% 29% 13% 5%	3099
June	1st to 10th	Night	18% 6% 16% 34% 22% 3	1710
	11th to 20th	Night	17% 6% 16% 32% 23% 7%	1710
	21st to end	Night	22% 6% 14% 31% 22% 4	1710
July	1st to 10th	Night	21% 7% 24% 39% 9% 1	2805
	11th to 20th	Night	16% 6% 19% 38% 19% 2	2796
	21st to end	Night	20% 9% 25% 34% 12% 1	2999
August	1st to 10th	Night	10% 4 13% 38% 33% 1	2948
	11th to 20th	Night	17% 5% 27% 36% 13% 2	3143
	21st to end	Night	20% 10% 22% 25% 20% 2	3566
September	1st to 10th	Night	28% 8% 13% 23% 19% 10%	2090
	11th to 20th	Night	33% 6% 15% 23% 17% 6%	2090
	21st to end	Night	26% 6% 11% 22% 21% 14%	2090
October	1st to 10th	Night	11% 3 8% 15% 22% 39%	3480
	11th to 20th	Night	19% 4 8% 18% 30% 20%	3571
	21st to end	Night	20% 3 5% 21% 34% 16%	4120
November	1st to 10th	Night	28% 5% 6% 21% 24% 15%	2298
	11th to 20th	Night	26% 5% 6% 22% 22% 18%	2470
	21st to end	Night	36% 4 8% 15% 21% 16%	2470
December	1st to 10th	Night	31% 4 8% 19% 25% 13%	2470
	11th to 20th	Night	38% 3 5% 13% 20% 20%	3037
	21st to end	Night	31% 3 4 15% 29% 17%	4532

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	17% 18% 37% 23% 5% 1	270
	11th to 20th	Day	21% 13% 33% 24% 7% 1	270
	21st to end	Day	14% 17% 39% 24% 6%	297
February	1st to 10th	Day	21% 18% 32% 22% 7%	270
	11th to 20th	Day	21% 19% 37% 19% 4	270
	21st to end	Day	22% 19% 39% 17% 3	225
March	1st to 10th	Day	18% 17% 41% 20% 4	270
	11th to 20th	Day	17% 20% 38% 19% 6%	270
	21st to end	Day	15% 20% 43% 16% 4	297
April	1st to 10th	Day	15% 22% 41% 19% 3	270
	11th to 20th	Day	17% 19% 39% 20% 5%	366
	21st to end	Day	14% 16% 44% 19% 7%	558
May	1st to 10th	Day	12% 14% 40% 26% 8%	653
	11th to 20th	Day	16% 10% 33% 28% 11% 2	675
	21st to end	Day	12% 8% 29% 34% 14% 2	734
June	1st to 10th	Day	5% 3 21% 43% 24% 4	680
	11th to 20th	Day	5% 3 19% 52% 19% 3	680
	21st to end	Day	5% 1 14% 43% 31% 6%	680
July	1st to 10th	Day	7% 1 9% 39% 33% 11%	671
	11th to 20th	Day	4 1 6% 43% 40% 7%	668
	21st to end	Day	4 1 6% 40% 38% 12%	739
August	1st to 10th	Day	3 4 40% 41% 13%	600
	11th to 20th	Day	8% 1 6% 34% 38% 13%	477
	21st to end	Day	5% 1 6% 28% 44% 17%	496
September	1st to 10th	Day	11% 1 6% 26% 39% 18%	300
	11th to 20th	Day	7% 8% 26% 44% 16%	300
	21st to end	Day	12% 1 7% 33% 37% 12%	300
October	1st to 10th	Day	6% 4 11% 35% 35% 9%	300
	11th to 20th	Day	10% 5% 23% 41% 20% 2	300
	21st to end	Day	19% 13% 25% 26% 16% 1	330
November	1st to 10th	Day	20% 7% 27% 34% 11% 2	282
	11th to 20th	Day	15% 14% 26% 30% 9% 6%	270
	21st to end	Day	22% 16% 33% 19% 7% 3	270
December	1st to 10th	Day	15% 10% 33% 29% 10% 3	270
	11th to 20th	Day	17% 17% 36% 21% 8%	270
	21st to end	Day	16% 13% 35% 25% 10%	297
January	1st to 10th	Night	15% 10% 39% 30% 6%	950
	11th to 20th	Night	16% 11% 36% 31% 6%	950
	21st to end	Night	15% 11% 38% 29% 6%	879
February	1st to 10th	Night	18% 11% 41% 25% 6%	760
	11th to 20th	Night	17% 13% 42% 25% 3	744
	21st to end	Night	17% 18% 45% 20% 1	628
March	1st to 10th	Night	14% 17% 40% 27% 2	653
	11th to 20th	Night	15% 11% 42% 27% 4	570
	21st to end	Night	11% 14% 49% 23% 4	627
April	1st to 10th	Night	8% 14% 51% 24% 2	570
	11th to 20th	Night	12% 16% 48% 22% 3	563
	21st to end	Night	11% 10% 52% 20% 6%	570
May	1st to 10th	Night	10% 13% 46% 28% 4	570
	11th to 20th	Night	9% 8% 41% 32% 9% 1	561
	21st to end	Night	8% 7% 41% 33% 11%	617
June	1st to 10th	Night	2 1 29% 48% 19% 1	570
	11th to 20th	Night	4 2 36% 46% 11%	570
	21st to end	Night	5% 3 20% 49% 22% 2	570
July	1st to 10th	Night	5% 2 12% 53% 26% 2	555
	11th to 20th	Night	3 1 11% 59% 25% 1	552
	21st to end	Night	3 10% 60% 24% 3	624
August	1st to 10th	Night	1 8% 59% 30% 3	567
	11th to 20th	Night	5% 9% 55% 28% 4	564
	21st to end	Night	5% 1 7% 50% 32% 6%	627
September	1st to 10th	Night	9% 1 11% 42% 31% 5%	570
	11th to 20th	Night	11% 1 9% 41% 35% 3	570
	21st to end	Night	9% 13% 47% 29% 2	570
October	1st to 10th	Night	5% 2 16% 49% 27% 1	570
	11th to 20th	Night	12% 2 25% 45% 15% 1	630
	21st to end	Night	13% 9% 31% 30% 16% 1	836
November	1st to 10th	Night	12% 6% 29% 38% 13% 1	778
	11th to 20th	Night	9% 9% 32% 37% 13% 1	950
	21st to end	Night	16% 11% 32% 30% 10% 1	950
December	1st to 10th	Night	13% 8% 35% 36% 8%	950
	11th to 20th	Night	17% 10% 37% 32% 5%	950
	21st to end	Night	13% 12% 36% 32% 6%	1045

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

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