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Astronomical Society of Northern New England

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Talmage Observatory at Starfield
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Talmage Observatory at Starfield clear sky chart from 2005-11-06 to 2024-11-06.

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	18% 8% 2 6% 4 4 4 4 5% 7% 38%	101281
	Night	18% 8% 2 6% 4 4 4 3 5% 6% 39%	97794
Transparency	Day	45% 4 12% 23% 14% 2	104819
	Night	45% 4 11% 23% 15% 2	102345
Seeing	Day	23% 17% 33% 19% 7% 2	14994
	Night	22% 13% 31% 25% 8% 1	23809

By Month

Percentage Cloud Cover NE (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	15% 9% 2 5% 4 4 4 2 5% 5% 44%	2517
	11th to 20th	Day	17% 7% 3 6% 4 4 4 3 5% 6% 41%	2520
	21st to end	Day	17% 11% 3 7% 4 3 5% 4 4 5% 38%	2772
February	1st to 10th	Day	17% 9% 3 6% 4 4 5% 4 6% 6% 37%	1706
	11th to 20th	Day	13% 8% 3 7% 4 3 4 4 6% 6% 41%	1848
	21st to end	Day	15% 11% 3 7% 6% 4 4 4 5% 5% 37%	1570
March	1st to 10th	Day	26% 13% 2 6% 4 4 3 3 4 5% 30%	3116
	11th to 20th	Day	16% 8% 2 6% 4 4 4 3 5% 7% 42%	3379
	21st to end	Day	23% 10% 3 6% 3 3 3 3 5% 6% 35%	3960
April	1st to 10th	Day	19% 11% 3 6% 4 4 3 2 4 6% 38%	2280
	11th to 20th	Day	17% 7% 2 6% 4 4 5% 4 6% 7% 39%	2318
	21st to end	Day	21% 8% 3 7% 5% 4 4 3 4 5% 35%	2470
May	1st to 10th	Day	23% 13% 3 7% 4 4 4 4 5% 6% 27%	4106
	11th to 20th	Day	21% 8% 3 8% 5% 5% 4 3 4 7% 33%	4161
	21st to end	Day	17% 5% 2 6% 4 4 5% 4 6% 8% 40%	4837
June	1st to 10th	Day	22% 7% 2 6% 4 5% 4 4 6% 7% 32%	2660
	11th to 20th	Day	16% 6% 2 6% 4 4 5% 4 5% 8% 39%	2660
	21st to end	Day	21% 7% 3 6% 5% 4 5% 4 6% 8% 33%	2660
July	1st to 10th	Day	13% 7% 3 7% 4 6% 6% 4 6% 9% 36%	4440
	11th to 20th	Day	11% 6% 2 6% 5% 4 6% 5% 8% 10% 38%	4440
	21st to end	Day	18% 7% 3 6% 4 4 4 4 6% 7% 36%	4814
August	1st to 10th	Day	15% 6% 3 7% 5% 4 5% 4 7% 8% 36%	4144
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 3 6% 9% 34%	4045
	21st to end	Day	9% 4 2 5% 5% 4 6% 4 7% 10% 45%	4258
September	1st to 10th	Day	12% 4 1 5% 4 4 4 4 5% 7% 49%	2252
	11th to 20th	Day	14% 6% 2 4 3 3 2 3 4 5% 55%	2090
	21st to end	Day	15% 6% 2 5% 4 3 5% 3 5% 6% 47%	2090
October	1st to 10th	Day	19% 8% 2 6% 4 3 4 3 5% 5% 40%	2090
	11th to 20th	Day	16% 6% 2 5% 4 4 4 3 5% 6% 45%	1838
	21st to end	Day	22% 7% 2 5% 4 3 4 3 4 5% 41%	1881
November	1st to 10th	Day	16% 6% 2 4 3 3 4 3 5% 6% 48%	1717
	11th to 20th	Day	21% 5% 1 4 3 3 3 3 5% 6% 46%	1710
	21st to end	Day	21% 8% 2 5% 3 3 3 3 4 7% 42%	1710
December	1st to 10th	Day	20% 9% 2 5% 5% 4 4 3 4 6% 37%	1544
	11th to 20th	Day	23% 6% 2 5% 4 3 3 2 5% 4 43%	1906
	21st to end	Day	25% 11% 2 5% 3 3 4 3 5% 6% 33%	2772
January	1st to 10th	Night	18% 8% 2 5% 3 3 3 3 5% 6% 45%	4429
	11th to 20th	Night	14% 8% 3 10% 5% 4 4 3 5% 6% 39%	4440
	21st to end	Night	21% 12% 3 6% 4 4 3 3 5% 5% 33%	4884
February	1st to 10th	Night	15% 9% 4 7% 4 5% 4 4 5% 6% 38%	2467
	11th to 20th	Night	13% 10% 3 6% 5% 4 5% 4 4 6% 41%	2218
	21st to end	Night	15% 10% 3 6% 5% 4 4 4 4 6% 42%	1884
March	1st to 10th	Night	28% 10% 2 5% 4 3 3 3 4 4 34%	3724
	11th to 20th	Night	13% 8% 3 8% 5% 5% 5% 4 6% 6% 37%	3578
	21st to end	Night	25% 8% 2 5% 4 3 4 4 6% 6% 33%	3668
April	1st to 10th	Night	20% 9% 3 5% 4 3 4 4 5% 6% 37%	1900
	11th to 20th	Night	19% 8% 3 5% 4 3 4 3 4 6% 41%	1810
	21st to end	Night	20% 9% 2 6% 5% 4 3 3 4 6% 38%	1710
May	1st to 10th	Night	24% 11% 4 6% 4 4 4 3 7% 7% 27%	2834
	11th to 20th	Night	16% 8% 3 8% 6% 6% 6% 5% 7% 8% 26%	2762
	21st to end	Night	18% 7% 2 6% 5% 4 4 3 4 7% 40%	2738
June	1st to 10th	Night	21% 8% 2 7% 5% 4 4 3 6% 6% 34%	1520
	11th to 20th	Night	18% 8% 3 5% 4 4 4 4 5% 7% 39%	1520
	21st to end	Night	21% 6% 2 6% 5% 3 4 4 5% 7% 36%	1520
July	1st to 10th	Night	11% 6% 2 8% 6% 5% 6% 5% 7% 10% 34%	2520
	11th to 20th	Night	11% 6% 3 7% 4 4 5% 4 7% 9% 39%	2520
	21st to end	Night	16% 6% 2 6% 4 4 5% 4 6% 7% 40%	2739
August	1st to 10th	Night	20% 7% 2 7% 5% 5% 5% 4 5% 7% 33%	2752
	11th to 20th	Night	15% 9% 3 6% 4 4 5% 4 6% 7% 36%	2782
	21st to end	Night	10% 4 2 5% 4 4 5% 4 6% 8% 50%	3394
September	1st to 10th	Night	13% 5% 2 5% 4 3 5% 3 5% 6% 50%	1928
	11th to 20th	Night	15% 5% 2 5% 3 3 3 2 5% 8% 51%	2090
	21st to end	Night	16% 5% 2 5% 3 4 4 3 4 6% 48%	2090
October	1st to 10th	Night	19% 7% 2 7% 4 4 5% 3 5% 5% 40%	2090
	11th to 20th	Night	16% 5% 2 6% 4 4 4 3 5% 6% 44%	2340
	21st to end	Night	23% 8% 2 6% 3 3 4 3 4 5% 39%	2717
November	1st to 10th	Night	16% 6% 2 5% 4 3 4 4 5% 6% 45%	2483
	11th to 20th	Night	19% 6% 1 6% 4 4 4 2 4 5% 45%	2470
	21st to end	Night	17% 7% 3 5% 4 3 4 3 5% 6% 44%	2470
December	1st to 10th	Night	20% 9% 3 7% 4 4 3 3 4 6% 37%	2631
	11th to 20th	Night	21% 8% 2 5% 4 3 4 3 5% 5% 41%	3288
	21st to end	Night	24% 10% 3 7% 4 4 3 2 4 4 35%	4884

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	42% 3 10% 30% 13% 1	2518
	11th to 20th	Day	45% 3 12% 24% 12% 3	2520
	21st to end	Day	50% 3 10% 24% 12% 1	2772
February	1st to 10th	Day	46% 3 13% 21% 13% 3	1706
	11th to 20th	Day	42% 5% 11% 23% 15% 4	1857
	21st to end	Day	51% 2 10% 20% 14% 3	1570
March	1st to 10th	Day	59% 3 9% 13% 14% 3	3119
	11th to 20th	Day	42% 3 13% 20% 16% 6%	3379
	21st to end	Day	50% 3 4 16% 18% 8%	3960
April	1st to 10th	Day	49% 3 8% 19% 17% 4	2280
	11th to 20th	Day	43% 5% 11% 23% 15% 3	2318
	21st to end	Day	51% 3 9% 17% 16% 3	2470
May	1st to 10th	Day	58% 4 11% 15% 10% 1	4120
	11th to 20th	Day	52% 5% 15% 17% 9% 2	4165
	21st to end	Day	41% 6% 14% 23% 14% 2	4837
June	1st to 10th	Day	50% 6% 12% 22% 10%	2660
	11th to 20th	Day	43% 3 13% 22% 15% 3	2660
	21st to end	Day	48% 6% 13% 21% 12% 1	2660
July	1st to 10th	Day	45% 4 12% 25% 13%	4370
	11th to 20th	Day	39% 5% 17% 26% 13%	4365
	21st to end	Day	46% 4 14% 22% 13% 1	4661
August	1st to 10th	Day	45% 5% 16% 25% 9%	4130
	11th to 20th	Day	48% 4 15% 25% 8% 1	4084
	21st to end	Day	34% 4 15% 27% 19% 1	4258
September	1st to 10th	Day	34% 5% 13% 29% 18% 1	2252
	11th to 20th	Day	34% 3 9% 29% 23% 3	2090
	21st to end	Day	39% 5% 9% 27% 19% 2	2090
October	1st to 10th	Day	47% 2 7% 24% 18% 2	3480
	11th to 20th	Day	34% 2 8% 31% 22% 2	3028
	21st to end	Day	36% 2 8% 29% 22% 3	3081
November	1st to 10th	Day	38% 3 13% 26% 17% 2	1717
	11th to 20th	Day	39% 4 10% 23% 21% 3	1710
	21st to end	Day	44% 3 16% 21% 14% 1	1710
December	1st to 10th	Day	48% 3 14% 20% 14% 2	1544
	11th to 20th	Day	44% 4 9% 21% 17% 5%	1906
	21st to end	Day	55% 3 12% 19% 10% 2	2772
January	1st to 10th	Night	42% 2 12% 30% 10% 3	4429
	11th to 20th	Night	46% 4 11% 22% 12% 4	4440
	21st to end	Night	54% 3 9% 21% 11% 2	4884
February	1st to 10th	Night	47% 4 12% 19% 14% 3	2467
	11th to 20th	Night	45% 4 9% 22% 17% 4	2220
	21st to end	Night	45% 3 10% 23% 14% 5%	1884
March	1st to 10th	Night	55% 3 10% 17% 12% 3	3734
	11th to 20th	Night	46% 3 10% 20% 17% 3	3579
	21st to end	Night	51% 3 6% 15% 18% 7%	3668
April	1st to 10th	Night	48% 4 9% 19% 16% 4	1900
	11th to 20th	Night	45% 3 8% 22% 19% 2	1810
	21st to end	Night	48% 3 10% 19% 16% 4	1710
May	1st to 10th	Night	57% 4 12% 18% 8% 2	2840
	11th to 20th	Night	54% 5% 16% 16% 7% 2	2763
	21st to end	Night	45% 5% 15% 19% 14% 2	2739
June	1st to 10th	Night	51% 5% 11% 20% 12% 1	1520
	11th to 20th	Night	44% 5% 13% 21% 14% 3	1520
	21st to end	Night	48% 5% 13% 22% 11% 1	1520
July	1st to 10th	Night	45% 5% 14% 22% 13% 1	2480
	11th to 20th	Night	41% 5% 14% 24% 16%	2472
	21st to end	Night	43% 4 11% 27% 14% 1	2651
August	1st to 10th	Night	52% 5% 13% 20% 10% 1	2742
	11th to 20th	Night	47% 4 14% 23% 12%	2809
	21st to end	Night	33% 3 15% 27% 21% 1	3394
September	1st to 10th	Night	35% 5% 11% 28% 19% 1	1928
	11th to 20th	Night	34% 4 9% 29% 21% 2	2090
	21st to end	Night	38% 5% 9% 29% 17% 2	2090
October	1st to 10th	Night	46% 3 11% 23% 15% 2	3480
	11th to 20th	Night	31% 3 9% 28% 26% 4	3889
	21st to end	Night	38% 2 9% 29% 19% 3	4467
November	1st to 10th	Night	40% 5% 11% 25% 18% 2	2483
	11th to 20th	Night	42% 4 9% 23% 19% 3	2470
	21st to end	Night	42% 3 14% 25% 14% 2	2470
December	1st to 10th	Night	50% 4 11% 23% 12% 1	2631
	11th to 20th	Night	45% 4 11% 19% 20% 1	3288
	21st to end	Night	54% 3 9% 23% 11% 1	4884

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	27% 24% 28% 17% 3 1	180
	11th to 20th	Day	29% 26% 29% 13% 2 1	180
	21st to end	Day	20% 23% 38% 13% 5%	198
February	1st to 10th	Day	29% 21% 37% 12% 1	344
	11th to 20th	Day	27% 27% 30% 15% 2	456
	21st to end	Day	28% 21% 32% 15% 4	382
March	1st to 10th	Day	30% 21% 34% 12% 3	460
	11th to 20th	Day	27% 26% 32% 10% 4 1	460
	21st to end	Day	28% 22% 32% 12% 4 2	506
April	1st to 10th	Day	33% 23% 27% 11% 5% 1	460
	11th to 20th	Day	29% 23% 28% 12% 7% 1	452
	21st to end	Day	30% 20% 32% 12% 5% 1	460
May	1st to 10th	Day	31% 21% 33% 11% 3 2	463
	11th to 20th	Day	22% 18% 37% 16% 5% 1	487
	21st to end	Day	19% 19% 34% 20% 6% 1	529
June	1st to 10th	Day	22% 17% 36% 18% 6% 1	490
	11th to 20th	Day	16% 19% 36% 21% 6% 2	490
	21st to end	Day	23% 13% 38% 17% 8% 1	490
July	1st to 10th	Day	18% 8% 37% 27% 7% 3	485
	11th to 20th	Day	14% 8% 36% 28% 11% 3	484
	21st to end	Day	16% 6% 40% 27% 9% 2	532
August	1st to 10th	Day	14% 10% 33% 28% 13% 2	486
	11th to 20th	Day	19% 7% 33% 24% 12% 5%	479
	21st to end	Day	14% 8% 34% 28% 10% 5%	539
September	1st to 10th	Day	16% 10% 30% 28% 11% 5%	490
	11th to 20th	Day	19% 12% 29% 23% 9% 7%	490
	21st to end	Day	15% 11% 37% 22% 8% 6%	490
October	1st to 10th	Day	24% 13% 28% 22% 11% 2	490
	11th to 20th	Day	21% 16% 27% 25% 10% 2	410
	21st to end	Day	28% 14% 32% 19% 7%	429
November	1st to 10th	Day	22% 15% 32% 23% 7% 1	381
	11th to 20th	Day	29% 18% 29% 19% 4 1	370
	21st to end	Day	26% 20% 30% 18% 5% 1	370
December	1st to 10th	Day	21% 27% 32% 15% 3	204
	11th to 20th	Day	28% 24% 36% 10% 3	180
	21st to end	Day	32% 20% 31% 13% 5%	198
January	1st to 10th	Night	23% 19% 36% 20% 2	760
	11th to 20th	Night	27% 17% 35% 17% 4	760
	21st to end	Night	20% 20% 35% 21% 3	836
February	1st to 10th	Night	22% 19% 40% 17% 2	760
	11th to 20th	Night	21% 21% 38% 18% 2	743
	21st to end	Night	23% 16% 35% 22% 4	628
March	1st to 10th	Night	26% 16% 38% 18% 2	760
	11th to 20th	Night	23% 18% 34% 19% 6%	760
	21st to end	Night	27% 15% 35% 18% 5%	836
April	1st to 10th	Night	28% 16% 32% 20% 4	760
	11th to 20th	Night	23% 15% 33% 23% 6%	686
	21st to end	Night	24% 14% 32% 24% 5%	570
May	1st to 10th	Night	24% 9% 35% 26% 6% 1	570
	11th to 20th	Night	20% 12% 32% 28% 7% 1	537
	21st to end	Night	23% 8% 28% 30% 9% 1	411
June	1st to 10th	Night	23% 8% 29% 29% 10% 1	380
	11th to 20th	Night	22% 5% 27% 32% 13% 1	380
	21st to end	Night	24% 3 24% 38% 11%	380
July	1st to 10th	Night	18% 2 22% 43% 15% 1	370
	11th to 20th	Night	15% 4 22% 40% 19% 1	368
	21st to end	Night	14% 3 19% 47% 14% 2	416
August	1st to 10th	Night	15% 5% 23% 41% 15%	520
	11th to 20th	Night	15% 6% 25% 34% 18% 2	562
	21st to end	Night	16% 6% 22% 36% 18% 2	780
September	1st to 10th	Night	14% 5% 26% 37% 18% 1	760
	11th to 20th	Night	17% 7% 26% 27% 18% 4	760
	21st to end	Night	19% 7% 27% 30% 15% 2	760
October	1st to 10th	Night	23% 9% 25% 27% 15% 1	760
	11th to 20th	Night	18% 11% 32% 27% 11% 1	760
	21st to end	Night	27% 13% 30% 25% 6%	836
November	1st to 10th	Night	19% 13% 35% 25% 7% 1	764
	11th to 20th	Night	23% 18% 31% 21% 6% 1	760
	21st to end	Night	20% 20% 32% 24% 4	760
December	1st to 10th	Night	25% 15% 38% 18% 4	760
	11th to 20th	Night	24% 20% 33% 20% 3	760
	21st to end	Night	27% 16% 35% 20% 2	836

Page generated at 2024-11-03 13:19:02. Version ac07

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