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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 2024-03-18.

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	17% 7% 3 5% 5% 3 4 4 5% 7% 40%	78516
	Night	18% 7% 3 5% 5% 3 4 4 5% 6% 40%	81258
Transparency	Day	44% 4 12% 23% 14% 2	78221
	Night	45% 4 11% 23% 15% 2	81087
Seeing	Day	23% 17% 33% 19% 7% 2	14086
	Night	22% 13% 31% 25% 8% 1	23081

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% 5% 3 4 3 5% 5% 44%	2517
	11th to 20th	Day	17% 7% 3 5% 5% 3 4 4 5% 6% 41%	2520
	21st to end	Day	18% 11% 3 6% 4 2 5% 4 4 5% 38%	2772
February	1st to 10th	Day	17% 9% 3 6% 4 3 5% 4 5% 7% 37%	1706
	11th to 20th	Day	13% 8% 3 6% 5% 3 4 5% 6% 6% 42%	1848
	21st to end	Day	15% 11% 4 6% 7% 3 4 4 4 5% 37%	1570
March	1st to 10th	Day	17% 10% 2 5% 6% 3 4 4 5% 6% 37%	1897
	11th to 20th	Day	16% 7% 3 6% 4 3 4 3 5% 7% 43%	1997
	21st to end	Day	17% 9% 3 6% 4 2 4 3 5% 5% 41%	2254
April	1st to 10th	Day	19% 10% 4 6% 4 3 3 3 4 6% 39%	2160
	11th to 20th	Day	16% 7% 2 6% 5% 3 5% 5% 6% 7% 39%	2194
	21st to end	Day	22% 8% 3 6% 6% 3 5% 4 4 6% 34%	2340
May	1st to 10th	Day	24% 7% 3 5% 5% 3 4 5% 5% 6% 33%	2340
	11th to 20th	Day	18% 7% 3 6% 5% 3 4 4 5% 7% 38%	2339
	21st to end	Day	17% 6% 2 5% 4 3 5% 6% 6% 7% 39%	2725
June	1st to 10th	Day	22% 7% 3 6% 5% 4 5% 5% 6% 7% 32%	2520
	11th to 20th	Day	17% 6% 2 5% 4 3 5% 5% 5% 8% 40%	2520
	21st to end	Day	21% 7% 3 5% 5% 3 5% 5% 5% 8% 33%	2520
July	1st to 10th	Day	16% 5% 3 5% 5% 3 6% 5% 6% 9% 38%	2520
	11th to 20th	Day	13% 6% 2 5% 6% 3 5% 7% 8% 9% 37%	2520
	21st to end	Day	13% 5% 3 5% 5% 4 5% 6% 7% 8% 39%	2744
August	1st to 10th	Day	12% 5% 3 5% 6% 3 5% 6% 7% 9% 39%	2352
	11th to 20th	Day	13% 6% 2 6% 5% 3 5% 5% 7% 10% 38%	2304
	21st to end	Day	13% 4 2 4 5% 3 5% 5% 6% 9% 44%	2426
September	1st to 10th	Day	13% 4 2 5% 4 3 5% 5% 5% 8% 47%	2134
	11th to 20th	Day	14% 6% 2 4 4 2 3 3 3 5% 55%	1980
	21st to end	Day	15% 6% 2 4 5% 2 4 4 5% 6% 48%	1980
October	1st to 10th	Day	20% 8% 2 6% 5% 2 4 4 5% 5% 40%	1980
	11th to 20th	Day	16% 6% 3 5% 5% 3 4 4 5% 6% 44%	1742
	21st to end	Day	23% 7% 2 4 4 3 4 4 4 5% 39%	1782
November	1st to 10th	Day	17% 6% 2 3 3 3 3 4 5% 6% 49%	1671
	11th to 20th	Day	21% 4 2 3 3 2 3 4 4 6% 46%	1710
	21st to end	Day	21% 7% 2 4 4 2 3 4 4 7% 43%	1710
December	1st to 10th	Day	20% 8% 3 5% 5% 3 4 5% 4 6% 37%	1544
	11th to 20th	Day	23% 5% 3 5% 4 2 3 3 5% 4 44%	1906
	21st to end	Day	26% 10% 2 4 4 2 4 4 5% 6% 33%	2772
January	1st to 10th	Night	18% 7% 2 4 3 2 3 4 5% 6% 45%	4429
	11th to 20th	Night	14% 7% 3 9% 6% 3 4 4 5% 6% 39%	4440
	21st to end	Night	21% 11% 3 6% 5% 3 4 4 5% 5% 34%	4884
February	1st to 10th	Night	16% 8% 4 6% 5% 3 5% 4 4 6% 38%	2467
	11th to 20th	Night	13% 9% 3 5% 5% 4 5% 5% 4 6% 41%	2218
	21st to end	Night	15% 9% 3 5% 5% 3 4 4 4 6% 42%	1884
March	1st to 10th	Night	16% 9% 3 5% 5% 3 5% 4 5% 5% 40%	2270
	11th to 20th	Night	17% 7% 2 6% 5% 3 4 5% 5% 6% 39%	2126
	21st to end	Night	18% 8% 3 5% 4 2 3 3 4 6% 43%	2098
April	1st to 10th	Night	21% 8% 3 4 5% 3 4 5% 4 6% 37%	1800
	11th to 20th	Night	18% 8% 3 4 4 2 4 4 4 6% 42%	1714
	21st to end	Night	22% 8% 2 5% 5% 3 4 3 4 7% 36%	1620
May	1st to 10th	Night	22% 8% 3 5% 5% 3 4 4 6% 7% 33%	1620
	11th to 20th	Night	17% 6% 3 7% 7% 4 6% 5% 5% 7% 33%	1570
	21st to end	Night	19% 8% 2 5% 5% 2 5% 4 5% 7% 37%	1550
June	1st to 10th	Night	22% 7% 2 6% 5% 3 4 4 5% 6% 34%	1440
	11th to 20th	Night	19% 7% 2 5% 4 3 5% 4 5% 6% 40%	1440
	21st to end	Night	21% 6% 2 5% 5% 3 4 5% 5% 8% 38%	1440
July	1st to 10th	Night	15% 5% 3 5% 6% 3 6% 5% 5% 8% 39%	1440
	11th to 20th	Night	15% 5% 3 5% 5% 3 5% 4 7% 11% 37%	1440
	21st to end	Night	13% 4 2 5% 4 3 5% 5% 7% 8% 44%	1574
August	1st to 10th	Night	12% 5% 2 5% 5% 3 4 5% 6% 9% 44%	1566
	11th to 20th	Night	14% 6% 2 5% 6% 4 4 6% 6% 9% 39%	1596
	21st to end	Night	16% 4 2 5% 4 3 4 5% 5% 7% 46%	1926
September	1st to 10th	Night	13% 5% 2 4 5% 2 4 4 5% 6% 50%	1826
	11th to 20th	Night	16% 5% 2 4 4 2 2 3 4 7% 52%	1980
	21st to end	Night	16% 5% 2 4 4 3 4 4 4 6% 49%	1980
October	1st to 10th	Night	20% 6% 2 5% 5% 2 5% 4 4 6% 40%	1980
	11th to 20th	Night	16% 5% 2 5% 6% 3 5% 4 5% 6% 43%	2216
	21st to end	Night	24% 8% 2 5% 4 3 4 4 4 5% 37%	2574
November	1st to 10th	Night	16% 6% 2 4 4 2 4 5% 5% 6% 45%	2407
	11th to 20th	Night	19% 6% 1 5% 4 3 3 3 4 6% 45%	2470
	21st to end	Night	17% 6% 3 4 4 2 4 4 5% 7% 44%	2470
December	1st to 10th	Night	20% 8% 4 6% 5% 3 4 4 4 6% 37%	2631
	11th to 20th	Night	21% 7% 2 5% 4 2 4 4 5% 5% 41%	3288
	21st to end	Night	24% 9% 3 6% 5% 3 3 3 4 4 36%	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	49% 3 11% 17% 15% 5%	1900
	11th to 20th	Day	43% 3 10% 21% 18% 5%	1997
	21st to end	Day	47% 3 6% 20% 17% 7%	2254
April	1st to 10th	Day	48% 3 8% 19% 17% 4	2160
	11th to 20th	Day	44% 5% 11% 22% 15% 3	2194
	21st to end	Day	52% 3 9% 16% 15% 3	2340
May	1st to 10th	Day	51% 4 8% 20% 15% 2	2340
	11th to 20th	Day	45% 6% 9% 20% 17% 3	2343
	21st to end	Day	44% 6% 14% 22% 11% 3	2725
June	1st to 10th	Day	51% 6% 12% 21% 10%	2520
	11th to 20th	Day	43% 4 12% 22% 16% 3	2520
	21st to end	Day	47% 6% 14% 21% 11% 1	2520
July	1st to 10th	Day	40% 6% 14% 23% 16% 1	2450
	11th to 20th	Day	40% 7% 15% 25% 12% 1	2445
	21st to end	Day	39% 6% 16% 24% 12% 2	2591
August	1st to 10th	Day	39% 6% 18% 25% 11% 1	2338
	11th to 20th	Day	40% 5% 16% 27% 11% 1	2304
	21st to end	Day	36% 5% 13% 25% 18% 2	2426
September	1st to 10th	Day	35% 6% 13% 29% 17% 1	2134
	11th to 20th	Day	34% 3 8% 28% 24% 3	1980
	21st to end	Day	38% 5% 9% 27% 19% 2	1980
October	1st to 10th	Day	46% 4 9% 23% 15% 3	1980
	11th to 20th	Day	41% 3 11% 31% 12% 1	1742
	21st to end	Day	48% 4 10% 22% 14% 2	1782
November	1st to 10th	Day	37% 3 13% 26% 17% 2	1671
	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	46% 4 9% 21% 16% 4	2280
	11th to 20th	Night	46% 4 9% 20% 16% 5%	2127
	21st to end	Night	44% 3 9% 18% 21% 6%	2098
April	1st to 10th	Night	48% 4 9% 19% 16% 4	1800
	11th to 20th	Night	44% 3 8% 24% 19% 2	1714
	21st to end	Night	50% 4 10% 19% 14% 4	1620
May	1st to 10th	Night	50% 5% 8% 22% 12% 3	1620
	11th to 20th	Night	50% 6% 10% 18% 13% 4	1571
	21st to end	Night	48% 6% 13% 19% 12% 2	1551
June	1st to 10th	Night	52% 5% 10% 20% 12% 1	1440
	11th to 20th	Night	45% 5% 12% 21% 14% 2	1440
	21st to end	Night	47% 5% 13% 23% 11% 1	1440
July	1st to 10th	Night	42% 6% 15% 22% 14% 1	1400
	11th to 20th	Night	40% 6% 16% 27% 11%	1392
	21st to end	Night	36% 6% 14% 30% 11% 1	1486
August	1st to 10th	Night	38% 6% 15% 27% 13% 1	1556
	11th to 20th	Night	41% 6% 16% 22% 14%	1596
	21st to end	Night	38% 5% 10% 26% 20% 1	1926
September	1st to 10th	Night	35% 6% 11% 28% 19% 1	1826
	11th to 20th	Night	34% 4 9% 29% 21% 2	1980
	21st to end	Night	37% 5% 9% 29% 18% 2	1980
October	1st to 10th	Night	45% 4 11% 23% 14% 3	1980
	11th to 20th	Night	41% 4 12% 28% 13% 1	2216
	21st to end	Night	49% 3 9% 23% 13% 2	2574
November	1st to 10th	Night	40% 5% 10% 25% 18% 3	2407
	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% 11% 4 1	449
	21st to end	Day	26% 20% 34% 13% 5% 2	462
April	1st to 10th	Day	32% 22% 28% 11% 5% 1	420
	11th to 20th	Day	28% 23% 28% 13% 7% 1	412
	21st to end	Day	32% 19% 30% 12% 5% 1	420
May	1st to 10th	Day	31% 21% 32% 11% 3 2	423
	11th to 20th	Day	21% 19% 37% 16% 5% 1	447
	21st to end	Day	19% 19% 33% 21% 7% 1	485
June	1st to 10th	Day	23% 17% 35% 18% 7% 1	450
	11th to 20th	Day	17% 19% 37% 20% 5% 2	450
	21st to end	Day	22% 13% 37% 18% 9% 2	450
July	1st to 10th	Day	19% 8% 36% 27% 8% 3	445
	11th to 20th	Day	15% 8% 35% 29% 10% 3	444
	21st to end	Day	14% 6% 41% 28% 9% 2	488
August	1st to 10th	Day	14% 10% 33% 28% 13% 3	446
	11th to 20th	Day	18% 8% 32% 24% 12% 5%	439
	21st to end	Day	15% 9% 33% 28% 10% 5%	495
September	1st to 10th	Day	17% 9% 30% 28% 12% 4	450
	11th to 20th	Day	20% 13% 30% 22% 9% 6%	450
	21st to end	Day	14% 12% 38% 22% 8% 6%	450
October	1st to 10th	Day	25% 14% 26% 23% 10% 2	450
	11th to 20th	Day	20% 16% 28% 25% 10% 1	378
	21st to end	Day	29% 14% 31% 18% 6% 1	396
November	1st to 10th	Day	22% 15% 32% 22% 7% 1	365
	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%	752
	21st to end	Night	26% 15% 35% 19% 5%	792
April	1st to 10th	Night	28% 17% 31% 20% 4	720
	11th to 20th	Night	23% 14% 33% 24% 6%	650
	21st to end	Night	25% 14% 31% 24% 6%	540
May	1st to 10th	Night	24% 9% 35% 25% 6% 1	540
	11th to 20th	Night	21% 13% 33% 27% 6% 1	509
	21st to end	Night	24% 8% 28% 31% 9% 1	389
June	1st to 10th	Night	23% 8% 29% 29% 10% 1	360
	11th to 20th	Night	23% 5% 27% 32% 13% 1	360
	21st to end	Night	23% 2 24% 38% 12%	360
July	1st to 10th	Night	18% 3 22% 41% 15% 1	350
	11th to 20th	Night	16% 3 21% 40% 20% 1	348
	21st to end	Night	14% 4 19% 47% 14% 2	394
August	1st to 10th	Night	14% 5% 24% 41% 16%	492
	11th to 20th	Night	15% 6% 24% 35% 18% 2	532
	21st to end	Night	16% 6% 23% 36% 18% 2	738
September	1st to 10th	Night	14% 4 26% 37% 18% 1	720
	11th to 20th	Night	17% 8% 28% 26% 18% 4	720
	21st to end	Night	18% 7% 28% 29% 15% 2	720
October	1st to 10th	Night	23% 10% 25% 26% 15% 1	720
	11th to 20th	Night	19% 11% 31% 27% 11% 1	720
	21st to end	Night	28% 13% 30% 24% 6%	792
November	1st to 10th	Night	19% 13% 34% 26% 7% 1	740
	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 2024-03-15 14:01:45. Version ac07

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