Stardust Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Stardust Observatory clear sky chart from 2005-11-06 to 2024-03-08.

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	16% 9% 4 7% 6% 4 5% 5% 5% 7% 32%	78557
	Night	16% 9% 4 7% 6% 3 5% 5% 5% 7% 35%	81004
Transparency	Day	51% 5% 11% 20% 11% 2	78267
	Night	48% 5% 12% 21% 12% 1	80813
Seeing	Day	22% 13% 27% 22% 12% 4	13804
	Night	21% 12% 25% 29% 11% 1	23435

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	15% 16% 8% 9% 6% 3 4 4 4 5% 27%	2526
	11th to 20th	Day	11% 17% 10% 13% 9% 4 4 4 4 4 19%	2840
	21st to end	Day	21% 18% 8% 11% 8% 4 4 4 4 4 17%	3124
February	1st to 10th	Day	15% 15% 6% 10% 7% 3 5% 4 4 6% 24%	1710
	11th to 20th	Day	14% 10% 5% 10% 7% 5% 5% 5% 7% 6% 27%	1663
	21st to end	Day	18% 11% 4 9% 6% 4 5% 4 5% 6% 29%	1544
March	1st to 10th	Day	15% 10% 4 6% 6% 4 5% 4 4 7% 35%	2050
	11th to 20th	Day	18% 11% 4 8% 6% 4 5% 5% 4 6% 29%	1980
	21st to end	Day	18% 10% 4 7% 6% 4 5% 4 4 5% 33%	2183
April	1st to 10th	Day	16% 9% 4 6% 7% 3 5% 5% 5% 7% 33%	2160
	11th to 20th	Day	16% 10% 3 6% 5% 4 4 4 6% 6% 35%	2134
	21st to end	Day	22% 7% 4 6% 6% 4 5% 4 5% 6% 33%	2236
May	1st to 10th	Day	20% 7% 3 7% 5% 3 5% 6% 5% 7% 31%	2340
	11th to 20th	Day	21% 7% 3 6% 6% 3 5% 4 5% 7% 32%	2428
	21st to end	Day	15% 6% 2 6% 6% 3 5% 5% 6% 8% 38%	2725
June	1st to 10th	Day	14% 6% 3 6% 7% 4 6% 5% 6% 8% 35%	2520
	11th to 20th	Day	16% 5% 3 6% 6% 4 6% 6% 6% 8% 35%	2520
	21st to end	Day	13% 5% 2 5% 5% 3 5% 5% 6% 10% 39%	2520
July	1st to 10th	Day	10% 6% 3 6% 7% 4 6% 6% 7% 9% 37%	2520
	11th to 20th	Day	9% 5% 3 6% 7% 4 6% 6% 7% 10% 38%	2484
	21st to end	Day	11% 6% 3 6% 6% 4 6% 6% 7% 8% 36%	2547
August	1st to 10th	Day	11% 5% 2 5% 7% 4 8% 8% 8% 10% 33%	2327
	11th to 20th	Day	14% 6% 2 6% 7% 4 6% 5% 7% 8% 34%	2290
	21st to end	Day	14% 6% 3 6% 5% 4 5% 6% 7% 8% 36%	2376
September	1st to 10th	Day	18% 5% 2 5% 5% 3 5% 4 4 6% 42%	2160
	11th to 20th	Day	15% 4 2 4 4 2 4 4 5% 7% 47%	2138
	21st to end	Day	20% 6% 3 5% 5% 3 4 4 6% 7% 37%	1890
October	1st to 10th	Day	17% 8% 3 6% 5% 4 4 4 5% 7% 38%	1800
	11th to 20th	Day	18% 7% 3 7% 5% 4 4 6% 6% 6% 35%	1800
	21st to end	Day	19% 9% 3 6% 5% 3 5% 5% 4 6% 35%	1980
November	1st to 10th	Day	12% 7% 3 6% 5% 3 5% 6% 5% 6% 42%	1756
	11th to 20th	Day	16% 11% 4 7% 6% 4 5% 5% 6% 6% 31%	1564
	21st to end	Day	17% 11% 3 7% 7% 4 6% 4 6% 6% 29%	1520
December	1st to 10th	Day	18% 14% 6% 8% 7% 3 6% 5% 5% 6% 21%	1520
	11th to 20th	Day	18% 14% 6% 8% 4 3 4 4 4 6% 27%	1910
	21st to end	Day	22% 16% 6% 9% 8% 3 6% 5% 4 4 17%	2772
January	1st to 10th	Night	14% 13% 7% 10% 8% 4 4 5% 6% 6% 25%	4415
	11th to 20th	Night	15% 14% 6% 12% 7% 3 5% 4 5% 6% 22%	4120
	21st to end	Night	23% 12% 6% 11% 6% 4 4 3 4 5% 22%	4532
February	1st to 10th	Night	15% 10% 5% 9% 6% 3 5% 4 4 7% 30%	2470
	11th to 20th	Night	16% 9% 3 7% 7% 4 6% 6% 5% 6% 30%	2403
	21st to end	Night	16% 11% 4 9% 6% 4 5% 4 4 5% 32%	1908
March	1st to 10th	Night	15% 8% 3 5% 5% 3 5% 5% 6% 6% 39%	2069
	11th to 20th	Night	17% 9% 4 6% 5% 3 5% 4 4 5% 37%	1980
	21st to end	Night	18% 8% 3 7% 6% 3 5% 4 4 6% 38%	2171
April	1st to 10th	Night	17% 11% 4 8% 6% 3 4 4 5% 6% 33%	1800
	11th to 20th	Night	16% 7% 2 6% 5% 3 4 6% 6% 6% 39%	1775
	21st to end	Night	18% 6% 2 6% 5% 3 4 5% 5% 7% 37%	1738
May	1st to 10th	Night	20% 6% 3 6% 6% 4 5% 5% 5% 6% 36%	1620
	11th to 20th	Night	19% 6% 3 6% 3 3 5% 5% 5% 6% 39%	1461
	21st to end	Night	12% 6% 3 5% 5% 3 4 5% 6% 9% 43%	1550
June	1st to 10th	Night	13% 5% 3 5% 5% 2 4 4 6% 8% 45%	1440
	11th to 20th	Night	12% 6% 3 7% 5% 3 4 6% 7% 9% 39%	1440
	21st to end	Night	11% 5% 2 4 4 4 5% 4 8% 10% 44%	1440
July	1st to 10th	Night	11% 4 3 5% 5% 3 4 5% 5% 8% 46%	1440
	11th to 20th	Night	7% 4 2 5% 4 3 3 6% 7% 10% 48%	1472
	21st to end	Night	10% 4 2 5% 6% 4 5% 6% 7% 9% 43%	1771
August	1st to 10th	Night	8% 5% 3 5% 5% 3 5% 5% 6% 10% 45%	1611
	11th to 20th	Night	12% 6% 2 5% 5% 4 5% 5% 6% 7% 42%	1598
	21st to end	Night	12% 5% 2 5% 5% 3 5% 5% 6% 9% 44%	1975
September	1st to 10th	Night	17% 4 2 4 5% 3 5% 4 5% 8% 44%	1800
	11th to 20th	Night	13% 5% 2 4 3 3 3 4 4 8% 51%	1819
	21st to end	Night	17% 6% 3 5% 4 4 5% 4 4 7% 42%	2069
October	1st to 10th	Night	17% 6% 2 5% 4 3 4 4 4 7% 44%	2160
	11th to 20th	Night	17% 7% 2 6% 5% 2 3 5% 5% 7% 42%	2160
	21st to end	Night	21% 8% 3 4 4 3 4 4 5% 6% 37%	2376
November	1st to 10th	Night	11% 6% 2 5% 4 2 5% 4 4 6% 50%	2320
	11th to 20th	Night	17% 9% 4 5% 5% 2 5% 4 5% 7% 36%	2612
	21st to end	Night	17% 10% 5% 6% 5% 3 5% 5% 6% 6% 33%	2660
December	1st to 10th	Night	19% 10% 3 8% 6% 4 5% 5% 6% 7% 26%	2660
	11th to 20th	Night	18% 11% 4 8% 6% 3 6% 5% 4 6% 30%	3285
	21st to end	Night	20% 12% 5% 8% 7% 4 6% 6% 6% 6% 21%	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	59% 6% 11% 17% 5% 2	2527
	11th to 20th	Day	69% 3 8% 12% 7% 1	2840
	21st to end	Day	72% 4 7% 12% 4 1	3124
February	1st to 10th	Day	61% 4 12% 15% 7% 1	1710
	11th to 20th	Day	55% 6% 9% 22% 8% 1	1672
	21st to end	Day	57% 3 11% 19% 8% 3	1544
March	1st to 10th	Day	50% 4 12% 24% 9% 1	2050
	11th to 20th	Day	56% 4 10% 18% 10% 2	1980
	21st to end	Day	54% 3 9% 19% 13% 2	2183
April	1st to 10th	Day	51% 4 10% 20% 12% 2	2160
	11th to 20th	Day	48% 5% 9% 19% 16% 3	2134
	21st to end	Day	52% 4 8% 21% 13% 3	2236
May	1st to 10th	Day	52% 5% 10% 19% 12% 2	2340
	11th to 20th	Day	51% 5% 12% 17% 13% 2	2432
	21st to end	Day	44% 6% 15% 22% 10% 2	2725
June	1st to 10th	Day	46% 6% 11% 23% 14% 1	2520
	11th to 20th	Day	46% 6% 12% 21% 13% 2	2520
	21st to end	Day	40% 6% 13% 27% 13%	2520
July	1st to 10th	Day	43% 8% 11% 21% 13% 3	2450
	11th to 20th	Day	39% 9% 12% 25% 15% 1	2409
	21st to end	Day	42% 7% 12% 22% 16% 1	2405
August	1st to 10th	Day	42% 9% 14% 24% 12%	2314
	11th to 20th	Day	45% 7% 12% 22% 12% 1	2290
	21st to end	Day	44% 6% 10% 22% 15% 3	2376
September	1st to 10th	Day	44% 4 10% 23% 17% 3	2160
	11th to 20th	Day	36% 5% 11% 27% 19% 2	2138
	21st to end	Day	45% 5% 11% 21% 17% 1	1890
October	1st to 10th	Day	47% 5% 11% 21% 15% 1	1800
	11th to 20th	Day	49% 6% 11% 24% 11%	1800
	21st to end	Day	50% 5% 11% 22% 11% 1	1980
November	1st to 10th	Day	41% 5% 13% 21% 16% 3	1756
	11th to 20th	Day	54% 4 10% 20% 10% 2	1564
	21st to end	Day	55% 4 12% 21% 8%	1520
December	1st to 10th	Day	62% 6% 12% 14% 6%	1520
	11th to 20th	Day	59% 5% 12% 19% 5%	1906
	21st to end	Day	69% 6% 10% 11% 3	2772
January	1st to 10th	Night	57% 4 12% 19% 7% 1	4415
	11th to 20th	Night	62% 5% 13% 14% 6% 1	4120
	21st to end	Night	67% 3 8% 16% 5% 1	4532
February	1st to 10th	Night	54% 5% 12% 21% 8% 1	2470
	11th to 20th	Night	53% 5% 10% 19% 12% 1	2405
	21st to end	Night	55% 5% 9% 19% 11% 2	1908
March	1st to 10th	Night	43% 6% 12% 26% 13% 1	2069
	11th to 20th	Night	48% 5% 10% 22% 13% 2	1980
	21st to end	Night	49% 4 9% 20% 16% 3	2171
April	1st to 10th	Night	53% 4 10% 19% 14% 1	1800
	11th to 20th	Night	44% 6% 10% 23% 15% 2	1775
	21st to end	Night	46% 4 10% 23% 14% 3	1738
May	1st to 10th	Night	49% 6% 10% 19% 12% 4	1620
	11th to 20th	Night	46% 5% 11% 19% 16% 2	1462
	21st to end	Night	38% 7% 16% 23% 14% 3	1551
June	1st to 10th	Night	38% 5% 14% 26% 15% 2	1440
	11th to 20th	Night	40% 8% 13% 23% 15% 2	1440
	21st to end	Night	34% 8% 13% 29% 14% 1	1440
July	1st to 10th	Night	37% 8% 13% 24% 15% 3	1400
	11th to 20th	Night	30% 8% 15% 27% 19% 2	1424
	21st to end	Night	34% 8% 17% 22% 16% 2	1672
August	1st to 10th	Night	34% 8% 16% 26% 15% 1	1600
	11th to 20th	Night	39% 7% 15% 23% 16% 1	1598
	21st to end	Night	37% 6% 13% 24% 15% 3	1975
September	1st to 10th	Night	39% 5% 11% 24% 17% 3	1800
	11th to 20th	Night	32% 5% 11% 31% 19% 2	1819
	21st to end	Night	43% 5% 10% 23% 18% 1	2069
October	1st to 10th	Night	41% 5% 13% 25% 15% 1	2160
	11th to 20th	Night	43% 5% 12% 25% 14% 1	2160
	21st to end	Night	47% 4 10% 23% 14% 1	2376
November	1st to 10th	Night	37% 4 13% 25% 18% 3	2320
	11th to 20th	Night	47% 5% 10% 23% 13% 3	2612
	21st to end	Night	50% 4 13% 23% 9% 1	2660
December	1st to 10th	Night	56% 7% 13% 18% 6%	2660
	11th to 20th	Night	56% 5% 11% 20% 7%	3288
	21st to end	Night	61% 7% 12% 16% 3	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	28% 23% 32% 10% 5% 2	184
	11th to 20th	Day	35% 20% 32% 12% 1	270
	21st to end	Day	26% 19% 36% 14% 4 1	297
February	1st to 10th	Day	30% 20% 34% 13% 3	270
	11th to 20th	Day	35% 21% 35% 9% 1	270
	21st to end	Day	35% 17% 29% 17% 2	356
March	1st to 10th	Day	29% 19% 28% 20% 4	448
	11th to 20th	Day	29% 20% 30% 15% 5% 1	420
	21st to end	Day	29% 18% 30% 15% 5% 3	462
April	1st to 10th	Day	27% 18% 30% 18% 6% 1	420
	11th to 20th	Day	21% 20% 25% 19% 11% 4	412
	21st to end	Day	31% 14% 32% 15% 7% 2	420
May	1st to 10th	Day	28% 14% 30% 13% 11% 4	423
	11th to 20th	Day	26% 15% 27% 17% 12% 4	447
	21st to end	Day	20% 8% 26% 22% 17% 7%	485
June	1st to 10th	Day	17% 14% 26% 27% 11% 4	450
	11th to 20th	Day	21% 9% 24% 27% 14% 4	450
	21st to end	Day	15% 8% 30% 29% 14% 4	450
July	1st to 10th	Day	15% 6% 23% 26% 19% 11%	445
	11th to 20th	Day	9% 4 29% 31% 20% 8%	444
	21st to end	Day	15% 6% 28% 29% 17% 6%	488
August	1st to 10th	Day	11% 5% 24% 28% 22% 10%	446
	11th to 20th	Day	14% 5% 22% 28% 20% 11%	439
	21st to end	Day	16% 5% 24% 28% 15% 13%	495
September	1st to 10th	Day	20% 5% 19% 27% 19% 10%	450
	11th to 20th	Day	17% 4 19% 28% 24% 10%	450
	21st to end	Day	24% 9% 24% 22% 15% 6%	450
October	1st to 10th	Day	22% 9% 19% 24% 20% 6%	450
	11th to 20th	Day	22% 14% 29% 24% 10% 1	450
	21st to end	Day	24% 14% 32% 23% 6% 1	495
November	1st to 10th	Day	18% 15% 29% 24% 13% 2	406
	11th to 20th	Day	25% 21% 29% 16% 8%	224
	21st to end	Day	24% 17% 38% 18% 2 1	180
December	1st to 10th	Day	32% 19% 34% 9% 5% 1	180
	11th to 20th	Day	27% 22% 31% 18% 2	180
	21st to end	Day	29% 18% 30% 17% 6%	198
January	1st to 10th	Night	24% 19% 33% 20% 4	760
	11th to 20th	Night	29% 14% 31% 23% 3	760
	21st to end	Night	23% 18% 33% 23% 3	836
February	1st to 10th	Night	26% 17% 29% 26% 2	760
	11th to 20th	Night	28% 21% 32% 18% 1	743
	21st to end	Night	28% 16% 32% 21% 2	628
March	1st to 10th	Night	24% 15% 33% 25% 3	751
	11th to 20th	Night	27% 15% 29% 23% 6% 1	720
	21st to end	Night	23% 15% 32% 23% 6% 1	792
April	1st to 10th	Night	26% 17% 29% 23% 5%	720
	11th to 20th	Night	20% 13% 32% 26% 8% 1	711
	21st to end	Night	23% 12% 28% 30% 7%	658
May	1st to 10th	Night	24% 7% 24% 33% 11% 1	540
	11th to 20th	Night	20% 8% 27% 35% 10% 1	400
	21st to end	Night	14% 6% 21% 38% 20% 2	389
June	1st to 10th	Night	15% 4 21% 41% 19% 1	360
	11th to 20th	Night	16% 5% 23% 38% 18% 1	360
	21st to end	Night	12% 5% 22% 44% 16% 1	360
July	1st to 10th	Night	13% 5% 16% 43% 20% 4	350
	11th to 20th	Night	8% 2 17% 42% 29% 3	380
	21st to end	Night	11% 3 17% 44% 24% 1	591
August	1st to 10th	Night	9% 2 15% 43% 30% 2	537
	11th to 20th	Night	15% 5% 10% 38% 27% 5%	534
	21st to end	Night	14% 4 16% 34% 29% 3	787
September	1st to 10th	Night	18% 3 16% 35% 23% 4	720
	11th to 20th	Night	15% 4 16% 32% 28% 5%	720
	21st to end	Night	19% 8% 18% 31% 21% 3	720
October	1st to 10th	Night	20% 7% 20% 30% 20% 3	720
	11th to 20th	Night	20% 13% 25% 31% 11% 1	720
	21st to end	Night	26% 12% 23% 31% 7% 1	792
November	1st to 10th	Night	16% 11% 27% 33% 12% 1	740
	11th to 20th	Night	23% 17% 24% 26% 8% 1	760
	21st to end	Night	24% 15% 28% 28% 5% 1	760
December	1st to 10th	Night	29% 15% 30% 21% 5%	760
	11th to 20th	Night	26% 16% 29% 26% 4	760
	21st to end	Night	26% 15% 29% 27% 2	836

Page generated at 2024-03-05 07:24:00. Version ac07

Copyright © 2024 Attilla Danko.