Rutenbeck Observatory
Clear Sky Chart
History

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

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	13% 8% 3 7% 5% 4 4 4 6% 7% 38%	101519
	Night	13% 9% 3 7% 5% 4 4 3 5% 6% 40%	97730
Transparency	Day	42% 7% 13% 23% 14% 2	105072
	Night	43% 6% 12% 23% 15% 2	102317
Seeing	Day	15% 9% 28% 27% 15% 5%	15860
	Night	17% 9% 31% 31% 12% 1	25694

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	11% 12% 9% 15% 6% 6% 4 4 4 5% 24%	2527
	11th to 20th	Day	11% 11% 4 13% 9% 5% 6% 5% 8% 5% 20%	2530
	21st to end	Day	17% 18% 9% 12% 6% 4 4 3 5% 6% 17%	3071
February	1st to 10th	Day	12% 14% 5% 9% 6% 5% 5% 4 4 5% 29%	1710
	11th to 20th	Day	14% 10% 2 7% 5% 6% 5% 3 5% 7% 36%	1770
	21st to end	Day	13% 13% 4 10% 5% 4 4 3 5% 8% 31%	1570
March	1st to 10th	Day	15% 11% 4 7% 4 4 3 3 5% 6% 39%	3120
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 4 7% 7% 44%	3448
	21st to end	Day	21% 13% 5% 11% 5% 4 5% 4 5% 6% 21%	4059
April	1st to 10th	Day	16% 11% 3 9% 5% 4 4 4 4 7% 33%	2280
	11th to 20th	Day	16% 9% 3 8% 5% 5% 4 3 4 7% 36%	2254
	21st to end	Day	21% 9% 3 6% 4 4 4 4 5% 6% 34%	2280
May	1st to 10th	Day	15% 8% 3 9% 4 4 4 4 5% 8% 36%	4223
	11th to 20th	Day	16% 7% 2 6% 4 4 4 3 5% 7% 41%	4399
	21st to end	Day	12% 6% 3 6% 5% 4 4 4 6% 8% 42%	4824
June	1st to 10th	Day	9% 5% 2 5% 5% 4 5% 5% 7% 8% 45%	2660
	11th to 20th	Day	10% 5% 2 5% 4 4 5% 4 6% 9% 46%	2660
	21st to end	Day	10% 7% 2 6% 6% 4 5% 4 6% 8% 40%	2660
July	1st to 10th	Day	9% 8% 3 7% 6% 5% 6% 4 7% 10% 34%	4440
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 6% 9% 53%	4440
	21st to end	Day	7% 5% 2 7% 5% 5% 5% 5% 7% 10% 40%	4813
August	1st to 10th	Day	7% 5% 2 6% 4 5% 5% 6% 8% 10% 42%	4178
	11th to 20th	Day	10% 5% 2 6% 4 4 5% 4 6% 9% 43%	3829
	21st to end	Day	8% 6% 2 6% 4 4 5% 3 6% 8% 50%	4180
September	1st to 10th	Day	13% 4 2 5% 4 3 4 4 6% 8% 48%	2280
	11th to 20th	Day	10% 4 2 3 3 4 3 3 5% 6% 55%	2249
	21st to end	Day	10% 5% 2 6% 4 3 4 3 6% 7% 48%	2085
October	1st to 10th	Day	12% 6% 3 5% 3 4 3 4 5% 6% 48%	1900
	11th to 20th	Day	16% 9% 3 6% 4 4 4 3 4 7% 41%	1900
	21st to end	Day	19% 8% 3 6% 4 3 4 2 5% 6% 41%	1976
November	1st to 10th	Day	12% 8% 3 5% 4 4 3 4 5% 7% 44%	1762
	11th to 20th	Day	14% 12% 4 9% 5% 4 4 3 5% 7% 33%	1701
	21st to end	Day	17% 12% 4 8% 4 3 4 3 4 5% 36%	1520
December	1st to 10th	Day	15% 13% 3 11% 5% 4 4 3 5% 7% 31%	1520
	11th to 20th	Day	14% 13% 5% 9% 5% 6% 4 3 5% 6% 29%	1918
	21st to end	Day	22% 19% 8% 13% 6% 4 4 3 3 5% 15%	2783
January	1st to 10th	Night	13% 13% 7% 14% 5% 4 4 3 4 5% 29%	4428
	11th to 20th	Night	13% 16% 6% 12% 6% 4 4 5% 7% 5% 21%	4440
	21st to end	Night	18% 19% 7% 10% 5% 3 3 3 4 4 23%	4592
February	1st to 10th	Night	14% 13% 4 8% 6% 4 4 3 4 5% 34%	2470
	11th to 20th	Night	13% 10% 3 7% 5% 4 5% 3 5% 6% 41%	2297
	21st to end	Night	15% 12% 4 7% 4 4 3 2 4 6% 38%	1884
March	1st to 10th	Night	19% 9% 3 5% 3 3 4 2 3 5% 42%	3733
	11th to 20th	Night	9% 6% 2 7% 5% 4 3 3 5% 6% 50%	3526
	21st to end	Night	23% 12% 5% 10% 5% 5% 4 3 4 4 25%	3572
April	1st to 10th	Night	17% 10% 2 6% 4 4 3 3 5% 6% 40%	1900
	11th to 20th	Night	18% 8% 3 6% 5% 3 3 3 4 5% 41%	1875
	21st to end	Night	17% 9% 3 7% 5% 5% 4 3 5% 7% 35%	1900
May	1st to 10th	Night	18% 8% 2 8% 5% 5% 4 4 6% 6% 35%	2673
	11th to 20th	Night	14% 6% 3 6% 6% 5% 5% 4 5% 6% 41%	2506
	21st to end	Night	8% 5% 2 5% 4 4 5% 4 7% 8% 47%	2743
June	1st to 10th	Night	7% 5% 2 5% 5% 4 4 5% 7% 8% 49%	1520
	11th to 20th	Night	8% 6% 2 5% 4 4 4 5% 7% 9% 46%	1520
	21st to end	Night	10% 5% 2 5% 5% 6% 6% 4 6% 8% 43%	1520
July	1st to 10th	Night	14% 6% 2 7% 5% 4 5% 3 6% 8% 40%	2530
	11th to 20th	Night	5% 4 2 5% 3 3 4 4 6% 8% 58%	2530
	21st to end	Night	5% 4 2 5% 4 5% 5% 5% 7% 10% 47%	2750
August	1st to 10th	Night	4 4 2 5% 4 4 5% 4 7% 8% 53%	2759
	11th to 20th	Night	6% 4 2 6% 4 3 4 4 6% 7% 53%	3003
	21st to end	Night	8% 4 2 5% 4 3 4 3 5% 8% 53%	3476
September	1st to 10th	Night	9% 5% 2 4 3 3 3 2 4 6% 57%	1900
	11th to 20th	Night	10% 4 1 5% 4 4 4 3 6% 8% 51%	1911
	21st to end	Night	8% 5% 2 6% 4 4 4 3 5% 7% 52%	2091
October	1st to 10th	Night	11% 5% 2 5% 4 3 3 2 4 7% 54%	2280
	11th to 20th	Night	14% 8% 3 6% 4 3 4 3 4 6% 47%	2280
	21st to end	Night	19% 8% 3 7% 4 4 4 3 4 6% 38%	2621
November	1st to 10th	Night	12% 7% 2 6% 3 3 3 2 5% 6% 51%	2536
	11th to 20th	Night	15% 9% 4 8% 5% 4 3 3 5% 5% 38%	2481
	21st to end	Night	17% 9% 3 7% 4 3 4 3 4 6% 39%	2660
December	1st to 10th	Night	15% 11% 4 10% 5% 4 5% 3 5% 6% 32%	2660
	11th to 20th	Night	15% 11% 5% 9% 5% 4 4 4 5% 7% 32%	3279
	21st to end	Night	21% 17% 6% 11% 5% 5% 4 4 5% 5% 18%	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	60% 7% 12% 15% 6%	2528
	11th to 20th	Day	61% 5% 13% 12% 8% 1	2530
	21st to end	Day	69% 6% 11% 10% 5%	3071
February	1st to 10th	Day	55% 5% 13% 17% 9% 1	1710
	11th to 20th	Day	47% 6% 12% 24% 10% 1	1779
	21st to end	Day	51% 7% 12% 21% 8% 2	1570
March	1st to 10th	Day	44% 6% 13% 22% 12% 2	3120
	11th to 20th	Day	36% 7% 14% 30% 12%	3448
	21st to end	Day	60% 9% 14% 13% 3 1	4059
April	1st to 10th	Day	51% 7% 12% 21% 9%	2280
	11th to 20th	Day	48% 6% 11% 21% 12% 2	2254
	21st to end	Day	49% 8% 12% 18% 12% 2	2280
May	1st to 10th	Day	44% 8% 12% 20% 14% 1	4261
	11th to 20th	Day	41% 7% 11% 28% 13%	4403
	21st to end	Day	37% 8% 12% 24% 15% 4	4837
June	1st to 10th	Day	33% 9% 14% 25% 17% 2	2660
	11th to 20th	Day	34% 6% 13% 22% 21% 3	2660
	21st to end	Day	39% 9% 13% 24% 13% 2	2660
July	1st to 10th	Day	44% 8% 13% 25% 9% 2	4371
	11th to 20th	Day	27% 7% 17% 31% 17% 2	4365
	21st to end	Day	35% 10% 17% 18% 18% 2	4662
August	1st to 10th	Day	33% 9% 17% 27% 13% 1	4163
	11th to 20th	Day	35% 7% 15% 27% 15% 1	3867
	21st to end	Day	31% 6% 12% 32% 16% 2	4179
September	1st to 10th	Day	34% 7% 12% 25% 19% 3	2280
	11th to 20th	Day	29% 6% 12% 30% 20% 3	2249
	21st to end	Day	34% 6% 11% 29% 19% 2	2085
October	1st to 10th	Day	23% 4 6% 32% 34% 1	3160
	11th to 20th	Day	29% 4 11% 25% 28% 3	3140
	21st to end	Day	41% 4 10% 29% 13% 3	3240
November	1st to 10th	Day	39% 6% 15% 26% 12% 2	1762
	11th to 20th	Day	51% 5% 14% 20% 9% 1	1701
	21st to end	Day	51% 6% 14% 21% 8%	1520
December	1st to 10th	Day	53% 6% 14% 18% 8% 1	1520
	11th to 20th	Day	54% 7% 14% 17% 8% 1	1915
	21st to end	Day	74% 5% 8% 8% 4	2783
January	1st to 10th	Night	56% 7% 13% 17% 8%	4428
	11th to 20th	Night	61% 5% 13% 14% 8%	4440
	21st to end	Night	64% 6% 9% 15% 5% 1	4592
February	1st to 10th	Night	51% 5% 11% 19% 12% 1	2470
	11th to 20th	Night	45% 5% 12% 24% 13% 1	2298
	21st to end	Night	48% 5% 12% 21% 12% 2	1884
March	1st to 10th	Night	44% 5% 12% 23% 14% 2	3733
	11th to 20th	Night	34% 6% 11% 29% 18% 2	3526
	21st to end	Night	62% 7% 10% 16% 5% 1	3572
April	1st to 10th	Night	45% 6% 11% 23% 14% 2	1900
	11th to 20th	Night	45% 5% 8% 21% 17% 4	1875
	21st to end	Night	47% 7% 11% 21% 12% 2	1900
May	1st to 10th	Night	46% 10% 10% 16% 15% 3	2700
	11th to 20th	Night	40% 10% 13% 23% 14% 1	2507
	21st to end	Night	30% 10% 13% 25% 20% 3	2751
June	1st to 10th	Night	29% 9% 16% 24% 19% 3	1520
	11th to 20th	Night	33% 7% 10% 23% 23% 3	1520
	21st to end	Night	37% 10% 12% 21% 16% 4	1520
July	1st to 10th	Night	43% 6% 14% 22% 13% 3	2490
	11th to 20th	Night	24% 6% 15% 35% 19% 2	2482
	21st to end	Night	29% 10% 19% 20% 18% 5%	2662
August	1st to 10th	Night	25% 9% 16% 31% 18% 2	2750
	11th to 20th	Night	28% 7% 15% 31% 17% 1	3031
	21st to end	Night	29% 7% 11% 30% 19% 4	3476
September	1st to 10th	Night	28% 6% 11% 25% 27% 3	1900
	11th to 20th	Night	30% 6% 10% 30% 20% 4	1911
	21st to end	Night	32% 6% 11% 28% 20% 3	2091
October	1st to 10th	Night	23% 4 7% 34% 30% 3	3800
	11th to 20th	Night	29% 4 9% 22% 32% 4	3779
	21st to end	Night	44% 4 8% 24% 16% 3	4307
November	1st to 10th	Night	35% 6% 12% 27% 18% 3	2536
	11th to 20th	Night	47% 4 12% 22% 13% 1	2481
	21st to end	Night	47% 5% 12% 25% 10% 1	2660
December	1st to 10th	Night	52% 5% 13% 21% 8% 1	2660
	11th to 20th	Night	50% 6% 14% 22% 8% 1	3281
	21st to end	Night	67% 7% 9% 12% 4	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	19% 11% 33% 26% 10% 1	270
	11th to 20th	Day	21% 13% 43% 17% 6%	270
	21st to end	Day	20% 9% 38% 25% 7% 1	297
February	1st to 10th	Day	19% 15% 39% 23% 5%	270
	11th to 20th	Day	22% 19% 30% 23% 7%	270
	21st to end	Day	20% 16% 42% 16% 5%	225
March	1st to 10th	Day	15% 20% 41% 19% 6%	270
	11th to 20th	Day	22% 18% 33% 20% 6% 1	270
	21st to end	Day	26% 15% 34% 18% 6% 2	439
April	1st to 10th	Day	23% 13% 36% 23% 5%	460
	11th to 20th	Day	21% 17% 29% 20% 11% 2	452
	21st to end	Day	26% 11% 31% 21% 9% 1	460
May	1st to 10th	Day	19% 11% 32% 27% 8% 2	550
	11th to 20th	Day	21% 10% 28% 24% 13% 4	675
	21st to end	Day	15% 11% 25% 26% 16% 7%	734
June	1st to 10th	Day	9% 6% 25% 34% 19% 6%	680
	11th to 20th	Day	10% 5% 32% 32% 18% 4	680
	21st to end	Day	13% 8% 28% 30% 16% 5%	680
July	1st to 10th	Day	10% 4 16% 30% 26% 14%	671
	11th to 20th	Day	9% 5% 21% 33% 22% 10%	668
	21st to end	Day	6% 2 20% 39% 27% 6%	739
August	1st to 10th	Day	7% 3 21% 33% 28% 9%	676
	11th to 20th	Day	12% 4 19% 29% 23% 13%	543
	21st to end	Day	8% 3 17% 35% 27% 10%	539
September	1st to 10th	Day	14% 6% 20% 28% 23% 9%	490
	11th to 20th	Day	8% 3 18% 38% 23% 10%	490
	21st to end	Day	11% 10% 29% 24% 20% 7%	485
October	1st to 10th	Day	14% 8% 28% 28% 18% 4	300
	11th to 20th	Day	20% 21% 32% 18% 8% 1	300
	21st to end	Day	27% 16% 28% 24% 4 1	330
November	1st to 10th	Day	17% 14% 34% 22% 9% 4	300
	11th to 20th	Day	23% 17% 33% 17% 7% 3	270
	21st to end	Day	24% 13% 33% 24% 5%	270
December	1st to 10th	Day	16% 15% 39% 21% 7% 2	270
	11th to 20th	Day	17% 11% 39% 24% 9%	270
	21st to end	Day	27% 10% 43% 18% 2	297
January	1st to 10th	Night	18% 11% 38% 26% 6%	950
	11th to 20th	Night	18% 11% 37% 27% 5% 1	950
	21st to end	Night	20% 12% 35% 29% 4	1045
February	1st to 10th	Night	22% 9% 39% 26% 5%	950
	11th to 20th	Night	18% 11% 38% 28% 5%	822
	21st to end	Night	22% 11% 40% 23% 3 1	628
March	1st to 10th	Night	23% 9% 38% 24% 5%	760
	11th to 20th	Night	16% 10% 35% 32% 7%	603
	21st to end	Night	26% 10% 34% 25% 5%	627
April	1st to 10th	Night	23% 11% 37% 24% 4	570
	11th to 20th	Night	21% 12% 31% 28% 7% 1	563
	21st to end	Night	21% 10% 31% 29% 7% 1	570
May	1st to 10th	Night	17% 8% 36% 31% 7% 1	570
	11th to 20th	Night	17% 6% 30% 33% 13%	561
	21st to end	Night	12% 5% 30% 35% 17% 2	617
June	1st to 10th	Night	7% 5% 23% 49% 16% 1	570
	11th to 20th	Night	11% 3 29% 42% 14% 1	570
	21st to end	Night	10% 5% 28% 40% 16% 1	570
July	1st to 10th	Night	10% 3 12% 41% 30% 4	555
	11th to 20th	Night	7% 3 18% 42% 27% 3	552
	21st to end	Night	8% 1 14% 45% 29% 2	624
August	1st to 10th	Night	4 2 16% 42% 32% 4	567
	11th to 20th	Night	6% 2 13% 42% 32% 5%	564
	21st to end	Night	9% 1 15% 44% 28% 3	627
September	1st to 10th	Night	11% 3 18% 38% 26% 4	570
	11th to 20th	Night	10% 3 22% 35% 27% 4	581
	21st to end	Night	10% 9% 26% 33% 21% 1	760
October	1st to 10th	Night	12% 7% 28% 33% 19% 1	760
	11th to 20th	Night	19% 13% 28% 28% 12%	760
	21st to end	Night	23% 11% 31% 26% 8%	836
November	1st to 10th	Night	16% 8% 39% 27% 9% 1	780
	11th to 20th	Night	19% 14% 36% 24% 6%	767
	21st to end	Night	21% 12% 33% 26% 7%	950
December	1st to 10th	Night	21% 12% 37% 23% 6%	950
	11th to 20th	Night	22% 10% 33% 28% 7%	950
	21st to end	Night	27% 11% 35% 24% 3	1045

Page generated at 2024-11-08 05:44:46. Version ac07

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