Hahnenberg Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hahnenberg Observatory clear sky chart from 2005-11-06 to 2024-11-30.

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% 11% 4 10% 6% 4 4 3 5% 6% 34%	101364
	Night	14% 13% 5% 11% 6% 5% 4 3 4 5% 28%	98332
Transparency	Day	50% 6% 11% 21% 11% 1	104874
	Night	57% 6% 10% 17% 9% 1	102910
Seeing	Day	17% 9% 26% 27% 16% 4	15835
	Night	20% 10% 26% 29% 13% 2	25721

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	12% 24% 16% 21% 8% 6% 2 1 2 3 5%	2527
	11th to 20th	Day	13% 18% 9% 24% 17% 9% 2 2 2 2 3	2530
	21st to end	Day	17% 22% 11% 16% 8% 5% 4 3 3 3 7%	2783
February	1st to 10th	Day	9% 19% 7% 17% 15% 7% 4 2 3 4 12%	1613
	11th to 20th	Day	12% 15% 7% 18% 11% 7% 5% 3 3 5% 15%	1848
	21st to end	Day	12% 18% 6% 12% 9% 6% 5% 4 6% 5% 18%	1570
March	1st to 10th	Day	12% 13% 4 10% 6% 3 4 3 5% 6% 33%	3118
	11th to 20th	Day	8% 10% 6% 16% 7% 4 4 4 5% 6% 29%	3372
	21st to end	Day	16% 12% 7% 16% 6% 5% 4 3 4 4 22%	3991
April	1st to 10th	Day	18% 14% 3 8% 5% 4 4 3 5% 6% 30%	2280
	11th to 20th	Day	19% 12% 4 6% 4 4 4 3 5% 6% 35%	2341
	21st to end	Day	15% 9% 3 9% 4 5% 4 4 6% 6% 35%	2470
May	1st to 10th	Day	12% 8% 3 7% 5% 4 4 3 5% 6% 43%	4108
	11th to 20th	Day	10% 7% 2 6% 5% 3 4 3 4 6% 49%	4265
	21st to end	Day	11% 6% 2 6% 4 4 4 4 6% 8% 44%	4837
June	1st to 10th	Day	12% 5% 2 6% 5% 4 4 4 6% 7% 45%	2666
	11th to 20th	Day	11% 5% 2 6% 4 5% 5% 4 6% 9% 44%	2841
	21st to end	Day	12% 7% 2 6% 4 3 4 4 6% 7% 45%	2660
July	1st to 10th	Day	17% 7% 2 5% 4 3 4 4 6% 8% 42%	4440
	11th to 20th	Day	7% 4 2 4 3 3 4 4 6% 9% 55%	4440
	21st to end	Day	8% 4 2 5% 4 3 4 4 6% 9% 51%	4814
August	1st to 10th	Day	7% 5% 2 7% 4 5% 5% 4 7% 10% 43%	4275
	11th to 20th	Day	14% 5% 2 5% 3 3 3 3 5% 6% 50%	4044
	21st to end	Day	12% 7% 3 7% 4 4 4 3 5% 6% 46%	4318
September	1st to 10th	Day	14% 6% 2 5% 4 4 4 4 5% 7% 44%	2266
	11th to 20th	Day	13% 4 3 6% 3 4 4 4 6% 8% 46%	2090
	21st to end	Day	16% 6% 2 7% 4 4 5% 4 7% 7% 38%	2090
October	1st to 10th	Day	17% 8% 3 8% 5% 4 3 3 4 7% 37%	2090
	11th to 20th	Day	23% 15% 4 10% 5% 5% 5% 3 5% 5% 21%	1791
	21st to end	Day	24% 14% 5% 12% 5% 5% 5% 4 4 5% 17%	1881
November	1st to 10th	Day	17% 18% 4 7% 6% 4 4 2 5% 6% 26%	1762
	11th to 20th	Day	14% 22% 6% 15% 6% 5% 5% 3 5% 5% 15%	1800
	21st to end	Day	17% 24% 9% 14% 6% 4 4 3 3 4 13%	1682
December	1st to 10th	Day	15% 27% 12% 19% 5% 4 3 2 2 2 8%	1330
	11th to 20th	Day	14% 22% 8% 17% 10% 6% 4 2 4 4 8%	1671
	21st to end	Day	20% 22% 10% 14% 8% 5% 4 2 3 4 8%	2760
January	1st to 10th	Night	13% 26% 9% 21% 8% 5% 2 2 1 2 10%	4428
	11th to 20th	Night	12% 18% 8% 23% 17% 8% 3 2 2 2 6%	4440
	21st to end	Night	15% 23% 10% 16% 10% 6% 4 2 3 3 7%	4884
February	1st to 10th	Night	10% 18% 6% 18% 14% 8% 4 3 2 3 13%	2566
	11th to 20th	Night	12% 15% 7% 17% 10% 6% 4 3 4 4 18%	2218
	21st to end	Night	15% 16% 5% 14% 6% 4 4 4 4 6% 21%	1884
March	1st to 10th	Night	15% 12% 3 7% 4 4 3 3 5% 6% 39%	3722
	11th to 20th	Night	7% 14% 5% 10% 6% 4 5% 4 4 6% 34%	3586
	21st to end	Night	14% 11% 6% 13% 7% 5% 4 3 5% 6% 26%	3671
April	1st to 10th	Night	18% 13% 3 9% 5% 4 4 3 5% 6% 30%	1900
	11th to 20th	Night	20% 8% 3 8% 4 4 3 3 5% 5% 35%	1787
	21st to end	Night	16% 10% 3 7% 4 5% 4 4 5% 5% 36%	1710
May	1st to 10th	Night	15% 9% 2 6% 4 4 5% 3 5% 7% 40%	2833
	11th to 20th	Night	12% 8% 2 7% 5% 4 5% 4 6% 6% 41%	2632
	21st to end	Night	17% 7% 2 5% 4 4 3 3 6% 7% 43%	2750
June	1st to 10th	Night	13% 7% 2 6% 5% 5% 4 3 5% 6% 43%	1501
	11th to 20th	Night	12% 5% 3 6% 4 5% 5% 4 6% 8% 43%	1330
	21st to end	Night	11% 6% 2 7% 5% 4 4 3 5% 8% 45%	1514
July	1st to 10th	Night	13% 6% 3 7% 3 4 4 4 6% 8% 42%	2530
	11th to 20th	Night	7% 4 2 6% 3 3 4 3 6% 7% 54%	2530
	21st to end	Night	9% 5% 2 6% 5% 4 4 4 6% 8% 49%	2750
August	1st to 10th	Night	11% 6% 3 8% 6% 5% 4 4 5% 7% 42%	2657
	11th to 20th	Night	13% 5% 1 5% 3 4 4 3 4 8% 49%	2785
	21st to end	Night	12% 6% 2 6% 4 4 4 3 5% 7% 47%	3336
September	1st to 10th	Night	11% 7% 3 5% 4 4 4 3 4 7% 49%	1900
	11th to 20th	Night	13% 5% 2 5% 4 4 4 3 6% 7% 47%	2085
	21st to end	Night	17% 6% 3 8% 4 4 4 4 6% 8% 37%	2090
October	1st to 10th	Night	18% 8% 3 8% 5% 4 3 3 4 6% 37%	2090
	11th to 20th	Night	22% 13% 4 9% 4 4 4 4 5% 5% 25%	2387
	21st to end	Night	23% 14% 4 11% 6% 5% 4 3 4 5% 22%	2717
November	1st to 10th	Night	16% 16% 4 10% 5% 4 5% 2 4 6% 27%	2536
	11th to 20th	Night	16% 21% 6% 13% 6% 5% 4 3 4 4 18%	2600
	21st to end	Night	16% 23% 7% 15% 6% 5% 4 3 4 4 13%	2705
December	1st to 10th	Night	14% 25% 10% 18% 8% 4 3 2 2 3 9%	2850
	11th to 20th	Night	13% 22% 9% 20% 9% 5% 4 2 4 3 10%	3526
	21st to end	Night	23% 22% 9% 13% 5% 4 4 3 3 4 10%	4902

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	89% 4 4 3	2528
	11th to 20th	Day	91% 4 3 2	2530
	21st to end	Day	83% 7% 7% 3 1	2783
February	1st to 10th	Day	78% 4 7% 10% 1	1613
	11th to 20th	Day	73% 6% 8% 9% 4	1858
	21st to end	Day	66% 7% 8% 14% 4 1	1570
March	1st to 10th	Day	51% 5% 14% 20% 10% 1	3120
	11th to 20th	Day	54% 6% 14% 19% 6% 1	3372
	21st to end	Day	62% 6% 9% 16% 5% 1	3991
April	1st to 10th	Day	55% 5% 10% 20% 10%	2280
	11th to 20th	Day	49% 5% 10% 20% 14% 2	2341
	21st to end	Day	47% 6% 12% 17% 16% 3	2470
May	1st to 10th	Day	40% 6% 11% 24% 18% 2	4120
	11th to 20th	Day	35% 6% 10% 30% 17% 2	4269
	21st to end	Day	36% 6% 13% 23% 19% 3	4837
June	1st to 10th	Day	37% 6% 12% 27% 16% 2	2666
	11th to 20th	Day	36% 7% 13% 24% 18% 2	2841
	21st to end	Day	37% 7% 15% 26% 14% 1	2660
July	1st to 10th	Day	41% 5% 15% 25% 13% 2	4371
	11th to 20th	Day	26% 5% 15% 38% 14% 1	4365
	21st to end	Day	29% 7% 12% 32% 19% 1	4662
August	1st to 10th	Day	34% 6% 16% 30% 12% 1	4260
	11th to 20th	Day	35% 6% 13% 32% 13% 1	4083
	21st to end	Day	39% 5% 14% 30% 11% 1	4317
September	1st to 10th	Day	39% 5% 14% 26% 14% 1	2266
	11th to 20th	Day	35% 7% 15% 30% 12% 1	2090
	21st to end	Day	44% 6% 15% 26% 10%	2090
October	1st to 10th	Day	35% 5% 9% 32% 19% 1	3480
	11th to 20th	Day	57% 4 9% 19% 10%	2955
	21st to end	Day	64% 5% 13% 16% 3	3081
November	1st to 10th	Day	60% 6% 10% 17% 7%	1762
	11th to 20th	Day	71% 6% 10% 10% 4	1800
	21st to end	Day	77% 4 10% 7% 1	1682
December	1st to 10th	Day	86% 3 5% 5% 1	1330
	11th to 20th	Day	81% 7% 6% 4 1	1671
	21st to end	Day	81% 6% 8% 4 2	2760
January	1st to 10th	Night	83% 5% 6% 6% 1	4428
	11th to 20th	Night	89% 3 4 3	4440
	21st to end	Night	84% 6% 6% 3 1	4884
February	1st to 10th	Night	78% 4 7% 8% 3	2566
	11th to 20th	Night	71% 6% 8% 12% 3	2219
	21st to end	Night	65% 6% 11% 15% 3	1884
March	1st to 10th	Night	47% 5% 16% 23% 9%	3733
	11th to 20th	Night	50% 6% 11% 23% 8% 1	3587
	21st to end	Night	59% 6% 12% 17% 6% 1	3671
April	1st to 10th	Night	55% 6% 9% 18% 11% 1	1900
	11th to 20th	Night	51% 5% 8% 19% 14% 3	1787
	21st to end	Night	49% 6% 9% 19% 14% 3	1710
May	1st to 10th	Night	44% 6% 11% 21% 16% 3	2840
	11th to 20th	Night	41% 7% 8% 28% 15% 1	2633
	21st to end	Night	40% 7% 13% 20% 14% 6%	2751
June	1st to 10th	Night	40% 6% 10% 28% 14% 1	1501
	11th to 20th	Night	37% 7% 13% 23% 17% 3	1330
	21st to end	Night	39% 5% 12% 26% 16% 2	1514
July	1st to 10th	Night	40% 5% 14% 24% 13% 4	2490
	11th to 20th	Night	28% 6% 14% 31% 19% 1	2482
	21st to end	Night	35% 6% 12% 26% 20% 1	2662
August	1st to 10th	Night	41% 6% 14% 26% 13% 1	2648
	11th to 20th	Night	35% 6% 15% 29% 15% 1	2812
	21st to end	Night	37% 5% 14% 25% 18% 1	3336
September	1st to 10th	Night	36% 7% 13% 24% 20% 1	1900
	11th to 20th	Night	37% 7% 14% 28% 13%	2085
	21st to end	Night	45% 8% 14% 24% 9% 1	2090
October	1st to 10th	Night	42% 5% 9% 31% 12%	3480
	11th to 20th	Night	51% 5% 11% 22% 11%	3962
	21st to end	Night	57% 5% 12% 20% 5%	4467
November	1st to 10th	Night	59% 6% 10% 17% 6% 1	2536
	11th to 20th	Night	72% 5% 9% 9% 5% 1	2600
	21st to end	Night	76% 6% 9% 8% 1	2705
December	1st to 10th	Night	84% 4 5% 6% 1	2850
	11th to 20th	Night	81% 5% 8% 4 2	3525
	21st to end	Night	80% 7% 9% 3 1	4902

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	18% 16% 37% 21% 7% 2	270
	11th to 20th	Day	23% 13% 37% 22% 4 1	270
	21st to end	Day	23% 13% 32% 26% 6% 1	297
February	1st to 10th	Day	21% 19% 37% 16% 6% 1	270
	11th to 20th	Day	17% 19% 39% 18% 6%	270
	21st to end	Day	17% 25% 41% 15% 2	225
March	1st to 10th	Day	20% 16% 40% 20% 5%	270
	11th to 20th	Day	19% 14% 29% 25% 11% 2	391
	21st to end	Day	24% 12% 29% 24% 10% 1	506
April	1st to 10th	Day	23% 12% 30% 26% 8% 1	460
	11th to 20th	Day	25% 13% 28% 19% 11% 3	452
	21st to end	Day	18% 10% 29% 27% 14% 3	460
May	1st to 10th	Day	17% 10% 30% 27% 12% 4	463
	11th to 20th	Day	15% 5% 27% 34% 14% 4	593
	21st to end	Day	13% 7% 22% 30% 23% 5%	734
June	1st to 10th	Day	13% 5% 25% 32% 20% 4	680
	11th to 20th	Day	13% 4 25% 33% 20% 5%	680
	21st to end	Day	15% 5% 20% 34% 21% 5%	680
July	1st to 10th	Day	10% 2 17% 36% 27% 8%	671
	11th to 20th	Day	9% 4 22% 33% 24% 8%	668
	21st to end	Day	8% 3 19% 35% 29% 6%	739
August	1st to 10th	Day	9% 4 18% 33% 28% 9%	593
	11th to 20th	Day	12% 3 17% 30% 28% 10%	479
	21st to end	Day	16% 4 19% 29% 25% 7%	539
September	1st to 10th	Day	17% 7% 22% 24% 22% 8%	490
	11th to 20th	Day	11% 4 22% 26% 26% 10%	490
	21st to end	Day	19% 8% 17% 30% 21% 6%	490
October	1st to 10th	Day	20% 12% 25% 24% 15% 4	490
	11th to 20th	Day	27% 14% 29% 24% 6% 1	357
	21st to end	Day	30% 15% 27% 22% 5% 1	330
November	1st to 10th	Day	29% 15% 27% 18% 11% 1	300
	11th to 20th	Day	19% 20% 40% 17% 4	300
	21st to end	Day	27% 21% 33% 16% 3	276
December	1st to 10th	Day	31% 16% 33% 13% 7% 1	180
	11th to 20th	Day	27% 22% 33% 16% 3 1	180
	21st to end	Day	26% 20% 37% 13% 2 1	292
January	1st to 10th	Night	20% 15% 37% 22% 6% 1	950
	11th to 20th	Night	25% 15% 31% 21% 7% 1	950
	21st to end	Night	20% 11% 33% 26% 8% 1	1045
February	1st to 10th	Night	17% 15% 34% 26% 8% 1	865
	11th to 20th	Night	20% 13% 35% 24% 8%	743
	21st to end	Night	23% 15% 30% 27% 5%	628
March	1st to 10th	Night	17% 10% 30% 31% 11% 1	760
	11th to 20th	Night	15% 11% 35% 29% 9% 1	760
	21st to end	Night	21% 8% 26% 34% 10% 1	754
April	1st to 10th	Night	23% 9% 29% 31% 8% 1	570
	11th to 20th	Night	23% 9% 25% 31% 11% 1	563
	21st to end	Night	18% 6% 28% 34% 12% 1	570
May	1st to 10th	Night	17% 5% 26% 35% 16% 1	570
	11th to 20th	Night	18% 3 22% 39% 17% 1	561
	21st to end	Night	13% 4 21% 34% 25% 3	617
June	1st to 10th	Night	17% 3 21% 37% 21% 1	551
	11th to 20th	Night	11% 4 19% 41% 22% 2	380
	21st to end	Night	13% 2 18% 38% 26% 2	564
July	1st to 10th	Night	11% 2 13% 43% 28% 5%	555
	11th to 20th	Night	11% 1 17% 37% 29% 5%	552
	21st to end	Night	9% 3 17% 37% 31% 4	624
August	1st to 10th	Night	11% 1 15% 42% 28% 3	567
	11th to 20th	Night	11% 4 15% 32% 32% 6%	564
	21st to end	Night	15% 3 15% 38% 27% 2	627
September	1st to 10th	Night	15% 3 20% 32% 27% 4	570
	11th to 20th	Night	16% 4 18% 32% 25% 5%	755
	21st to end	Night	19% 7% 19% 30% 19% 5%	760
October	1st to 10th	Night	23% 9% 21% 29% 16% 2	760
	11th to 20th	Night	29% 11% 25% 26% 8% 1	760
	21st to end	Night	32% 11% 27% 23% 7% 1	836
November	1st to 10th	Night	27% 14% 24% 28% 6% 1	780
	11th to 20th	Night	29% 16% 31% 19% 4	800
	21st to end	Night	28% 17% 30% 21% 4	865
December	1st to 10th	Night	27% 20% 31% 18% 4	950
	11th to 20th	Night	25% 15% 35% 18% 5% 1	950
	21st to end	Night	30% 13% 35% 20% 2	1045

Page generated at 2024-11-27 17:30:51. Version ac07

Copyright © 2024 Attilla Danko.