Marra's Frustration Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Marra's Frustration Center clear sky chart from 2005-11-06 to 2024-11-04.

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	14% 9% 3 7% 5% 4 4 4 5% 7% 37%	101301
	Night	15% 10% 3 7% 4 4 4 3 5% 7% 37%	97640
Transparency	Day	46% 3 10% 24% 15% 2	104983
	Night	46% 3 10% 24% 16% 2	102097
Seeing	Day	19% 11% 26% 23% 15% 6%	15344
	Night	19% 8% 25% 30% 15% 2	25047

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% 18% 6% 9% 4 4 3 4 4 5% 26%	2527
	11th to 20th	Day	16% 14% 6% 12% 6% 6% 5% 4 4 4 22%	2729
	21st to end	Day	29% 17% 8% 8% 4 4 3 2 3 4 18%	3124
February	1st to 10th	Day	19% 14% 4 9% 5% 4 4 4 4 5% 29%	1813
	11th to 20th	Day	16% 12% 4 10% 6% 5% 4 4 4 6% 31%	1848
	21st to end	Day	19% 13% 5% 9% 6% 3 4 3 4 5% 30%	1570
March	1st to 10th	Day	22% 16% 5% 9% 4 4 3 2 4 4 26%	3141
	11th to 20th	Day	14% 8% 3 7% 4 3 4 4 5% 7% 41%	3480
	21st to end	Day	18% 9% 3 7% 5% 4 5% 4 5% 7% 35%	3815
April	1st to 10th	Day	14% 11% 3 7% 6% 4 4 4 4 7% 35%	2247
	11th to 20th	Day	16% 9% 3 7% 4 4 3 4 5% 6% 39%	2302
	21st to end	Day	18% 8% 3 6% 5% 4 4 4 5% 7% 36%	2470
May	1st to 10th	Day	21% 10% 4 7% 5% 4 5% 4 5% 7% 29%	4082
	11th to 20th	Day	21% 8% 3 6% 4 3 3 3 5% 8% 37%	4081
	21st to end	Day	10% 6% 3 7% 6% 5% 6% 5% 8% 10% 34%	4476
June	1st to 10th	Day	12% 5% 3 7% 5% 4 5% 5% 7% 8% 40%	2479
	11th to 20th	Day	9% 5% 2 6% 5% 4 5% 4 7% 8% 44%	2660
	21st to end	Day	9% 6% 3 6% 5% 5% 5% 5% 6% 9% 40%	2660
July	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 5% 6% 10% 37%	4440
	11th to 20th	Day	7% 4 2 6% 5% 5% 5% 4 6% 10% 47%	4294
	21st to end	Day	11% 6% 2 8% 6% 6% 6% 6% 7% 10% 31%	4466
August	1st to 10th	Day	9% 5% 2 5% 4 4 5% 5% 7% 10% 43%	4104
	11th to 20th	Day	8% 6% 2 6% 4 5% 5% 4 7% 10% 43%	4044
	21st to end	Day	6% 4 2 5% 3 4 4 4 6% 8% 54%	4194
September	1st to 10th	Day	12% 5% 2 4 4 5% 3 4 5% 7% 48%	2166
	11th to 20th	Day	8% 6% 2 6% 4 4 4 3 7% 8% 49%	2090
	21st to end	Day	15% 6% 2 5% 4 4 3 3 4 6% 46%	2090
October	1st to 10th	Day	11% 5% 2 6% 4 5% 4 3 5% 7% 48%	2090
	11th to 20th	Day	12% 7% 2 6% 5% 4 3 3 5% 7% 46%	1933
	21st to end	Day	20% 8% 2 6% 4 4 4 3 4 7% 38%	1939
November	1st to 10th	Day	8% 6% 3 5% 3 3 4 3 4 6% 53%	1699
	11th to 20th	Day	14% 10% 4 8% 5% 3 4 3 6% 7% 37%	1710
	21st to end	Day	18% 10% 4 7% 5% 4 3 3 4 6% 36%	1710
December	1st to 10th	Day	21% 14% 5% 9% 6% 4 4 4 4 5% 25%	1710
	11th to 20th	Day	16% 14% 5% 9% 5% 4 5% 4 4 5% 29%	2153
	21st to end	Day	21% 20% 5% 10% 5% 4 4 3 5% 5% 17%	2965
January	1st to 10th	Night	16% 18% 6% 11% 6% 5% 4 3 5% 5% 21%	4428
	11th to 20th	Night	15% 17% 6% 14% 7% 4 4 2 4 5% 22%	4214
	21st to end	Night	26% 18% 5% 8% 4 3 3 2 4 4 22%	4532
February	1st to 10th	Night	21% 12% 3 10% 5% 4 4 4 4 5% 29%	2366
	11th to 20th	Night	16% 10% 4 10% 5% 5% 4 4 5% 7% 30%	2218
	21st to end	Night	22% 13% 3 8% 4 4 3 3 5% 6% 30%	1884
March	1st to 10th	Night	22% 13% 3 6% 4 4 4 3 4 5% 33%	3711
	11th to 20th	Night	13% 8% 3 6% 5% 4 4 3 5% 7% 44%	3480
	21st to end	Night	17% 8% 3 8% 4 4 4 4 4 6% 39%	3817
April	1st to 10th	Night	14% 9% 3 6% 4 5% 4 4 5% 6% 38%	1948
	11th to 20th	Night	14% 8% 2 6% 5% 4 3 4 6% 8% 40%	1825
	21st to end	Night	16% 8% 2 6% 5% 4 5% 4 6% 7% 37%	1710
May	1st to 10th	Night	22% 11% 4 8% 5% 4 5% 3 5% 6% 27%	2813
	11th to 20th	Night	18% 7% 2 6% 4 4 4 3 6% 8% 38%	2812
	21st to end	Night	10% 4 2 5% 4 4 5% 4 6% 10% 45%	3079
June	1st to 10th	Night	9% 6% 2 4 6% 5% 4 4 4 9% 49%	1694
	11th to 20th	Night	8% 5% 2 5% 3 4 5% 4 7% 11% 47%	1520
	21st to end	Night	6% 4 2 6% 4 5% 5% 4 7% 10% 47%	1520
July	1st to 10th	Night	11% 5% 2 5% 4 3 4 4 5% 8% 49%	2530
	11th to 20th	Night	6% 4 2 5% 3 4 4 4 6% 9% 52%	2654
	21st to end	Night	10% 6% 3 7% 5% 5% 5% 4 8% 10% 37%	3087
August	1st to 10th	Night	8% 7% 3 7% 4 4 5% 4 6% 9% 44%	2825
	11th to 20th	Night	8% 6% 2 7% 4 5% 5% 4 5% 9% 45%	2785
	21st to end	Night	3 3 1 5% 3 4 4 4 6% 9% 58%	3444
September	1st to 10th	Night	12% 5% 2 4 4 3 3 4 5% 7% 51%	1994
	11th to 20th	Night	8% 5% 1 6% 3 3 4 3 5% 6% 56%	2090
	21st to end	Night	14% 6% 2 6% 4 3 4 3 3 5% 49%	2090
October	1st to 10th	Night	8% 4 2 6% 3 4 3 3 4 7% 55%	2090
	11th to 20th	Night	14% 6% 2 6% 5% 4 4 3 4 7% 45%	2247
	21st to end	Night	17% 9% 3 6% 4 3 4 3 5% 6% 41%	2655
November	1st to 10th	Night	13% 8% 2 5% 3 4 4 3 5% 5% 48%	2452
	11th to 20th	Night	16% 8% 3 8% 4 4 4 3 5% 6% 40%	2470
	21st to end	Night	19% 12% 4 6% 5% 4 4 3 5% 7% 32%	2470
December	1st to 10th	Night	21% 12% 4 9% 4 4 4 3 5% 5% 29%	2470
	11th to 20th	Night	18% 13% 5% 8% 5% 4 3 3 5% 6% 29%	3042
	21st to end	Night	21% 19% 5% 11% 6% 5% 4 3 4 5% 17%	4674

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	61% 2 10% 17% 10%	2528
	11th to 20th	Day	67% 2 10% 14% 7%	2729
	21st to end	Day	72% 1 9% 15% 3 1	3124
February	1st to 10th	Day	59% 2 9% 19% 11% 1	1813
	11th to 20th	Day	56% 3 9% 22% 10% 1	1858
	21st to end	Day	58% 2 8% 22% 9% 2	1570
March	1st to 10th	Day	64% 1 6% 19% 8% 1	3141
	11th to 20th	Day	45% 2 9% 26% 17% 1	3480
	21st to end	Day	51% 2 11% 25% 11% 1	3815
April	1st to 10th	Day	49% 2 11% 23% 14% 1	2247
	11th to 20th	Day	46% 2 9% 24% 15% 3	2302
	21st to end	Day	49% 3 10% 24% 12% 2	2470
May	1st to 10th	Day	56% 2 11% 22% 8% 1	4120
	11th to 20th	Day	48% 2 13% 24% 12%	4085
	21st to end	Day	44% 4 11% 21% 17% 2	4489
June	1st to 10th	Day	42% 4 10% 25% 17% 2	2479
	11th to 20th	Day	37% 4 14% 25% 18% 2	2660
	21st to end	Day	39% 5% 14% 22% 16% 4	2660
July	1st to 10th	Day	43% 4 11% 22% 18% 2	4371
	11th to 20th	Day	32% 5% 10% 32% 20% 1	4219
	21st to end	Day	46% 6% 13% 18% 14% 3	4324
August	1st to 10th	Day	33% 6% 15% 32% 13% 1	4091
	11th to 20th	Day	35% 5% 11% 33% 16% 1	4083
	21st to end	Day	28% 4 13% 31% 20% 3	4193
September	1st to 10th	Day	36% 3 10% 25% 20% 6%	2166
	11th to 20th	Day	34% 3 9% 28% 22% 3	2090
	21st to end	Day	40% 3 9% 25% 22% 2	2090
October	1st to 10th	Day	24% 3 7% 33% 30% 2	3480
	11th to 20th	Day	31% 3 8% 31% 26% 2	3186
	21st to end	Day	37% 2 9% 26% 24% 2	3176
November	1st to 10th	Day	34% 3 8% 30% 22% 3	1699
	11th to 20th	Day	48% 2 8% 24% 15% 3	1710
	21st to end	Day	51% 2 8% 24% 13% 1	1710
December	1st to 10th	Day	63% 2 9% 19% 6%	1710
	11th to 20th	Day	59% 2 7% 21% 11%	2150
	21st to end	Day	71% 3 8% 11% 7%	2965
January	1st to 10th	Night	66% 2 8% 15% 9%	4428
	11th to 20th	Night	68% 1 9% 15% 7%	4214
	21st to end	Night	68% 1 7% 17% 6% 1	4532
February	1st to 10th	Night	60% 2 9% 20% 8% 1	2366
	11th to 20th	Night	54% 2 9% 21% 12% 1	2219
	21st to end	Night	57% 2 10% 18% 10% 2	1884
March	1st to 10th	Night	55% 2 6% 24% 12% 1	3711
	11th to 20th	Night	42% 2 11% 27% 17% 2	3480
	21st to end	Night	48% 2 8% 29% 12% 1	3817
April	1st to 10th	Night	46% 3 9% 26% 13% 2	1948
	11th to 20th	Night	43% 2 10% 20% 20% 5%	1825
	21st to end	Night	45% 3 12% 23% 14% 3	1710
May	1st to 10th	Night	59% 3 9% 20% 8% 2	2840
	11th to 20th	Night	46% 2 13% 27% 10% 1	2813
	21st to end	Night	35% 3 14% 29% 15% 5%	3087
June	1st to 10th	Night	35% 4 10% 28% 21% 3	1694
	11th to 20th	Night	31% 5% 15% 24% 22% 4	1520
	21st to end	Night	31% 6% 17% 23% 18% 5%	1520
July	1st to 10th	Night	35% 5% 10% 25% 18% 7%	2490
	11th to 20th	Night	27% 5% 13% 32% 20% 2	2606
	21st to end	Night	40% 5% 12% 24% 14% 4	2988
August	1st to 10th	Night	36% 5% 13% 32% 12% 2	2814
	11th to 20th	Night	35% 6% 10% 31% 18% 1	2812
	21st to end	Night	23% 5% 15% 33% 22% 3	3444
September	1st to 10th	Night	33% 3 12% 26% 20% 7%	1994
	11th to 20th	Night	29% 3 8% 27% 28% 3	2090
	21st to end	Night	40% 2 7% 23% 26% 2	2090
October	1st to 10th	Night	23% 2 6% 29% 37% 3	3480
	11th to 20th	Night	29% 1 8% 27% 33% 2	3733
	21st to end	Night	35% 3 7% 24% 28% 5%	4368
November	1st to 10th	Night	39% 2 10% 23% 23% 4	2452
	11th to 20th	Night	46% 2 8% 23% 19% 3	2470
	21st to end	Night	53% 2 10% 22% 11% 1	2470
December	1st to 10th	Night	57% 3 10% 21% 9% 1	2470
	11th to 20th	Night	57% 1 8% 23% 10% 1	3044
	21st to end	Night	72% 2 8% 14% 5%	4674

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	26% 18% 36% 15% 4	270
	11th to 20th	Day	29% 23% 32% 12% 3	270
	21st to end	Day	33% 21% 28% 14% 4	297
February	1st to 10th	Day	30% 22% 30% 15% 2	270
	11th to 20th	Day	28% 26% 33% 11% 2 1	270
	21st to end	Day	32% 14% 43% 9% 1	225
March	1st to 10th	Day	29% 26% 30% 14% 1	278
	11th to 20th	Day	28% 18% 32% 17% 5%	460
	21st to end	Day	32% 14% 31% 16% 6% 1	506
April	1st to 10th	Day	23% 16% 30% 20% 9% 1	460
	11th to 20th	Day	24% 18% 25% 20% 10% 3	452
	21st to end	Day	24% 16% 34% 15% 8% 2	460
May	1st to 10th	Day	28% 10% 31% 18% 9% 4	463
	11th to 20th	Day	23% 11% 28% 22% 11% 5%	487
	21st to end	Day	14% 6% 27% 27% 17% 9%	529
June	1st to 10th	Day	13% 8% 24% 30% 18% 7%	499
	11th to 20th	Day	11% 7% 26% 30% 20% 6%	680
	21st to end	Day	11% 6% 29% 30% 17% 8%	680
July	1st to 10th	Day	13% 4 18% 27% 23% 15%	671
	11th to 20th	Day	9% 5% 23% 29% 21% 12%	587
	21st to end	Day	13% 3 16% 31% 24% 13%	532
August	1st to 10th	Day	9% 5% 15% 28% 27% 15%	486
	11th to 20th	Day	12% 4 20% 31% 20% 13%	479
	21st to end	Day	10% 4 15% 28% 29% 15%	539
September	1st to 10th	Day	12% 4 16% 28% 30% 11%	490
	11th to 20th	Day	11% 3 14% 27% 32% 14%	490
	21st to end	Day	18% 8% 21% 24% 21% 7%	490
October	1st to 10th	Day	11% 7% 23% 30% 22% 7%	490
	11th to 20th	Day	16% 13% 31% 23% 12% 4	490
	21st to end	Day	24% 11% 36% 22% 5% 1	388
November	1st to 10th	Day	11% 16% 36% 23% 11% 3	279
	11th to 20th	Day	24% 20% 26% 21% 8% 1	270
	21st to end	Day	26% 15% 37% 16% 5%	270
December	1st to 10th	Day	22% 21% 34% 15% 6% 1	270
	11th to 20th	Day	22% 19% 37% 16% 6%	270
	21st to end	Day	33% 15% 33% 14% 3 1	297
January	1st to 10th	Night	23% 16% 30% 25% 6%	950
	11th to 20th	Night	30% 14% 30% 22% 3	815
	21st to end	Night	26% 13% 31% 27% 3	836
February	1st to 10th	Night	30% 10% 30% 27% 3	760
	11th to 20th	Night	24% 15% 34% 24% 3	743
	21st to end	Night	29% 13% 32% 24% 2	628
March	1st to 10th	Night	23% 12% 33% 26% 5%	760
	11th to 20th	Night	24% 12% 33% 24% 6% 1	760
	21st to end	Night	25% 11% 29% 28% 7%	836
April	1st to 10th	Night	19% 12% 34% 25% 9%	618
	11th to 20th	Night	20% 9% 33% 27% 11% 1	563
	21st to end	Night	19% 7% 39% 26% 9% 1	570
May	1st to 10th	Night	22% 9% 29% 28% 12% 1	570
	11th to 20th	Night	19% 5% 25% 32% 17% 2	561
	21st to end	Night	10% 3 23% 35% 25% 4	617
June	1st to 10th	Night	10% 4 19% 43% 22% 2	570
	11th to 20th	Night	11% 3 18% 43% 22% 4	570
	21st to end	Night	6% 2 24% 39% 26% 3	570
July	1st to 10th	Night	13% 2 11% 34% 32% 8%	555
	11th to 20th	Night	8% 3 16% 36% 34% 4	552
	21st to end	Night	11% 2 14% 41% 29% 4	624
August	1st to 10th	Night	9% 3 11% 37% 36% 4	567
	11th to 20th	Night	9% 1 11% 45% 28% 5%	564
	21st to end	Night	6% 1 13% 34% 40% 6%	627
September	1st to 10th	Night	15% 2 14% 31% 34% 4	664
	11th to 20th	Night	9% 3 14% 33% 35% 6%	760
	21st to end	Night	17% 6% 19% 31% 24% 3	760
October	1st to 10th	Night	12% 3 22% 36% 23% 4	760
	11th to 20th	Night	19% 9% 25% 30% 16% 1	760
	21st to end	Night	23% 9% 31% 25% 11% 1	836
November	1st to 10th	Night	18% 8% 28% 29% 17% 1	755
	11th to 20th	Night	21% 12% 28% 27% 11% 1	760
	21st to end	Night	26% 9% 26% 31% 7% 1	760
December	1st to 10th	Night	29% 10% 30% 25% 6%	760
	11th to 20th	Night	24% 9% 33% 28% 6% 1	760
	21st to end	Night	32% 12% 29% 23% 4	926

Page generated at 2024-11-01 22:47:40. Version ac07

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