Taché Observation Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Taché Observation Point clear sky chart from 2005-11-06 to 2024-12-09.

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	12% 9% 3 9% 6% 5% 5% 4 6% 7% 34%	102147
	Night	10% 10% 4 10% 6% 6% 5% 4 6% 7% 33%	97804
Transparency	Day	47% 6% 15% 24% 7%	105591
	Night	49% 5% 14% 23% 8% 1	102445
Seeing	Day	14% 9% 31% 28% 14% 4	16346
	Night	15% 7% 31% 33% 13% 1	26322

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	6% 18% 5% 13% 10% 5% 7% 6% 6% 4 20%	2218
	11th to 20th	Day	4 10% 5% 18% 13% 12% 9% 8% 7% 4 10%	2220
	21st to end	Day	9% 18% 8% 17% 8% 7% 6% 4 5% 5% 14%	2766
February	1st to 10th	Day	7% 12% 7% 12% 7% 6% 8% 6% 9% 5% 20%	1653
	11th to 20th	Day	7% 10% 4 10% 7% 9% 7% 6% 8% 7% 26%	1664
	21st to end	Day	6% 11% 5% 12% 8% 9% 8% 5% 6% 5% 24%	1474
March	1st to 10th	Day	10% 13% 4 10% 10% 6% 6% 5% 6% 7% 24%	3235
	11th to 20th	Day	7% 10% 5% 16% 13% 8% 5% 4 5% 6% 22%	3480
	21st to end	Day	9% 15% 6% 12% 7% 5% 4 3 6% 6% 28%	3814
April	1st to 10th	Day	9% 12% 4 8% 6% 6% 4 4 5% 6% 35%	2306
	11th to 20th	Day	13% 10% 3 9% 6% 4 5% 4 5% 7% 34%	2442
	21st to end	Day	16% 9% 4 7% 5% 4 4 4 6% 7% 34%	2470
May	1st to 10th	Day	17% 10% 3 7% 4 4 4 4 5% 7% 35%	4264
	11th to 20th	Day	20% 8% 3 6% 5% 5% 4 3 5% 7% 33%	4571
	21st to end	Day	20% 9% 3 7% 4 4 4 3 5% 6% 33%	5173
June	1st to 10th	Day	14% 7% 2 7% 5% 6% 5% 5% 6% 8% 35%	2850
	11th to 20th	Day	15% 8% 2 6% 6% 5% 4 4 7% 8% 36%	2850
	21st to end	Day	12% 6% 2 7% 5% 5% 5% 5% 8% 9% 35%	2850
July	1st to 10th	Day	9% 4 1 5% 4 5% 6% 5% 7% 10% 43%	4750
	11th to 20th	Day	8% 4 1 5% 3 4 5% 4 7% 9% 49%	4750
	21st to end	Day	7% 3 2 5% 5% 4 5% 4 6% 9% 50%	5123
August	1st to 10th	Day	8% 5% 2 6% 4 4 5% 4 6% 10% 46%	4228
	11th to 20th	Day	11% 5% 2 6% 4 4 5% 3 6% 8% 46%	4041
	21st to end	Day	13% 5% 2 5% 4 3 4 3 6% 9% 45%	4532
September	1st to 10th	Day	11% 5% 2 5% 4 3 4 3 6% 9% 49%	2361
	11th to 20th	Day	13% 7% 2 7% 4 4 4 4 6% 8% 40%	2090
	21st to end	Day	16% 8% 3 5% 4 3 4 3 5% 8% 41%	2090
October	1st to 10th	Day	17% 9% 3 7% 5% 4 5% 3 5% 6% 35%	1924
	11th to 20th	Day	14% 11% 3 8% 6% 4 5% 4 6% 6% 33%	1884
	21st to end	Day	16% 15% 4 9% 5% 4 6% 4 5% 6% 26%	1881
November	1st to 10th	Day	16% 14% 5% 10% 5% 4 5% 4 4 6% 27%	1581
	11th to 20th	Day	11% 17% 6% 13% 8% 5% 4 3 5% 6% 23%	1600
	21st to end	Day	13% 14% 5% 14% 9% 6% 4 4 4 5% 22%	1505
December	1st to 10th	Day	8% 15% 8% 14% 7% 7% 6% 6% 5% 6% 17%	1386
	11th to 20th	Day	9% 15% 6% 15% 8% 5% 5% 4 5% 9% 18%	1679
	21st to end	Day	9% 14% 5% 12% 8% 7% 7% 6% 8% 7% 17%	2442
January	1st to 10th	Night	5% 14% 6% 13% 8% 10% 8% 5% 6% 6% 19%	4737
	11th to 20th	Night	5% 13% 6% 17% 12% 11% 10% 6% 5% 4 12%	4750
	21st to end	Night	9% 19% 8% 14% 7% 6% 5% 5% 5% 5% 18%	4896
February	1st to 10th	Night	8% 12% 5% 12% 7% 7% 7% 6% 6% 5% 24%	2527
	11th to 20th	Night	6% 10% 4 8% 7% 8% 7% 5% 6% 6% 33%	2403
	21st to end	Night	6% 12% 5% 13% 7% 6% 6% 4 5% 7% 30%	1998
March	1st to 10th	Night	11% 11% 4 11% 8% 6% 5% 3 6% 6% 29%	3611
	11th to 20th	Night	5% 9% 4 11% 6% 5% 4 4 5% 8% 40%	3479
	21st to end	Night	11% 13% 5% 10% 5% 5% 4 3 5% 6% 33%	3817
April	1st to 10th	Night	12% 8% 3 6% 5% 4 4 4 7% 7% 40%	1871
	11th to 20th	Night	14% 10% 4 8% 5% 5% 3 4 4 6% 36%	1689
	21st to end	Night	13% 9% 3 7% 7% 4 5% 4 6% 7% 37%	1710
May	1st to 10th	Night	18% 9% 3 6% 4 4 4 3 6% 8% 35%	2686
	11th to 20th	Night	18% 6% 3 6% 4 4 4 3 6% 6% 41%	2332
	21st to end	Night	18% 8% 3 5% 4 3 3 3 4 6% 43%	2414
June	1st to 10th	Night	12% 6% 2 7% 5% 4 5% 3 7% 9% 42%	1330
	11th to 20th	Night	13% 5% 2 7% 5% 4 4 4 5% 7% 44%	1330
	21st to end	Night	11% 4 2 6% 5% 5% 5% 4 6% 9% 43%	1330
July	1st to 10th	Night	7% 3 1 4 4 4 5% 4 7% 10% 51%	2220
	11th to 20th	Night	5% 3 1 4 3 3 4 3 6% 10% 56%	2220
	21st to end	Night	5% 3 1 4 4 5% 5% 5% 7% 12% 49%	2439
August	1st to 10th	Night	6% 4 2 5% 4 4 5% 5% 8% 8% 49%	2710
	11th to 20th	Night	9% 4 1 5% 4 4 4 4 5% 9% 51%	2798
	21st to end	Night	10% 5% 2 6% 4 4 5% 3 6% 8% 47%	3135
September	1st to 10th	Night	10% 4 2 5% 4 4 4 3 5% 8% 53%	1816
	11th to 20th	Night	14% 6% 2 5% 3 4 4 3 6% 7% 45%	2090
	21st to end	Night	15% 7% 2 6% 5% 3 4 3 5% 8% 41%	2090
October	1st to 10th	Night	17% 8% 3 6% 5% 4 5% 4 5% 7% 37%	2237
	11th to 20th	Night	15% 12% 3 7% 5% 4 5% 4 5% 6% 34%	2294
	21st to end	Night	14% 12% 4 9% 5% 5% 4 3 6% 6% 31%	2717
November	1st to 10th	Night	13% 14% 5% 11% 5% 5% 5% 3 5% 5% 29%	2717
	11th to 20th	Night	11% 16% 5% 11% 7% 5% 5% 4 5% 5% 26%	2800
	21st to end	Night	12% 13% 6% 14% 8% 7% 5% 3 4 5% 23%	2891
December	1st to 10th	Night	8% 13% 5% 15% 11% 7% 6% 5% 6% 6% 20%	2977
	11th to 20th	Night	9% 17% 6% 14% 7% 5% 6% 4 5% 5% 22%	3518
	21st to end	Night	9% 11% 4 13% 9% 7% 7% 5% 6% 6% 22%	5225

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	64% 4 13% 14% 4	2219
	11th to 20th	Day	72% 5% 11% 9% 2	2220
	21st to end	Day	73% 4 7% 12% 4	2766
February	1st to 10th	Day	60% 5% 14% 13% 8%	1653
	11th to 20th	Day	54% 6% 13% 20% 7%	1673
	21st to end	Day	59% 5% 11% 15% 9%	1474
March	1st to 10th	Day	58% 6% 14% 18% 5%	3237
	11th to 20th	Day	61% 6% 12% 16% 5%	3480
	21st to end	Day	55% 6% 12% 21% 6%	3814
April	1st to 10th	Day	49% 5% 10% 25% 11%	2306
	11th to 20th	Day	49% 5% 11% 22% 11% 1	2442
	21st to end	Day	48% 5% 16% 22% 7% 2	2470
May	1st to 10th	Day	47% 6% 10% 25% 10% 1	4275
	11th to 20th	Day	49% 6% 11% 23% 10% 1	4575
	21st to end	Day	51% 6% 10% 23% 9% 1	5173
June	1st to 10th	Day	44% 7% 16% 23% 10%	2850
	11th to 20th	Day	46% 6% 14% 24% 10% 1	2850
	21st to end	Day	43% 8% 18% 23% 7%	2850
July	1st to 10th	Day	33% 9% 24% 27% 6%	4676
	11th to 20th	Day	29% 7% 22% 35% 7%	4669
	21st to end	Day	29% 6% 21% 35% 7%	4960
August	1st to 10th	Day	33% 6% 19% 32% 10%	4212
	11th to 20th	Day	35% 6% 21% 34% 5%	4080
	21st to end	Day	37% 5% 22% 30% 6%	4531
September	1st to 10th	Day	32% 7% 18% 33% 10% 1	2361
	11th to 20th	Day	41% 7% 20% 27% 5%	2090
	21st to end	Day	43% 5% 14% 31% 7%	2090
October	1st to 10th	Day	39% 4 16% 30% 11%	3197
	11th to 20th	Day	43% 4 12% 27% 14%	3113
	21st to end	Day	51% 5% 16% 23% 6%	3091
November	1st to 10th	Day	58% 6% 14% 17% 4 1	1581
	11th to 20th	Day	63% 7% 14% 13% 4	1600
	21st to end	Day	65% 6% 14% 13% 2	1505
December	1st to 10th	Day	65% 8% 14% 10% 4	1386
	11th to 20th	Day	63% 5% 16% 13% 4	1680
	21st to end	Day	62% 8% 10% 15% 5%	2442
January	1st to 10th	Night	63% 6% 13% 13% 5%	4737
	11th to 20th	Night	73% 5% 7% 13% 2	4750
	21st to end	Night	67% 5% 12% 13% 3	4896
February	1st to 10th	Night	58% 5% 12% 15% 8%	2527
	11th to 20th	Night	49% 6% 15% 20% 10% 1	2404
	21st to end	Night	55% 5% 12% 18% 10%	1998
March	1st to 10th	Night	55% 5% 11% 20% 9%	3622
	11th to 20th	Night	41% 7% 17% 24% 11% 1	3480
	21st to end	Night	51% 6% 10% 23% 9% 1	3817
April	1st to 10th	Night	42% 5% 11% 24% 16% 2	1871
	11th to 20th	Night	49% 4 8% 21% 16% 2	1689
	21st to end	Night	46% 5% 12% 25% 10% 2	1710
May	1st to 10th	Night	47% 5% 11% 25% 12%	2695
	11th to 20th	Night	43% 5% 12% 28% 10% 3	2333
	21st to end	Night	43% 5% 12% 26% 13% 1	2414
June	1st to 10th	Night	38% 7% 17% 24% 13% 1	1330
	11th to 20th	Night	40% 5% 17% 23% 12% 2	1330
	21st to end	Night	36% 8% 20% 26% 8% 1	1330
July	1st to 10th	Night	27% 9% 24% 32% 8% 1	2185
	11th to 20th	Night	22% 6% 22% 40% 9%	2178
	21st to end	Night	26% 7% 23% 36% 8% 1	2362
August	1st to 10th	Night	30% 6% 17% 34% 13% 1	2702
	11th to 20th	Night	30% 5% 25% 30% 9%	2825
	21st to end	Night	35% 5% 19% 32% 9%	3135
September	1st to 10th	Night	31% 5% 17% 34% 14% 1	1816
	11th to 20th	Night	38% 6% 17% 27% 11% 1	2090
	21st to end	Night	42% 5% 14% 28% 11% 1	2090
October	1st to 10th	Night	40% 4 11% 34% 12%	3731
	11th to 20th	Night	43% 4 13% 30% 10%	3805
	21st to end	Night	46% 4 14% 29% 6%	4467
November	1st to 10th	Night	57% 5% 15% 16% 6% 1	2717
	11th to 20th	Night	60% 6% 14% 14% 5% 1	2800
	21st to end	Night	64% 5% 13% 12% 5%	2891
December	1st to 10th	Night	63% 7% 16% 11% 3	2977
	11th to 20th	Night	63% 6% 13% 13% 5%	3516
	21st to end	Night	59% 6% 12% 17% 6%	5225

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	11% 9% 33% 31% 14% 2	270
	11th to 20th	Day	11% 7% 30% 37% 14% 1	270
	21st to end	Day	14% 9% 29% 30% 13% 4	297
February	1st to 10th	Day	14% 10% 30% 36% 8% 2	270
	11th to 20th	Day	11% 12% 35% 26% 12% 5%	270
	21st to end	Day	10% 5% 46% 27% 11% 1	225
March	1st to 10th	Day	12% 9% 35% 30% 13% 1	270
	11th to 20th	Day	11% 12% 37% 23% 15% 3	270
	21st to end	Day	12% 11% 33% 29% 12% 3	297
April	1st to 10th	Day	13% 8% 33% 31% 11% 3	486
	11th to 20th	Day	18% 11% 33% 24% 13% 1	640
	21st to end	Day	17% 10% 33% 26% 11% 2	650
May	1st to 10th	Day	17% 14% 31% 25% 12% 2	653
	11th to 20th	Day	20% 11% 26% 25% 14% 3	675
	21st to end	Day	21% 10% 25% 27% 15% 3	734
June	1st to 10th	Day	14% 13% 30% 25% 12% 6%	680
	11th to 20th	Day	15% 13% 33% 28% 8% 3	680
	21st to end	Day	12% 8% 27% 30% 17% 5%	680
July	1st to 10th	Day	9% 7% 29% 27% 19% 10%	671
	11th to 20th	Day	10% 7% 30% 29% 18% 6%	668
	21st to end	Day	7% 6% 29% 30% 19% 8%	739
August	1st to 10th	Day	7% 8% 27% 30% 23% 5%	676
	11th to 20th	Day	10% 5% 24% 34% 17% 9%	665
	21st to end	Day	14% 7% 31% 27% 17% 4	748
September	1st to 10th	Day	10% 8% 31% 34% 15% 2	571
	11th to 20th	Day	12% 13% 38% 27% 8% 3	300
	21st to end	Day	21% 10% 32% 28% 9% 1	300
October	1st to 10th	Day	20% 13% 25% 30% 8% 4	300
	11th to 20th	Day	13% 12% 37% 30% 8% 1	300
	21st to end	Day	28% 8% 32% 22% 8% 2	330
November	1st to 10th	Day	23% 8% 30% 26% 12% 2	300
	11th to 20th	Day	19% 10% 40% 21% 9% 1	300
	21st to end	Day	17% 12% 40% 25% 6%	300
December	1st to 10th	Day	14% 6% 35% 31% 13% 2	294
	11th to 20th	Day	14% 9% 43% 26% 7% 1	270
	21st to end	Day	13% 6% 30% 33% 14% 4	297
January	1st to 10th	Night	11% 7% 34% 31% 14% 2	950
	11th to 20th	Night	15% 6% 32% 36% 11% 1	950
	21st to end	Night	14% 7% 33% 33% 11% 1	1045
February	1st to 10th	Night	13% 7% 26% 38% 14% 1	950
	11th to 20th	Night	11% 6% 30% 36% 14% 3	929
	21st to end	Night	10% 7% 36% 32% 14% 1	742
March	1st to 10th	Night	15% 7% 30% 32% 14% 2	700
	11th to 20th	Night	12% 8% 39% 28% 13% 1	570
	21st to end	Night	18% 8% 27% 30% 14% 3	627
April	1st to 10th	Night	14% 8% 29% 37% 11% 2	570
	11th to 20th	Night	18% 6% 30% 34% 11% 1	563
	21st to end	Night	16% 7% 32% 34% 12%	570
May	1st to 10th	Night	19% 7% 35% 29% 10%	570
	11th to 20th	Night	17% 8% 30% 30% 14% 1	561
	21st to end	Night	17% 8% 33% 32% 10% 1	617
June	1st to 10th	Night	14% 5% 32% 33% 17%	570
	11th to 20th	Night	15% 7% 31% 32% 15%	570
	21st to end	Night	11% 7% 20% 42% 19% 2	570
July	1st to 10th	Night	5% 5% 24% 43% 22% 1	555
	11th to 20th	Night	9% 4 24% 41% 20% 2	552
	21st to end	Night	8% 3 23% 42% 21% 3	624
August	1st to 10th	Night	8% 4 22% 46% 18% 2	567
	11th to 20th	Night	10% 4 21% 40% 23% 3	564
	21st to end	Night	12% 5% 26% 39% 19%	627
September	1st to 10th	Night	12% 5% 28% 37% 17% 2	570
	11th to 20th	Night	15% 6% 28% 38% 14%	570
	21st to end	Night	19% 6% 33% 31% 11% 1	570
October	1st to 10th	Night	20% 8% 33% 30% 8%	717
	11th to 20th	Night	19% 8% 34% 28% 9% 1	774
	21st to end	Night	21% 9% 30% 30% 8% 1	1045
November	1st to 10th	Night	18% 9% 37% 27% 9% 1	975
	11th to 20th	Night	19% 8% 34% 28% 9% 2	1000
	21st to end	Night	18% 10% 39% 25% 7% 1	1000
December	1st to 10th	Night	12% 6% 34% 35% 12% 2	993
	11th to 20th	Night	17% 8% 35% 31% 9% 1	950
	21st to end	Night	19% 7% 32% 29% 12% 1	1045

Page generated at 2024-12-06 02:54:53. Version ac07

Copyright © 2024 Attilla Danko.