Heavens Gate Farm Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Heavens Gate Farm Observatory 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	11% 8% 3 7% 4 4 4 4 6% 8% 41%	101625
	Night	12% 8% 3 7% 4 4 4 3 5% 7% 42%	98228
Transparency	Day	40% 5% 12% 24% 16% 2	105244
	Night	41% 5% 11% 24% 17% 3	102749
Seeing	Day	15% 11% 28% 27% 15% 5%	15817
	Night	16% 10% 30% 30% 13% 1	25677

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% 11% 5% 14% 6% 5% 4 3 5% 6% 29%	2527
	11th to 20th	Day	11% 11% 4 11% 6% 6% 6% 3 6% 5% 31%	2702
	21st to end	Day	15% 19% 10% 10% 5% 4 3 3 4 4 25%	3135
February	1st to 10th	Day	14% 11% 5% 9% 5% 5% 3 4 4 6% 34%	1710
	11th to 20th	Day	12% 11% 3 8% 4 5% 5% 4 5% 7% 36%	1770
	21st to end	Day	14% 11% 4 8% 5% 4 4 3 4 6% 37%	1570
March	1st to 10th	Day	15% 12% 4 7% 4 4 3 3 4 5% 40%	3215
	11th to 20th	Day	9% 8% 2 5% 4 4 4 3 5% 8% 47%	3480
	21st to end	Day	17% 12% 4 8% 5% 5% 4 3 5% 7% 31%	3990
April	1st to 10th	Day	13% 9% 3 8% 4 4 4 4 4 8% 40%	2280
	11th to 20th	Day	15% 9% 3 8% 4 4 3 3 5% 7% 39%	2254
	21st to end	Day	20% 6% 3 8% 5% 3 4 4 5% 7% 35%	2280
May	1st to 10th	Day	11% 8% 3 7% 5% 5% 6% 4 7% 9% 33%	3975
	11th to 20th	Day	17% 8% 3 7% 4 4 3 4 5% 8% 38%	4399
	21st to end	Day	10% 6% 2 7% 5% 4 4 4 5% 7% 46%	4824
June	1st to 10th	Day	6% 4 2 6% 4 4 5% 5% 8% 10% 46%	2660
	11th to 20th	Day	7% 5% 2 5% 5% 5% 5% 5% 6% 9% 47%	2660
	21st to end	Day	7% 6% 2 5% 5% 5% 5% 4 8% 8% 44%	2660
July	1st to 10th	Day	12% 6% 3 6% 5% 5% 5% 4 8% 10% 38%	4440
	11th to 20th	Day	5% 5% 2 6% 4 5% 5% 4 7% 10% 48%	4440
	21st to end	Day	7% 5% 2 7% 4 5% 5% 5% 8% 12% 40%	4600
August	1st to 10th	Day	5% 4 1 6% 4 5% 6% 5% 7% 10% 48%	4104
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 7% 9% 41%	3819
	21st to end	Day	5% 4 1 4 4 4 5% 5% 7% 11% 50%	4180
September	1st to 10th	Day	12% 5% 2 4 3 4 4 3 5% 8% 51%	2280
	11th to 20th	Day	9% 6% 2 4 4 3 3 3 6% 8% 52%	2280
	21st to end	Day	8% 5% 2 6% 4 4 5% 4 6% 7% 50%	2038
October	1st to 10th	Day	11% 5% 2 5% 3 4 3 2 5% 6% 53%	1900
	11th to 20th	Day	14% 7% 2 6% 4 3 4 3 5% 5% 48%	1900
	21st to end	Day	17% 8% 3 6% 4 3 3 3 4 7% 43%	2076
November	1st to 10th	Day	11% 7% 2 5% 3 4 4 3 4 7% 51%	1762
	11th to 20th	Day	15% 8% 3 6% 3 4 3 3 4 6% 44%	1800
	21st to end	Day	15% 11% 4 7% 4 4 4 3 4 6% 38%	1630
December	1st to 10th	Day	11% 12% 4 7% 4 4 3 3 4 6% 41%	1584
	11th to 20th	Day	13% 10% 4 6% 4 5% 5% 4 6% 6% 37%	1918
	21st to end	Day	18% 18% 6% 11% 5% 4 4 3 5% 5% 22%	2783
January	1st to 10th	Night	12% 11% 6% 13% 5% 4 4 3 4 5% 32%	4428
	11th to 20th	Night	12% 14% 6% 11% 5% 5% 7% 5% 5% 4 26%	4266
	21st to end	Night	19% 18% 6% 10% 4 4 3 3 3 5% 24%	4532
February	1st to 10th	Night	15% 12% 5% 8% 5% 5% 4 4 5% 6% 33%	2470
	11th to 20th	Night	13% 8% 3 8% 6% 4 5% 3 5% 6% 40%	2295
	21st to end	Night	16% 9% 3 7% 5% 4 3 3 4 5% 41%	1884
March	1st to 10th	Night	18% 11% 3 5% 4 3 3 3 5% 5% 41%	3654
	11th to 20th	Night	12% 7% 2 6% 4 4 3 3 4 5% 50%	3480
	21st to end	Night	19% 11% 4 7% 5% 5% 4 4 5% 6% 29%	3640
April	1st to 10th	Night	12% 6% 3 7% 5% 4 4 4 5% 7% 44%	1900
	11th to 20th	Night	13% 7% 3 6% 4 4 4 4 5% 6% 44%	1875
	21st to end	Night	17% 9% 3 6% 4 3 4 3 5% 6% 40%	1900
May	1st to 10th	Night	16% 8% 3 7% 5% 4 4 5% 5% 8% 35%	2906
	11th to 20th	Night	12% 8% 3 7% 5% 4 5% 3 5% 8% 41%	2506
	21st to end	Night	8% 6% 2 5% 4 4 4 4 5% 8% 50%	2743
June	1st to 10th	Night	6% 5% 2 4 3 5% 3 4 6% 8% 53%	1520
	11th to 20th	Night	7% 5% 2 7% 4 3 4 4 5% 10% 49%	1520
	21st to end	Night	6% 3 2 5% 4 5% 5% 4 7% 10% 48%	1520
July	1st to 10th	Night	11% 7% 2 8% 4 4 4 3 6% 9% 41%	2530
	11th to 20th	Night	3 3 1 5% 4 4 4 3 6% 8% 58%	2530
	21st to end	Night	9% 5% 2 7% 4 4 5% 4 8% 10% 43%	2960
August	1st to 10th	Night	4 3 2 4 3 3 3 4 6% 9% 59%	2836
	11th to 20th	Night	8% 5% 2 5% 4 4 4 4 5% 8% 51%	3013
	21st to end	Night	3 3 1 5% 4 4 5% 4 7% 10% 54%	3476
September	1st to 10th	Night	10% 5% 1 4 3 3 3 4 5% 6% 55%	1900
	11th to 20th	Night	7% 5% 2 5% 3 4 3 3 6% 7% 52%	1900
	21st to end	Night	7% 5% 2 5% 3 4 5% 3 5% 8% 53%	2119
October	1st to 10th	Night	8% 5% 2 4 4 3 4 3 4 7% 57%	2280
	11th to 20th	Night	13% 6% 2 5% 4 3 3 3 5% 6% 52%	2280
	21st to end	Night	17% 7% 3 5% 3 3 3 4 4 6% 45%	2522
November	1st to 10th	Night	10% 6% 2 5% 4 3 3 3 5% 6% 53%	2536
	11th to 20th	Night	12% 7% 3 7% 4 4 3 3 5% 6% 47%	2600
	21st to end	Night	16% 9% 3 6% 4 4 3 3 5% 6% 41%	2765
December	1st to 10th	Night	13% 10% 4 7% 5% 4 4 4 6% 6% 36%	2779
	11th to 20th	Night	15% 9% 4 8% 4 4 3 3 4 6% 41%	3279
	21st to end	Night	18% 19% 7% 12% 6% 4 4 3 4 4 20%	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	54% 5% 10% 22% 9% 1	2528
	11th to 20th	Day	55% 5% 13% 19% 9%	2702
	21st to end	Day	64% 4 9% 14% 9% 1	3135
February	1st to 10th	Day	52% 5% 11% 20% 10% 2	1710
	11th to 20th	Day	47% 5% 12% 22% 13% 1	1779
	21st to end	Day	49% 4 10% 23% 11% 3	1570
March	1st to 10th	Day	47% 4 8% 22% 17% 2	3215
	11th to 20th	Day	35% 6% 13% 26% 18% 3	3480
	21st to end	Day	52% 7% 17% 19% 5% 1	3990
April	1st to 10th	Day	44% 5% 11% 25% 14% 1	2280
	11th to 20th	Day	45% 4 10% 25% 14% 2	2254
	21st to end	Day	47% 6% 12% 19% 14% 1	2280
May	1st to 10th	Day	44% 8% 14% 22% 12%	4010
	11th to 20th	Day	46% 6% 11% 28% 9% 1	4403
	21st to end	Day	37% 6% 9% 24% 23% 1	4837
June	1st to 10th	Day	30% 9% 15% 28% 16% 3	2660
	11th to 20th	Day	32% 7% 13% 25% 20% 3	2660
	21st to end	Day	34% 8% 15% 23% 17% 3	2660
July	1st to 10th	Day	40% 7% 13% 26% 13% 2	4371
	11th to 20th	Day	31% 6% 15% 28% 19% 2	4365
	21st to end	Day	36% 5% 21% 26% 12% 1	4455
August	1st to 10th	Day	29% 6% 16% 35% 12% 1	4090
	11th to 20th	Day	38% 6% 13% 27% 15% 1	3857
	21st to end	Day	29% 5% 18% 30% 14% 5%	4179
September	1st to 10th	Day	31% 6% 11% 26% 21% 6%	2280
	11th to 20th	Day	30% 4 9% 30% 22% 4	2280
	21st to end	Day	32% 5% 10% 28% 23% 2	2038
October	1st to 10th	Day	21% 3 6% 17% 47% 6%	3160
	11th to 20th	Day	25% 3 7% 21% 37% 7%	3140
	21st to end	Day	39% 3 7% 24% 24% 2	3402
November	1st to 10th	Day	35% 4 12% 25% 20% 4	1762
	11th to 20th	Day	41% 3 10% 24% 18% 4	1800
	21st to end	Day	48% 5% 10% 25% 12%	1630
December	1st to 10th	Day	46% 5% 14% 23% 12% 1	1584
	11th to 20th	Day	46% 5% 11% 25% 11% 2	1915
	21st to end	Day	64% 4 10% 14% 6% 1	2783
January	1st to 10th	Night	53% 5% 10% 22% 9%	4428
	11th to 20th	Night	60% 4 9% 18% 9% 1	4266
	21st to end	Night	63% 4 10% 17% 6% 1	4532
February	1st to 10th	Night	52% 5% 11% 20% 10% 2	2470
	11th to 20th	Night	44% 5% 11% 22% 15% 2	2296
	21st to end	Night	45% 4 11% 22% 14% 3	1884
March	1st to 10th	Night	45% 5% 9% 25% 15% 1	3654
	11th to 20th	Night	37% 5% 8% 27% 19% 5%	3480
	21st to end	Night	53% 8% 11% 22% 5%	3640
April	1st to 10th	Night	39% 5% 13% 23% 16% 4	1900
	11th to 20th	Night	39% 4 11% 24% 17% 4	1875
	21st to end	Night	46% 5% 9% 21% 16% 2	1900
May	1st to 10th	Night	46% 7% 14% 22% 11% 1	2936
	11th to 20th	Night	41% 8% 12% 27% 12% 1	2507
	21st to end	Night	31% 6% 13% 22% 25% 3	2751
June	1st to 10th	Night	27% 6% 16% 28% 19% 3	1520
	11th to 20th	Night	31% 7% 11% 22% 25% 4	1520
	21st to end	Night	30% 8% 16% 22% 21% 4	1520
July	1st to 10th	Night	40% 4 13% 28% 12% 3	2490
	11th to 20th	Night	23% 4 13% 34% 23% 2	2482
	21st to end	Night	35% 5% 19% 24% 16% 1	2866
August	1st to 10th	Night	21% 6% 19% 35% 18% 2	2826
	11th to 20th	Night	31% 5% 12% 30% 21% 1	3041
	21st to end	Night	25% 5% 20% 31% 16% 4	3476
September	1st to 10th	Night	29% 5% 10% 24% 26% 7%	1900
	11th to 20th	Night	30% 5% 10% 24% 26% 5%	1900
	21st to end	Night	30% 4 9% 26% 27% 4	2119
October	1st to 10th	Night	20% 3 6% 22% 45% 4	3800
	11th to 20th	Night	25% 3 8% 22% 35% 7%	3779
	21st to end	Night	35% 3 9% 23% 25% 4	4146
November	1st to 10th	Night	32% 5% 12% 27% 20% 5%	2536
	11th to 20th	Night	39% 3 10% 26% 20% 3	2600
	21st to end	Night	45% 4 11% 25% 14% 1	2765
December	1st to 10th	Night	47% 5% 13% 23% 11% 1	2779
	11th to 20th	Night	45% 4 11% 25% 13% 1	3281
	21st to end	Night	69% 4 8% 12% 7% 1	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% 20% 34% 21% 5% 1	270
	11th to 20th	Day	27% 21% 37% 13% 2	270
	21st to end	Day	18% 21% 38% 20% 3	297
February	1st to 10th	Day	25% 17% 39% 14% 4	270
	11th to 20th	Day	21% 23% 34% 15% 5%	270
	21st to end	Day	23% 20% 37% 17% 2	225
March	1st to 10th	Day	17% 24% 45% 12% 2	270
	11th to 20th	Day	27% 17% 33% 20% 3 1	270
	21st to end	Day	32% 16% 32% 15% 4 1	396
April	1st to 10th	Day	20% 16% 33% 23% 7% 1	460
	11th to 20th	Day	21% 17% 31% 20% 10% 1	452
	21st to end	Day	22% 16% 33% 22% 6% 1	460
May	1st to 10th	Day	16% 14% 36% 24% 9% 1	525
	11th to 20th	Day	19% 11% 28% 27% 13% 3	675
	21st to end	Day	13% 9% 28% 28% 15% 7%	734
June	1st to 10th	Day	7% 5% 24% 34% 22% 8%	680
	11th to 20th	Day	8% 3 26% 36% 21% 6%	680
	21st to end	Day	9% 8% 29% 34% 17% 5%	680
July	1st to 10th	Day	10% 3 16% 36% 23% 13%	671
	11th to 20th	Day	7% 3 21% 36% 26% 7%	668
	21st to end	Day	9% 3 17% 33% 31% 7%	739
August	1st to 10th	Day	6% 3 17% 40% 26% 7%	676
	11th to 20th	Day	8% 4 19% 32% 29% 10%	533
	21st to end	Day	9% 2 14% 33% 31% 10%	539
September	1st to 10th	Day	12% 3 16% 32% 28% 10%	490
	11th to 20th	Day	9% 3 16% 34% 27% 11%	490
	21st to end	Day	9% 10% 23% 31% 19% 8%	436
October	1st to 10th	Day	11% 8% 30% 31% 13% 7%	300
	11th to 20th	Day	13% 22% 35% 20% 9%	300
	21st to end	Day	25% 19% 31% 21% 4	330
November	1st to 10th	Day	13% 12% 37% 25% 9% 3	300
	11th to 20th	Day	21% 17% 34% 18% 8% 1	300
	21st to end	Day	27% 13% 36% 18% 6% 1	300
December	1st to 10th	Day	13% 21% 42% 15% 6% 3	294
	11th to 20th	Day	23% 13% 42% 17% 6%	270
	21st to end	Day	26% 23% 36% 13% 2	297
January	1st to 10th	Night	16% 17% 40% 22% 5%	950
	11th to 20th	Night	20% 17% 36% 22% 5%	950
	21st to end	Night	20% 15% 37% 25% 2	1045
February	1st to 10th	Night	21% 14% 40% 22% 4	950
	11th to 20th	Night	17% 15% 39% 25% 3	820
	21st to end	Night	22% 16% 38% 21% 3	628
March	1st to 10th	Night	19% 14% 40% 22% 4	720
	11th to 20th	Night	19% 13% 35% 27% 5%	570
	21st to end	Night	24% 12% 33% 26% 4	627
April	1st to 10th	Night	16% 15% 38% 26% 5%	570
	11th to 20th	Night	16% 13% 34% 29% 8%	563
	21st to end	Night	21% 9% 35% 29% 5%	570
May	1st to 10th	Night	16% 7% 35% 33% 8% 1	570
	11th to 20th	Night	16% 6% 27% 38% 12% 1	561
	21st to end	Night	13% 5% 26% 33% 20% 3	617
June	1st to 10th	Night	7% 6% 21% 45% 21% 1	570
	11th to 20th	Night	9% 2 23% 44% 20% 2	570
	21st to end	Night	7% 3 25% 41% 22% 1	570
July	1st to 10th	Night	11% 2 10% 38% 34% 4	555
	11th to 20th	Night	6% 2 17% 44% 29% 3	552
	21st to end	Night	9% 1 13% 43% 33% 1	624
August	1st to 10th	Night	7% 2 11% 44% 32% 3	567
	11th to 20th	Night	8% 1 14% 39% 32% 5%	564
	21st to end	Night	5% 1 14% 37% 40% 3	627
September	1st to 10th	Night	13% 3 15% 37% 27% 5%	570
	11th to 20th	Night	9% 2 17% 36% 29% 6%	570
	21st to end	Night	9% 7% 23% 33% 23% 5%	738
October	1st to 10th	Night	10% 5% 28% 32% 23% 3	760
	11th to 20th	Night	15% 11% 33% 29% 11% 1	760
	21st to end	Night	22% 11% 34% 26% 7%	836
November	1st to 10th	Night	14% 9% 38% 30% 9% 1	780
	11th to 20th	Night	15% 14% 39% 26% 5% 1	800
	21st to end	Night	21% 14% 36% 23% 5%	965
December	1st to 10th	Night	19% 13% 38% 25% 5% 1	993
	11th to 20th	Night	22% 11% 33% 28% 6%	950
	21st to end	Night	24% 17% 35% 22% 3	1045

Page generated at 2024-12-06 02:54:48. Version ac07

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