Heaven's Gate
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Heaven's Gate clear sky chart from 2005-11-06 to 2024-03-01.

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	9% 11% 5% 8% 6% 3 5% 5% 5% 6% 37%	78125
	Night	8% 11% 5% 8% 6% 4 5% 5% 5% 7% 36%	81278
Transparency	Day	47% 7% 10% 17% 13% 5%	77829
	Night	48% 8% 11% 18% 11% 3	81095
Seeing	Day	17% 22% 32% 20% 7% 1	13367
	Night	17% 13% 29% 28% 11% 1	23026

By Month

Percentage Cloud Cover SW (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% 14% 10% 16% 9% 4 6% 6% 5% 6% 17%	2539
	11th to 20th	Day	6% 16% 9% 15% 9% 3 4 4 4 5% 25%	2540
	21st to end	Day	6% 16% 6% 10% 10% 5% 7% 6% 6% 6% 21%	2794
February	1st to 10th	Day	9% 19% 7% 11% 8% 3 6% 3 6% 7% 22%	1571
	11th to 20th	Day	6% 18% 9% 12% 9% 4 6% 5% 4 5% 21%	1850
	21st to end	Day	5% 18% 9% 17% 10% 4 5% 5% 5% 4 17%	1570
March	1st to 10th	Day	7% 16% 8% 13% 9% 5% 6% 6% 5% 5% 19%	1801
	11th to 20th	Day	6% 18% 6% 10% 9% 4 7% 6% 4 6% 23%	1884
	21st to end	Day	10% 22% 9% 12% 8% 5% 6% 5% 5% 4 14%	2301
April	1st to 10th	Day	11% 18% 8% 11% 7% 4 5% 5% 6% 5% 20%	2160
	11th to 20th	Day	11% 17% 6% 10% 7% 3 4 4 4 6% 28%	2185
	21st to end	Day	17% 18% 4 8% 7% 3 4 3 4 6% 25%	2340
May	1st to 10th	Day	10% 13% 4 7% 5% 4 5% 5% 5% 7% 35%	2340
	11th to 20th	Day	17% 10% 3 7% 6% 4 6% 5% 7% 7% 29%	2467
	21st to end	Day	20% 13% 4 8% 7% 4 6% 5% 5% 6% 22%	2723
June	1st to 10th	Day	16% 10% 3 7% 7% 3 4 6% 6% 8% 29%	2520
	11th to 20th	Day	16% 8% 4 6% 6% 4 4 5% 5% 6% 36%	2520
	21st to end	Day	7% 3 2 4 4 3 4 4 5% 7% 57%	2520
July	1st to 10th	Day	3 3 1 3 4 3 5% 5% 6% 7% 61%	2520
	11th to 20th	Day	2 2 1 2 3 2 3 4 5% 6% 70%	2520
	21st to end	Day	2 1 1 3 3 2 2 3 5% 6% 72%	2741
August	1st to 10th	Day	4 3 1 4 4 3 4 5% 5% 7% 60%	2482
	11th to 20th	Day	3 2 1 2 3 2 3 5% 5% 7% 66%	2299
	21st to end	Day	4 3 1 3 4 2 4 4 5% 7% 63%	2417
September	1st to 10th	Day	5% 3 1 4 3 2 4 3 3 6% 66%	2160
	11th to 20th	Day	6% 5% 2 5% 5% 3 4 5% 5% 6% 54%	2016
	21st to end	Day	9% 6% 2 5% 4 3 4 5% 4 7% 51%	1980
October	1st to 10th	Day	13% 11% 3 6% 5% 3 4 4 4 5% 42%	1980
	11th to 20th	Day	11% 9% 3 7% 6% 3 4 4 5% 6% 42%	1690
	21st to end	Day	12% 12% 5% 7% 6% 4 5% 5% 5% 7% 32%	1782
November	1st to 10th	Day	12% 15% 5% 8% 7% 3 5% 5% 5% 7% 28%	1674
	11th to 20th	Day	9% 14% 6% 9% 7% 5% 6% 6% 6% 7% 24%	1710
	21st to end	Day	6% 14% 7% 8% 7% 4 5% 5% 6% 7% 31%	1576
December	1st to 10th	Day	9% 13% 6% 8% 9% 4 6% 5% 6% 6% 27%	1368
	11th to 20th	Day	6% 14% 7% 12% 10% 4 7% 5% 7% 8% 19%	1791
	21st to end	Day	6% 14% 8% 11% 7% 4 5% 5% 6% 8% 26%	2794
January	1st to 10th	Night	8% 15% 8% 12% 9% 3 6% 5% 6% 8% 20%	4406
	11th to 20th	Night	10% 17% 9% 12% 8% 4 5% 4 5% 5% 21%	4420
	21st to end	Night	4 14% 6% 11% 8% 6% 6% 7% 6% 7% 25%	4862
February	1st to 10th	Night	9% 18% 7% 13% 8% 4 5% 5% 4 5% 22%	2606
	11th to 20th	Night	8% 18% 6% 11% 7% 5% 6% 6% 5% 5% 24%	2218
	21st to end	Night	6% 16% 7% 14% 10% 5% 6% 5% 4 7% 19%	1884
March	1st to 10th	Night	8% 15% 7% 10% 7% 4 7% 6% 6% 5% 26%	2165
	11th to 20th	Night	8% 12% 5% 10% 7% 4 6% 6% 6% 8% 29%	2075
	21st to end	Night	12% 16% 6% 10% 7% 4 7% 6% 7% 7% 19%	2052
April	1st to 10th	Night	9% 16% 7% 9% 8% 4 5% 5% 5% 6% 27%	1800
	11th to 20th	Night	14% 12% 4 7% 6% 3 5% 5% 5% 5% 34%	1723
	21st to end	Night	14% 13% 5% 8% 6% 3 5% 5% 5% 7% 30%	1620
May	1st to 10th	Night	12% 9% 3 5% 6% 4 4 4 6% 7% 40%	1620
	11th to 20th	Night	13% 8% 2 6% 6% 3 5% 5% 6% 8% 38%	1423
	21st to end	Night	18% 11% 3 6% 6% 3 4 4 4 9% 31%	1552
June	1st to 10th	Night	17% 7% 3 6% 6% 3 5% 6% 6% 8% 34%	1440
	11th to 20th	Night	17% 6% 2 4 4 3 5% 4 5% 8% 43%	1440
	21st to end	Night	6% 3 2 3 3 2 5% 4 5% 8% 58%	1440
July	1st to 10th	Night	2 2 1 3 3 2 3 4 5% 7% 68%	1440
	11th to 20th	Night	2 1 1 2 2 2 4 3 5% 6% 73%	1440
	21st to end	Night	2 2 1 2 2 2 2 3 5% 6% 74%	1576
August	1st to 10th	Night	4 3 2 3 4 2 3 4 5% 8% 62%	1457
	11th to 20th	Night	2 1 1 2 3 2 3 5% 6% 7% 68%	1602
	21st to end	Night	4 3 1 3 3 2 3 4 5% 5% 65%	1935
September	1st to 10th	Night	4 2 1 3 3 2 4 4 5% 7% 66%	1800
	11th to 20th	Night	6% 4 2 3 4 3 4 5% 5% 6% 57%	1944
	21st to end	Night	12% 5% 2 5% 4 2 3 3 5% 6% 54%	1980
October	1st to 10th	Night	12% 9% 3 5% 5% 4 4 4 4 6% 44%	1980
	11th to 20th	Night	9% 10% 3 6% 7% 3 5% 4 5% 6% 43%	2267
	21st to end	Night	13% 11% 4 7% 7% 4 5% 5% 4 6% 35%	2574
November	1st to 10th	Night	13% 13% 4 7% 6% 3 5% 6% 6% 7% 31%	2405
	11th to 20th	Night	12% 14% 5% 9% 6% 4 6% 5% 5% 6% 28%	2470
	21st to end	Night	7% 13% 7% 10% 7% 4 5% 4 5% 6% 33%	2603
December	1st to 10th	Night	8% 12% 5% 8% 7% 4 7% 5% 6% 7% 30%	2785
	11th to 20th	Night	5% 13% 6% 9% 9% 5% 6% 6% 7% 8% 24%	3412
	21st to end	Night	6% 14% 7% 11% 7% 4 5% 4 5% 7% 30%	4862

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	67% 10% 12% 8% 1 1	2539
	11th to 20th	Day	64% 5% 9% 12% 8% 2	2540
	21st to end	Day	64% 11% 13% 8% 4	2794
February	1st to 10th	Day	63% 11% 11% 13% 2	1571
	11th to 20th	Day	66% 7% 10% 11% 5%	1860
	21st to end	Day	70% 7% 8% 9% 5% 1	1570
March	1st to 10th	Day	68% 9% 9% 10% 5%	1801
	11th to 20th	Day	62% 7% 10% 16% 5%	1884
	21st to end	Day	73% 7% 9% 10% 1	2301
April	1st to 10th	Day	64% 8% 11% 13% 3	2160
	11th to 20th	Day	56% 7% 10% 16% 9% 1	2188
	21st to end	Day	60% 6% 10% 16% 7%	2340
May	1st to 10th	Day	46% 7% 12% 24% 11%	2340
	11th to 20th	Day	52% 7% 12% 21% 7% 1	2470
	21st to end	Day	61% 7% 11% 14% 6%	2724
June	1st to 10th	Day	52% 7% 12% 22% 6%	2520
	11th to 20th	Day	48% 6% 9% 20% 13% 3	2520
	21st to end	Day	27% 5% 8% 28% 27% 5%	2520
July	1st to 10th	Day	21% 6% 8% 21% 29% 15%	2451
	11th to 20th	Day	15% 4 6% 18% 31% 26%	2445
	21st to end	Day	14% 4 5% 15% 39% 24%	2589
August	1st to 10th	Day	23% 5% 7% 21% 29% 15%	2465
	11th to 20th	Day	17% 5% 8% 24% 32% 14%	2299
	21st to end	Day	21% 4 7% 26% 29% 12%	2417
September	1st to 10th	Day	21% 3 9% 22% 28% 17%	2160
	11th to 20th	Day	29% 6% 10% 22% 25% 9%	2016
	21st to end	Day	34% 4 10% 28% 19% 4	1980
October	1st to 10th	Day	45% 5% 10% 23% 16% 2	1980
	11th to 20th	Day	43% 5% 12% 26% 13% 1	1690
	21st to end	Day	52% 9% 11% 18% 11% 1	1782
November	1st to 10th	Day	56% 9% 13% 17% 5% 1	1674
	11th to 20th	Day	58% 10% 15% 14% 4	1710
	21st to end	Day	54% 8% 14% 15% 9% 1	1576
December	1st to 10th	Day	58% 14% 11% 10% 6% 1	1368
	11th to 20th	Day	63% 15% 10% 10% 2	1791
	21st to end	Day	55% 14% 13% 13% 5% 1	2794
January	1st to 10th	Night	63% 10% 14% 11% 1 1	4406
	11th to 20th	Night	64% 7% 9% 14% 6% 1	4420
	21st to end	Night	58% 16% 11% 11% 4	4862
February	1st to 10th	Night	66% 9% 10% 12% 2 1	2606
	11th to 20th	Night	62% 8% 11% 13% 5% 1	2219
	21st to end	Night	66% 7% 8% 13% 5% 1	1884
March	1st to 10th	Night	58% 10% 12% 14% 6%	2165
	11th to 20th	Night	54% 10% 12% 19% 6%	2075
	21st to end	Night	63% 10% 13% 12% 2	2052
April	1st to 10th	Night	57% 7% 13% 18% 5% 1	1800
	11th to 20th	Night	52% 6% 11% 20% 10% 2	1723
	21st to end	Night	53% 6% 13% 20% 8%	1620
May	1st to 10th	Night	42% 7% 13% 29% 10%	1620
	11th to 20th	Night	42% 7% 17% 25% 8%	1423
	21st to end	Night	51% 5% 17% 22% 5%	1552
June	1st to 10th	Night	47% 9% 18% 22% 5%	1440
	11th to 20th	Night	40% 5% 15% 25% 13% 2	1440
	21st to end	Night	25% 6% 13% 30% 22% 5%	1440
July	1st to 10th	Night	15% 6% 10% 26% 31% 13%	1400
	11th to 20th	Night	13% 4 9% 26% 25% 22%	1392
	21st to end	Night	12% 3 4 22% 40% 19%	1488
August	1st to 10th	Night	20% 5% 8% 26% 27% 13%	1449
	11th to 20th	Night	15% 5% 9% 25% 31% 15%	1602
	21st to end	Night	20% 4 8% 26% 30% 11%	1935
September	1st to 10th	Night	18% 5% 9% 25% 28% 16%	1800
	11th to 20th	Night	26% 6% 10% 25% 24% 10%	1944
	21st to end	Night	31% 4 10% 27% 19% 8%	1980
October	1st to 10th	Night	41% 6% 10% 24% 16% 3	1980
	11th to 20th	Night	41% 6% 12% 24% 15% 2	2267
	21st to end	Night	50% 8% 9% 18% 13% 1	2574
November	1st to 10th	Night	52% 10% 10% 19% 7% 2	2405
	11th to 20th	Night	56% 10% 13% 18% 4	2470
	21st to end	Night	52% 6% 11% 18% 11% 1	2603
December	1st to 10th	Night	54% 12% 14% 13% 6% 2	2785
	11th to 20th	Night	57% 15% 11% 13% 3 1	3412
	21st to end	Night	55% 9% 15% 14% 5% 2	4862

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	23% 22% 39% 13% 3 1	180
	11th to 20th	Day	26% 27% 29% 7% 10% 1	180
	21st to end	Day	20% 24% 36% 18% 2	198
February	1st to 10th	Day	22% 34% 34% 8% 1	216
	11th to 20th	Day	21% 34% 30% 12% 3	455
	21st to end	Day	24% 30% 33% 11% 2	382
March	1st to 10th	Day	22% 38% 28% 11% 1	421
	11th to 20th	Day	18% 31% 33% 14% 4	420
	21st to end	Day	26% 33% 26% 12% 3	462
April	1st to 10th	Day	25% 26% 29% 15% 4 1	420
	11th to 20th	Day	26% 26% 26% 16% 4 1	412
	21st to end	Day	30% 25% 24% 16% 5%	420
May	1st to 10th	Day	20% 20% 33% 20% 6% 1	423
	11th to 20th	Day	29% 18% 28% 17% 7% 2	448
	21st to end	Day	26% 14% 25% 25% 7% 3	485
June	1st to 10th	Day	19% 17% 32% 23% 7% 2	450
	11th to 20th	Day	22% 25% 30% 17% 5% 1	450
	21st to end	Day	7% 17% 37% 28% 9% 2	450
July	1st to 10th	Day	4 15% 43% 27% 9% 1	446
	11th to 20th	Day	4 20% 39% 28% 8% 1	444
	21st to end	Day	2 15% 41% 29% 11% 2	487
August	1st to 10th	Day	6% 13% 38% 31% 10% 2	447
	11th to 20th	Day	5% 10% 30% 36% 15% 3	437
	21st to end	Day	5% 15% 37% 28% 12% 2	495
September	1st to 10th	Day	8% 15% 32% 30% 12% 3	450
	11th to 20th	Day	9% 18% 30% 29% 11% 2	450
	21st to end	Day	13% 18% 35% 22% 10% 2	450
October	1st to 10th	Day	19% 21% 28% 21% 9% 2	450
	11th to 20th	Day	16% 22% 34% 15% 10% 3	338
	21st to end	Day	25% 24% 26% 19% 5% 1	297
November	1st to 10th	Day	28% 20% 30% 18% 3	270
	11th to 20th	Day	20% 26% 26% 23% 5% 1	270
	21st to end	Day	17% 22% 39% 21% 2	206
December	1st to 10th	Day	24% 22% 27% 16% 11% 1	180
	11th to 20th	Day	24% 37% 27% 9% 3	180
	21st to end	Day	26% 31% 29% 8% 5% 2	198
January	1st to 10th	Night	24% 19% 34% 17% 5%	760
	11th to 20th	Night	24% 19% 31% 21% 6% 1	760
	21st to end	Night	17% 20% 32% 25% 5% 1	836
February	1st to 10th	Night	21% 20% 39% 17% 3 1	760
	11th to 20th	Night	20% 19% 34% 24% 3	744
	21st to end	Night	18% 23% 35% 18% 6%	628
March	1st to 10th	Night	17% 23% 34% 20% 6% 1	722
	11th to 20th	Night	16% 18% 33% 23% 9% 1	720
	21st to end	Night	19% 16% 35% 24% 5% 1	792
April	1st to 10th	Night	19% 14% 29% 26% 11% 2	720
	11th to 20th	Night	20% 13% 31% 25% 9% 1	655
	21st to end	Night	22% 10% 27% 31% 9% 1	540
May	1st to 10th	Night	19% 9% 25% 36% 11% 1	540
	11th to 20th	Night	14% 9% 22% 32% 22% 1	361
	21st to end	Night	22% 8% 19% 30% 19% 2	389
June	1st to 10th	Night	19% 6% 23% 33% 18% 2	360
	11th to 20th	Night	21% 5% 27% 33% 14%	360
	21st to end	Night	8% 4 23% 43% 22%	360
July	1st to 10th	Night	5% 3 17% 52% 22% 1	350
	11th to 20th	Night	3 1 23% 57% 15%	348
	21st to end	Night	4 3 20% 50% 23% 1	394
August	1st to 10th	Night	5% 3 20% 45% 28%	383
	11th to 20th	Night	3 2 20% 46% 28% 2	534
	21st to end	Night	6% 3 24% 40% 25% 2	747
September	1st to 10th	Night	6% 3 19% 47% 23% 3	720
	11th to 20th	Night	7% 5% 21% 37% 26% 5%	720
	21st to end	Night	15% 5% 23% 32% 22% 3	720
October	1st to 10th	Night	17% 7% 25% 33% 18% 1	720
	11th to 20th	Night	16% 11% 27% 31% 13% 3	720
	21st to end	Night	23% 10% 31% 25% 8% 3	792
November	1st to 10th	Night	21% 15% 36% 24% 4	740
	11th to 20th	Night	24% 18% 34% 19% 4 1	760
	21st to end	Night	16% 19% 34% 22% 8% 1	760
December	1st to 10th	Night	19% 18% 35% 22% 5%	885
	11th to 20th	Night	20% 23% 36% 18% 3	890
	21st to end	Night	22% 24% 37% 14% 2 1	836

Page generated at 2024-02-27 04:30:15. Version ac07

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