Ghost Pine Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Ghost Pine Observatory clear sky chart from 2005-11-06 to 2024-11-10.

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	6% 3 1 3 2 2 3 2 4 5% 67%	105196
	Night	7% 4 1 3 2 3 3 3 4 5% 64%	102683
Transparency	Day	20% 4 8% 18% 25% 25%	104951
	Night	22% 5% 9% 18% 23% 24%	102517
Seeing	Day	7% 8% 18% 27% 28% 12%	15288
	Night	8% 6% 18% 34% 30% 5%	24529

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	13% 9% 2 6% 4 4 4 3 5% 7% 42%	2603
	11th to 20th	Day	17% 9% 4 8% 4 4 4 3 4 7% 37%	2860
	21st to end	Day	20% 9% 3 7% 4 4 4 3 5% 7% 35%	3146
February	1st to 10th	Day	13% 6% 1 4 4 4 3 4 5% 6% 51%	1710
	11th to 20th	Day	10% 6% 2 6% 4 4 4 3 5% 7% 49%	1719
	21st to end	Day	11% 4 2 5% 4 4 4 4 5% 6% 51%	1570
March	1st to 10th	Day	12% 8% 3 8% 5% 5% 5% 4 6% 8% 36%	3371
	11th to 20th	Day	8% 5% 1 4 4 3 3 3 5% 5% 59%	3490
	21st to end	Day	12% 7% 2 7% 5% 5% 5% 5% 6% 7% 40%	3882
April	1st to 10th	Day	9% 6% 3 6% 4 4 5% 3 5% 8% 47%	2280
	11th to 20th	Day	8% 3 1 4 3 3 3 3 5% 7% 58%	2249
	21st to end	Day	3 3 1 3 3 3 3 3 6% 8% 63%	2280
May	1st to 10th	Day	5% 2 1 2 2 1 2 1 3 6% 76%	4013
	11th to 20th	Day	2 1 2 1 1 2 2 4 5% 79%	4253
	21st to end	Day	2 1 1 2 1 2 2 2 4 6% 78%	4813
June	1st to 10th	Day	4 2 1 2 3 3 3 3 5% 8% 66%	2660
	11th to 20th	Day	1 1 2 2 1 2 2 3 5% 80%	2660
	21st to end	Day	1 1 1 1 1 1 2 2 3 87%	2660
July	1st to 10th	Day	1 1 1 1 2 93%	4420
	11th to 20th	Day	1 1 1 1 1 1 1 2 3 87%	4268
	21st to end	Day	1 1 1 1 1 2 3 91%	4455
August	1st to 10th	Day	2 1 1 1 2 3 3 5% 4 78%	4091
	11th to 20th	Day	1 1 1 1 1 1 2 3 90%	3884
	21st to end	Day	1 1 1 1 1 1 1 2 2 88%	4180
September	1st to 10th	Day	1 1 1 1 1 2 4 88%	2280
	11th to 20th	Day	2 2 1 2 2 2 2 2 3 4 79%	2280
	21st to end	Day	2 1 1 2 1 2 1 1 3 5% 81%	2011
October	1st to 10th	Day	2 2 1 3 1 2 2 2 4 5% 78%	3180
	11th to 20th	Day	3 3 1 2 2 2 2 2 4 4 75%	3161
	21st to end	Day	4 2 1 3 3 3 4 3 5% 6% 65%	3448
November	1st to 10th	Day	6% 4 1 3 3 3 4 4 5% 8% 60%	1870
	11th to 20th	Day	9% 4 2 5% 4 3 4 4 6% 7% 53%	1687
	21st to end	Day	7% 5% 2 4 3 3 3 3 4 6% 59%	1520
December	1st to 10th	Day	11% 7% 2 4 3 3 4 3 5% 8% 50%	1520
	11th to 20th	Day	24% 10% 3 7% 4 3 3 3 5% 5% 33%	1928
	21st to end	Day	19% 8% 2 5% 4 2 3 4 6% 8% 38%	2794
January	1st to 10th	Night	12% 7% 2 5% 3 4 3 3 6% 8% 46%	4342
	11th to 20th	Night	15% 9% 3 7% 4 5% 4 4 5% 6% 36%	4110
	21st to end	Night	19% 8% 3 7% 4 4 4 4 5% 6% 35%	4521
February	1st to 10th	Night	12% 5% 2 5% 4 3 4 4 5% 6% 51%	2470
	11th to 20th	Night	9% 5% 2 4 4 3 4 4 6% 9% 51%	2346
	21st to end	Night	10% 5% 2 4 3 3 3 3 5% 6% 57%	1884
March	1st to 10th	Night	9% 8% 2 6% 4 4 5% 4 6% 8% 44%	3500
	11th to 20th	Night	9% 5% 1 3 2 3 3 3 4 4 62%	3490
	21st to end	Night	11% 5% 2 6% 5% 5% 5% 4 5% 8% 45%	3769
April	1st to 10th	Night	5% 5% 2 6% 4 4 4 4 5% 6% 55%	1900
	11th to 20th	Night	6% 4 1 4 2 2 3 3 5% 6% 64%	1879
	21st to end	Night	4 2 1 2 2 2 3 2 4 8% 71%	1900
May	1st to 10th	Night	3 1 2 1 2 2 2 3 5% 78%	2956
	11th to 20th	Night	2 1 1 1 1 2 2 3 4 83%	2630
	21st to end	Night	2 1 1 1 1 1 2 3 4 84%	2762
June	1st to 10th	Night	4 2 2 3 2 3 3 5% 6% 71%	1520
	11th to 20th	Night	1 1 1 1 1 2 1 3 4 84%	1520
	21st to end	Night	1 1 1 1 1 2 2 2 2 3 85%	1520
July	1st to 10th	Night	1 1 1 2 94%	2540
	11th to 20th	Night	1 1 1 1 1 1 1 1 2 2 87%	2692
	21st to end	Night	1 1 1 1 1 2 3 89%	3109
August	1st to 10th	Night	3 2 1 2 1 1 2 2 3 4 79%	2848
	11th to 20th	Night	1 1 1 1 2 2 92%	2958
	21st to end	Night	2 1 1 1 1 1 1 1 2 89%	3498
September	1st to 10th	Night	1 1 1 1 1 1 1 2 3 89%	1900
	11th to 20th	Night	1 2 1 2 2 1 1 1 3 4 81%	1900
	21st to end	Night	1 1 1 1 1 2 1 3 5% 84%	2164
October	1st to 10th	Night	2 1 1 2 2 2 3 2 3 4 80%	3800
	11th to 20th	Night	2 1 1 2 1 2 3 2 4 5% 78%	3777
	21st to end	Night	4 2 1 3 2 3 3 3 5% 7% 68%	4121
November	1st to 10th	Night	6% 3 1 3 3 3 3 3 6% 8% 60%	2410
	11th to 20th	Night	8% 4 1 4 3 3 4 3 6% 7% 57%	2489
	21st to end	Night	7% 4 2 5% 3 3 3 3 4 6% 60%	2660
December	1st to 10th	Night	13% 5% 2 5% 3 4 4 3 5% 6% 50%	2660
	11th to 20th	Night	21% 10% 3 5% 3 3 3 3 5% 7% 36%	3276
	21st to end	Night	15% 9% 3 7% 4 5% 5% 4 5% 6% 37%	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	40% 10% 12% 27% 7% 3	2603
	11th to 20th	Day	48% 8% 10% 16% 11% 8%	2860
	21st to end	Day	49% 8% 11% 15% 13% 5%	3146
February	1st to 10th	Day	35% 5% 11% 21% 20% 9%	1710
	11th to 20th	Day	35% 5% 11% 19% 21% 9%	1728
	21st to end	Day	33% 6% 10% 25% 20% 7%	1570
March	1st to 10th	Day	44% 10% 13% 13% 16% 4	3371
	11th to 20th	Day	26% 5% 11% 25% 20% 13%	3490
	21st to end	Day	38% 11% 15% 19% 14% 3	3882
April	1st to 10th	Day	35% 6% 13% 21% 18% 7%	2280
	11th to 20th	Day	24% 8% 13% 22% 24% 8%	2252
	21st to end	Day	18% 6% 15% 28% 26% 8%	2280
May	1st to 10th	Day	12% 3 9% 28% 25% 22%	4013
	11th to 20th	Day	9% 3 7% 23% 38% 20%	4256
	21st to end	Day	9% 4 10% 35% 28% 13%	4814
June	1st to 10th	Day	17% 5% 11% 27% 28% 12%	2660
	11th to 20th	Day	8% 3 8% 19% 35% 26%	2660
	21st to end	Day	6% 2 3 13% 35% 40%	2660
July	1st to 10th	Day	3 1 2 6% 17% 72%	4351
	11th to 20th	Day	5% 1 2 7% 19% 65%	4193
	21st to end	Day	3 1 2 7% 25% 62%	4315
August	1st to 10th	Day	9% 2 3 9% 25% 52%	4076
	11th to 20th	Day	3 1 2 9% 43% 42%	3923
	21st to end	Day	6% 1 3 12% 38% 40%	4179
September	1st to 10th	Day	3 1 3 8% 29% 55%	2280
	11th to 20th	Day	10% 3 7% 23% 38% 19%	2280
	21st to end	Day	9% 3 5% 20% 30% 33%	2011
October	1st to 10th	Day	11% 2 4 12% 26% 46%	3180
	11th to 20th	Day	14% 3 5% 27% 30% 21%	3161
	21st to end	Day	19% 4 7% 24% 32% 15%	3448
November	1st to 10th	Day	23% 6% 9% 27% 23% 12%	1870
	11th to 20th	Day	30% 6% 13% 23% 22% 7%	1687
	21st to end	Day	27% 5% 12% 22% 22% 12%	1520
December	1st to 10th	Day	34% 7% 9% 21% 19% 10%	1520
	11th to 20th	Day	55% 5% 7% 13% 16% 4	1928
	21st to end	Day	44% 7% 15% 18% 12% 4	2794
January	1st to 10th	Night	34% 10% 19% 23% 10% 3	4342
	11th to 20th	Night	47% 9% 12% 13% 11% 8%	4110
	21st to end	Night	48% 7% 12% 13% 14% 5%	4521
February	1st to 10th	Night	34% 4 9% 20% 20% 12%	2470
	11th to 20th	Night	30% 6% 11% 21% 23% 9%	2348
	21st to end	Night	28% 5% 13% 23% 24% 7%	1884
March	1st to 10th	Night	35% 12% 18% 15% 17% 3	3500
	11th to 20th	Night	26% 4 9% 24% 25% 12%	3490
	21st to end	Night	34% 9% 16% 24% 13% 4	3769
April	1st to 10th	Night	29% 7% 13% 21% 21% 9%	1900
	11th to 20th	Night	21% 5% 14% 28% 19% 12%	1879
	21st to end	Night	14% 5% 14% 30% 30% 8%	1900
May	1st to 10th	Night	10% 4 8% 27% 31% 20%	2956
	11th to 20th	Night	7% 3 6% 20% 36% 28%	2630
	21st to end	Night	7% 2 9% 39% 27% 16%	2762
June	1st to 10th	Night	15% 5% 11% 25% 31% 14%	1520
	11th to 20th	Night	6% 3 6% 21% 33% 31%	1520
	21st to end	Night	7% 2 3 11% 30% 46%	1520
July	1st to 10th	Night	2 1 1 5% 17% 74%	2500
	11th to 20th	Night	6% 2 2 6% 13% 71%	2644
	21st to end	Night	3 1 2 5% 21% 68%	3011
August	1st to 10th	Night	11% 2 2 7% 23% 56%	2839
	11th to 20th	Night	3 1 2 5% 33% 56%	2985
	21st to end	Night	6% 1 2 8% 35% 47%	3498
September	1st to 10th	Night	4 1 2 6% 29% 57%	1900
	11th to 20th	Night	10% 2 6% 18% 38% 26%	1900
	21st to end	Night	6% 2 5% 18% 30% 39%	2164
October	1st to 10th	Night	10% 3 5% 10% 20% 53%	3800
	11th to 20th	Night	10% 3 7% 28% 31% 21%	3777
	21st to end	Night	16% 3 6% 24% 29% 22%	4121
November	1st to 10th	Night	23% 6% 10% 25% 21% 15%	2410
	11th to 20th	Night	25% 5% 12% 24% 22% 10%	2489
	21st to end	Night	26% 5% 9% 21% 25% 14%	2660
December	1st to 10th	Night	35% 6% 9% 19% 19% 11%	2660
	11th to 20th	Night	48% 7% 10% 14% 18% 4	3276
	21st to end	Night	45% 9% 12% 17% 14% 4	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	29% 11% 24% 20% 15%	218
	11th to 20th	Day	16% 11% 26% 28% 16% 4	370
	21st to end	Day	15% 9% 26% 23% 20% 6%	407
February	1st to 10th	Day	16% 13% 21% 27% 18% 5%	370
	11th to 20th	Day	15% 18% 27% 24% 13% 3	391
	21st to end	Day	11% 15% 25% 33% 13% 3	382
March	1st to 10th	Day	15% 19% 27% 25% 10% 4	460
	11th to 20th	Day	15% 14% 22% 26% 17% 6%	460
	21st to end	Day	13% 17% 27% 29% 12% 3	506
April	1st to 10th	Day	12% 13% 24% 29% 16% 7%	460
	11th to 20th	Day	10% 13% 26% 24% 17% 9%	452
	21st to end	Day	3 11% 24% 29% 24% 10%	460
May	1st to 10th	Day	6% 10% 27% 27% 23% 7%	463
	11th to 20th	Day	6% 6% 22% 27% 22% 18%	488
	21st to end	Day	4 7% 18% 26% 29% 17%	529
June	1st to 10th	Day	4 5% 19% 25% 33% 14%	490
	11th to 20th	Day	2 7% 18% 33% 33% 8%	490
	21st to end	Day	4 13% 30% 37% 16%	490
July	1st to 10th	Day	1 1 8% 30% 45% 15%	486
	11th to 20th	Day	1 8% 25% 43% 23%	484
	21st to end	Day	1 1 6% 26% 45% 22%	531
August	1st to 10th	Day	3 1 8% 27% 38% 23%	487
	11th to 20th	Day	2 1 9% 26% 38% 24%	477
	21st to end	Day	1 2 6% 23% 45% 24%	539
September	1st to 10th	Day	1 11% 30% 41% 18%	490
	11th to 20th	Day	3 4 12% 26% 38% 16%	490
	21st to end	Day	1 6% 19% 30% 30% 13%	490
October	1st to 10th	Day	3 9% 18% 27% 28% 15%	490
	11th to 20th	Day	5% 6% 19% 25% 32% 13%	490
	21st to end	Day	11% 8% 20% 27% 26% 9%	539
November	1st to 10th	Day	10% 9% 22% 21% 30% 8%	412
	11th to 20th	Day	9% 8% 17% 29% 28% 10%	259
	21st to end	Day	12% 7% 23% 33% 19% 6%	180
December	1st to 10th	Day	21% 11% 22% 24% 14% 8%	180
	11th to 20th	Day	17% 8% 30% 22% 16% 8%	180
	21st to end	Day	18% 15% 24% 20% 20% 3	198
January	1st to 10th	Night	17% 6% 22% 31% 19% 6%	760
	11th to 20th	Night	13% 8% 24% 35% 15% 4	760
	21st to end	Night	16% 7% 22% 32% 19% 4	836
February	1st to 10th	Night	14% 9% 19% 34% 20% 3	760
	11th to 20th	Night	12% 9% 22% 32% 20% 5%	744
	21st to end	Night	11% 11% 23% 36% 16% 2	628
March	1st to 10th	Night	15% 10% 23% 31% 19% 3	760
	11th to 20th	Night	14% 7% 22% 31% 24% 3	760
	21st to end	Night	13% 8% 28% 34% 16% 2	836
April	1st to 10th	Night	8% 7% 25% 38% 21% 3	760
	11th to 20th	Night	8% 9% 24% 35% 21% 4	751
	21st to end	Night	4 7% 25% 35% 23% 4	760
May	1st to 10th	Night	5% 7% 27% 32% 25% 4	627
	11th to 20th	Night	2 4 15% 36% 39% 4	449
	21st to end	Night	4 5% 18% 33% 36% 3	411
June	1st to 10th	Night	4 4 18% 37% 35% 2	380
	11th to 20th	Night	1 5% 16% 40% 37% 1	380
	21st to end	Night	1 1 12% 44% 40% 2	380
July	1st to 10th	Night	1 6% 37% 53% 3	370
	11th to 20th	Night	1 4 36% 53% 6%	455
	21st to end	Night	1 3 29% 57% 9%	624
August	1st to 10th	Night	3 4 29% 56% 8%	567
	11th to 20th	Night	2 5% 34% 49% 9%	645
	21st to end	Night	1 1 4 31% 56% 7%	836
September	1st to 10th	Night	1 1 7% 36% 49% 6%	760
	11th to 20th	Night	2 2 9% 34% 44% 8%	760
	21st to end	Night	1 3 13% 37% 36% 10%	760
October	1st to 10th	Night	4 6% 14% 35% 33% 8%	760
	11th to 20th	Night	4 5% 16% 33% 37% 6%	760
	21st to end	Night	8% 4 21% 30% 29% 9%	836
November	1st to 10th	Night	7% 6% 20% 29% 31% 6%	778
	11th to 20th	Night	9% 4 19% 35% 29% 3	760
	21st to end	Night	8% 7% 22% 39% 20% 5%	760
December	1st to 10th	Night	15% 8% 23% 29% 22% 4	760
	11th to 20th	Night	20% 6% 20% 32% 20% 3	760
	21st to end	Night	15% 11% 25% 30% 19% 1	836

Page generated at 2024-11-07 03:55:43. Version ac07

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