Galunlati 2 Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Galunlati 2 Observatory clear sky chart from 2005-11-06 to 2024-11-05.

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	13% 7% 2 6% 5% 4 5% 4 6% 8% 41%	101429
	Night	13% 7% 2 6% 4 4 4 3 5% 7% 44%	97574
Transparency	Day	39% 6% 11% 21% 18% 4	105204
	Night	37% 6% 10% 21% 20% 6%	101938
Seeing	Day	15% 6% 20% 24% 21% 14%	14911
	Night	15% 5% 23% 32% 22% 4	24478

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	17% 12% 3 6% 4 4 4 4 6% 5% 35%	2836
	11th to 20th	Day	22% 7% 2 9% 4 3 3 3 3 4 39%	2876
	21st to end	Day	22% 11% 4 5% 3 3 3 2 4 6% 37%	3476
February	1st to 10th	Day	21% 10% 3 6% 3 3 3 3 5% 5% 39%	1900
	11th to 20th	Day	21% 8% 4 6% 5% 4 4 2 4 5% 36%	1848
	21st to end	Day	22% 8% 3 7% 4 3 4 4 4 5% 37%	1570
March	1st to 10th	Day	23% 11% 3 8% 4 4 4 3 5% 6% 30%	3120
	11th to 20th	Day	14% 8% 2 6% 4 3 3 3 5% 7% 45%	3320
	21st to end	Day	14% 6% 2 7% 6% 5% 5% 4 6% 7% 39%	4029
April	1st to 10th	Day	14% 7% 2 5% 5% 4 4 3 6% 6% 44%	2280
	11th to 20th	Day	14% 6% 2 7% 4 4 3 3 5% 7% 44%	2254
	21st to end	Day	11% 5% 2 6% 5% 5% 4 4 6% 8% 43%	2280
May	1st to 10th	Day	15% 6% 3 6% 5% 5% 5% 4 6% 8% 39%	4082
	11th to 20th	Day	16% 7% 2 7% 5% 4 4 4 6% 7% 38%	4081
	21st to end	Day	13% 6% 3 6% 4 4 4 4 6% 9% 41%	4476
June	1st to 10th	Day	10% 6% 2 7% 6% 5% 5% 5% 6% 9% 39%	2470
	11th to 20th	Day	5% 5% 2 5% 5% 5% 6% 5% 8% 10% 46%	2512
	21st to end	Day	7% 5% 2 7% 6% 5% 6% 5% 8% 11% 40%	2660
July	1st to 10th	Day	6% 5% 2 8% 7% 6% 7% 6% 8% 12% 32%	4440
	11th to 20th	Day	9% 5% 2 6% 6% 6% 7% 5% 8% 11% 33%	4125
	21st to end	Day	15% 11% 3 9% 7% 5% 5% 5% 6% 8% 25%	4466
August	1st to 10th	Day	4 3 1 5% 4 5% 6% 5% 7% 11% 49%	3794
	11th to 20th	Day	6% 4 2 6% 5% 6% 6% 5% 7% 10% 43%	3729
	21st to end	Day	7% 4 2 6% 4 4 4 4 6% 7% 52%	4180
September	1st to 10th	Day	11% 6% 3 6% 4 5% 5% 5% 7% 8% 41%	2247
	11th to 20th	Day	12% 5% 2 6% 6% 4 4 4 6% 6% 44%	2090
	21st to end	Day	11% 4 2 5% 4 4 4 3 6% 8% 50%	2090
October	1st to 10th	Day	10% 4 2 5% 4 3 4 3 3 5% 56%	2090
	11th to 20th	Day	10% 4 2 5% 3 4 3 3 5% 7% 54%	2071
	21st to end	Day	15% 5% 2 5% 3 3 3 3 4 5% 52%	1922
November	1st to 10th	Day	11% 5% 1 4 4 3 3 3 4 5% 55%	1708
	11th to 20th	Day	14% 5% 2 5% 4 3 4 3 4 7% 49%	1710
	21st to end	Day	17% 6% 2 5% 4 4 4 5% 5% 7% 42%	1710
December	1st to 10th	Day	22% 9% 3 6% 4 4 4 4 4 4 35%	1710
	11th to 20th	Day	18% 8% 3 7% 4 4 4 3 4 5% 40%	2153
	21st to end	Day	18% 10% 3 8% 4 4 4 3 6% 7% 33%	3124
January	1st to 10th	Night	18% 12% 3 6% 3 3 4 3 4 5% 41%	4109
	11th to 20th	Night	20% 8% 3 8% 5% 3 3 3 4 4 40%	4082
	21st to end	Night	20% 14% 4 6% 3 3 3 2 4 4 38%	4180
February	1st to 10th	Night	19% 8% 3 6% 4 3 3 3 5% 6% 40%	2280
	11th to 20th	Night	22% 9% 3 6% 5% 3 3 3 4 4 39%	2218
	21st to end	Night	25% 8% 3 6% 4 4 4 3 5% 4 35%	1884
March	1st to 10th	Night	24% 8% 3 6% 4 4 4 3 4 6% 34%	3733
	11th to 20th	Night	12% 7% 2 6% 4 4 4 4 5% 7% 46%	3625
	21st to end	Night	16% 7% 3 8% 6% 5% 4 3 5% 4 41%	3629
April	1st to 10th	Night	12% 5% 3 6% 5% 3 4 4 6% 8% 46%	1900
	11th to 20th	Night	15% 5% 2 5% 3 3 3 4 5% 7% 47%	1875
	21st to end	Night	11% 6% 2 4 4 3 4 4 5% 7% 49%	1900
May	1st to 10th	Night	13% 7% 2 6% 4 4 4 4 5% 7% 43%	2813
	11th to 20th	Night	15% 8% 3 6% 4 5% 3 3 5% 7% 41%	2812
	21st to end	Night	7% 6% 3 6% 4 5% 5% 4 7% 10% 44%	3079
June	1st to 10th	Night	9% 5% 3 7% 5% 5% 5% 4 7% 9% 41%	1710
	11th to 20th	Night	3 3 2 4 3 4 5% 5% 7% 12% 53%	1659
	21st to end	Night	5% 5% 2 5% 4 5% 4 5% 7% 10% 48%	1520
July	1st to 10th	Night	7% 5% 2 8% 6% 6% 7% 5% 8% 9% 36%	2530
	11th to 20th	Night	8% 5% 2 6% 6% 4 5% 5% 8% 12% 38%	2826
	21st to end	Night	12% 10% 4 10% 7% 5% 6% 4 7% 9% 26%	3087
August	1st to 10th	Night	3 2 1 4 3 3 4 5% 8% 11% 57%	3131
	11th to 20th	Night	5% 3 2 4 4 4 5% 4 7% 11% 51%	3100
	21st to end	Night	5% 3 1 4 3 3 3 4 6% 8% 59%	3476
September	1st to 10th	Night	8% 5% 3 6% 4 4 4 4 6% 8% 48%	1914
	11th to 20th	Night	10% 6% 2 7% 5% 5% 4 3 5% 8% 45%	2090
	21st to end	Night	10% 4 2 5% 4 4 4 2 5% 6% 55%	2090
October	1st to 10th	Night	9% 3 1 4 4 3 3 3 4 6% 60%	2090
	11th to 20th	Night	12% 5% 2 6% 3 3 3 3 5% 5% 53%	2104
	21st to end	Night	13% 6% 1 5% 3 3 3 3 5% 5% 52%	2674
November	1st to 10th	Night	12% 5% 2 4 3 3 4 3 4 6% 53%	2470
	11th to 20th	Night	12% 6% 2 5% 4 3 3 3 5% 6% 52%	2470
	21st to end	Night	16% 7% 2 6% 4 3 3 3 4 6% 46%	2470
December	1st to 10th	Night	19% 8% 2 6% 4 4 4 3 5% 6% 38%	2470
	11th to 20th	Night	18% 6% 3 5% 3 3 3 3 4 5% 47%	3042
	21st to end	Night	17% 9% 4 8% 6% 4 5% 4 6% 7% 30%	4532

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	48% 4 7% 18% 20% 2	2837
	11th to 20th	Day	48% 4 8% 17% 21% 1	2876
	21st to end	Day	49% 4 8% 21% 16% 2	3476
February	1st to 10th	Day	48% 4 7% 20% 18% 4	1900
	11th to 20th	Day	51% 4 5% 19% 16% 5%	1858
	21st to end	Day	49% 4 8% 15% 18% 6%	1570
March	1st to 10th	Day	54% 5% 8% 11% 13% 9%	3120
	11th to 20th	Day	38% 6% 8% 24% 17% 7%	3320
	21st to end	Day	42% 7% 12% 21% 17% 2	4029
April	1st to 10th	Day	38% 5% 10% 23% 17% 5%	2280
	11th to 20th	Day	39% 4 8% 20% 23% 6%	2254
	21st to end	Day	36% 6% 11% 28% 16% 3	2280
May	1st to 10th	Day	40% 9% 13% 23% 14% 2	4120
	11th to 20th	Day	42% 8% 13% 25% 11%	4085
	21st to end	Day	37% 8% 11% 24% 18% 1	4489
June	1st to 10th	Day	39% 9% 14% 20% 16% 2	2470
	11th to 20th	Day	31% 9% 16% 25% 18% 2	2512
	21st to end	Day	35% 10% 17% 19% 15% 4	2660
July	1st to 10th	Day	41% 7% 21% 23% 6% 1	4371
	11th to 20th	Day	41% 8% 21% 23% 6% 1	4055
	21st to end	Day	55% 8% 13% 18% 5%	4324
August	1st to 10th	Day	26% 8% 12% 35% 17% 1	3781
	11th to 20th	Day	34% 7% 14% 27% 15% 3	3765
	21st to end	Day	31% 6% 12% 23% 26% 2	4179
September	1st to 10th	Day	37% 9% 15% 18% 17% 5%	2247
	11th to 20th	Day	38% 8% 11% 18% 21% 4	2090
	21st to end	Day	33% 5% 12% 23% 20% 7%	2090
October	1st to 10th	Day	21% 4 4 15% 38% 17%	3480
	11th to 20th	Day	21% 3 6% 18% 31% 21%	3427
	21st to end	Day	27% 3 6% 22% 33% 9%	3147
November	1st to 10th	Day	31% 4 8% 20% 29% 8%	1708
	11th to 20th	Day	36% 4 6% 21% 26% 7%	1710
	21st to end	Day	41% 5% 6% 20% 23% 6%	1710
December	1st to 10th	Day	50% 5% 7% 17% 18% 4	1710
	11th to 20th	Day	46% 4 8% 20% 19% 3	2150
	21st to end	Day	50% 6% 10% 20% 11% 3	3124
January	1st to 10th	Night	46% 4 6% 19% 23% 2	4109
	11th to 20th	Night	48% 4 7% 18% 17% 6%	4082
	21st to end	Night	50% 4 5% 19% 18% 3	4180
February	1st to 10th	Night	45% 4 9% 19% 19% 4	2280
	11th to 20th	Night	49% 4 7% 17% 16% 7%	2219
	21st to end	Night	51% 4 7% 15% 16% 7%	1884
March	1st to 10th	Night	51% 6% 8% 13% 16% 7%	3733
	11th to 20th	Night	36% 6% 8% 21% 20% 10%	3625
	21st to end	Night	45% 6% 9% 19% 20% 2	3629
April	1st to 10th	Night	35% 6% 12% 21% 21% 4	1900
	11th to 20th	Night	35% 4 9% 19% 23% 11%	1875
	21st to end	Night	33% 5% 12% 26% 20% 4	1900
May	1st to 10th	Night	38% 9% 11% 24% 16% 2	2840
	11th to 20th	Night	41% 8% 14% 22% 14% 1	2813
	21st to end	Night	32% 10% 14% 25% 18% 2	3087
June	1st to 10th	Night	36% 10% 12% 22% 18% 3	1710
	11th to 20th	Night	22% 10% 18% 28% 19% 3	1659
	21st to end	Night	28% 10% 15% 25% 17% 4	1520
July	1st to 10th	Night	41% 9% 20% 22% 7% 2	2490
	11th to 20th	Night	35% 7% 25% 24% 7% 2	2773
	21st to end	Night	54% 9% 14% 16% 7% 1	2988
August	1st to 10th	Night	19% 8% 13% 38% 22% 1	3120
	11th to 20th	Night	27% 7% 21% 27% 17% 2	3130
	21st to end	Night	23% 6% 15% 26% 27% 3	3476
September	1st to 10th	Night	32% 8% 17% 22% 16% 6%	1914
	11th to 20th	Night	37% 7% 13% 16% 23% 3	2090
	21st to end	Night	30% 5% 10% 24% 22% 9%	2090
October	1st to 10th	Night	20% 4 5% 17% 35% 19%	3480
	11th to 20th	Night	21% 2 4 18% 32% 23%	3487
	21st to end	Night	23% 2 4 27% 27% 15%	4399
November	1st to 10th	Night	32% 4 8% 21% 24% 11%	2470
	11th to 20th	Night	33% 3 7% 19% 27% 10%	2470
	21st to end	Night	40% 3 6% 19% 25% 6%	2470
December	1st to 10th	Night	46% 5% 8% 19% 18% 3	2470
	11th to 20th	Night	40% 3 7% 20% 26% 5%	3044
	21st to end	Night	50% 6% 9% 19% 13% 2	4532

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	25% 15% 35% 16% 8%	270
	11th to 20th	Day	26% 13% 39% 16% 4 3	270
	21st to end	Day	17% 16% 43% 18% 5% 1	297
February	1st to 10th	Day	27% 12% 36% 18% 7%	270
	11th to 20th	Day	33% 14% 35% 14% 3 1	270
	21st to end	Day	35% 16% 30% 16% 4	225
March	1st to 10th	Day	23% 12% 35% 24% 5% 1	270
	11th to 20th	Day	21% 13% 33% 24% 8% 1	365
	21st to end	Day	20% 11% 33% 25% 10% 1	506
April	1st to 10th	Day	17% 13% 28% 26% 12% 5%	460
	11th to 20th	Day	17% 9% 28% 31% 13% 3	452
	21st to end	Day	16% 6% 26% 32% 16% 4	460
May	1st to 10th	Day	14% 8% 24% 28% 19% 7%	463
	11th to 20th	Day	11% 5% 19% 28% 24% 14%	487
	21st to end	Day	12% 4 15% 27% 22% 21%	529
June	1st to 10th	Day	12% 3 12% 26% 26% 21%	490
	11th to 20th	Day	8% 2 11% 21% 29% 30%	532
	21st to end	Day	7% 2 13% 25% 33% 19%	680
July	1st to 10th	Day	9% 2 8% 23% 30% 28%	671
	11th to 20th	Day	10% 1 6% 17% 28% 39%	488
	21st to end	Day	10% 2 7% 18% 31% 32%	532
August	1st to 10th	Day	8% 1 8% 20% 36% 27%	486
	11th to 20th	Day	9% 1 7% 23% 38% 22%	479
	21st to end	Day	13% 2 6% 16% 32% 30%	539
September	1st to 10th	Day	8% 2 9% 22% 38% 21%	490
	11th to 20th	Day	13% 1 10% 22% 31% 22%	490
	21st to end	Day	15% 2 12% 25% 33% 13%	490
October	1st to 10th	Day	10% 2 15% 33% 25% 14%	490
	11th to 20th	Day	9% 6% 27% 34% 21% 4	471
	21st to end	Day	21% 7% 20% 30% 18% 5%	330
November	1st to 10th	Day	17% 4 26% 29% 20% 4	282
	11th to 20th	Day	13% 9% 34% 33% 9% 1	270
	21st to end	Day	17% 9% 32% 24% 14% 3	270
December	1st to 10th	Day	26% 14% 27% 22% 9% 1	270
	11th to 20th	Day	19% 13% 33% 20% 13% 1	270
	21st to end	Day	23% 12% 37% 22% 5% 1	297
January	1st to 10th	Night	22% 8% 38% 27% 5% 1	760
	11th to 20th	Night	23% 10% 35% 25% 7%	760
	21st to end	Night	18% 10% 40% 29% 3	836
February	1st to 10th	Night	22% 8% 36% 28% 7%	760
	11th to 20th	Night	26% 9% 33% 30% 2	743
	21st to end	Night	26% 13% 33% 26% 2	628
March	1st to 10th	Night	19% 8% 34% 32% 6%	760
	11th to 20th	Night	17% 7% 37% 31% 8% 1	760
	21st to end	Night	17% 7% 32% 32% 11%	725
April	1st to 10th	Night	12% 8% 34% 31% 14% 1	570
	11th to 20th	Night	15% 5% 31% 36% 11% 2	563
	21st to end	Night	13% 6% 26% 37% 17% 1	570
May	1st to 10th	Night	11% 3 25% 36% 21% 3	570
	11th to 20th	Night	13% 1 16% 40% 24% 4	561
	21st to end	Night	8% 1 10% 38% 37% 6%	617
June	1st to 10th	Night	11% 2 10% 36% 36% 5%	570
	11th to 20th	Night	5% 1 8% 34% 44% 9%	570
	21st to end	Night	8% 1 6% 34% 43% 8%	570
July	1st to 10th	Night	9% 1 6% 28% 43% 12%	555
	11th to 20th	Night	8% 1 3 22% 50% 15%	552
	21st to end	Night	10% 1 6% 26% 45% 12%	624
August	1st to 10th	Night	5% 1 4 23% 55% 13%	567
	11th to 20th	Night	8% 1 7% 31% 43% 9%	564
	21st to end	Night	10% 1 4 26% 49% 10%	627
September	1st to 10th	Night	9% 1 8% 32% 41% 8%	584
	11th to 20th	Night	12% 2 10% 31% 39% 6%	760
	21st to end	Night	11% 1 12% 33% 39% 4	760
October	1st to 10th	Night	9% 2 16% 36% 29% 7%	760
	11th to 20th	Night	14% 4 23% 38% 20% 2	760
	21st to end	Night	14% 5% 21% 38% 19% 3	836
November	1st to 10th	Night	14% 5% 21% 36% 21% 3	760
	11th to 20th	Night	14% 5% 32% 35% 13% 1	760
	21st to end	Night	18% 6% 27% 34% 14% 1	760
December	1st to 10th	Night	22% 7% 31% 31% 7% 1	760
	11th to 20th	Night	23% 6% 31% 31% 10%	760
	21st to end	Night	24% 7% 31% 32% 6%	836

Page generated at 2024-11-03 01:11:15. Version ac07

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