Kathik-B Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Kathik-B Observatory clear sky chart from 2005-11-06 to 2024-05-15.

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	16% 10% 3 8% 5% 5% 5% 4 5% 6% 32%	83427
	Night	17% 11% 4 8% 5% 4 4 4 5% 6% 31%	86093
Transparency	Day	51% 7% 11% 20% 10% 1	83132
	Night	53% 6% 11% 19% 10% 1	85922
Seeing	Day	22% 15% 30% 21% 9% 3	13802
	Night	22% 13% 30% 25% 9% 1	23042

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	15% 15% 5% 11% 7% 4 6% 4 5% 5% 22%	2517
	11th to 20th	Day	14% 13% 5% 13% 7% 6% 5% 4 5% 5% 23%	2520
	21st to end	Day	15% 16% 7% 13% 6% 7% 5% 4 4 5% 18%	2901
February	1st to 10th	Day	14% 15% 5% 12% 6% 6% 5% 4 6% 5% 24%	1710
	11th to 20th	Day	13% 14% 5% 9% 6% 5% 5% 3 4 7% 29%	1667
	21st to end	Day	18% 13% 4 9% 6% 4 5% 4 6% 5% 26%	1570
March	1st to 10th	Day	20% 13% 4 9% 6% 5% 4 4 4 5% 27%	3116
	11th to 20th	Day	12% 14% 5% 9% 7% 6% 5% 4 5% 6% 29%	3480
	21st to end	Day	12% 9% 3 7% 5% 4 3 3 5% 6% 43%	4026
April	1st to 10th	Day	21% 12% 3 6% 4 4 4 3 5% 6% 31%	2280
	11th to 20th	Day	21% 9% 2 7% 4 4 4 3 4 5% 36%	2254
	21st to end	Day	22% 9% 3 7% 6% 4 4 3 4 5% 32%	2408
May	1st to 10th	Day	19% 8% 3 7% 5% 4 5% 4 5% 6% 34%	2660
	11th to 20th	Day	15% 8% 3 6% 5% 4 4 4 5% 6% 39%	2534
	21st to end	Day	15% 6% 3 6% 6% 5% 5% 4 6% 7% 38%	2725
June	1st to 10th	Day	21% 7% 3 7% 5% 6% 5% 5% 5% 6% 30%	2520
	11th to 20th	Day	14% 6% 2 5% 5% 4 5% 4 7% 8% 38%	2520
	21st to end	Day	16% 8% 3 8% 5% 5% 6% 5% 5% 7% 32%	2520
July	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 5% 6% 8% 41%	2520
	11th to 20th	Day	12% 6% 3 6% 4 5% 6% 4 7% 9% 39%	2520
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 5% 7% 10% 39%	2744
August	1st to 10th	Day	11% 6% 2 7% 5% 5% 5% 5% 6% 8% 40%	2465
	11th to 20th	Day	11% 6% 2 8% 4 6% 5% 4 6% 8% 40%	2277
	21st to end	Day	12% 6% 2 6% 4 5% 5% 5% 6% 8% 40%	2376
September	1st to 10th	Day	13% 6% 2 7% 5% 4 6% 3 5% 8% 42%	2160
	11th to 20th	Day	13% 4 2 6% 4 3 5% 3 6% 9% 45%	2160
	21st to end	Day	16% 6% 2 6% 5% 5% 4 3 7% 7% 39%	1921
October	1st to 10th	Day	19% 9% 3 6% 5% 4 4 4 6% 5% 36%	1800
	11th to 20th	Day	22% 9% 2 8% 6% 6% 5% 4 6% 6% 28%	1800
	21st to end	Day	25% 11% 3 8% 4 4 5% 3 5% 4 28%	1839
November	1st to 10th	Day	15% 9% 3 7% 5% 5% 4 4 5% 8% 33%	1671
	11th to 20th	Day	18% 12% 3 8% 7% 5% 5% 3 5% 6% 28%	1528
	21st to end	Day	21% 13% 3 10% 7% 5% 6% 4 4 6% 20%	1520
December	1st to 10th	Day	21% 17% 4 11% 6% 5% 4 4 6% 6% 17%	1520
	11th to 20th	Day	21% 15% 4 9% 5% 5% 5% 3 4 5% 24%	1906
	21st to end	Day	27% 17% 5% 11% 5% 3 3 2 2 3 20%	2772
January	1st to 10th	Night	16% 16% 6% 13% 6% 5% 4 3 5% 5% 21%	4429
	11th to 20th	Night	12% 13% 5% 13% 8% 7% 5% 4 5% 5% 22%	4440
	21st to end	Night	17% 20% 6% 11% 5% 5% 4 3 4 4 21%	4752
February	1st to 10th	Night	13% 15% 5% 11% 7% 6% 5% 4 5% 6% 22%	2470
	11th to 20th	Night	14% 13% 5% 12% 7% 5% 4 3 5% 4 29%	2399
	21st to end	Night	16% 13% 4 8% 7% 5% 4 3 5% 6% 28%	1884
March	1st to 10th	Night	21% 12% 4 8% 5% 4 4 3 4 5% 31%	3707
	11th to 20th	Night	17% 15% 5% 10% 6% 4 3 4 5% 6% 26%	3479
	21st to end	Night	16% 9% 3 6% 4 4 4 3 5% 7% 40%	3605
April	1st to 10th	Night	20% 11% 3 7% 4 4 4 3 5% 6% 32%	1900
	11th to 20th	Night	19% 9% 3 8% 5% 3 4 3 4 6% 36%	1875
	21st to end	Night	21% 8% 3 8% 5% 3 4 3 6% 6% 33%	1787
May	1st to 10th	Night	21% 7% 2 6% 4 3 6% 4 6% 7% 34%	1520
	11th to 20th	Night	17% 9% 2 5% 4 4 4 4 5% 5% 41%	1447
	21st to end	Night	12% 6% 3 6% 5% 4 4 3 7% 8% 44%	1550
June	1st to 10th	Night	16% 8% 2 7% 6% 5% 5% 4 6% 10% 32%	1440
	11th to 20th	Night	14% 6% 3 7% 3 5% 4 3 5% 8% 42%	1440
	21st to end	Night	16% 8% 2 6% 5% 3 5% 4 6% 8% 36%	1440
July	1st to 10th	Night	11% 5% 1 6% 5% 4 4 4 5% 9% 45%	1440
	11th to 20th	Night	11% 6% 2 5% 4 4 5% 5% 6% 9% 42%	1440
	21st to end	Night	9% 6% 2 6% 5% 6% 5% 5% 6% 7% 44%	1574
August	1st to 10th	Night	7% 6% 3 9% 5% 4 5% 4 6% 9% 42%	1471
	11th to 20th	Night	9% 6% 2 7% 4 5% 4 4 6% 8% 45%	1605
	21st to end	Night	11% 5% 3 7% 4 4 5% 4 6% 8% 45%	1980
September	1st to 10th	Night	11% 6% 3 6% 4 5% 4 4 5% 7% 46%	1800
	11th to 20th	Night	14% 4 2 5% 3 3 4 4 5% 8% 48%	1800
	21st to end	Night	16% 6% 2 6% 5% 4 4 3 4 6% 44%	2034
October	1st to 10th	Night	17% 9% 3 7% 3 4 5% 4 6% 6% 37%	2160
	11th to 20th	Night	21% 9% 3 7% 5% 4 5% 3 5% 7% 31%	2160
	21st to end	Night	23% 10% 4 7% 5% 5% 4 3 5% 6% 28%	2516
November	1st to 10th	Night	19% 11% 4 6% 5% 3 4 3 4 6% 35%	2407
	11th to 20th	Night	18% 11% 3 8% 6% 5% 5% 3 5% 6% 31%	2650
	21st to end	Night	20% 14% 5% 9% 5% 5% 4 4 5% 6% 24%	2660
December	1st to 10th	Night	20% 17% 5% 9% 7% 5% 5% 4 6% 5% 17%	2660
	11th to 20th	Night	21% 16% 4 9% 5% 4 3 3 4 5% 26%	3288
	21st to end	Night	30% 17% 4 10% 4 4 4 3 3 4 18%	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	63% 9% 13% 10% 6% 1	2518
	11th to 20th	Day	63% 6% 11% 13% 7% 1	2520
	21st to end	Day	68% 7% 10% 9% 5%	2901
February	1st to 10th	Day	61% 5% 10% 18% 4 2	1710
	11th to 20th	Day	57% 5% 11% 17% 9% 1	1676
	21st to end	Day	59% 6% 10% 14% 10% 1	1570
March	1st to 10th	Day	59% 5% 9% 17% 9% 1	3119
	11th to 20th	Day	56% 5% 12% 15% 10% 2	3480
	21st to end	Day	42% 5% 7% 24% 19% 3	4026
April	1st to 10th	Day	54% 4 7% 19% 13% 3	2280
	11th to 20th	Day	51% 4 7% 21% 15% 2	2254
	21st to end	Day	55% 5% 8% 15% 14% 4	2408
May	1st to 10th	Day	50% 5% 8% 19% 14% 4	2660
	11th to 20th	Day	45% 7% 7% 22% 17% 3	2538
	21st to end	Day	44% 7% 12% 21% 13% 2	2725
June	1st to 10th	Day	53% 6% 10% 18% 12% 1	2520
	11th to 20th	Day	42% 8% 11% 24% 13% 3	2520
	21st to end	Day	49% 9% 11% 19% 11% 1	2520
July	1st to 10th	Day	37% 7% 13% 27% 15% 1	2450
	11th to 20th	Day	38% 8% 15% 27% 11%	2445
	21st to end	Day	40% 10% 13% 27% 11%	2591
August	1st to 10th	Day	40% 9% 15% 25% 10%	2451
	11th to 20th	Day	40% 8% 15% 26% 10% 1	2277
	21st to end	Day	40% 7% 13% 27% 12% 1	2376
September	1st to 10th	Day	39% 8% 13% 28% 12%	2160
	11th to 20th	Day	36% 8% 12% 31% 13% 1	2160
	21st to end	Day	43% 7% 14% 27% 9%	1921
October	1st to 10th	Day	49% 7% 11% 23% 10% 1	1800
	11th to 20th	Day	56% 7% 14% 16% 7% 1	1800
	21st to end	Day	59% 5% 12% 15% 8% 1	1839
November	1st to 10th	Day	48% 8% 14% 22% 7% 1	1671
	11th to 20th	Day	57% 6% 12% 15% 9% 1	1528
	21st to end	Day	64% 6% 12% 10% 7%	1520
December	1st to 10th	Day	68% 7% 11% 10% 3 1	1520
	11th to 20th	Day	62% 7% 13% 13% 5%	1906
	21st to end	Day	72% 4 6% 14% 3	2772
January	1st to 10th	Night	65% 6% 14% 11% 4	4429
	11th to 20th	Night	62% 8% 13% 12% 5%	4440
	21st to end	Night	66% 7% 10% 11% 6% 1	4752
February	1st to 10th	Night	62% 5% 10% 15% 7% 1	2470
	11th to 20th	Night	57% 4 11% 19% 8% 1	2401
	21st to end	Night	57% 5% 9% 19% 10% 1	1884
March	1st to 10th	Night	56% 5% 9% 19% 9% 2	3717
	11th to 20th	Night	58% 6% 12% 15% 8% 1	3480
	21st to end	Night	44% 5% 8% 22% 18% 3	3605
April	1st to 10th	Night	53% 5% 8% 18% 14% 2	1900
	11th to 20th	Night	50% 5% 7% 21% 16% 1	1875
	21st to end	Night	51% 5% 8% 17% 16% 3	1787
May	1st to 10th	Night	48% 6% 7% 19% 14% 5%	1520
	11th to 20th	Night	44% 5% 7% 23% 18% 3	1448
	21st to end	Night	38% 6% 15% 20% 18% 3	1551
June	1st to 10th	Night	47% 8% 11% 23% 10% 1	1440
	11th to 20th	Night	40% 6% 11% 23% 18% 2	1440
	21st to end	Night	45% 8% 12% 20% 13% 1	1440
July	1st to 10th	Night	35% 8% 11% 27% 17% 2	1400
	11th to 20th	Night	37% 7% 13% 31% 13%	1392
	21st to end	Night	36% 7% 15% 27% 14%	1486
August	1st to 10th	Night	37% 9% 16% 23% 14% 1	1461
	11th to 20th	Night	36% 8% 15% 28% 12%	1605
	21st to end	Night	36% 8% 15% 29% 12%	1980
September	1st to 10th	Night	38% 7% 10% 29% 14% 1	1800
	11th to 20th	Night	34% 7% 13% 35% 10% 1	1800
	21st to end	Night	42% 6% 11% 30% 11%	2034
October	1st to 10th	Night	47% 6% 10% 22% 14% 1	2160
	11th to 20th	Night	53% 6% 12% 20% 9%	2160
	21st to end	Night	58% 6% 12% 16% 8%	2516
November	1st to 10th	Night	51% 5% 14% 21% 9% 1	2407
	11th to 20th	Night	54% 6% 12% 18% 9% 1	2650
	21st to end	Night	60% 6% 13% 15% 5%	2660
December	1st to 10th	Night	68% 7% 9% 12% 4	2660
	11th to 20th	Night	61% 5% 9% 16% 7% 1	3288
	21st to end	Night	73% 4 7% 13% 4	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	23% 21% 30% 22% 4	180
	11th to 20th	Day	27% 21% 33% 14% 3 1	180
	21st to end	Day	21% 19% 36% 20% 5%	235
February	1st to 10th	Day	30% 22% 34% 13% 1	270
	11th to 20th	Day	24% 28% 38% 8% 1	274
	21st to end	Day	28% 21% 34% 14% 3	382
March	1st to 10th	Day	26% 17% 34% 17% 5%	460
	11th to 20th	Day	25% 18% 36% 17% 3 1	460
	21st to end	Day	29% 21% 27% 15% 7% 1	506
April	1st to 10th	Day	29% 20% 30% 15% 5% 1	460
	11th to 20th	Day	32% 20% 21% 16% 9% 2	452
	21st to end	Day	33% 18% 28% 15% 6% 2	460
May	1st to 10th	Day	25% 14% 31% 22% 7% 2	463
	11th to 20th	Day	18% 18% 34% 21% 7% 3	463
	21st to end	Day	17% 15% 33% 23% 11% 1	485
June	1st to 10th	Day	24% 12% 32% 22% 8% 2	450
	11th to 20th	Day	16% 16% 29% 25% 12% 3	450
	21st to end	Day	17% 15% 30% 24% 10% 4	450
July	1st to 10th	Day	11% 8% 29% 33% 15% 4	445
	11th to 20th	Day	13% 8% 30% 30% 14% 4	444
	21st to end	Day	14% 8% 30% 30% 15% 3	488
August	1st to 10th	Day	15% 7% 29% 28% 18% 4	446
	11th to 20th	Day	12% 8% 23% 31% 17% 9%	439
	21st to end	Day	14% 11% 28% 24% 13% 8%	495
September	1st to 10th	Day	16% 12% 28% 20% 15% 8%	450
	11th to 20th	Day	13% 8% 28% 24% 18% 10%	450
	21st to end	Day	17% 10% 32% 20% 16% 5%	450
October	1st to 10th	Day	27% 12% 25% 20% 12% 6%	450
	11th to 20th	Day	25% 19% 27% 21% 6% 2	450
	21st to end	Day	30% 18% 24% 23% 4	424
November	1st to 10th	Day	25% 16% 32% 17% 8% 1	365
	11th to 20th	Day	28% 19% 34% 12% 5% 2	188
	21st to end	Day	29% 17% 34% 14% 4 1	180
December	1st to 10th	Day	32% 14% 36% 16% 2 1	180
	11th to 20th	Day	29% 26% 31% 11% 2 1	180
	21st to end	Day	34% 19% 31% 13% 2 1	198
January	1st to 10th	Night	26% 16% 35% 20% 4	760
	11th to 20th	Night	26% 18% 30% 20% 5%	760
	21st to end	Night	20% 13% 35% 27% 5%	836
February	1st to 10th	Night	23% 17% 35% 22% 4	760
	11th to 20th	Night	21% 19% 38% 18% 3	743
	21st to end	Night	25% 18% 30% 22% 4	628
March	1st to 10th	Night	24% 16% 33% 23% 4	760
	11th to 20th	Night	23% 20% 32% 20% 6%	760
	21st to end	Night	24% 16% 28% 25% 7%	836
April	1st to 10th	Night	26% 16% 30% 23% 5%	760
	11th to 20th	Night	25% 19% 26% 23% 8%	751
	21st to end	Night	26% 14% 28% 24% 7% 1	647
May	1st to 10th	Night	23% 9% 30% 29% 9% 1	380
	11th to 20th	Night	22% 13% 28% 27% 10%	362
	21st to end	Night	13% 7% 41% 25% 14%	389
June	1st to 10th	Night	18% 6% 32% 34% 8% 1	360
	11th to 20th	Night	17% 8% 28% 34% 13% 1	360
	21st to end	Night	20% 6% 31% 30% 13% 1	360
July	1st to 10th	Night	9% 7% 26% 43% 14% 1	350
	11th to 20th	Night	13% 6% 24% 41% 15% 1	348
	21st to end	Night	10% 4 30% 41% 14% 2	394
August	1st to 10th	Night	9% 4 26% 39% 21%	397
	11th to 20th	Night	12% 2 22% 37% 24% 3	541
	21st to end	Night	13% 6% 27% 32% 20% 2	792
September	1st to 10th	Night	14% 6% 31% 30% 18% 1	720
	11th to 20th	Night	16% 7% 22% 31% 20% 3	720
	21st to end	Night	18% 10% 26% 26% 19% 2	720
October	1st to 10th	Night	20% 11% 27% 25% 15% 1	720
	11th to 20th	Night	26% 13% 29% 23% 8% 1	720
	21st to end	Night	27% 15% 28% 25% 6%	792
November	1st to 10th	Night	27% 13% 28% 22% 9% 1	740
	11th to 20th	Night	23% 17% 33% 17% 9% 1	760
	21st to end	Night	29% 16% 26% 21% 7%	760
December	1st to 10th	Night	30% 16% 30% 19% 4	760
	11th to 20th	Night	28% 16% 30% 20% 5% 1	760
	21st to end	Night	34% 14% 30% 18% 4	836

Page generated at 2024-05-12 00:20:36. Version ac07

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