Bateson Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bateson Observatory clear sky chart from 2005-11-06 to 2024-11-12.

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	2 4 2 5% 4 4 4 3 5% 6% 61%	105294
	Night	3 5% 2 5% 4 4 4 4 5% 7% 58%	102612
Transparency	Day	22% 6% 10% 19% 23% 20%	105039
	Night	24% 8% 12% 21% 21% 15%	102456
Seeing	Day	11% 16% 27% 27% 16% 3	15010
	Night	7% 10% 20% 38% 23% 3	24244

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	2 8% 3 8% 6% 7% 7% 6% 9% 8% 35%	2539
	11th to 20th	Day	3 8% 4 10% 8% 8% 7% 6% 7% 7% 31%	2608
	21st to end	Day	6% 15% 4 10% 6% 6% 6% 4 5% 7% 30%	3146
February	1st to 10th	Day	4 6% 2 7% 4 5% 6% 6% 10% 8% 43%	1710
	11th to 20th	Day	2 7% 3 8% 5% 5% 5% 4 7% 8% 46%	1777
	21st to end	Day	2 6% 2 8% 7% 5% 6% 5% 7% 9% 43%	1570
March	1st to 10th	Day	3 11% 3 11% 7% 7% 8% 6% 7% 7% 30%	3160
	11th to 20th	Day	2 7% 2 5% 4 4 4 4 6% 7% 58%	3490
	21st to end	Day	3 10% 3 8% 6% 6% 6% 5% 8% 8% 37%	4024
April	1st to 10th	Day	3 8% 3 7% 5% 4 6% 5% 7% 7% 44%	2280
	11th to 20th	Day	4 7% 2 6% 4 4 4 4 6% 8% 51%	2249
	21st to end	Day	4 5% 2 5% 4 5% 5% 3 5% 7% 54%	2280
May	1st to 10th	Day	3 4 2 5% 3 3 3 3 4 5% 67%	4086
	11th to 20th	Day	2 3 1 4 3 3 3 2 4 6% 70%	4377
	21st to end	Day	3 4 2 5% 3 3 3 3 4 6% 63%	4813
June	1st to 10th	Day	3 3 2 6% 4 4 4 4 6% 8% 56%	2660
	11th to 20th	Day	1 3 1 3 3 3 4 2 4 5% 70%	2660
	21st to end	Day	1 2 1 2 2 2 2 3 3 4 77%	2660
July	1st to 10th	Day	1 1 1 1 1 1 1 2 3 88%	4420
	11th to 20th	Day	1 2 1 2 2 2 2 2 3 4 80%	4420
	21st to end	Day	1 1 1 1 2 2 2 2 3 5% 81%	4677
August	1st to 10th	Day	2 2 1 3 2 2 3 3 4 5% 74%	4091
	11th to 20th	Day	1 1 1 1 2 1 2 3 88%	3796
	21st to end	Day	1 1 1 1 1 2 1 2 2 87%	4180
September	1st to 10th	Day	1 1 1 2 2 2 2 2 4 83%	2280
	11th to 20th	Day	1 2 1 4 3 3 3 2 4 5% 72%	2280
	21st to end	Day	2 2 1 3 2 2 2 2 3 7% 74%	2061
October	1st to 10th	Day	2 2 1 3 2 2 3 2 4 5% 74%	3180
	11th to 20th	Day	2 3 2 5% 2 2 3 2 4 6% 68%	3161
	21st to end	Day	2 2 1 4 4 4 5% 4 6% 7% 62%	3392
November	1st to 10th	Day	4 4 2 5% 5% 4 5% 5% 7% 8% 52%	1764
	11th to 20th	Day	2 4 2 5% 4 5% 7% 6% 7% 11% 47%	1719
	21st to end	Day	1 4 2 6% 5% 5% 6% 5% 6% 9% 51%	1542
December	1st to 10th	Day	4 7% 3 7% 5% 4 5% 5% 8% 9% 43%	1520
	11th to 20th	Day	9% 12% 4 7% 7% 7% 7% 5% 8% 9% 26%	1928
	21st to end	Day	2 7% 3 11% 8% 6% 7% 5% 7% 10% 33%	2794
January	1st to 10th	Night	3 7% 3 9% 6% 6% 7% 4 8% 9% 39%	4406
	11th to 20th	Night	2 7% 3 11% 8% 8% 8% 6% 8% 9% 31%	4354
	21st to end	Night	7% 14% 4 11% 6% 6% 6% 4 5% 7% 30%	4521
February	1st to 10th	Night	3 6% 2 6% 3 5% 6% 5% 7% 10% 47%	2470
	11th to 20th	Night	2 5% 2 5% 5% 5% 6% 5% 8% 8% 49%	2289
	21st to end	Night	2 7% 2 5% 5% 5% 5% 6% 7% 9% 48%	1884
March	1st to 10th	Night	2 9% 3 8% 6% 7% 8% 6% 8% 9% 35%	3710
	11th to 20th	Night	1 5% 2 5% 4 4 4 4 6% 7% 57%	3490
	21st to end	Night	2 9% 3 9% 7% 6% 6% 6% 8% 9% 35%	3628
April	1st to 10th	Night	1 5% 3 6% 5% 6% 5% 4 7% 10% 47%	1900
	11th to 20th	Night	4 5% 2 4 4 4 4 5% 6% 10% 52%	1879
	21st to end	Night	2 3 2 4 4 3 4 5% 6% 7% 60%	1900
May	1st to 10th	Night	3 5% 1 5% 3 3 3 3 5% 6% 62%	2878
	11th to 20th	Night	2 2 1 3 2 3 2 2 4 5% 73%	2516
	21st to end	Night	3 3 1 4 3 3 3 3 5% 5% 66%	2762
June	1st to 10th	Night	3 5% 2 5% 4 3 3 4 5% 8% 57%	1520
	11th to 20th	Night	2 2 1 2 3 3 3 3 3 7% 72%	1520
	21st to end	Night	1 2 1 3 3 3 3 2 3 4 76%	1520
July	1st to 10th	Night	1 1 1 1 1 2 3 88%	2540
	11th to 20th	Night	2 2 1 2 1 2 2 2 2 3 82%	2540
	21st to end	Night	1 1 1 2 1 1 2 2 2 4 83%	2874
August	1st to 10th	Night	2 2 1 2 2 2 2 2 5% 6% 74%	2848
	11th to 20th	Night	1 1 1 2 1 1 1 1 2 3 86%	3049
	21st to end	Night	1 2 1 2 1 1 1 1 1 2 85%	3498
September	1st to 10th	Night	2 1 1 2 1 2 1 1 2 4 83%	1900
	11th to 20th	Night	3 2 1 2 2 2 2 2 4 5% 75%	1900
	21st to end	Night	2 2 1 2 1 2 2 2 4 6% 76%	2114
October	1st to 10th	Night	2 2 1 2 2 3 3 2 2 3 78%	3800
	11th to 20th	Night	1 2 1 2 2 2 3 2 4 5% 75%	3777
	21st to end	Night	2 2 1 3 3 3 5% 4 6% 7% 63%	4173
November	1st to 10th	Night	4 4 1 5% 4 4 5% 4 8% 9% 52%	2535
	11th to 20th	Night	2 4 2 5% 4 4 5% 5% 7% 10% 53%	2483
	21st to end	Night	2 2 1 4 4 5% 4 6% 7% 10% 55%	2636
December	1st to 10th	Night	4 6% 2 6% 4 3 5% 5% 7% 9% 48%	2660
	11th to 20th	Night	10% 10% 3 7% 7% 5% 5% 5% 7% 10% 30%	3276
	21st to end	Night	4 9% 4 10% 6% 6% 6% 5% 7% 9% 33%	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	38% 12% 21% 24% 5%	2539
	11th to 20th	Day	43% 13% 17% 16% 8% 2	2608
	21st to end	Day	51% 8% 13% 19% 8% 1	3146
February	1st to 10th	Day	33% 10% 16% 25% 13% 3	1710
	11th to 20th	Day	33% 7% 16% 26% 16% 2	1786
	21st to end	Day	35% 10% 16% 23% 14% 3	1570
March	1st to 10th	Day	45% 12% 15% 16% 10% 1	3160
	11th to 20th	Day	24% 6% 14% 34% 21% 1	3490
	21st to end	Day	37% 10% 20% 21% 10% 2	4024
April	1st to 10th	Day	35% 10% 13% 25% 15% 3	2280
	11th to 20th	Day	28% 7% 16% 25% 20% 4	2252
	21st to end	Day	28% 6% 15% 27% 21% 3	2280
May	1st to 10th	Day	18% 5% 10% 32% 30% 4	4086
	11th to 20th	Day	16% 4 8% 20% 41% 11%	4380
	21st to end	Day	21% 5% 10% 32% 29% 3	4814
June	1st to 10th	Day	24% 6% 12% 22% 29% 7%	2660
	11th to 20th	Day	16% 3 8% 21% 35% 18%	2660
	21st to end	Day	11% 3 4 14% 33% 34%	2660
July	1st to 10th	Day	5% 1 3 6% 14% 71%	4351
	11th to 20th	Day	9% 1 3 8% 16% 63%	4345
	21st to end	Day	8% 2 2 6% 25% 57%	4529
August	1st to 10th	Day	13% 2 4 8% 20% 53%	4076
	11th to 20th	Day	5% 1 2 7% 35% 49%	3833
	21st to end	Day	6% 1 3 11% 41% 38%	4179
September	1st to 10th	Day	8% 1 3 9% 30% 49%	2280
	11th to 20th	Day	13% 3 9% 18% 33% 24%	2280
	21st to end	Day	13% 2 5% 23% 32% 24%	2061
October	1st to 10th	Day	14% 3 5% 14% 33% 31%	3180
	11th to 20th	Day	16% 5% 7% 28% 35% 9%	3161
	21st to end	Day	18% 5% 12% 31% 27% 7%	3392
November	1st to 10th	Day	27% 7% 15% 22% 23% 6%	1764
	11th to 20th	Day	27% 10% 18% 26% 18% 1	1719
	21st to end	Day	27% 9% 14% 25% 22% 3	1542
December	1st to 10th	Day	34% 10% 15% 23% 17% 1	1520
	11th to 20th	Day	50% 10% 13% 19% 8%	1928
	21st to end	Day	39% 13% 20% 20% 8% 1	2794
January	1st to 10th	Night	36% 11% 22% 23% 8%	4406
	11th to 20th	Night	40% 14% 21% 13% 8% 3	4354
	21st to end	Night	51% 8% 12% 18% 9% 1	4521
February	1st to 10th	Night	29% 11% 13% 28% 16% 4	2470
	11th to 20th	Night	29% 8% 18% 28% 16% 1	2291
	21st to end	Night	29% 11% 18% 24% 14% 4	1884
March	1st to 10th	Night	35% 16% 20% 17% 10% 2	3710
	11th to 20th	Night	21% 10% 12% 38% 17% 1	3490
	21st to end	Night	36% 14% 20% 21% 9% 1	3628
April	1st to 10th	Night	28% 11% 18% 27% 13% 4	1900
	11th to 20th	Night	25% 9% 19% 25% 18% 4	1879
	21st to end	Night	21% 8% 18% 32% 17% 3	1900
May	1st to 10th	Night	21% 6% 13% 32% 23% 6%	2878
	11th to 20th	Night	15% 4 8% 22% 38% 13%	2516
	21st to end	Night	17% 6% 13% 33% 27% 3	2762
June	1st to 10th	Night	24% 7% 14% 25% 25% 6%	1520
	11th to 20th	Night	14% 3 10% 23% 38% 12%	1520
	21st to end	Night	13% 3 5% 16% 32% 32%	1520
July	1st to 10th	Night	5% 1 2 7% 17% 67%	2500
	11th to 20th	Night	9% 2 3 7% 15% 64%	2492
	21st to end	Night	8% 2 2 7% 31% 51%	2784
August	1st to 10th	Night	12% 2 3 9% 21% 53%	2839
	11th to 20th	Night	7% 1 2 8% 37% 45%	3078
	21st to end	Night	9% 1 2 13% 41% 34%	3498
September	1st to 10th	Night	8% 2 2 9% 29% 50%	1900
	11th to 20th	Night	13% 3 7% 19% 30% 28%	1900
	21st to end	Night	11% 3 6% 21% 32% 26%	2114
October	1st to 10th	Night	14% 2 5% 12% 32% 35%	3800
	11th to 20th	Night	12% 4 7% 32% 35% 10%	3777
	21st to end	Night	15% 7% 11% 30% 26% 11%	4173
November	1st to 10th	Night	25% 10% 15% 22% 20% 8%	2535
	11th to 20th	Night	24% 10% 17% 26% 21% 2	2483
	21st to end	Night	21% 10% 17% 28% 19% 5%	2636
December	1st to 10th	Night	30% 12% 13% 23% 19% 3	2660
	11th to 20th	Night	46% 10% 12% 18% 14% 1	3276
	21st to end	Night	42% 12% 17% 19% 10% 1	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	26% 17% 28% 20% 8% 1	180
	11th to 20th	Day	19% 19% 22% 27% 12% 1	222
	21st to end	Day	13% 17% 29% 28% 12% 1	407
February	1st to 10th	Day	16% 20% 28% 27% 7% 1	370
	11th to 20th	Day	18% 25% 25% 24% 8%	419
	21st to end	Day	18% 20% 27% 29% 7%	382
March	1st to 10th	Day	23% 25% 31% 15% 5% 1	460
	11th to 20th	Day	22% 20% 26% 21% 11%	460
	21st to end	Day	20% 27% 26% 20% 6%	506
April	1st to 10th	Day	16% 25% 30% 20% 7% 1	460
	11th to 20th	Day	21% 24% 25% 21% 8% 2	452
	21st to end	Day	13% 23% 26% 23% 13% 2	460
May	1st to 10th	Day	15% 21% 32% 20% 10% 2	463
	11th to 20th	Day	12% 22% 27% 22% 11% 5%	488
	21st to end	Day	12% 15% 27% 25% 17% 4	529
June	1st to 10th	Day	10% 16% 28% 23% 17% 6%	490
	11th to 20th	Day	9% 20% 32% 22% 14% 3	490
	21st to end	Day	3 13% 28% 32% 19% 5%	490
July	1st to 10th	Day	1 8% 31% 33% 21% 6%	486
	11th to 20th	Day	1 7% 30% 32% 23% 7%	484
	21st to end	Day	2 6% 28% 36% 21% 7%	531
August	1st to 10th	Day	3 8% 29% 29% 24% 7%	487
	11th to 20th	Day	2 10% 25% 30% 24% 9%	477
	21st to end	Day	3 9% 29% 32% 23% 5%	539
September	1st to 10th	Day	3 9% 29% 34% 22% 4	490
	11th to 20th	Day	4 12% 28% 32% 21% 3	490
	21st to end	Day	5% 13% 26% 34% 19% 3	490
October	1st to 10th	Day	6% 16% 26% 26% 24% 3	490
	11th to 20th	Day	10% 14% 18% 32% 24% 2	490
	21st to end	Day	12% 14% 25% 29% 17% 2	507
November	1st to 10th	Day	12% 14% 23% 29% 20% 2	300
	11th to 20th	Day	8% 11% 28% 26% 22% 5%	273
	21st to end	Day	8% 17% 23% 32% 17% 4	190
December	1st to 10th	Day	20% 14% 22% 21% 18% 4	180
	11th to 20th	Day	12% 14% 32% 21% 17% 4	180
	21st to end	Day	17% 12% 28% 25% 16% 2	198
January	1st to 10th	Night	11% 14% 22% 33% 17% 5%	760
	11th to 20th	Night	8% 13% 21% 37% 19% 2	760
	21st to end	Night	10% 8% 25% 34% 19% 3	836
February	1st to 10th	Night	9% 12% 24% 36% 17% 2	760
	11th to 20th	Night	8% 14% 21% 35% 18% 3	744
	21st to end	Night	11% 16% 22% 37% 14% 1	628
March	1st to 10th	Night	11% 18% 25% 30% 14% 3	760
	11th to 20th	Night	11% 14% 22% 30% 21% 2	760
	21st to end	Night	10% 22% 25% 29% 13% 1	836
April	1st to 10th	Night	7% 16% 26% 36% 14% 1	760
	11th to 20th	Night	13% 15% 22% 30% 17% 3	751
	21st to end	Night	6% 14% 24% 33% 19% 3	760
May	1st to 10th	Night	7% 16% 29% 30% 16% 2	588
	11th to 20th	Night	7% 7% 23% 37% 23% 3	374
	21st to end	Night	7% 8% 21% 37% 25% 2	411
June	1st to 10th	Night	4 8% 19% 40% 26% 2	380
	11th to 20th	Night	3 7% 23% 43% 22% 1	380
	21st to end	Night	2 3 17% 49% 28% 1	380
July	1st to 10th	Night	1 1 13% 52% 33% 1	370
	11th to 20th	Night	2 2 12% 58% 26% 1	368
	21st to end	Night	1 1 8% 49% 38% 3	480
August	1st to 10th	Night	3 10% 49% 34% 4	567
	11th to 20th	Night	2 3 16% 44% 33% 3	699
	21st to end	Night	1 2 16% 47% 32% 2	836
September	1st to 10th	Night	3 2 15% 43% 33% 4	760
	11th to 20th	Night	5% 4 15% 36% 34% 6%	760
	21st to end	Night	3 5% 17% 37% 30% 8%	760
October	1st to 10th	Night	6% 6% 18% 39% 27% 5%	760
	11th to 20th	Night	5% 7% 16% 36% 31% 5%	760
	21st to end	Night	7% 8% 17% 35% 24% 9%	836
November	1st to 10th	Night	8% 11% 20% 34% 23% 5%	780
	11th to 20th	Night	7% 8% 23% 41% 18% 3	764
	21st to end	Night	4 12% 19% 39% 23% 3	760
December	1st to 10th	Night	11% 12% 18% 37% 19% 3	760
	11th to 20th	Night	13% 11% 19% 37% 17% 4	760
	21st to end	Night	11% 15% 23% 36% 13% 1	836

Page generated at 2024-11-08 19:45:37. Version ac07

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