Brandon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brandon clear sky chart from 2005-11-05 to 2017-09-16.

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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
38%
16285
12%
46793
7%
16244
43%
16244
21%
32872

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 15thNight
28%
898
11%
2655
7%
895
32%
895
15%
2015
January16th to endNight
23%
960
10%
2688
3%
960
29%
960
13%
2108
February1st to 15thNight
32%
875
10%
2420
3%
875
38%
875
19%
1799
February16th to endNight
40%
672
15%
1934
9%
672
44%
672
21%
1391
March1st to 15thNight
35%
695
11%
2135
7%
695
39%
695
17%
1563
March16th to endNight
40%
576
13%
2067
11%
576
46%
576
16%
1440
April1st to 15thNight
40%
539
15%
1737
12%
539
49%
539
23%
1113
April16th to endNight
38%
540
13%
1620
10%
540
42%
540
20%
1145
May1st to 15thNight
40%
540
11%
1482
4%
540
42%
540
23%
1036
May16th to endNight
41%
563
11%
1311
5%
561
43%
561
28%
949
June1st to 15thNight
40%
540
4%
1260
2%
540
43%
540
32%
871
June16th to endNight
49%
540
4%
1260
3%
540
51%
540
33%
856
July1st to 15thNight
58%
510
6%
1190
3%
510
59%
510
43%
740
July16th to endNight
65%
564
13%
1348
7%
531
66%
531
46%
784
August1st to 15thNight
59%
539
17%
1471
9%
536
62%
536
39%
869
August16th to endNight
59%
573
23%
1719
20%
573
64%
573
38%
967
September1st to 15thNight
55%
540
17%
1839
16%
540
61%
540
33%
1019
September16th to endNight
45%
495
21%
1826
19%
495
53%
495
25%
1061
October1st to 15thNight
36%
611
17%
1931
10%
611
42%
611
20%
1304
October16th to endNight
34%
880
14%
2288
6%
880
37%
880
21%
1659
November1st to 15thNight
32%
875
14%
2353
5%
875
38%
875
21%
1691
November16th to endNight
29%
900
13%
2679
7%
900
36%
900
16%
1977
December1st to 15thNight
28%
900
6%
2700
3%
900
31%
900
11%
2199
December16th to endNight
24%
960
8%
2880
4%
960
29%
960
10%
2316

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 ForecastData
Points
Cloud CoverDay
12%8%46%6%35%45%7%34%
47984
Night
11%9%47%6%345%5%7%35%
46948
Cloud CoverDay
12%8%46%6%35%45%7%34%
47993
Night
11%9%47%6%345%5%7%34%
46952
Cloud CoverDay
12%8%46%6%35%45%7%34%
47994
Night
11%9%47%6%35%45%7%35%
46953
Cloud CoverDay
12%8%37%6%35%45%7%34%
47992
Night
11%9%47%6%35%45%7%35%
46953
TransparencyDay
47%7%14%22%7%
47656
Night
47%6%14%22%8%
46793
SeeingDay
16%6%28%28%16%3
6266
Night
15%5%29%32%14%1
16292

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
7%13%6%10%7%46%5%6%7%25%
1280
16th to endDay
7%14%6%9%9%46%45%8%22%
1536
February1st to 15thDay
9%11%5%9%9%36%45%7%26%
1443
16th to endDay
10%13%5%8%8%47%7%6%6%21%
1548
March1st to 15thDay
9%13%6%9%8%46%46%7%23%
1814
16th to endDay
13%10%6%9%7%35%5%5%6%25%
2156
April1st to 15thDay
11%9%46%425%45%7%36%
2210
16th to endDay
16%9%35%7%35%445%34%
2340
May1st to 15thDay
19%9%36%5%33346%34%
2465
16th to endDay
21%7%345%25%45%8%32%
2803
June1st to 15thDay
16%6%36%6%45%5%6%7%30%
2700
16th to endDay
14%6%26%5%35%46%7%36%
2700
July1st to 15thDay
8%425%5%35%5%6%9%42%
2700
16th to endDay
7%424435%6%7%10%44%
2724
August1st to 15thDay
9%5%25%5%345%5%8%43%
2481
16th to endDay
9%41343445%7%51%
2483
September1st to 15thDay
10%6%25%4235%5%6%47%
2120
16th to endDay
14%5%235%24445%47%
1823
October1st to 15thDay
16%10%37%433237%37%
1684
16th to endDay
15%10%46%5%3335%5%34%
1584
November1st to 15thDay
15%11%6%7%42435%5%32%
1505
16th to endDay
11%14%5%9%6%25%447%27%
1281
December1st to 15thDay
10%13%8%12%11%446%5%6%15%
1260
16th to endDay
11%15%7%10%7%47%45%7%18%
1344
January1st to 15thNight
10%12%6%10%7%45%6%47%25%
2655
16th to endNight
10%13%6%10%6%36%6%5%6%23%
2688
February1st to 15thNight
9%10%49%8%45%5%6%7%29%
2417
16th to endNight
9%10%5%7%7%35%5%6%8%29%
1934
March1st to 15thNight
10%12%48%6%35%5%6%7%28%
2122
16th to endNight
12%9%36%6%45%5%5%8%31%
2067
April1st to 15thNight
7%8%37%6%26%5%5%6%40%
1737
16th to endNight
16%9%35%6%3445%7%32%
1620
May1st to 15thNight
17%7%26%43445%7%36%
1482
16th to endNight
19%7%2441436%7%38%
1310
June1st to 15thNight
15%425%5%2446%8%40%
1260
16th to endNight
9%425%4245%5%11%43%
1260
July1st to 15thNight
8%31342436%7%54%
1260
16th to endNight
321342446%10%56%
1442
August1st to 15thNight
7%31342445%8%53%
1479
16th to endNight
8%41441335%7%55%
1719
September1st to 15thNight
8%5%2342345%6%53%
1839
16th to endNight
14%5%24413347%46%
1826
October1st to 15thNight
14%8%35%6%34447%38%
1931
16th to endNight
14%9%45%6%3445%6%35%
2288
November1st to 15thNight
12%10%47%5%2445%7%34%
2353
16th to endNight
12%10%48%6%2445%7%31%
2679
December1st to 15thNight
9%14%6%11%9%46%5%5%7%17%
2700
16th to endNight
10%15%8%12%7%35%5%6%6%17%
2880

Percentage Cloud Cover NW (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
7%13%6%10%7%45%5%7%7%25%
1281
16th to endDay
7%14%6%8%9%45%45%8%22%
1536
February1st to 15thDay
9%10%5%10%9%36%5%6%6%26%
1443
16th to endDay
11%12%5%8%8%5%7%7%6%6%21%
1548
March1st to 15thDay
9%14%6%9%8%36%46%7%23%
1824
16th to endDay
13%10%5%9%7%35%45%7%25%
2154
April1st to 15thDay
11%8%46%5%345%6%7%36%
2210
16th to endDay
16%9%36%6%34445%33%
2340
May1st to 15thDay
18%8%36%5%34346%34%
2465
16th to endDay
20%7%25%43445%8%31%
2803
June1st to 15thDay
16%6%36%6%46%5%6%7%30%
2700
16th to endDay
14%5%26%5%45%5%5%7%36%
2700
July1st to 15thDay
8%4245%35%5%6%9%42%
2700
16th to endDay
7%3245%25%6%7%10%44%
2724
August1st to 15thDay
9%425%5%35%5%5%8%43%
2481
16th to endDay
8%42342445%8%51%
2483
September1st to 15thDay
9%6%25%5%235%5%6%46%
2120
16th to endDay
14%5%245%24345%47%
1823
October1st to 15thDay
16%10%36%433327%37%
1684
16th to endDay
15%10%47%6%3435%6%33%
1584
November1st to 15thDay
15%10%7%7%5%24445%32%
1505
16th to endDay
10%15%5%8%6%35%447%26%
1281
December1st to 15thDay
11%13%8%13%10%45%6%6%6%14%
1260
16th to endDay
11%15%7%10%8%36%46%6%18%
1344
January1st to 15thNight
10%12%6%10%6%46%5%47%25%
2655
16th to endNight
9%13%6%10%6%37%6%5%7%24%
2688
February1st to 15thNight
9%10%5%9%7%45%5%6%7%29%
2410
16th to endNight
9%9%6%8%6%46%5%5%8%30%
1934
March1st to 15thNight
11%12%49%6%35%46%7%28%
2135
16th to endNight
12%9%46%6%446%5%8%31%
2065
April1st to 15thNight
7%8%36%5%35%5%5%7%40%
1737
16th to endNight
17%9%35%6%34447%32%
1620
May1st to 15thNight
16%8%26%434447%36%
1481
16th to endNight
19%7%3432436%7%37%
1311
June1st to 15thNight
15%5%2442446%8%40%
1260
16th to endNight
9%425%3245%5%10%44%
1260
July1st to 15thNight
8%32242337%7%53%
1260
16th to endNight
321343347%9%56%
1442
August1st to 15thNight
7%31442445%9%52%
1479
16th to endNight
8%31432325%8%55%
1719
September1st to 15thNight
8%5%2342345%6%53%
1839
16th to endNight
14%6%25%413447%47%
1826
October1st to 15thNight
14%8%35%6%34446%37%
1931
16th to endNight
14%9%35%6%35%45%6%35%
2288
November1st to 15thNight
12%11%47%5%24448%34%
2353
16th to endNight
11%11%48%7%245%5%7%31%
2679
December1st to 15thNight
9%14%6%12%9%46%5%6%6%17%
2700
16th to endNight
10%15%8%12%8%45%5%6%7%17%
2880

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
7%12%6%10%7%35%5%6%7%25%
1280
16th to endDay
7%14%7%9%8%46%45%8%22%
1536
February1st to 15thDay
9%11%49%9%46%5%5%7%26%
1443
16th to endDay
10%13%49%7%47%6%6%6%21%
1548
March1st to 15thDay
9%13%6%9%7%46%46%7%23%
1824
16th to endDay
13%10%6%9%7%35%5%5%6%25%
2156
April1st to 15thDay
11%9%46%425%45%7%36%
2210
16th to endDay
16%9%36%6%35%445%33%
2340
May1st to 15thDay
19%9%36%5%24346%34%
2465
16th to endDay
21%7%25%5%25%45%8%31%
2803
June1st to 15thDay
16%6%36%6%45%5%6%7%30%
2700
16th to endDay
14%6%26%5%35%5%6%7%36%
2700
July1st to 15thDay
8%425%436%5%7%9%42%
2700
16th to endDay
7%4145%346%7%10%44%
2724
August1st to 15thDay
9%5%25%5%345%5%8%43%
2481
16th to endDay
9%414334447%51%
2483
September1st to 15thDay
10%6%25%5%235%5%6%47%
2120
16th to endDay
14%6%23424345%47%
1823
October1st to 15thDay
16%11%27%433336%37%
1684
16th to endDay
15%11%46%6%3345%5%34%
1584
November1st to 15thDay
15%11%6%7%42435%6%32%
1505
16th to endDay
11%13%5%9%6%25%447%26%
1281
December1st to 15thDay
10%13%8%12%10%45%6%6%6%15%
1260
16th to endDay
11%15%7%11%7%46%45%6%18%
1344
January1st to 15thNight
9%12%6%10%6%46%5%47%25%
2655
16th to endNight
9%13%6%10%7%37%6%5%6%24%
2688
February1st to 15thNight
9%10%48%8%45%6%5%7%29%
2410
16th to endNight
9%10%5%7%7%35%5%6%8%29%
1934
March1st to 15thNight
11%12%5%8%6%35%5%5%7%28%
2135
16th to endNight
12%10%36%6%45%5%5%8%31%
2067
April1st to 15thNight
7%8%37%5%35%5%5%7%40%
1737
16th to endNight
17%9%35%6%3445%7%32%
1620
May1st to 15thNight
17%8%26%43445%7%36%
1481
16th to endNight
19%6%3442426%7%38%
1310
June1st to 15thNight
15%425%5%2446%9%40%
1260
16th to endNight
9%425%425%5%5%11%43%
1260
July1st to 15thNight
8%31332336%8%53%
1260
16th to endNight
321242446%9%56%
1442
August1st to 15thNight
7%31341445%8%53%
1479
16th to endNight
8%41441335%7%55%
1719
September1st to 15thNight
9%42342345%6%53%
1839
16th to endNight
14%5%24413347%46%
1826
October1st to 15thNight
14%8%35%6%34447%38%
1931
16th to endNight
14%9%35%5%3445%6%35%
2288
November1st to 15thNight
12%10%5%6%5%24447%34%
2353
16th to endNight
12%10%5%8%6%35%45%7%30%
2679
December1st to 15thNight
9%14%7%11%9%46%5%5%6%18%
2700
16th to endNight
10%15%8%12%7%45%5%6%7%17%
2880

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
7%12%7%9%6%46%6%5%8%26%
1280
16th to endDay
8%13%6%9%8%46%448%24%
1536
February1st to 15thDay
8%11%49%8%46%6%5%7%27%
1443
16th to endDay
10%13%49%8%47%6%5%7%22%
1548
March1st to 15thDay
10%12%6%10%7%5%5%46%8%23%
1824
16th to endDay
13%10%5%9%7%345%6%6%26%
2154
April1st to 15thDay
10%10%47%42445%7%36%
2210
16th to endDay
16%9%27%6%34446%34%
2340
May1st to 15thDay
19%9%36%5%34336%34%
2465
16th to endDay
20%8%24425%46%7%31%
2803
June1st to 15thDay
16%7%36%6%45%5%6%7%30%
2700
16th to endDay
14%6%26%5%35%5%6%8%36%
2700
July1st to 15thDay
8%425%5%36%5%6%9%42%
2700
16th to endDay
7%3145%35%5%7%10%45%
2724
August1st to 15thDay
9%5%245%35%45%9%42%
2481
16th to endDay
9%41432345%7%51%
2483
September1st to 15thDay
10%6%25%43445%6%47%
2120
16th to endDay
14%5%24424445%47%
1823
October1st to 15thDay
16%9%37%424336%38%
1684
16th to endDay
15%10%46%6%3445%5%34%
1584
November1st to 15thDay
16%10%6%6%6%23347%31%
1505
16th to endDay
12%13%5%9%6%25%5%5%6%27%
1281
December1st to 15thDay
10%13%8%12%11%345%7%7%15%
1260
16th to endDay
11%15%7%11%6%36%5%47%18%
1344
January1st to 15thNight
10%12%6%9%7%45%6%47%25%
2655
16th to endNight
9%13%6%10%6%36%5%5%6%24%
2688
February1st to 15thNight
9%9%48%8%45%5%5%7%29%
2410
16th to endNight
9%10%48%6%35%5%6%8%29%
1934
March1st to 15thNight
11%12%5%8%5%45%46%7%28%
2135
16th to endNight
13%9%37%5%35%5%5%8%31%
2067
April1st to 15thNight
7%8%37%5%35%5%5%6%40%
1737
16th to endNight
16%9%35%5%35%35%6%33%
1620
May1st to 15thNight
17%8%26%4245%5%7%36%
1481
16th to endNight
19%6%25%31436%6%38%
1310
June1st to 15thNight
15%43443445%7%41%
1260
16th to endNight
9%5%244245%6%11%43%
1260
July1st to 15thNight
8%31432345%8%53%
1260
16th to endNight
3334245%5%9%57%
1442
August1st to 15thNight
7%3134335%5%8%52%
1479
16th to endNight
8%314333348%55%
1719
September1st to 15thNight
8%5%1342345%7%53%
1839
16th to endNight
14%6%34413446%47%
1826
October1st to 15thNight
13%8%35%6%33447%38%
1931
16th to endNight
14%9%45%5%25%5%5%6%35%
2288
November1st to 15thNight
12%10%5%6%6%24447%34%
2353
16th to endNight
12%10%5%8%6%345%47%31%
2679
December1st to 15thNight
8%14%7%11%10%46%45%7%18%
2700
16th to endNight
10%14%8%12%7%45%5%5%7%17%
2880

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
54%7%11%20%5%
1281
16th to endDay
58%7%10%17%5%
1536
February1st to 15thDay
54%6%17%17%4
1444
16th to endDay
59%6%11%16%5%
1548
March1st to 15thDay
59%6%12%17%4
1824
16th to endDay
57%7%13%16%4
2156
April1st to 15thDay
45%6%16%22%8%1
2210
16th to endDay
51%6%11%16%11%
2340
May1st to 15thDay
51%411%23%7%1
2465
16th to endDay
50%5%12%20%9%
2807
June1st to 15thDay
49%8%14%18%8%
2700
16th to endDay
44%8%17%22%5%
2700
July1st to 15thDay
35%9%19%27%7%
2541
16th to endDay
32%9%19%28%9%
2555
August1st to 15thDay
37%8%20%25%7%
2465
16th to endDay
30%6%17%34%10%
2483
September1st to 15thDay
36%6%18%29%7%1
2120
16th to endDay
39%6%13%31%9%
1823
October1st to 15thDay
49%5%12%24%7%
1684
16th to endDay
51%6%14%21%6%
1584
November1st to 15thDay
53%5%13%17%8%1
1505
16th to endDay
56%5%16%16%4
1281
December1st to 15thDay
66%9%10%11%2
1260
16th to endDay
63%7%11%13%3
1344
January1st to 15thNight
56%7%10%18%7%
2655
16th to endNight
57%8%13%13%7%
2688
February1st to 15thNight
52%6%15%18%7%
2420
16th to endNight
50%5%13%20%9%
1934
March1st to 15thNight
53%6%15%18%5%
2135
16th to endNight
49%7%15%21%4
2067
April1st to 15thNight
41%6%11%23%14%1
1737
16th to endNight
51%412%17%12%1
1620
May1st to 15thNight
46%5%11%23%11%
1482
16th to endNight
45%6%10%21%15%
1311
June1st to 15thNight
39%6%17%25%9%
1260
16th to endNight
34%9%21%25%7%
1260
July1st to 15thNight
28%6%17%34%12%
1190
16th to endNight
22%7%18%36%12%1
1348
August1st to 15thNight
28%7%17%35%9%1
1471
16th to endNight
28%6%14%33%15%2
1719
September1st to 15thNight
30%6%16%30%15%1
1839
16th to endNight
37%5%15%28%12%
1826
October1st to 15thNight
45%6%14%24%7%
1931
16th to endNight
48%6%14%23%6%
2288
November1st to 15thNight
48%6%15%20%7%2
2353
16th to endNight
51%8%14%19%5%
2679
December1st to 15thNight
64%7%12%13%2
2700
16th to endNight
63%7%12%13%3
2880

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 15thDay
10%5%28%32%22%1
90
16th to endDay
18%6%29%26%19%
96
February1st to 15thDay
17%348%20%10%
90
16th to endDay
13%335%30%14%1
81
March1st to 15thDay
13%14%21%42%8%
90
16th to endDay
25%5%34%17%16%2
140
April1st to 15thDay
15%10%32%27%11%1
329
16th to endDay
18%6%31%27%12%2
450
May1st to 15thDay
22%6%28%29%11%1
468
16th to endDay
21%7%26%24%17%2
517
June1st to 15thDay
17%9%27%26%13%4
495
16th to endDay
16%8%25%30%15%3
495
July1st to 15thDay
10%323%33%21%7%
475
16th to endDay
8%7%25%30%22%5%
515
August1st to 15thDay
11%326%30%17%9%
493
16th to endDay
10%6%22%30%24%5%
523
September1st to 15thDay
12%8%35%25%16%2
275
16th to endDay
20%8%28%30%10%1
92
October1st to 15thDay
27%5%34%21%8%2
90
16th to endDay
37%5%22%17%13%3
96
November1st to 15thDay
18%10%25%25%17%2
90
16th to endDay
28%6%22%26%13%2
90
December1st to 15thDay
15%5%35%23%15%4
90
16th to endDay
17%440%23%9%4
96
January1st to 15thNight
16%6%32%31%11%1
900
16th to endNight
16%8%37%29%7%
960
February1st to 15thNight
14%5%32%31%12%3
880
16th to endNight
12%329%35%15%3
672
March1st to 15thNight
16%6%28%30%13%3
695
16th to endNight
17%425%33%16%2
576
April1st to 15thNight
10%5%33%35%13%1
539
16th to endNight
20%428%33%12%1
540
May1st to 15thNight
21%7%27%30%12%
540
16th to endNight
20%5%26%33%14%
563
June1st to 15thNight
17%432%29%16%
540
16th to endNight
12%328%37%18%
540
July1st to 15thNight
10%322%36%25%
510
16th to endNight
5%123%47%20%1
564
August1st to 15thNight
9%122%40%22%3
539
16th to endNight
10%322%37%22%2
573
September1st to 15thNight
11%325%37%19%2
540
16th to endNight
14%8%26%33%15%1
495
October1st to 15thNight
18%8%31%30%10%
611
16th to endNight
19%7%29%31%10%
880
November1st to 15thNight
16%8%32%28%11%2
875
16th to endNight
18%7%34%28%9%1
900
December1st to 15thNight
15%6%31%30%13%3
900
16th to endNight
18%7%29%28%13%3
960
Page generated at 2017-09-17 11:05:40. Version ac04

Copyright 2017 A. Danko


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