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exam2solutions - AST 3722C - Spring 2008 Final solutions...

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Unformatted text preview: AST 3722C - Spring 2008 Final solutions Part A. 1. You need to calculate declination first to do this problem. Using handout #5 you should find that = 16 25 04 . Then you can use the formula for finding H , and you get H = 03 h 40 m 53 . 6 s . Since A is a western azimuth you should know that H must be positive. 2. 1 hour later in solar time = (1 / . 99727) hours of sidereal time. So just add that on to the H from problem 1. H = 04 h 41 m 03 . 4 s . 3. You need to find H first and then relate it to the H from problems 1 or 2. You should get that H = 05 h 03 m 09 . 8 s when a = 20 . Thats 1 hour, 22 minutes, 16.2 seconds of sidereal time later than the H in problem 1. Thats 1 hour, 22 minutes, 2.7 seconds of solar time. So the clock time is 10:52:03 pm . 4. This question asks at what time the next day has exactly 1 sidereal day passed? 24 hours of sidereal time is 23 hours, 56 minutes, 04 seconds of solar time, so the time has to be 10:48:07 pm . 5. H = LST , so = LST H . Get H from problem 1, so = 06 h 29 m 37 . 4 s . 6. This happens when the Suns R.A. is 12 hours away from the objects R.A. So = 18 h 29 m 37 . 4 s . Recall that on the winter solstice = 18 h . The Sun changes R.A. by (360 / 365 . 25) = 0 . 9856 per day, which is like 3 m 56 . 6 s of R.A. per day. So it gets to 18 h 29 m 37 . 4 s about 7 to 8 days after the winter solstice, which is about December 29 . (If youre within a day or two of this thats fine.) Alternate interpretation: Find when this object transits at midnight. In other words on what day is LST 06:29:37 at local time of 12:00 am? Let tonight be April 22. I tell you that LST is 10:10:31 at local time 9:30 pm tonight. So 2.5 hours later, when its 12 midnight, LST will be 10:10:31 +(2 . 5 / . 99727) = 12:40:56. Every 24-hour time interval later, LST will be later by (24 / . 99727) = 24 h 03 m 56 . 5 s . Similary, every 24-hour time interval earlier, LST will be earlier by 24 h 03 m 56 . 5 s . Or in other words, LST shifts backward by 3 m 56 . 5...
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exam2solutions - AST 3722C - Spring 2008 Final solutions...

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