### Frequently Asked Questions Concerning the Activities

Updated January 2013
1. What exactly is meant by "these activities are to be done individually"? Can I go out with a friend to make the observations?

You may certainly undertake the observations with a friend. If you feel unsafe doing the nighttime observations, by all means go out with someone else. There is nothing wrong with consulting with others to make sure you are measuring the right thing. But you must do your own observations. You must record your own observations (no sharing logbooks). You must analyze your data and write your report by yourself. If you share a computer with someone else in the course, be sure to generate your own unique text and figures.

2. I could not find a place where I can see the sun set on the horizon.

That is a common problem here on Long Island. There always seem to be trees or buildings in the way. The solution is to use the trees and buildings as a pseudo-horizon. So long as they don't move over the course of the semester, they provide a reference against which to measure the location of the sunset (in other words, do not use a truck or a car as a reference point!).

3. How do I measure the distance of the moon from the horizon?

• A knuckle at arm's length subtends about 2 degrees.
• Your open hand at arm's length from thumb-tip to the end of your little finger subtends about 20 degrees.
You can verify these angular measures by measuring the length of your arm and the length of your hand, fist, etc with a yardstick, and then drawing the correct triangles and solving for the angle.

4. In activity 2, could I take pictures of the sunset using a panoramic camera instead of drawing the landscape?

Yes, but be sure to annotate the pictures appropriately when you hand them in. A sketch is more convenient, because you can draw many sunsets on a single sketch. The analysis of a series of photographs may be more complicated.

5. In activity 2, should I plot the quantities together on a single plot or each on their own plot?

That is up to you. If you use a single plot, make sure that the different plots are distinguishable. Use colors.

6. For how long should I continue Activity 2?

For as long as you can. The longer you go, the more clearly you will be able to see trends. Remember, to do this properly would require a full year. Go for at least 2 months, and preferably up to the week the activity is due.

7. In activity 3, do I need to observe the Moon every night from the same place?

No. You need to orient yourself so that you know roughly where North is (so you can give the direction of the Moon), and you should observe from a place where you can see (or at least estimate) the horizon (so you can measure the altitude). Note that for activity 2, you do need to observe from the same place, because the Solar motions are slower than the Lunar motions, and you need a stable reference against which to measure it.

8. Can I do my observations from the roof of the ESS building?

Yes, if it is open. It is a public place, and it affords a good view of the western horizon. But be careful. The roof is dark and has cracked tiles and protruding vents that one can easily trip on. In winter snow and ice may accumulate of the roof. One you get to the roof, wait a minute or two to let your eyes adapt to the dark before venturing forth, or carry a flashlight.

You were all told the combination to the roof door lock; if you have forgotten it please ask your TA or instructor.

The ESS building is nominally closed on weekends, but you can often find an open door. Plan around this,

Note that the telescope dome is not open to the public except at scheduled times.

9. Do we necessarily need to use a logbook for the sketch? May I just use the white papers (printing papers)? I will staple all of the works together.

You may use individual sheets stapled together. Make sure the staples hold, because we'll have a lot of reports coming in. Put your name on each page just in case.

10. What do I do when the time shifts from daylight savings time to standard time?

You will have to account for this.
Activity 1: I leave it up to you. What is the question you are asking? The plots will look nicer if you correct all times to standard times, or to DST. But the correct answer to a question may depend on whether or not you make a correction.
Activity 2: you will have to adjust your schedule to the time of sunset (or sunrise), which will shift by an hour.
Activity 3: do the lunar observations one hour earlier (or later), depending on the semester.

11. I can't see the moon at the regular time tonight. What do I do?

That depends on the circumstances. If there are clouds about, then you should probably confirm the non-detection a little later, or the next night. If your sky is obscured by trees/buildings, move around a bit to see if the moon is hidden. But if the sky is clear, and your sky is unobstructed, then the absence of the moon is a legitimate observation.

12. Can I observe sunrise instead of sunset?

Absolutely. But be consistent - don't mix sunrise and sunset. I tend to refer to sunset observations because most students are asleep at sunrise.