The rules: Collaborative work is encouraged. This homework can be done in consultation with your fellow classmates, the AI, or the professor. However, everyone must submit their own solutions to get credit, and all help should be acknowledged (a single sentence mentioning the others in your study group is sufficient). Show your work.
1. Just the facts [5 pts]
(a) [2 pts] During the entire year, roughly what percentage of the
celestial sphere can you see from the north pole?
(b) [3 pts]
Using a diagram, explain why the tilt of the Earth's axis
relative to the Earth's orbit causes the seasons as we orbit the sun.
2. Observing from the roof top [45 pts]
(a) [4 pts] You are planning a set of observations from the
roof of Swain Hall West (latitude of 39o 09.9' North;
longitude of 86o 31.5' West; height = 229m above sea
level) for the night of September 14-15, 2009. You have looked up the
GMST in the Astronomical Almanac
and found that on Sept 15, 2009, 0h UT, GMST is 23:36:21.05.
In order to prepare for your observing run,
calculate both the Universal Time (UT) and Local Sidereal Time
(LST) at midnight in Bloomington that evening.
(b) [6 pts] Next, determine when (in EDT) the following astronomical
objects will cross through upper transit on the night of September 14-15, 2009:
| Object | RA(2009.5) | Dec(2009.5) |
| h m s | deg m s | |
| Jupiter | 21 24 55.8 | -16 20 38 |
| Andromeda Galaxy (NGC 224 = M31) | 00 43 15.6 | +41 19 15 |
| The Moon | 08 11 54.5 | 19 49 02 |
(c) [6 pts] Now, calculate the hour angles (HA) at which
the above objects will rise and set.
(d) [6 pts] Using the transit times from (b) and the HA limits from (c),
calculate the rise and set times (EDT) in order to plan your observations.
(e) [1 pt] Which object should you observe first in the night?
Which one should you do last? Explain your reasoning.
(f) [22 pts] Repeat the above calculations (a-d) for observations conducted at the Cerro Tololo Interamerican Observatory (located in Chile), with a longitude of -70o 48.9' and a latitude of -30o 09.9'. Be sure to calculate the rise and set times in the time zone appropriate for the observatory.