Astronomy quiz question: last constellation to set

Astronomy 210 Quiz 1, fall semester 2017
Cuesta College, San Luis Obispo, CA

The diagram at right shows the positions at 11:00 PM of constellations Cygnus, Aquila, and Hercules as seen by an observer in San Luis Obispo, CA. Ignore daylight saving time. Within the next 24 hours, __________ will be the last constellation to completely set below the horizon.
(A) Cygnus.
(B) Aquila.
(C) Hercules.
(D) (There is a tie.)
(E) (None of these constellations will completely set below the horizon.)

Correct answer (highlight to unhide): (A)

As read off from a starwheel, Hercules is above the south horizon as shown at 11:00 PM on September 25. Advancing time forward (while keeping the date on September 26 once the time is after midnight) indicates that Cygnus will be the last of these three constellations to set, approximately eight hours later the following day.

Section 70158
Exam code: quiz01S3aN
(A) : 24 students
(B) : 9 students
(C) : 5 students
(D) : 0 students
(E) : 2 students

Success level: 51% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.39

Section 70160
Exam code: quiz01nMm5
(A) : 19 students
(B) : 1 students
(C) : 3 students
(D) : 0 students
(E) : 4 students

Success level: 61% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.44