Astronomy quiz question: HESS interferometry

Astronomy 210 Quiz 3, fall semester 2012
Cuesta College, San Luis Obispo, CA

Consider two of the High Energy Stereoscopic System telescopes, located near Windhoek, Namibia. These two reflector telescopes have different diameters, and different focal lengths. These and other HESS telescopes were constructed to be spread out from each other to improve:
(A) light-gathering power.
(B) resolving power.
(C) magnifying power.
(D) (Two of the above choices.)
(E) (All of the above choices.)
(F) (None of the above choices.)

(Image credit: HESS Collaboration/Stefan Schwarzburg, http://www.mpi-hd.mpg.de/hfm/HESS/pages/press/2012/HESS_II_first_light/.)

Correct answer: (B)

Increasing the distance between telescopes creates a much larger effective diameter to increase resolving power.

Section 70158
Exam code: quiz03s3Er
(A) : 2 students
(B) : 20 students
(C) : 1 student
(D) : 7 students
(E) : 6 students
(F) : 1 student

Success level: 58% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.50

Section 70160
Exam code: quiz03ni3R
(A) : 3 students
(B) : 17 students
(C) : 3 students
(D) : 4 student
(E) : 2 students
(F) : 0 students

Success level: 62% (including partial credit for multiple-choice)
Discrimination index (Aubrecht & Aubrecht, 1983): 0.56