7/27/2019 Soal Latihan Instrumentasi

1/1

Soal-Soal Latihan Instrumentasi astronomi (P. Hakim)1. If the moon can be photographed in one second with a telescope of 45 cm aperture

and 90 cm focal length, how long a time would be required to photograph the moonwith a telescope of 90 cm aperture and 360 cm focal length?

2. The 2,4 m reflector can be operated as a f/6 prime focus or as f/12 cassegrain

telescope.a. In which of these modes can an extended object be exposed fastest, and by whatfactor?

b. Which mode has a fainter limiting magnitude?3. Determine parameters of one of the telescopes at Bosscha Observatory! (use 3

eyepieces: 5 mm, 15 mm, 25 mm)

1. What would be the size of the image of the moon, produced by the 5,08 meterstelescope with focal length 16,76 meters?

2. What is the smallest angle that could theoretically be resolved by the 5,08 meterstelescope at a wavelength of 5000 ?

3. What kind of telescope would you use to take a color photograph entirely free ofchromatic aberration? Why?4. Ordinary 7 x 50 binoculars magnify seven times (magnifying power: 7) and have

objective lenses of 50 mm aperture. For light of 5000 what is the smallest anglethat can be resolved by the lenses of binoculars? Could two stars separated by thisangle actually be seen as separate stars when viewed through 7 x 50 binoculars?Why?

5. When Mars is at its closest, it subtends about 24 in the sky. The diameter ofMars is about 6800 km. In principle, how close together could two features onMars be and still be distinguished with the 5,08 m telescope? In practice, becauseof the limitations set by the Earths atmosphere, how close together can they be?

With a 60 cm telescope, could a person be sure that the canals on Mars wereonly 3 km wide? Why?6. Suppose that all stars emitted exactly the same total amount of light and that stars

were distributed uniformly throughout space. Show that the depth in space towhich stars could be observed would (ideally) be proportional to the aperture ofthe telescope used!

7. Tychos Supernova of 1572 attained is greatest brilliance at magnitude -4 onapproximately 1st October, and thereafter began to fade, finally becominginvisible to the unaided eye on approximately 1st March 1574. If the apparentbrightness at a time after 1st Oct 1572 is related to the apparent brightness on thedate by the equation p = bo x 10-t/T

8. When performing photoelectric photometry with a particular system, it is noted asa 4th magnitude star generates 104 primary photoelectrons per second. What is theintegration time required to achieve accuracy 1% on a 9th magnitude star? (assumethe background count to be zero).