Positional and Observational Astronomy

How many coordinates are needed on a surface of a sphere to describe the position of an object

• 3

• 2

• 4

• 1

A closed figure formed by three mutually intersecting great circles on a sphere is called a spherical triangle. Select all the correct options with the help of this diagram

• The sum of three angles is greater than 180 degrees

• The sum of three angles is equal to 180 degrees

• Any side is less than 180 degrees

• Any angle is less than 180 degrees

Calculate the coordinates in horizon system for the pole star as depicted in the diagram, azimuth angle measured with respect to North (Latitude is given by alpha) first coordinate is azimuth and second is altitude.

• (0,alpha)

• (alpha,0)

• (0,180 west)

• (180 west, alpha)

What is the full form of CLASS survey(hint: related to the talk)

• Colour Lens All Sky Survey

• Cepheid Luminosity Average Sky Survey

• Cosmic Lens All Sky Survey

• Compact Lens Array Sky Survey

Which was the farthest star ever observed and the phenomena responsible for it is?

• Sirius and weak lensing

• Icarus and microlensing

• Antares and strong lensing

• Aldebaran and occultation

What is this lensed configurations name

• Einstein's Cross

• Einstein's Ring

• Eddington's Cross

• Eddington's Ring

a) A gravitational lens causes maximum deflection of light that passes closest to its center and minimum deflection of light that travels farthest from its center. b)This behavior is similar to optical lens

• a) False b)Ture

• a) False b)False

• a)True b)True

• a) True b)False

A lensing field's shear(distortion) measurement gives a good measure of the

• Dark Energy distribution in the background

• Dark matter distribution in the background

• Large Scale Structure of the Universe

• Galactic Evolution of the lens

What conditions are believed to be required for the observation of Einstein's ring

• Circular Symmetry of Lens

• Hydrostatic Equilibrium of the intervening star

• Light source, Lens and Observer lie in a straight line

• Lensing object is quite small compared to the light source

Newton's prediction of light deflection from Sun was half of that of Einstein's GR

• False

• True