Practice and Theory 6

At western elongation, the pole star moves

• a. eastward

• b. westward

• c. northward

• d. southward

Pick up the correct statement from the following :

• a. Refraction correction is zero when the celestial body is in the zenith

• b. Refraction correction is 33' when the celestial body is on the horizon

• c. Refraction correction of celestial bodies depends upon their altitudes

• d. all the above.

The hour angle of the heavenly body for Greenwich meridian equals the hour angle of the body for any other meridian + longitude :

• a. mean sun

• b. true sun

• c. vernal equinox, star

• d. all the above.

By raising the z-column of right projector, maximum y-parallax is introduced in the model at

• a. position 1

• b. position 2

• c. position 4

• d. position 4 and 6.

The height displacement on a vertical photograph

• a. increases as the horizontal distance increases from the principal point

• b. increases as the ground elevation increases

• c. decreases as the flying height increases

• d. all the above.

The equation which is obtained by multiplying each equation by the coefficient of its un-knowns and by adding the equations thus formed, is known as

• a. observation equation

• b. conditional equation

• c. normal equation

• d. none of these.

Accidental errors

• a. do not follow any definite mathematical law

• b. cannot be removed by applying corrections to the observed values

• c. are generally small and are also known as compensating errors

• d. all the above.

If θ and δ be the latitude of a place and declination of a star respectively, the upper culmination of the star will be north of zenith if its zenith distance, is

• a. δ - θ

• b. θ - δ

• c. θ + δ

• d. θ + δ

  2

In a tropical year, the number of sidereal days are

• a. one less than mean solar days

• b. one more than mean solar days

• c. equal to mean solar days

• d. none of these.

The position of a heavenly body on the celestial sphere can be completely specified by

• a. its altitude and azimuth

• b. its declination and hour angle

• c. its declination and right ascension

• d. all the above.