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

All listed here
Its declination and hour angle
Its declination and right ascension
Its altitude and azimuth

ANSWER DOWNLOAD EXAMIANS APP

Surveying
The error due to eccentricity of inner and outer axes can be eliminated by

taking both face observations and taking the mean of the two
double sighting
reading both verniers and taking the mean of the two
taking mean of several readings distributed over different portions of the graduated circle

ANSWER DOWNLOAD EXAMIANS APP