The optical requirement of sextant include possession of two mirrors which should be perpendicular if parallel mirrors are placed reading should be zero and optical axis must be parallel to plane of graduated arc.

Astronomical triangle involves usage of spherical co-ordinates. By using triangle, we are able to derive a relation for spherical co-ordinates by using certain cases which provide different outputs based on placement of star.

The permanent adjustments include making index glass perpendicular with graduated arc, horizon glass perpendicular with graduated arc, and line of sight parallel to plane of graduated arc etc. se are required for every instrument for having a better output.

When star is positioned at prime vertical, it is having a chance of attaining a right angled astronomical triangle. By joining prime vertical and meridian, declination of circle can be found out.

For determining correction for index error, calculate mean reading = (18?24?52?? + 18?23?24??) / 2 = 18?24?8??
Index error for face right can be given as 18?24?8?? ? 18?23?24?? = +44??.

Zenith telescope liquid mirror will cost about 1% of general telescopic mirror. This may help in its economical point of view, but in terms of work it might lag behind in some aspects.

The independent system is used for publication of stars ephemerides and also position of stars. For this it requires circle of references, which can be taken as equatorial circle and declination circle.

A sextant involves in sighting two different objects simultaneously, which can be able to determine angle between m. Horizontal as well as vertical angles can be measured with help of sextant.

A star is said to be culminative when it is crosses observer?s meridian. There is a possibility for formation of two culminatives one is lower culminative and upper culminate. It depends on altitude at which star is placed.

Here, declination of a star is greater than latitude ,
Zenith distance = ZP ? AP
Zenith distance = (90-?)- (90-?)
Zenith distance = 90-54?21?-90+74?32?
Zenith distance = 20?11?.