How is index error eliminated?

How is index error eliminated?

To eliminate index error, clamp the index bar at zero and looking through the telescope, turn the third adjustment Screw, till the true horizon and its reflection appear in alignment. The error of collimation is due to the axis of the telescope not being parallel to the plane of the instrument.

What is vertical circle index error?

An index error exists if the vertical circle is not correctly oriented to gravity when the instrument is leveled. Some earlier theodolites, particularly control quality instruments, had a separate bubble for vertical circle orientation.

How many types of errors are in theodolite?

Sources of error in theodolite work are classified into three groups: 1. Instrumental Errors 2. Observational Errors 3. Natural Errors.

What are the errors in theodolite?

Theodolite errors: The trunnion axis is not perpendicular to the vertical axis. The line of sight is not perpendicular to the trunnion axis. The vertical axis is not plumb.

How do you fix an index error on a sextant?

Index error We look at the horizon with the telescope: direct horizon and the reflected horizon should be a straight line. We move the drum until we see a straight line: the reading is the index error. the “index error” must be removed or reduced using the adjusting screw on the horizon mirror (adjustig screw no. 2).

What are the error in total station?

Tilting axis or tilt error is the error when the axis to the total station is not perpendicular to the vertical axis or plumb line. The error effect on horizontal readings when the instrument is tilted (steep sightings) but have no effect on sightings taken when the instrument is horizontal.

How do you calculate index error?

Checking Index Error By Horizon Observation

1. Clamp the index bar at zero.
2. Hold the sextant vertically and view the horizon through the telescope.
3. If true horizon and its reflected image appear in one line, Index Error is not present.
4. If they appear vertically displaced that means Index Error is present.

What is Bowditch’s rule?

1)Bowditch’s Rule: The Bowditch’s rule, also termed as the compass rule, is mostly used to balance traverse when linear and angular measurements are equally precise. By this rule, the total error in latitude or departure is distributed in proportion to the lengths of the traverse legs.

How do I get rid of index error in theodolite?

This error is eliminated by reading the angle from both the faces (left and right) and take the average of the reading. 73. Sources of Error in Theodolite Horizontal axis not being perpendicular to vertical axis • If the horizontal axis is not perpendicular to the vertical axis, there is an angular error.

How do I fix Index errors?

To solve the “indexerror: list index out of range” error, you should make sure that you’re not trying to access a non-existent item in a list. If you are using a loop to access an item, make sure that loop accounts for the fact that lists are indexed from zero.