control survey- polaris-ii by d.m siddique

7/30/2019 CONTROL SURVEY- POLARIS-II By D.M Siddique

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02/11/2012

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ADVANCE ENGINEERING SURVEYING

(3+1)

LECTURE 15: CONTROL SURVEY- POLARIS-II

INSTRUCTORINSTRUCTOR

Date: 01/11/2012

DR. MOHSIN SIDDIQUE

ASSIST. PROFESSOR

DEPARTMENT OF CIVIL ENGINEERINGFAST-NUCES, LAHORE

[email protected]



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Purpose for observing the Polaris is

Bearing of line w.r.t. true North

It can be done by observing

Polaris

Sun

Procedure for observing PolarisProcedure for observing Polaris2

For case of Polaris, the ideal time for observations is just before night fallbecause

It can be identified easily

Illumination not required for note keeping and target viewing

To sight Polaris at dusk, north must be approximated through compass



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The following describe a procedure for observation of Polaris

1. Prepare note forms in advance

2. Check to see that equipment is working properly and that an adequate

supply of batteries is available

3. Determine the latitude (can be scaled from topographic map)


4. After carefully setting up instrument (station 102), determineapproximately the direction of north and establish or identify a target

5. With horizontal scales zeroed, sight at the reference station (station 103)

6. sight an object at least 250m away and focus carefully, this is instrument’s

infinite focus, which must be set when sighting the star.



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7. If the telescope has been directed properly towards north, if the correct

approximate altitude has been set on the vertical circle, and if the focus

adjustment has been set properly, Polaris should appear in the telescope atleast 15 min before nightfall.

8. At the instant the star has been centered carefully on the cross hairs, record

the time and record and book the horizontal angle.

9. Transit the telesco e and re-si ht the star. Once a ain record the time and


horizontal angle. 10. Finally sight the telescope back on original reference station (103) and

note the angle (it should be 180o00’). This procedure may be repeated if

higher accuracy is required.

11. Use the average time for bearing calculations for Polaris and use the

average angle to determine bearing of line



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Computation technique for Azimuth DeterminationComputation technique for Azimuth Determination--

Tabular SolutionTabular Solution6



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Surveying: Principles and Application

Eighth edition

By Barry Kavanagh

Google search engine

ReferencesReferences11



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Questions….Questions….

12 Thank you !Thank you !

I am greatly thankful to all the information sources oninternet that I accessed and utilized for thepreparation of present lecture.

control survey- polaris-ii by d.m siddique

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