CONTROL SURVEY- POLARIS-II By D.M Siddique
Transcript of CONTROL SURVEY- POLARIS-II By D.M Siddique
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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
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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)
Procedure for observing PolarisProcedure for observing Polaris3
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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Procedure for observing PolarisProcedure for observing Polaris4
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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
Procedure for observing PolarisProcedure for observing Polaris5
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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Computation technique for Azimuth DeterminationComputation technique for Azimuth Determination--
Tabular SolutionTabular Solution7
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Computation technique for Azimuth DeterminationComputation technique for Azimuth Determination--
Tabular SolutionTabular Solution8
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Computation technique for Azimuth DeterminationComputation technique for Azimuth Determination--
Tabular SolutionTabular Solution9
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Computation technique for Azimuth DeterminationComputation technique for Azimuth Determination--
Tabular SolutionTabular Solution10
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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.