Analysis of random errors in horizontal sextant angles by Gerald B. Mills

Cover of: Analysis of random errors in horizontal sextant angles | Gerald B. Mills

Published by Naval Postgraduate School in Monterey, California .

Written in English

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Subjects:

  • Oceanography

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Book details

ContributionsNaval Postgraduate School (U.S.)
The Physical Object
Pagination1 v. :
ID Numbers
Open LibraryOL25510137M

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by Mills, Gerald B. Publication date some content may be lost due to the binding of the book. Addeddate Call number o Camera Canon 5DPages: Details - Analysis of random errors in horizontal sextant angles.

- Biodiversity Heritage Library The Biodiversity Heritage Library works collaboratively to make biodiversity literature openly available to the world as part of a global biodiversity community. BHL works best with JavaScript enabled. Analysis of Random Errors in Horizontal Sextant Angles I.

Tv^e ow «e^oi»T * pcrioo covcmeo By Gerald B. Mills, Read Instructions, Gerald B. Mills, M Cnntwollino and Ano Adohcss Abstract. Analysis of random errors in horizontal sextant angles. By Gerald B.

Mills and Naval Postgraduate School (U.S.) Topics: Oceanography. The Horizontal Sextant. I enjoyed reading John Hocking’s article on Sextant Piloting. It brought back memories of past writing and using the technique in my naval career.

First I want the reader to understand why. Navy ships use cross bearings instead of sextant angles. Or you can measure the angle by turning your sextant horizontally and measuring the angle between the two points (and calculating for index error).

Step 3. If the angle you get is less than 90º then subtract the angle from 90º to get the construction angle. If the angle is greater than 90º then you subtract 90º to get the construction angle. It is observed by holding the sextant horizontally, moving the arm so that the reflected image of one object is seen on the second object.

The angle is then measured is horizontal sextant angle. When the horizontal angle between two terrestrial objects is known, a circle of position can be obtained which is drawn on the chart.

has three legs, and the sextant is stored in its box or on a horizontal surface. The. handle. is on the same side as the legs, and is for holding the sextant while in use. To take the sextant from the box, lift it by the frame with the left hand, then transfer it to the right hand and hold it.

Random Errors Remain after mistakes are prevented or eliminated and measurements corrected for systematic errors Random errors are as likely to be positive as negative Small random errors are much more likely than large ones.

Study of random errors began in the 18th Century 9File Size: KB. Statistical or Random Errors. Every measurement an experimenter makes is uncertain to some degree. The uncertainties are of two kinds: (1) random errors, or (2) systematic errors.

22, ss E N of east and north coordinates respectively; variances 2 2 22, s s ssα βθ l of directions, angles, bearings and distances respectively; or their standard deviations s s ss E N, etc.α β noting that standard deviation is defined as the positive square-root of the variance.

It is common practice to assess the quality of traverses by comparing angular/linear misclosures File Size: KB. EXPECTED ERROR IN SUM OF ANGLES: This is the value that you would expect a field crew to close within 68% of the time.

If you were checking closure then use a 95% confidence level, or thus a t, n-1 multiplier. Since each angle measured only twice, n. There are three main errors of marine sextant, which can quite easily be corrected by the mariner. A fourth error, for “collimation”, can also be corrected, with care and attention, but only to an older sextant where telescope collars are fitted with adjusting screws.

In these circumstances the angle between the first and last direction of the ray of light is twice the angle between the index and horizon mirrors. ERRORS The sextant suffers from two main types of error, correctable and non-correctable. The latter as the name suggests may only be rectified by returning the device to the manufacturer for Size: KB.

General Accuracy and Precision Errors and Classification of Accuracy Observation vs. Measurement Linear Measurement Angular Measurement Vertical Measurement.

General. Basic field operations performed by a surveyor involve linear and angular measurements. Through application of mathematics (geometry and trigonometry) and. methods to determine compass error: 1.

transit bearing. horizontal sextant angle(hsa). vertical sextant angle(vsa). h (sun, moon, planet. Marine Sextant – Principle and Errors. A sextant is merely an instrument that measures the angle of a heavenly body (star, planet, sun and moon) makes with the visible horizon or the vertical or horizontal angle between two terrestrial objects.

It derives its name from the arc at the bottom which is one-sixth of a circle. Sextant and Errors. Sextant and Errors. Skip navigation AusNav #11 Horizontal Sextant Angles - Tutorial 36 fix position bearing and vertical sextant angle bearing and vertical sextant.

CHARLES D. GHILANI, PhD, is Professor of Engineering and Program Chair for the B.S. in Surveying program at Pennsylvania State University. Paul R. Wolf, PhD, deceased, was Emeritus Professor, Department of Civil and Environmental Engineering, University of was the author of Elements of Photogrammetry and coauthor of the bestselling.

The Ball Recording Sextant (figs. 1, 2) is used without a visible horizon to obtain the altitude of a celestial body by determining the angle between the axis of a sighting tube directed at the body and the line of fall of metal balls toward the center of the earth (fig.

The angle actually determined is the zenith distance. These sights are used for finding position or distance off. The 3-body position sight is one of the most accurate piloting techniques. It can be executed to very good precision with a simple, inexpensive Davis Mark 3 sextant.

In this sight we need to measure the angles between 3 bodies: L on the left, M in the middle, and R on the right. III. Measurements and Errors An azimuth is a horizontal angle measured clockwise from a defined reference (typically geodetic north). Horizontal distance and angle measurements are then used to calculate the position of a point on the horizontal plane.

Random errors conform to the laws of probability and are therefore equally distributedFile Size: KB. INDEX MIRROR: Is A Piece Of Silvered Plate Glass Mounted On The Index Arm, Perpendicular To The Plane Of The Instrument, With The Center Of The Reflecting Surface Directly Over The Pivot Of The Index Arm.

INDEX SHADES: Colored Transparent Substances Are Mounted On The Sextant’s Frame In Front Of The Index Mirror And Horizon Glass. They Can Be Moved Into. You don't take horizontal angles. Only vertical: The angle between the horizon and the chosen celestial object.

The easiest (and safest!) example is for latitude at night. Measure the angle between the Pole Star or Southern Cross and the horizon, and that's your latitude. If it is zero (instrument not required!) then you are at the Equator.

2 HOW TO USE PLASTIC SEXTANTS Figure This sample of the origi-nal US Navy lifeboat sextant (Culver ) is part of the collection of Francois Meyrier, sailor, celestial naviga-tion instructor, and au-thor.

It is slightly larger and of heavier plastic than its grandchild, the Davis Mark 3. hand here is to explain the issues and then pro. CHARLES D. GHILANI, PhD, is Professor of Engineering in the Surveying Engineering program at The Pennsylvania State University.

Adjustments and errors in the pratical use of the nautical sextant - mirrors perpendicularity, side and index errors in a marine sextant, correction tables.

Chapter 3 Surveying Equipment, Measurements and Errors Table of Contents SURVEYING EQUIPMENT, MEASUREMENTS AND ERRORS May Field Adjustments A total station is used for measuring both horizontal and zenith angles as well as slope distances.

In addition, they also have features for measurement to points that cannotFile Size: KB. Celestial Navigation takes you to correct the sextant, to the sight form to the Nautical Almanac to sight calculation table to the plot fix on the chart.

The use of the two minute Star Finder. The Sextant Handbook is dedicated to the premise that electronic navigation devices, while too convenient to disregard, are too vulnerable to rely on exclusively.

The book is designed to make beginner and expert alike conversant with this most beautiful and /5(83). Surveying Errors and Adjustment A short Training Course Prepared By: Dr. Maher A. El-Hallaq Lecturer of Surveying Faculty of Engineering The Islamic University of GazaFile Size: 1MB.

Surveyors express angles in several ways. When specifying directions, as is done in the preparation of a property survey, angles may be specified as bearings or azimuths. A bearing is an angle less than 90° within a quadrant defined by the cardinal directions. An azimuth is an angle between 0° and ° measured clockwise from North.

"South. Figure U.S. Navy Mark 2 micrometer drum sextant. The index arm, D, is a movable bar of the same material as the pivots about the center of curvature of the limb. The tangent screw, E, is mounted perpendicularly on the end of the index arm, where it engages the teeth of the e the observer can move the index arm through the length of the.

Moving to my shelf of instant favourites, Sextant is one of those books that keep you reading through an entire night without noticing time going by. Barrie enlightened my world by retelling the brialliant discovery stories of Cook, Bligh, Vancouver, Flinders, FitzRoy and many others, and by which navigational techniques those Masters of the Oceans used to find their way.4/5.

So, you’ve done your basic research and you think you know the topic area you want to write for your dissertation project. You then start to research further, in an attempt to define a unique Author: Proofreadmyessay. Your sextant now reads 30~ 04’ (Fig.

As you continue moving the index arm, successive divisions of the vernier will come into alignment with a division of the arc. When the last mark on the vernier (60’) is in alignment with a division of the arc, the sextant will read 3l~. In Figure 2 below, the sextant reads 26’.File Size: KB.

Everything Angus R said. However, if I really needed to do vertical angles to a shoreside object I would rather use a stadimeter than a sextant, although a sextant will do the job. But if I'm just using my sextant to get a terrestrial fix, I would much rather do two horizontal angles and plot them with a three-arm protractor.

By taking a sextant shot of the sun, you are finding the angle between the sun and the horizon. Thinking back to high school trigonometry courses, recall that if you know an angle, then you can calculate the distance. In Figure 2 (next page), imagine a very long pole sticking straight out of the ground to the sun.

If you know AngleFile Size: KB. A second observation will give you a second circle of position. You are at the intersection of the circles of position.

In fact, there is most often two intersections but your estimated position or a third observation will help you to choose the right one. If you don't observe a lighthouse but the angle between your horizon and a star, you are doing celestial navigation.

The sextant is equipped with an event timer switch. This button switch provides a timing pulse on the spacecraft recording system at the time of sextant angle measurements. The sextant measured angle is displayed on the "counter" below the eyepiece. The least count of the display is ".

Two miniature red lamps illuminate the counter. A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation.

The estimation of this angle, the altitude, is known as sighting or shooting the object, or taking a sight. To use a sextant to find the angle of elevation of an object, you’ll need to know your elevation above sea level.

Sight the horizon by looking through the horizon mirror, then move the sextant’s index arm until the object you’re trying to find is also visible on the horizon. Clamp the index arm in place with the flip-lock, then turn the micrometer knob to fine-tune the sextant 93%(14).This bundle includes 5 angle relationships activities!

You will save over 20% by buying this bundle rather than buying each product individually. Please view the individual product descriptions and previews to make sure these activities are appropriate for your classroom.**************************** Let your students be the teachers and do the 4/5(27).

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