Land Surveyor Forum

Replies

• GEO Ambassador

  Jaybird February 29, 2016 at 4:58pm

  The angular measure of an object is usually expressed in degrees, arcminutes or arcseconds. Just as an hour is divided into 60 minutes and a minute into 60 seconds, a degree is divided into 60 arcminutes and an arcminute is divided into 60 arcseconds.
  • 

    Billy Brooks > Jaybird February 29, 2016 at 5:46pm

    Thanks Justin,  Very good clip.

    Billy
• 

  Billy Brooks February 27, 2016 at 12:03am

  Hello Raymond, this is a good  math ? with out looking it up,  It deals with the speed of light and a arc second of time. How long does it take sun light to reach earth . This  formula  will also tell you how long it takes your GPS to receive  to and from a satellite  and did you know time is included  on this  data so how far are those satellite. they are far enough that time is corrected from there time to yours. What is this correction ?

  Billy
• 

  Billy Brooks February 26, 2016 at 10:21pm

  Hello Raymond, If you are asking what is a arc second,  This is used in many different ways. A arc second is  found in many different  subjects. They may be defined as how many arc seconds are in one degree ,There are 3600 of them. I have this stored in my calculators data list which I am talking about now. on another forum . Always watch for rounding of this .One  radian  is equal 206264.806247 arc seconds or 57.2957795131 degrees You see this a lot in curve equations for arc definition curves.A degree of curve and radius equ. You will see the constant of 5729.58 ,  D=5729.58 divided by the radius,  D being the DEGREE of the curve. The same as D=18000.00 divided (pie x R),  A second of arc is equal  to one sixtieth of a arc minute. This is some times used in fire arms  on how the bullet  spins from the twist in the barrel plus on scope adjustment factors .It is also used in Cartography . Cadastral surveying , which you are familiar with,  Global positioning and Astronomy . used in Positioning the are given in D M S of ARC's for latitude, They are north and south of the equator and for longitude are east and west of the Prime Meridian  They are also express in fractions.  Degree ,   at one thousandth  of a degree have about one  fourth of precision of D M S  so 1 /3600 of a degree = to about 120 meters or about 400 ft.

   To scale lat and long on Quadrangle you  need to know how to scale one arc second on it to determine you position  Every second in you instrument  is a arc second to it. This has many definition applied to each categories .  In Astronomy  a parsec gets it's name from this a parallax second for those arc second ,  What is a arc second in a horiz curve it depends on the curve data of each curve degree  this is a Sexagesimal system where a Degree is 1/60 of a circle , a arc minitue is 1/60 of a Degree  , a arc second is 1/60 of a arc minute  also Radians are also divided  similar  and other circle system also like Gradians.  At sea level one arc minute  along the equator  is about one nautical mile. that's about 1.852 KM or1.151 MI. a second of arc is about 1/60 of that amount about 30 meters or about 100 ft. this changes along the meridian arc because of the shape of the earth.

   So I hope this helps you.

  Billy