1What are the four basic geodetic measurement quantities?
Time, length, angle and mass
2What is the mathematical model or device established to define position?
Reference system
3What is the physical realization of a reference system through control points?
Reference frame
4Which organization in Sevres, France maintains international reference standards?
Bureau International des Poids et Mesures (BIPM)
5Which SI unit is defined as 9,192,631,770 periods of radiation of the caesium-133 atom?
Second
6Which SI unit is defined as the distance light travels in a vacuum in 1/299,792,458 of a second?
Meter
7How was the meter first defined in 1791?
As one ten-millionth of the distance from the Equator to the North Pole along a great circle
8What alloy was the 1889 prototype meter bar made of?
Platinum with 10% iridium
9How was the kilogram originally defined in 1795?
As the mass of 1 liter of water
10Which constant was used to redefine the kilogram in 2019?
Planck constant
11Which angle unit is defined by an arc equal in length to the circle's radius?
Radian
12How many radians are in a full rotation?
2 pi radians
13Which angle format is preferred for computer processing and numerical algorithms?
Decimal degrees (DD)
14Which angle format is used in legacy data and field documentation?
Degrees-minutes-seconds (DMS)
15Which constant is used in orbital mechanics, gravity strength calculations and geoid modeling?
Gravitational constant (G)
16How is the distance from a satellite to a receiver computed from signal travel time?
Distance equals the speed of light multiplied by the elapsed signal travel time
17Which time system is based on the actual rotation of the Earth but is irregular?
Universal Time (UT1)
18Which time system is based on atomic clocks and is extremely stable?
International Atomic Time (TAI)
19Which time system uses TAI seconds plus leap seconds to stay within 0.9 seconds of UT1?
Coordinated Universal Time (UTC)
20What is the origin epoch of TAI?
January 1, 1958, 0 h
21Which sidereal time refers to the observer's local meridian and the true vernal equinox?
Local Apparent Sidereal Time (LAST)
22Which sidereal time refers to the mean vernal equinox?
Mean sidereal time
23Which time is related to a fictitious sun moving at a uniform rate?
Mean solar time (civil time)
24Which time is the actual sun time?
Apparent solar time
25What is the difference between apparent solar time and mean solar time?
Equation of time
26What is the obliquity of the ecliptic with respect to the equatorial plane?
23.5 degrees
27Which space-fixed equatorial system uses right ascension and declination?
Celestial Reference System (CRS)
28Which geocentric system rotates with the Earth?
Terrestrial Reference System (ECEF)
29Which bodies define the conventional celestial and terrestrial reference systems?
International Astronomical Union (IAU) and International Union of Geodesy and Geophysics (IUGG)
30Which service is responsible for realizing and maintaining reference frames?
International Earth Rotation and Reference Systems Service (IERS)
31What is the origin of the International Celestial Reference System?
The barycenter of the solar system (SSB)
32Which epoch defines the mean equator and equinox of the celestial reference frame?
J2000.0
33What is the intersection of the ecliptic and equator that the sun passes around March 21?
First point of Aries (vernal equinox)
34Which star catalog of 1963 contained 1,535 stars?
FK4
35Which catalog extension in 1991 added 3,117 new stars?
FK5 extension
36Which catalog (2000) is correlated with the ICRF through the Hipparcos satellite?
FK6
37What is the origin of the International Terrestrial Reference System?
The Earth's center of mass, including oceans and atmosphere
38What are the orientation references of the ITRS?
IERS Reference Pole (IRP) and IERS Reference Meridian (IRM)
39What is the approximate average position of the Earth's axis of rotation?
Conventional International Origin (CIO)
40Which frame is the realization of the ITRS using stations with precise coordinates and velocities?
International Terrestrial Reference Frame (ITRF)
41Which geocentric system is specified in IUGG Resolution No. 7?
Geodetic Reference System of 1980 (GRS80)
42Which reference system, based on geocentric GRS80, is used by GPS?
World Geodetic System of 1984 (WGS84)
43Which satellite system was used to realize WGS84 through Doppler observations?
TRANSIT
44What is the latest WGS84 realization in the notes?
G1762
45What are the reference points or surfaces to which surveying and mapping results are referred?
Geodetic datums
46What are the four kinds of geodetic datum?
Coordinate datums, vertical datums, sounding datums and gravity datums
47What is the standard reference system in the Philippines by EO No. 45?
Philippine Reference System of 1992 (PRS92)
48Which geoid model is used for elevation in the Philippines?
Philippine Geoid Model 2014 (PGM2014)
49Which triangulation station is the origin of the Luzon 1911 datum?
Balanacan, Marinduque
50Which spheroid does PRS92 use?
Clarke 1866
51Which network realizes a horizontal datum?
Horizontal control network
52Which network realizes a vertical datum, mainly through leveling?
Vertical control (leveling) network
53Which surface is commonly used in practice as the vertical datum, averaged from tide gauge records?
Mean sea level (MSL)
54How long is the astronomical tide cycle?
About 18.61 years
55Which space geodetic techniques are used to realize a 3D datum?
GNSS, VLBI, SLR and DORIS
56Which comprehensive 3D datum is formed after the combined adjustment of space geodetic networks?
ITRF
57What is the world's largest satellite geodetic control network?
International GNSS Service (IGS) network
58What is the sum of gravitational force and centrifugal force?
Gravity
59What is the unit of gravity acceleration in geodesy?
Gal (cm/s squared)
60What is the line of action of gravity called?
Plumb line
61What do you call a surface of constant geopotential?
Level surface (equipotential surface)
62Which equipotential surface approximately coincides with mean sea level?
Geoid
63Which height is measured along the plumb line from the geoid to a point?
Orthometric height (H)
64Which height is measured along the ellipsoid normal and can be obtained directly from GNSS?
Ellipsoidal height (h), also called geodetic height
65What is the distance along the ellipsoidal normal between the ellipsoid and the geoid?
Geoid height (N), also called geoid undulation or geoid separation
66What is the relationship between ellipsoidal, orthometric and geoid heights?
Ellipsoidal height equals orthometric height plus geoid height (h = H + N)
67Which height is measured from a point to the quasi-geoid?
Normal height
68Which height is the geopotential number divided by a constant reference gravity?
Dynamic height
69Which latitude of normal gravity is often used for dynamic heights?
45 degrees
70Which quantity, with units of work, is the potential difference between the geoid and a point?
Geopotential number
71What is the closing error of leveling loops caused by non-parallel level surfaces?
Theoretical misclosure