Some standard content:
GB/T 17943---2000
This standard is based on the "First-class Astronomical Measurement Regulations" issued by the State Bureau of Surveying and Mapping in 1977 and the "Second, Third and Fourth-class Astronomical Measurement Regulations" (draft) issued by the State Bureau of Surveying and Mapping and the General Staff Bureau of Surveying and Mapping in May 1965, combined with the new technology of geodetic astronomical measurement and actual production conditions, and formulated based on the principle of simplicity and applicability.
This standard shall be implemented from August 1, 2000. Appendices A to D and F of this standard are all standard appendices, and Appendix E is a prompt appendix. This standard is proposed and managed by the State Bureau of Surveying and Mapping. This standard is drafted by the Surveying and Mapping Standardization Institute of the State Bureau of Surveying and Mapping. The main drafters of this standard are: Zhang Yaomin, Liu Caizhang, Meng Juan, and Fu Zongyao. 310
1 Scope
National Standard of the People's Republic of China
Specifications for the geodetic astronomyGB/T17943—2000
This standard specifies the measurement principles, measurement methods and accuracy requirements for measuring astronomical longitude, astronomical latitude and astronomical azimuth on land.
This standard is applicable to first, second, and fourth grade geodetic astronomical survey operations. For other survey operations that require the measurement of astronomical longitude, latitude and azimuth, it can be implemented as a reference.
2 Referenced Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards are subject to revision, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T17942-2000 National triangulation specification GB/T 17944-2000
Rumi gravity measurement specification
GB 12897-1991
National first and second class leveling specification
CH1001—1995 Provisions for the compilation of surveying and mapping technical summaries CH 1002 --1995
Provisions for inspection and acceptance of surveying and mapping products
CH 1003-1995
Surveying and Mapping Product Quality Assessment Standard
JJG414—-1994
Measurement and Verification Procedure for Optical Theodolite
3 Principles of Surveying
3.1 Purpose and Tasks
3.1.1 Geodetic and astronomical surveying is a geodetic method that determines the astronomical longitude, astronomical latitude and astronomical azimuth of ground stations by observing stars.
3.1.2 Geodetic and astronomical surveying is mainly used for ground reference system orientation, geoid shape determination, engineering orientation and horizontal measurement control network direction error control.
3.1.3 The main tasks of geodetic and astronomical surveying at present are: a) to determine the vertical deviation for the establishment of national and regional geoid models; b) to conduct high-precision geodetic and astronomical surveying for the establishment of ground coordinate system orientation parameters; c) to conduct astronomical surveying for the establishment of precise engineering orientation base deduction. 3.2 Coordinate and time system
3.2.1 The FK5 system is used for the observed star coordinates. 3.2.2 The JYD1968.0 system is used for the polar coordinate system. When polar coordinate correction is made, the correction number of the polar coordinates contained in the "Earth Rotation Parameters Bulletin" of my country is generally used for correction. When other polar coordinate systems are used, they should be converted to the JYD1968.0 system. 3.2.3 The time system adopts the world time UT1 system relative to the JYD1968.0 system. When the time number is corrected, the correction number contained in the "Earth Rotation Parameters Bulletin" of my country is generally used for correction. When other time systems are used, they should be converted to the UT1 system approved by the State Administration of Quality and Technical Supervision on January 3, 2000 and implemented from August 1, 2000.
GB/T 17943.-2000
3.2.4 The earth ellipsoid parameters adopt the ellipsoid parameters of the 1980 Liang'an coordinate system. 3.3 Accuracy requirements
The minimum mean error of each level of geodetic and astronomical measurement shall be implemented in accordance with Table 1: Table 1 Accuracy requirements
3.4 Point layout principles
Latitude (\)
3.4.1 The layout density of astronomical stations shall be determined according to different purposes and their accuracy requirements. Azimuth (\)
3.4.2 The layout of Laplace points in the national horizontal geodetic network and national astronomical gravity leveling shall be implemented in accordance with GB/T17942 and GB/T17944
3.4.3 Astronomical stations should be selected in places with wide views, convenient joint measurement and long-term preservation, and stable foundations. 3.4.4 The azimuth observation sight line should be far away from obstacles, waters, deserts, Gobi, swamps, forests, grasslands, cement and asphalt covered areas and other areas with large side refraction and affecting the image quality of ground targets. The distance of the second-class azimuth observation sight line from obstacles in plain areas shall not be less than: 6m for the first class and 4m for the second class in mountainous areas; 4m for the first class and 2m for the second class. The azimuth observation sight line is further away from large obstacles. In addition, the growth of plants should be considered when determining the sight line height. 3.4.5 Markers shall be buried at astronomical observation sites, and astronomical observation piers shall be built at first- and second-class astronomical observation sites. The burial of marks and the construction of astronomical piers shall be carried out in accordance with GB/T17942.
3.4.6 The distance between the latitude and longitude eccentric observation point and the center point shall not be greater than 50m, and shall not be less than one and a half times the elevation at the center point, and it shall be convenient for direct determination of the centering element. The azimuth eccentric observation point should be set on the direction line from the center point to the ground target point as far as possible, and should not be set on its extension line, and the deviation from the direction line should not be greater than 1m. 3.5 Technical requirements for surveying
3.5.1 In geodetic and astronomical surveying operations, the appropriate observation method should be selected from Table 2 based on the surveying accuracy requirements, observation conditions, geographical location, etc.
Table 2 Observation methods
Observation methods
Determination of azimuth by arbitrary hour angle method of North Star
Determination of azimuth by transit hour angle method of North and South Stars
Determination of azimuth by solar hour angle method
Determination of longitude by Zinger method
Determination of longitude by east-west star altitude method
Determination of longitude and latitude by solar altitude method
Determination of latitude by Talcott method
Determination of latitude by star altitude method
Simultaneous determination of longitude and latitude by multi-star magnitude method
Instruments for first- and second-class astronomical observations should generally be equipped with observation curtains around the station to reduce the influence of wind on the instruments. The top cover of the observation curtain should be opened at least hours before observation to make the temperature inside and outside the observation curtain uniform. 312
GB/T 17943-2000
3.5.3 Before observation, a suitable wooden platform should be built around the astronomical tower. When it is difficult to build a platform, a shallow trench can be dug around the astronomical tower to prevent the instrument from being affected by vibration when the observer walks on the ground. When the instrument is placed on a tripod for observation, the instrument tripod should be placed on three particularly stable wooden stakes.
3.5.4 For astronomical points without elevation, an empty box barometer can be used to measure the elevation of the point, and its accuracy should not be less than ±50m: 3.5.5 For geodetic astronomical observations that require recording of observation time, the time number must be recorded at the beginning and end of each time period, that is, the observation outline of "collecting time-observing-collecting time" should be adopted. When the longitude observation time period exceeds 6h, the latitude and azimuth observation time period exceeds 8h, or the observation star group exceeds three groups, at least one time number should be recorded. When it is difficult to collect time, astronomical observations are allowed within one hour before the first time number is recorded or within one hour after the last time number is recorded. The time number recording method is shown in Appendix A. 3.5.6 For astronomical observations that require orientation, the instrument should be oriented according to the method specified in Appendix B before the measurement. 3.5.7
When conducting eccentric observations, the centering element must be determined. The determination of the centering element is shown in Appendix C. 3.5.8 Azimuth - Generally, it should be observed at the center point. Eccentric observations can only be carried out when necessary. 3.5.9 For measurement operations that require indoor calibration of the meridian or measurement of astronomical azimuth, refer to Appendix E for implementation. 3.5.10 When observing azimuth, the ground sighting target should be selected when the image is clear and stable. If the ground sighting target is blurred or jumps violently, observations shall not be carried out. The ground sighting target for first and second class observations should be backlight, and the size and brightness of the backlight should be adjusted appropriately. The focal length shall not be changed during the azimuth measurement observation. 3.5.11 The azimuth observation limit error and observation conditions and the treatment method for exceeding the limit shall be implemented in accordance with Table 3. Table 3 Azimuth observation limit error and conditions
Mutual error of eyepiece micrometer readings
Mutual error of two overlapping micrometer readings
Mutual error of two ground target direction values in half a survey round
Mutual error of two star direction values in half a survey round
Mutual error of 2C of ground sun mark in survey round
Mutual error of 2C of ground ear mark and star in survey round
Absolute value of 2C
Mutual error of azimuth in each survey round
Absolute value of target altitude angle
Horizontal circle deviation
Number of survey rounds (number of stars)
Minimum number of time periods
Maximum number of survey rounds per time period
Maximum number of survey rounds at night
Mostly the smallest division of the eyepiece micrometer.
DJ07DJ07
Over-limit processing
Restart reading
Restart reading twice
Remeasure half a round
Remeasure half a round
Remeasure - a round
Remeasure one round
Remeasure one round
Remeasure the over-limit round, the number of remeasured rounds
shall not exceed one-third of the total number of rounds
Read and record the reading of the level instrument on the sighting partAdd
Incorporate the horizontal axis tilt correction
Incorporate the line error correction
GB/T 17943—2000
3.5.12 The configuration of the degree disk for each azimuth observation is calculated according to the following formula: C-A+G+M+S
and: G=180×(i-1)/m
(taken to degrees)
M=dx(i-1)
S=Lx(i-0. 5)/m
Wherein: A——approximate value of direction;
—-measurement number;
㎡-measurement number;
d-degree disk grid value;
-micrometer circumference value.
L——
(to minute)
(to second)
Camp Snow Special Electric Center
3 The discrepancy between the positive and negative astronomical azimuths shall not be greater than: -First class: ±2.5\, second class: ±4\. The discrepancy between the positive and negative astronomical azimuths shall be calculated according to the following formula 3.5.13
Aα (α2 — α2 ± 180°) ( - A)sindm Where: α12α21—~--positive and negative astronomical azimuths; t,
astronomical longitudes of the two end points;
m——the average astronomical latitude of the two end points.
4“The time periods for first and second class astronomical longitude observations shall not be less than: -First class: 3, second class: 2. When measuring human and instrument errors, -time periods should be added3.5.14
; the number of time periods for first and second class astronomical latitude observations shall not be less than first class: 2, second class: 1. When measuring longitude and latitude at the same time, the maximum number of time periods shall be followed.“-The number of observations, star pairs, or stars observed in one time period shall not exceed one-third of their average3.5.15 The number of observations, star pairs, or stars discarded in a station, time period, or a star group shall not exceed one-third of its observation number, otherwise the observation results of the station, time period, or star group will be invalid. 4 Technical requirements for human and instrument errors
4.1 Requirements for observers
Observers should be technical personnel with high professional level, skilled technology, and stable human and instrument errors, and they can only take up their posts after special technical training and approval by technical departments.
4.2 Instruments
Main instrument requirements are shown in Table 4.
Table 4 Instruments
Theodolite
Quartz clock or electronic watch
Electronic timer
Shortwave receiver
4.3 Instrument inspection
Applicable level
Technical requirements
Theodolites for the first-class should be equipped with contact micrometers or photoelectric devices. The five-point difference of the clock speed should not exceed 5×2°/ms/h (for the level). 4.3.1 The inspection requirements for theodolites shall be implemented in accordance with JJG411. For the inspection items of components not involved in the use of theodolites, no inspection is required.
4.3.2 The specification and quality inspection of the level shall be implemented in accordance with Appendix B20 of GB12897--1991. 4.3.3 The following tests should be conducted on the additional devices and quartz clock of the theodolite: a) Determination of the wire distance of the telescope eyepiece micrometer (see Appendix D. Test once before measurement); 314
GB/T17943-2000
b) Determination of the gap difference of the contact micrometer (see Appendix D. Test once at each measuring station); c) Test of the astronomical clock (see Appendix D, test once before measurement). 4.3.4 The steel tape used to measure the centering element should be sent for inspection and testing every two years. 4.3.5 The chronograph should be tested regularly during operation to ensure that the chronograph is normal and reliable. If there is any fault, it should be sent to the special maintenance department for repair.
4.4 Determination of human instrument error
4.4.1 Observers who measure first- and second-class astronomical points should measure the human instrument error at the basic astronomical points with similar latitudes in the measuring area before and after each operation. The interval between two human instrument error measurements should not exceed one year. New observers should measure the instrumental error twice during the initial operation as appropriate. 4.4.2 The instrumental error and the longitude of the astronomical point should be measured by the same method and the same instrument. If the instrument is changed during the operation, the instrumental error must be measured again.
4.4.3 The change of the instrumental error between two consecutive measurements of first- and second-class astronomical measurements shall not exceed 0.04s and 0.06s respectively. 4.4.4 When measuring the instrumental error, any set of results whose error meets the tolerance limit shall not be discarded, and only one result shall be measured. 4.5 Instrument maintenance and use
4.5.1 The measuring instrument is a necessary tool for astronomical measurement. The surveyor must maintain and use it carefully to keep it in good condition at all times to ensure the smooth progress of astronomical measurement. The instrument needs to be maintained regularly, repaired in time, and files should be established in time to record the maintenance, inspection, verification and use of the instrument.
4.5.2 Theodolite
4.5.2.1 Precautions for packing the instrument: a) Clean all parts of the instrument; when the instrument is damp, it should be dried before packing; b) The horizontal axis journal and bracket bearings should be coated with high-grade watch oil and wrapped with soft paper; c) Micrometers, levels, etc. should also be wrapped with soft paper and tied with wire; d) The fixing screws between the instrument and the bottom of the box should be tightened, and other screws should be appropriately loosened; c) There should be a certain amount of air in the air chamber of the level to prevent the level tube from breaking; f) When transporting the instrument, the brake ring on the upper end of the base sleeve should be rotated to stop the ball bearing from working; g) When moving the instrument, do not hold the telescope, the degree plate and the bottom shell of the instrument base. 4.5.2.2 Matters needing attention in the transportation of instruments: a) When the instrument is consigned, it must be escorted by a special person. The top surface of the instrument box or box should be affixed with labels such as "precision instrument", "handle with care", "moisture-proof", "sunscreen", etc., and the side should be marked with upward arrows and other marks that cannot be inverted; b) When loading and unloading, there must be a special person on site to take care of it. When lifting the instrument, it should be carried flat and placed gently to avoid severe vibration and impact. Under no circumstances can the instrument be inverted or placed on its side; c) When transporting the instrument by car, the instrument box should be installed in the front of the car body, and the bottom of the box should be padded with a soft cushion: d) When raising or lowering the instrument to a high level, the firmness of the lifting tools such as ropes and pulleys and their ties must be strictly checked. During the whole process of raising and lowering the instrument, a dedicated person must be responsible for directing, with clear division of labor, coordinated actions, and organized and step-by-step operations. 4.5.2.3 Precautions for using the instrument: a) When placing the instrument, the horizontal axis journal and bracket bearing must be wiped clean. The journal and bearing can be gently wiped with silk cloth. It is forbidden to hold the journal polished part with hands. To prevent dust from falling on the journal, the journal should be covered with a protective cover; b) When adjusting the bubble length of the level, remember not to shake violently to avoid damaging the air chamber partition; when the hanging (cross) level is not in use, it should be placed in the instrument box:
) When using the fixing screw, it is best to rotate it until it just touches, and do not tighten it too much to avoid damage to the instrument. 4.5.2.4 After the daily observation, the following work should be done: a) Use a brush to wipe off the dust on the instrument. If there is dew on the lens of the objective lens and eyepiece, it can be gently wiped with lens paper, and it is not allowed to be wiped with alcohol or gasoline. Do not touch the lens surface with your fingers; b) Turn all micro-screws to the middle of the screw. Wipe the shaft neck with silk cloth, and apply surface oil when the air is humid; 31
GB/T 17943--2000
c) After the observation is completed every day, the instruments placed in the observation screen should be covered with instrument covers and must be supervised. If observing at the high standard 1, the instruments should be packed, covered with rainproof cloth and tied to the standard frame after each major work. 4.5.3 Astronomical clock
a) When receiving the astronomical clock, you must carefully check it and learn about its usage history in detail according to the archives of the clock as a reference during work. The clock must be maintained by the observer himself during use: b) The battery in the electronic clock should be removed when the station is moved. The clock shall not be checked in and must be carried by a dedicated person. Special attention should be paid to prevent vibration and rapid rotation; the clock should be handled with care when moving it, and attention should be paid to keeping the clock face level. 4.5.4 Electronic timer
The timer should be placed in a ventilated and dry place to prevent moisture; dust or dirt should be prevented from falling into the timer at any time, and the timer should be placed in a protective box at ordinary times; it should be prevented from vibration during use or transportation; the power should be turned off after work every night. 4.5.5 Receiver
The receiver and battery should be placed in a dry and ventilated place to prevent moisture and sunlight exposure. The battery should be removed when the station is moved. The external antenna should be grounded on rainy days to prevent lightning strikes. 5 Observation method
5.1 Determination of azimuth by the arbitrary hour angle method of the North Star5.1.1 The first outline - the observation procedure for the round is as follows:a) Observe the ground! mark;
b) Observe the North Star in the clockwise direction;
"c) Observe the North Star in the clockwise direction for the second time; d) Observe the ground target in the clockwise direction for the second time; e) Rotate the telescope vertically and repeat the above operation in the counterclockwise direction.5.1.2 The first outline - the observation procedure for the round is as follows;a) Observe the ground mark;
b) Observe the North Star in the clockwise direction;
c) Rotate the telescope vertically and observe the North Star in the clockwise direction for the second time; d) Rotate the telescope vertically and repeat the above operation in the counterclockwise direction. e) Repeat the above operation in the counterclockwise direction. 5.1.3-Generally, the first outline should be used. For the DKM3-A theodolite, the second outline should be used. 5.1.4 When using the DJ07 instrument to observe ground targets, use the moving wire of the telescope eyepiece micrometer to aim at the target for times, and read the micrometer drum reading each time, and then read the horizontal disk reading. When using other instruments to observe ground targets, read the horizontal disk reading after aiming once. 5.1.5 Using the DJ07 instrument When observing the North Star, first read the reading of the level; if you use the first outline, if you observe on a standard mark above 4m, you should immediately move the level 180°; use the moving wire to aim at the target three times and record the instantaneous clock face and micrometer drum reading each time; then read the reading of the level, and then read the horizontal disk reading; if you use the first outline, if you observe on a standard mark not exceeding 4m or a pier mark, you should move the level 180°. When using other instruments to observe the North Star, aim at the target three times and record the instantaneous clock face and micrometer drum reading each time; then read the reading of the level, and then read the horizontal disk reading. When the clock face of the North Star records the instant, then read the readings at both ends of the bubble of the level in the sighting part. 5.1.6 When using the DJ07 instrument to make a round of observation, the zero point change of the level shall not exceed 2.25 grids for the T4 instrument and 1.5 grids for the DKM3-A instrument. When observing at a height of more than 12m, the change can be relaxed to 3.0 grids for the T4 instrument and 2.0 grids for the DKM3-A instrument.
5.1.7-The azimuth observation value of the round is calculated as follows: α = Da -- (ML + Mr)/2(- (Mt - Mr)q/p + 0. 16\pcosg)where: 9-(cscZk-cscZL)/2
p=cScZ1+cscZR
**+(3 )
GB/T 17943--2000
Z-arccos(singsind+cosdcos dcost)M=D--arcsin(sintcosd/sinz)+Vctgzi±(m-1o)μcscz)t- 15(S-α)
）…Items that can be ignored for the third and fourth grades;
Wu Zhong:←
D------Observed value of the half-measurement degree disk position of the North Star;V——-Observed value of the vertical axis tilt;
\Micrometer scale value;
m--Micrometer reading;
DA\—--~Ground target--Observed value of the degree disk position of the survey;…·Left position of the North Star disk;
R-~Right position of the North Star disk;
SSidereal time when observing the North Star in half the survey;α…The apparent right equator of the North Star in half the survey;
----The apparent declination of the North Star in half the survey;
-Astronomical latitude of the station (the same as the symbol explanation below). 5.2 Determination of azimuth by the transit hour angle method of north and south stars 5.2.1 To observe stars, select a pair of north and south stars near the transit, and the pair of stars should meet the following conditions: a) The zenith distance should be greater than 15° and less than 75°
b) cosa/cosz should generally be less than 1.5, and the maximum should not be greater than 2; c) The absolute value of the difference between coso/sin of a pair of stars is less than .5; d) The sum of the difference between cos6/casz of all pairs of stars is not greater than 1; e) The difference between the right angles of two adjacent stars is greater than 12min; f) The angular distance of the star from the meridian should be less than 2.5°; g) The magnitude should be no weaker than 5.
5.2.2--Inter-meteorological observation procedures are as follows;
a) Observe ground targets;
b) Observe the south (or north) star in the clockwise direction; c) Observe the ground target for the second time in the clockwise direction; d) Vertically rotate the telescope and repeat the above operations in the counterclockwise direction. 5.2.3 When observing stars, the theodolite should be configured in advance according to the observation star catalog. After the star enters the field of view, read the readings at both ends of the alidade level. Use the crosshairs to aim at the star three times. Each time you aim, read the surface time and the horizontal disk reading at the same time, and then read the alidade reading. 5.2.4 The half-survey azimuth observation value is calculated according to the following formula: α Da - D + arcsin(sintcoso/sinz) - Vctgz Where: Zarccos(sinpsino+cosdcosocost)t-15(S--α)
Wherein, D is the observed value of the half-survey disk position of the north and south stars; DA is the observed value of the half-survey disk position on the ground; S is the sidereal time of the half-survey north and south stars;
α is the apparent right ascension of the half-survey north and south stars; — is the apparent declination of the half-survey north and south stars.
5.3 Determination of azimuth by solar hour angle method
5.3.］Choose the sun within 2 hours after sunrise and before sunset to determine the azimuth. 5.3.2 The observation procedure for the survey is as follows:
(4)
GB/T 17943-2000
a) Aim at the ground target and read the horizontal dial; b) Aim at the sun in the clockwise direction so that the image of the sun is located in the center of the right half of the vertical wire, and use the vertical wire to cut the left edge of the sun, and do this twice in a row. Each time you read the surface, you should read the horizontal dial reading; c) Vertically rotate the telescope and aim at the sun in the counterclockwise direction so that the image of the sun is located in the center of the left half of the vertical wire, and use the vertical wire to cut the right edge of the sun, and do this twice in a row. Each time you read the surface, you should read the horizontal dial reading; d) Aim at the ground target and read the horizontal dial reading. 5.3.3 The azimuth of a survey is calculated as follows: tgocose)
α Da -- D + arctglsint/(singcost -F: t== 15(S-α)
Wherein: D^”—the observed value of the ground target disk position of the survey; D)---——-the observed value of the sun disk position of the survey; the apparent right ascension of the sun of a survey, the calculation method is shown in Appendix F; --——-the apparent declination of the sun of a survey, the calculation method is shown in Appendix F; S-——the local sidereal time of the survey.
5.4 Zinger's legal longitude
5.4.1 The east-west star pair located in the same contour circle should be selected for star observation, and the star correspondence should meet the following conditions: a) The celestial distance of the star pair is between 20° and 55°, which can be relaxed to 60% in special areas; b) The azimuth of the east and west stars of a star pair is 1/4 of the azimuth of the east and west stars. Respectively in the range of 245°~295° and 65°~115°; (5)
c) The time interval between two adjacent star pairs shall be no less than 7 minutes based on the central time of the star pair, and can be shortened to 6 minutes by using an electromagnetic level; d) The magnitude is generally not weaker than 5.
5.4.2 Observation limits and conditions shall be implemented in accordance with Table 5. Zinger method observation longitude limits and conditions
Point observation star pairs three
Personal instrument error observation star pairs three
The mutual longitude difference of each star pair.3
Vertical axis tilt change ≤, grid
Bubble length change ≤, grid
5.4.3 The observation procedure for a pair of stars is as follows:
Methods for handling excess
Discard excess star pairs
Correct instruments
Re-observe
a) Place the theodolite according to the average zenith distance of the observed star pair and the azimuth of the east (or west) star, and accurately center the bubble of the horizontal axis level;
b) Set up the timekeeping equipment and prepare to record the time; c) After the star enters the field of view, read the horizontal axis water thruster reading as required for first and second order astronomical observations. When the star enters the observation area, use the moving wire to track the bisecting star image and record the time for first and second order astronomical observations, and read the time when the star passes the horizontal wire near the vertical wire for third and fourth order astronomical observations; d) Rotate the sighting part and observe the second star according to the above method. 5.4.4
The observation procedure for a group of stars should be carried out alternately in the order of east star, west star, west star, east star or in reverse order. - The astronomical longitude observation value of the star is calculated according to the following formula 5.4.5
=+nmt+++S
Where: α=（α+αw)/2
m=arctg(tgotgectgt)
n=arcsin(tgatgecasm/sint)
(8w0=)/2
8=(0+8w)/2
GB/T 17943-2000
t=15[(ae-aw)/2+(Xw-Xr)/2]
ou=士（iwi)t\/（60cosdsinAw）（When the small scale is near the objective lens end, it is +10, otherwise it is -）d, = -- MxsinZ/(2cospsintwcosow)o. 0. 021'cosZ
Z-arccos(singsindw+cosdcoswcostw)tw- 15(S.+^-αw--2min)
In the formula: αE, αw—apparent right ascension of east and west stars; E.ow—--apparent declination of east and west stars;
XE, Xw---surface time of east and west stars;
—latitude of measuring station;
\——approximate longitude of measuring station;
\—grid value of level;
-the sum of the left and right bubble readings of the level of east and west stars; tr.iw-
Mx-contact micrometer gap motion;
S.——Greenwich sidereal time at surface time (Xe + Xw)/2; Correction items that may not be calculated for third and fourth order astronomical measurements. 5.5 Determination of longitude by east-west star altitude method
5.5.1 When using this method for fourth-magnitude astronomical observations, the minimum number of east-west star pairs observed at each station is: 2 pairs of stars for DJ1 and 3 pairs of stars for DJ2. The mutual difference in longitude of the star pairs should be less than 1.0s, and the star pairs should meet the following conditions: a) the zenith distance of the star pairs should be less than 75° and as equal as possible; b) the azimuths of the east and west stars should be within the range of 240°~300° and 60°~120° respectively; c) the magnitude should be no weaker than the fifth magnitude.
5.5.2 The procedure for star observation is as follows:
a) Install the theodolite according to the zenith distance and azimuth for observing the east (or west) star, and read and record the air temperature and air pressure; b) Aim at the east (or west) star three times, and read the surface time and vertical disk reading each time; c) Vertically rotate the telescope and operate as in b);
d) Read and record the air temperature and air pressure;
e) Observe the west (or east) star and repeat the above operation. 5.5.3 The astronomical longitude observation value of a star is calculated according to the following formula: aa+tS.
t = arccos[(cosZ - sindsind)/(cosgcoso)J/15], where: ZZ'+R
where: α is the apparent right ascension of the star;
is the apparent declination of the star
Z is the average observed value of the zenith distance of the star;
R is the correction for atmospheric aberration;
S is the Greenwich sidereal time of the average observation time of the star; and the latitude of the observation station.
5.6 Determination of longitude or latitude by solar altitude method
5.6.1 Determine longitude near the oval circle where the solar zenith distance is not greater than 75°; determine latitude within 1.5 hours on both sides of the meridian (7)
5.6.2 The minimum number of measurements used for fourth-order astronomical observations using this method is: DJ1 is 4, DJ2 is 6. When determining longitude, the morning and afternoon periods should be as symmetrical as possible.
5.6.3---At the beginning of the measurement, the air temperature, humidity and air pressure should be recorded. 5.6.4- The observation procedure for the measurement is as follows:
GB/T 17943—-2000
a) At the left (or right) position of the disk, make the image of the sun in the center of the lower half of the field of view, use the horizontal wire to cut and push the upper edge of the sun, and cut it twice in succession. Each time the surface is read, it is recorded together with the vertical disk reading; b) Vertically rotate the telescope so that the sun is in the center of the upper half of the field of view, use the horizontal wire to cut the lower edge of the sun, and cut it twice in succession. Each time the surface is read, it is recorded together with the vertical disk reading.
For observation with the Garrovos prism, the intersection of the four sun images in the field of view should be made to coincide with the crosshairs and the prism position should be fixed, and the observation reading should be carried out according to the above steps.
-The longitude and latitude of the survey are calculated according to the following formula:
x-a+tS,
and: t=arccos[(cosz-singsino)/(cosdcoso)/15]t=[5(S-α)
m-arctg(tgd/cost)
n --arccos(cosZsinm/sing)
Z=Z'+R-Pasinz'
In the formula: α—-the apparent right ascension of the sun; the apparent declination of the sun;
2.---the observed value of the zenith distance;
P. —the parallax of the solar horizon, which can be taken as 8.8\; the Greenwich sidereal time of the S survey;
-the local sidereal time of the survey.
5.7 Determination of latitude by Talgett method
5.7.1 Using this method, each station shall observe at least 10 pairs of north and south star pairs at the time of transit with DJ05 instrument: 10 pairs for the first order and 6 pairs for the second order, and the star pairs shall meet the following conditions:
a) -- the average zenith distance of the star pairs is less than 40°; b) -- the difference in zenith distance between the south and north stars of a star pair shall not exceed 16'; c) -- the difference in right ascension of a star pair shall be between 3 and 15 minutes; d) the algebraic sum of the differences in zenith distance between the north and south stars of all star pairs shall not exceed ±20°. 5.7.2 The procedure for observing a pair of stars is as follows:
a) Adjust the theodolite according to the average zenith distance of the star pair and the azimuth of the first star, and adjust the horizontal axis level so that the bubble is centered; b) After the star enters the field of view, read the readings at both ends of the horizontal axis level, make the moving wire roughly bisect the star image, read the number of revolutions of the eyepiece micrometer, and when the star passes through five vertical fixed wires in turn, make the moving wire accurately bisect the star image along the direction of precession, and read the micrometer reading at the same time, and finally read the level reading again;
c) Rotate the instrument sighting part 180°, and observe the second star in the same way as the first star. 5.7.3 Matters to be noted during observation:
a) The observation procedure during the observation period should be carried out alternately with the level at the east, west, west, east or the reverse order of the telescope;
b) When the five-time micrometer reading of a star is found to increase or decrease, the eyepiece micrometer moving wire should be recalibrated to make it horizontal and the instrument should be re-oriented;
c) The inclination change of the telescope should not be too large. When (iw-i) is greater than 6, the instrument should be recalibrated. The bubble length change during the observation of a star should not exceed 0.4 grids;
GB/T 17943-2000
d) It is not allowed to measure the zenith star and use three consecutive stars to form two observation star pairs. The astronomical latitude observation value of a pair of stars is calculated as follows: 5.7.4
Φ=+AZ+(iw-i)t/4+K
and: 8=(8s+8.)/2
[180°--8N
(when the North Star is not at the lower zenith)
(when the North Star is at the lower zenith)
+(1+0. 0175sec2Z)(Mw-M)r/2
(1+-0.0175sec2Z)(Mw-Mr)r/2
K-- Fstgos +Fstgon
F=Ef2/(20p\)
Z-(8-8.)/2
Wherein: Os.ON
Mw, Me
-the apparent declination of the north and south stars;
the sum of the left and right bubble readings of the level at the east and west sides; the micrometer reading at the east and west sides;
the circumference of the eyepiece micrometer;
the grid value of the level;
f—the wire distance of the first moving wire.
5.8 Determination of latitude by the stellar altitude method
T4 instrument
DKM3 instrument
(10)
5.8.1 For star observation, use a north-south pair of stars or the North Star located near the zenith. For third-order observations, use a north-south pair of stars or the North Star. For areas where the latitude of the station is less than 15°, the North Star shall not be used. The number of observations shall not be less than 8 for third-order and 6 for fourth-order. The north-south pair of stars shall meet the following conditions:
a) the zenith distance shall be less than 70°;
b) the difference in zenith distance of the star pair shall be less than 20°;
c) the difference in right ascension of the star pair shall be less than 1h;
d) the angular distance from the meridian shall be greater than 3°.
5.8.2- The air temperature and pressure shall be recorded at the beginning and end of the observation. 5.8.3--The observation procedure is as follows;
a) Place the instrument according to the zenith distance and azimuth of the observed star; b) Aim at the star three times, and read the surface time and the vertical disk reading each time; c) Rotate the scope vertically and select the mirror, and operate as in b).
5.8.4 The half-round latitude observation value is calculated according to the following formula: #=m+n
H: m=arctg(tgo/cost)
n2earccos（cosZsinm/sind）(the southern star is ten, the northern star is one)Z=Z'→Rbzxz.net
t=15(S-α)
Wherein: α-the apparent right ascension of the star in the half-round;
-----the apparent declination of the star in the half-round;
2the observed value of the zenith distance in the half-round;
Rthe correction number for the atmospheric error,
Sthe sidereal time at the mean observation time of the half-round. 5.9 Simultaneous determination of longitude and latitude by the multi-star equi-elevation method
5.9.1 For observing stars, stars evenly distributed on the 60° or 45° equi-elevation circles are selected, and the angular distances of the stars from the meridian circle and the ovoid circle are not 321 respectively.
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