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PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING

For instance, the 1874 Samarkand Baseline was 1,605

sazhens or 3,424 meters.

The early baselines were measured with wooden rods,

however no information is available on what kind of wood

was used. In the United States during the same time

period, Magnolia wood was used for leveling rods because

it was believed to have the lowest coefficient of expansion

(from variations in temperature AND humidity) of all wood

species. Note that the Americans (Coast & Geodetic Survey)

still boiled their wood in paraffin just to make sure. (There’s

an interesting geodetic story on boiled wood I’ll have to tell

someday about Palmdale, CA.)

In order to make a topographic survey at 1:4,000 scale

of the City of Tashkent, a traverse net was established

in 1885 by Pomerantsev. The revised coordinates of the

Tashkent Observatory SW pillar used for the city survey

are: Φ

o

= 41

o

19’ 30.42” North, Λ

o

= 38

o

58’ 00.99” East of

Pulkovo, (or 69

o

17’ 39.54˝ East of Greenwich). The vertical

datum of Tashkent was determined by means of barometric

observations at the Meteorological Station of the Military

Topographic Department located in the residence of Colonel

Zhemchuznikov. The transfer of this vertical datum point

value to other horizontal datum origins with trigonometric

leveling techniques produced geodetic problems of mind-

boggling proportions!

The physical connection between the Tashkent Datum

of 1875 and the Indian Datum of 1916 in the Pamir region

was made by an exploratory triangulation party of the

International Geodetic Union. The expedition was led

by Professor Finsterwalder in the early part of the 20th

century. The 3-parameter shift from Tashkent to Indian is:

dX = -223.632 meters, dY = –281.310 meters, dZ = +304.059

meters. (The fit of two points agree to better than a meter.)

The Tashkent Datum of 1875 origin (at the Meridian Circle)

is: Φ

o

= 41

o

19’ 30.42” North, Λ

o

= 69

o

17’ 39.54˝ East of

Greenwich. The defining azimuth at the point of origin to the

North Stone Pillar (probably the mire) of the Observatory is:

α

o

= 00

o

52’ 08.25”, and the ellipsoid of reference is the Bessel

1841. The Indian Datum of 1916 origin at Kalianpur Hill

Station is: Φ

o

= 24

o

07’ 11.26” North, Λ

o

= 77

o

39’ 17.57˝ East

of Greenwich. The defining azimuth at the point of origin

to station Surantal is: α

o

= 190

o

27’ 05.10”. The ellipsoid of

reference is the Everest 1830, where a = 6,377,276.345

meters, and

1

/

= 300.8017.

The Kazalinsk Datum of 1891 origin at the finial Cross on the

Town Church is: Φ

o

= 45

o

45’ 46.450” North, Λ

o

= 62

o

06’ 01.66˝

East of Greenwich). The defining azimuth at the point of

origin to station Sulutan is: α

o

= 20

o

34’ 07.34”. The ellipsoid

of reference again is Bessel 1841. The 3-parameter shift from

Kazalinsk 1891 to Tashkent 1895 is: dX = +530 meters, dY =

– 160 meters, dZ = – 104 meters. (The fit of four points agrees

to about 20 meters in each geocentric component.)

TheOshDatumof 1901 origin is definedat Point II,Northwest

Base as: Φ

o

= 40

o

37’ 16.670” North, Λ

o

= 72

o

56’ 11.175” East

of Greenwich). The defining azimuth at the point of origin to

Point I, Southeast Base is: α

o

= 152

o

54’ 01.86”. The ellipsoid

of reference again is Bessel 1841. The 3- parameter shift from

Osh 1901 to Tashkent 1895 is: dX = – 146.633 meters, dY

= +472.553 meters, dZ = +508.352 meters. (The fit of seven

points agrees to 4.19 meters in each geocentric component.)

In order to better model the shift and reduce the fit errors,

I decided to try a Bursa-Wolfe 7-parameter shift. The results

yielded an average fit error in Latitude of 0.48 meters, the

error in Longitude was 1.09 meters, and the error in Height

was 0.09 meters. The parameters that give this fit are: dX =

+26.82 meters, dY = –183.11 meters, dZ = – 186.25 meters,

scale = 39.25 x 106, R

z

= – 07.79”, R

y

= +2.48”, R

x

= +21.49”.

As a computational “check point,” Point II, Northwest Base

on the Tashkent Datum of 1875 has the geodetic coordinates:

φ = 40

o

36’ 55.740” N, λ = 72

o

56’ 22.880” E.

Uzbekistan has only one Grid system, and that is based

on the Russia Belts, a series of Gauss-Kruger Transverse

Mercator projections that use the exact same rules and

parameters as UTM with two exceptions. The Krassovsky

1940 ellipsoid is used everywhere in the former USSR where

a = 6,378,245.0 meters, and 1/ f = 298.3. The scale factor at

origin is 1.0 rather than the 0.9996 scale factor used for UTM.

The single unifying datum used in all of the former USSR

is the “Coordinate System 1942,” a consistent marvel that is

the largest classical datum in the world! This datum is often

improperly referred to after its origin, Pulkovo Observatory,

where: Φ

o

= 59

o

46’ 18.55” North, Λ

o

= 30

o

19’ 42.09” East

of Greenwich. The defining azimuth at the point of origin

to Signal A is: α

o

= 317

o

02’ 50.62”. The latest 3-parameter

shift values published by the National Imagery and Mapping

Agency for the vicinity listed as Kazakhstan is from System

42 to WGS84, such that: dX = +15 meters, dY = – 130 meters,

dZ = – 84. The stated accuracy is 25 meters in each component,

which is the maximum error useable for 1:50,000 mapping,

and that was based on only two points.

U

pdate

A recent publication by Mirmakhmudov, E., Prenov Sh.,

Magdiev, Kh., and Fazzilova, D. on (the)

United Nations/Russian Federation Workshop on the

Applications of Global Navigation Satellite Systems,

Krasnoyarsk, 18-22.05.2015 states that Fazilova found in

2002 the transformation parameters

CS-42

WGS84

are:

D

X = +23 m,

D

Y = – 125 m,

D

Z = – 87 m. However, no

accuracy estimate is offered.

The contents of this column reflect the views of the author, who is

responsible for the facts and accuracy of the data presented herein. The

contents do not necessarily reflect the official views or policies of the

American Society for Photogrammetry and Remote Sensing and/or the

Louisiana State University Center for GeoInformatics (C

4

G).

This column was previously published in

.

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