1018
November 2014
PHOTOGRAMMETRIC ENGINEERING & REMOTE SENSING
33° 19′ 10.87″ N ± 0.20″, Λ
o
= 44° 43′ 25.54″ E ± 0.69″, α
o
=
10° 55′ 51.8 ± 1.16″ to North End Base, Clarke 1880 (ellipsoid
where:
a
= 6,378,249.2 m and
1
/
f
= 293.4660208. –
Ed
.)
“Another datum of importance was Fao (code FAO) at Fao
Roof where Φ
o
= 29° 58′ 23″ N and Λ
o
= 48° 28′ 55″ E, Everest
(ellipsoid where:
a
= 6,377,301.243 m,
1
/
f
= 300.8017 –
Ed
.). Also
given is Fao Flagstaff which is probably derived from Fao Roof.
Here Φ
o
= 29° 58′ 23.82″ N, Λ
o
= 48° 28′ 56.88″ E. Reference is
Triangulation in Arabia, Iraq & Persia; International (ellipsoid
where:
a
= 6,378, 388 m,
1
/
f
= 297 –
Ed.
) NH-39-M Fao, Survey
of India 1946. The description is “Mark engraved on floor of
roof of chief clerk’s quarters midway between chimney and
pillar and 18 feet 4 inches from edge of roof to north-west.
Astronomical observations for time, latitude and azimuth were
also taken here.”
“Another is Iraqi Date Society at Φ
o
= 30° 31′ 51.1″ N, Λ
o
=
47° 50′ 03.7″ E. This was taken from British Admiralty (BA)
chart 3846 (21 Oct 1926). Probably used on DA 3842 - 3845.
Without access to these charts, I can only surmise that this is
the approaches to Basra up the Shatt al Arab.
“The last I have for Iraq is M79 (code MSN) where Φ
o
= 35°
33′ 15.19 N, Λ
o
= 44° 18′ 21.77″ E. (Probably established by
W. E. Browne in 1927-31). Looking at an atlas, my guess is
that it had to do with the oil fields around Kirkuk.
(See further
discussion below – Ed.)
“Final Datum 58 (1958) (code FIN) was derived from
Nahrwan by the Iranian Oil Exploration and Producing
Companies (I.O.E.P.C.) for southwest Iran east to Bushehr.
When the surveys tied into the Bushehr datum area, the
whole of the I.O.E.P.C. area east to the Strait of Hormuz was
adjusted to Final Datum 58 and European Datum (1950). I
felt the connection to Nahrwan was poor but it did provide
a unified system for the I.O.E.P.C. I don’t think that Final
Datum 58 was ever applied to Iraq”
(John W. Hager, personal
communication, 05 March 2010)
.
The origin point for Final Datum 1958 is Maniyur where:
Φ
o
= 31° 23′ 59.19 N, Λ
o
= 48° 32′ 31.38″ E, and the network
was included in the Nahrwan 1967 Adjustment. With respect
to the
unverified
transformation parameters
from
Nahrwan
Datum of 1967 (Iraq Datum)
to
WGS84 Datum are: ΔX =
+65 m, ΔY = – 334 m, ΔZ = +267 m
(from unofficial source,
2005)
. A variation on Nahrwan is Karbala Datum which is the
realization in the city of Bagdad.
“The triangulation conducted by W.E. Browne of the Iraq
Petroleum Company in the years 1927-31 consists chiefly of a
main arc running fromMosul to Jabal Hamrin South and three
independent local systems in the immediate vicinity. Browne’s
triangulation, for the most part, has very good configuration,
which is composed mainly of braced quadrilaterals and
polygons. He has utilized a good number of short bases
(about 700 meters long) and rather frequent astronomical
azimuths. Some of his bases, however, were measured with an
unstandardized steel tape. Browne’s main arc from Mosul to
Jabal Hamrin South was originally surveyed in seven sections,
and finally consolidated into one continuous arc. However, this
consolidation was not rigorously done. The seven sections were
put together by average geographic differences at stations
common to two sections. The origin of this arc (Mosul to Jabal
Hamarin South) is station M79, whose geographics are above.
The task of rigorously adjusting Browne’s survey of Iraq datum
and eventually to new Egyptian datum is seriously hindered
by the lack of information at this headquarters
(Army Map
Service – Ed.)
dealing with Browne’s survey”
(Tentative
Procedure for the Adjustment of W.E. Browne’s Triangulation
in Iraq to New Egyptian Datum, Edmund A. Early, Army Map
Service Geodetic Memorandum, 7 July 1948)
.
“The Clarke 1880 new Egyptian datum geographics of the
origin of the Nahrwan system, (South End Base) are: φ
o
=
33° 19′ 17.4838″ N, λ
o
= 44° 43′ 21.1053″ E. In the adjustment
of Iraq to Syria at the border, a number of difficulties were
encountered. The border overlap does not consist of a continuous
group of common points, but of 2 separate groups of positions,
which on the Syrian side at least are not connected by a direct
arc of triangulation. In the northern group of common points,
use was made, on the Syrian side of first order positions only,
found in
fascicule V
of the latest French lists
(Coordonnées
Rectangulaires Lambert et Altitudes de Points Géodésiques du
Levant).
Iraq values of secondary qualitywere taken fromBritish
trig lists for Iraq
(Triangulation in Iraq, Syria, and Turkey, No.
37)
. The following 9 points were used in the northern connection
least squares solution: Tell Hanta, Tell Safra, Tell Hamidi, Tell
Brak, Tell Aarbib, Kapes Darh, Melzbate, Tell Ahmar, and
Tell Hamdoun. In the southern connection between Iraq and
Syria, 4 positions were found to be common to both Syrian and
British lists. These positions are Chaafu, Kamiyse, Abou Kemal
Minaret, and Tell Hedkouk”
(Conversion of Clarke 1880 Iraq
and Caucasus Zone Nahrwan datum Lambert grid coordinates
in Iraq and Iran to Clarke 1880 New Egyptian datum UTM grid
coordinates in Zones 37, 38, and 39, Patricia K. Hayden, Army
Map Service Geodetic Memorandum, 6 August 1948)
.
“The primary triangulation of Iraq wa executed between the
years 1930-35. It should be onsidered as having a secondary
order of precision. The primary triangulation is divided into
two series: the North Series and the South Series
(as detailed
in the above paragraph – Ed.)
. Both series are based on the
Nahrwan Base near Bagdad.
(By examination of the area just
east of Bagdad with Google Earth ™, one can see the NW to SE
irrigation canal segment that the baseline paralleled – Ed.)
. The
North Series closes on a measured base at Kirkuk and the South
Series on that at Batha. Discrepancies between the measured
and triangulated lengths of the Kirkuk and Batha bases are
said to have been adjusted these discrepancies are given as
follows: Kirkuk – 1/20,000, Batha – 1/15,000. The initial values
of the triangulation for latitude and longitude were taken at the
south end of the Nahrwan Base. Astronomic observations were
then made at Kirkuk and Batha Bases for latitude, longitude,
and azimuth
(LaPlace stations – Ed.)
. Average triangle closure
of the North Series is 1.48″ with a maximum of 5.31″ and the
closure of the South Series is 1.61″with a maximum of 5.39″.
“The Iraq Zone Grid B is one of the two overlapping grid
systems decided upon at the Cairo Conference in 1940 between
