“Suryavarman was an energetic ruler, anxious to make a difference. He may have been  responsible for the founding of Preah Khan of Kompong Svay, an important settlement about sixty miles (100 km) to the east; …

The king’s territory came to incorporate all that had belonged to his predecessors, with the probable addition of the Lopburi area in present-day Thailand, on the middle reaches of the Chao Phraya River. Part of northeastern Thailand, around Phimai, had a significant Khmer population and was incorporated within the Angkorian territory; “

                                                       Phimai : Naga « Bridge »

The first half of the eleventh century, during the  long reign of Suryavarman I, saw indeed the empire become more vast, populous and prosperous.

 The king established four linga to delimit his empire:

The first Linga was consecrated at Vat Baset, 70 km to the south-west of Angkor.

The three other Linga were established during 1018 CE at :

- Preah Vihear, on a promontory of the Dangrek Range, 140 km to the north-east of Angkor

- Phnom Chissor, a sacred hill located 270 km to the south-east.

- Isanatirthi, somewhere in the east.

We have discovered that the location of most sites mentioned above were related to the planetary diagrams established by Suryavarman I. One of these is a giant diagram, obeying the rules of the "Midnight" system, which determines the azimuth (ie the ecliptic longitude) of 15/04/967 Saturn . This diagram seems to have been designed to include the whole territory controled by Suryavarman I.

                                      Lop Buri : Phra Prang Sam Yot

 Saturn can be located to within 0.1° of its correct azimuth (longitude) if :

- we choose as observer the particular location determined previously on  Phnom Bok .

- we locate Lop Buri on the deferent after putting the centre of the Manda epicycle on the parallel of the Phnom Rung temple.

We discovered that the loxodromes drawn from Vat Ek (another temple built by Suryavarman I in the Vat Baset area) to the four temples of Lop Buri run through the « phnom » (hill) where the Prasat Khao Noi was erected during the 7th century. We suggest the temples of Lop Buri were located on the intersection of the deferent with the latter loxodromes.   

“Angkor: history, religion and culture” by Ian Mabbett

From “Angkor : celestial temples of the Khmer empire”

Author : Jon Ortner

Publisher : Abbeville Press Publishers, 2002

As noted earlier, the parallel of the Manda epicycle’s centre runs through the Phnom Rung temple. As it was our starting point, we chose the parallel of the eastern doorway (P). The coordinates were determined by Asger Mollerup.

It is worth noting the Prang Noi (red colour) was built during the 11th century, probably during the reign of Suryavarman I.

Background from  « Le cambodge II, les provinces siamoises »

 Etienne Aymonier


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Suryavarman I was also the founder of the big city of Preah Khan of Kompong Svay located at 95 km  to the east of Angkor Wat. It is probable Preah Khan KS was the king’s  provisional capital.  The unusual orientation of the complex (28° north of east), which has never been explained so far, is probably related to the Saturn’s diagram. The loxodrome running from the central temple along the axis of the city crosses indeed  the centre of the Sighra epicycle of Saturn. The latter axis is perpendicular to the loxodrome running from the central temple to the centre of the Rahal Baray of Koh Ker.

298.484 km

46.490 km

The location and the dimensions of the city of Preah Khan determine two ratios related to the Sighra epicycle of Saturn:

1 ) 4500 / 500 = 9 = Sighra ratio of Saturn.

With 4500 m = width of  median dyke of Preah Khan and 500 m = width of Rahal Baray of Koh Ker

2) 46.490 / 46.617 = 0.997

With 46. 490 km = distance from centre of Preah Khan to centre of Rahal Baray and 46.617 km = radius of Sighra epicycle of Saturn.

The Ta Muen Thom temple was built at the intersection of the southern limit of Dangrek Range with a loxodrome (BS) which is tangent to the Sighra epicycles of Saturn and Jupiter.

Asger Mollerup has shown previously that the Ta Muen Thom temple was located on a loxodrome which crosses three other temples located in the Dangrek Range :

- The small temples of Ta Bai Baek and Ta Khwai

- The big complex of Preah Vihear

Theoretically, this loxodrome crosses the Preah Vihear’s meridian between the fourth Gopura and the reservoir but it is possible the intended « target » was the third Gopura. We’ll see indeed  that a loxodrome (28°) running through the latter Gopura and Jupiter crosses the site of Neak Buos.

We have discovered those temples are separated by integers of kam.

The location of Saturn is indicated by the intersection of two loxodromes:

1) A huge loxodrome (551.5 km) running through the centre of the Phimai temple and through the natural Linga (Lingaparvata) standing on the summit of the Phou Kao Mountain (L) which overhangs the site of Vat Phou.

2) A loxodrome running along the great axis of the Vat Phou’s barays (B). Its azimuth is 5.6° south of east.

It is worth noting that the azimuth of Saturn , as observed from Phnom Bok, is -19° (from due east).

 The true longitude (from Sun) on 15/04/967 CE at 23:58:12 was -19.1°.

Table of 15/04 Saturn

Although it is not related to the diagram of Saturn, it should be noted that the solsticial line of Vat Phou is “broken” by the presence of the Phou Kao Mountain (N-W).  This explains why two barays were constructed side by side. The diagonal of northern baray indicates the azimuth of sunrise at winter solstice over the eastern slope of  Mekong River. The diagonal of southern baray indicates the azimuth of  sunset at summer solstice over the crest of Phou Kao Mountain.

The equant (E) of Saturn was located on the intersection of the Mars’ deferent with the loxodrome running from the centre of Angkor Wat (W) to the centre (B) of  the Banteay Chmar’s temple. We have seen that the loxodrome WB is the continuation of the diagonal of Angkor Wat’s moat

The apsidal line (OE) of Saturn runs through the intersection of the Great North Channel with the axis of the  “grid-like” enclosures discovered recently by the “Greater Angkor Project”. This axis is perpendicular to the apsidal line (see image at right).

Last modification : 25 / 02 / 2009

Copyright 2008  Jean-Pierre Lacroix & Robert Bywater  



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Corresponding JAVA applet

Corresponding JAVA applet

Corresponding JAVA applet

True ecliptic longitude from Sun on April 15 (Julian) 967  CE  = -19.10 ° at true midnight ie at 23:58:12  local civil time  (Meridian of Phnom Bok)

Observer : Phnom  Bok  ( 13.46708° N ; 103.98201° E )

Ecliptic longitude provided by  the Khmer diagram =  -19.00°

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Photo (GNU)

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License".

The natural Linga (Lingaparvata) standing on the summit of Phou Kao Mountain (L)

            Foreground : the causeway and the barays of  Vat Phou                 Background : the Mekong River

             By courtesy of Frans & Claire van der Lee     http://www.everywheremag.com/places/4807/20633

The continuation of the loxodrome BW to the south-east crosses Banteay Prei Nokor. It runs at 320 m from the towers of Preah Theat Tauch. By taking into account the distance between the latter monument and the central sanctuary of Banteay Prei Nokor, this distance of 320 m corresponds to a relative error of 0.08%.

110 km

271 km

It is worth noting that, on such distances, the trajectories of  loxodromes and orthodromes (great circles) are obviously different. A  great circle crossing the loxodrome in Banteay Chmar and Banteay Prei Nokor runs through the north-east part of Angkor Wat (pink line). We have concluded the Khmer conceived their alignments on the basis of loxodrome-like lines.

Corresponding Java applet

Corresponding Java applet

Corresponding Java applet

It should be noted  that the equant of Saturn has been very precisely located on the relevant loxodrome.

Corresponding Java applet

Table of 15/04 Saturn

The loxodrome from the equant to the centre of the Beng Mealea’s temple is tangent to the circle “H” (radius = radius of  deferent of Chau Srei Vibol Sun) which determined the location of several large hydraulic works of Greater Angkor.

The loxodrome from the eccentre to the centre of the Beng Mealea’s temple is tangent to the deferent of the Chau Srei Vibol Sun.