CIPA 2003 XIX th International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
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chronological range that depends mainly on the magnitude of 
the monument. 
3. THE CHURCH OF THE GREAT METEORO 
MONASTERY 
3. 1 Historical Information 
The "Meteora monastic community" is situated in the area of 
Kalabaka in central Greece. It is the second biggest group of 
Byzantine monuments in Greece. Today only six monasteries 
are open, from the twenty that had been erected there in a period 
of three centuries (14 th to 17 th ) (Sofianos, 1990). The Great 
Meteoro Monastery is the biggest one and is founded at the top 
of a rock, 588 m above mean sea level. The main church of the 
monastery is dedicated to the "Transfiguration of our Lord" 
which celebrates on August 6 th . 
According to historical sources (Sofianos, 1990) the first small 
building, which was located at the place of the church’s holy 
altar of today, was erected in 1360 by Saint Athanasius the 
Meteorist, who was the first inhabitant of this rock. After his 
death in 1388, the monk Ioasaf enlarged the building and 
erected the big church that exists today. This church is the 
biggest of the Meteora monastic community and has all the 
main characteristics of the late Byzantine architecture. The 
building is 25.8 m in length and 10 m in width. The frescos on 
the walls are dating from the 15 lh and 16 th century. 
At the South-East side of the church a little chapel was founded, 
dedicated to Saint John the Baptist and celebrating on January 
7 th each year. According to (Theocharidis, P, 1979), this 
building was constructed simultaneously with the main church 
and, initially, it had some other use. Its length is 7.25m and 
width 5m. It was converted to a chapel after the completion of 
the big church. 
3.2 Surveying the monument 
A polygonometric network was established inside and outside 
the monument, in order to survey it for a scale of 1:50. This 
network consists of 12 points (figure 1) which are placed at 
appropriate positions in order to measure all the detail - points 
of the monument. 
Figure 1. The polygonometric network. 
The elements of the network were measured using the method 
of the "three tripods", in order to eliminate the errors of centring 
and levelling of the instruments. The measurements of the detail 
points of the church were made using an integrated Total 
Station that measures without retroreflector and has a laser 
pointer, in order to mark each point accurately. The X, Y 
coordinates of each point of the monument were determined 
with an accuracy of ± 3 mm in the GGRS 87 (Greek Geodetic 
Reference System 87). 
The orthometric heights H of the points were also determined, 
with a little lower accuracy (about ± 1 cm). The digital drawing 
of the plan has all the details of the building. This plan is used 
for the determination of the main axis of the church, as well as 
for the extraction of any other geometric information of the 
monument. The final plan of the monument is presented in 
figure 2. 
Figure 2. The plan of the two Churches 
3.3 Determination of astronomical azimuth 
The investigation of the orientation of a monument requires the 
determination of the astronomical azimuth of a characteristic 
direction of the monument. This direction may be the main axis 
of the monument or another special direction, e.g. the direction 
between the middle of the Holy altar and the middle of an 
altar’s window or a specially placed line. For the determination 
of the astronomical azimuth of these lines, the plan of the 
monument needs to be astronomically oriented. This is achieved 
by determining the astronomical azimuth of one side of the 
polygonometric network, through astrogeodetic observations to 
the Pole Star (Polaris, aUMi). In this case, the observations 
consisted of 40 - 50 sightings of Polaris within 15 minutes, 
which enabled the determination of the azimuth with an 
accuracy of 0.5arcsec. This accuracy is much higher than the 
one achieved by classical methods, with poles and compass. 
The adjustment of the polygonometric network was done 
holding the azimuth of this direction constant to the value of the 
determined astronomical azimuth. Therefore, the plan of the 
monument was oriented with regard to the astronomical north. 
The astronomical observations were done using a new system 
which was especially developed for the purpose and consisting 
of a high accuracy digital total station, Leica TDM 5000, 
connected to a Trimble 4000DL GPS receiver, providing 
accurate UTC time. This system permits the determination of 
the astronomical azimuth of a direction in short fieldwork time 
and with high accuracy (Lambrou, 2003). 
In order to study the orientation of the church of "the 
Transfiguration of our Lord" two characteristic lines were 
examined. The first was the main axis of the monument, joining 
the middle of the holy altar with the middle of the main entrance 
(at a distance of 22m). The astronomical azimuth of this axis 
was found to be 119°34' ± O'.6. 
The second line is inscribed on a flat marble stone, different 
from all other flagstones (Picture 1), embedded on the floor in 
the middle of the church.