CIPA 2003 XIX 11 ' International Symposium, 30 September - 04 October, 2003, Antalya, Turkey 
Picture 1. The flat marble stone. 
This stone is placed under the dome, on the main axis of the 
church (figure 2). The inscribed line has a length of 70 cm and 
seems to indicate something, so its orientation was examined. 
The derived astronomical azimuth of this line is 70°35' ± 20'. 
The main axis of the chapel of Saint John the Baptist, defined 
by the middle of the Altar and the middle of the central window 
where the light enters, was also examined. This axis has the 
same orientation as the main axis of the church of “the 
Transfiguration of our Lord”. 
3.4 Determination of the perceptible horizon 
The perceptible horizon of a monument is of high importance 
because it permits, or restricts, the view of the Sun and the 
entrance of the sunlight in the holy altar. It is defined by natural 
terrain, mountains, rocks, and sea or by buildings that already 
existed at the time of construction of the monument. 
AZIMUTH(degrees) 
Figure 3. The diagram of the perceptible horizon towards the 
East 
Measurements of azimuth and altitude of characteristic points 
permit the creation of the diagram of the perceptible horizon. 
The measurements were done from a point of the network in 
front of the Altar. It is indispensable that all these measurements 
refer to the middle of the Altar, so that the drawing of the 
perceptible horizon corresponds to the view of the horizon from 
the Altar. 
The eastern horizon of the church is at a mean distance of 
1000 m and the determination of its diagram was done with an 
accuracy of 2 arcminutes, due to pointing uncertainties. The 
adjustment was easily calculated, since the coordinates of the 
points of the horizon, the network points and the altar were all 
known from the geodetic network and the digital plan of the 
church. The diagram of the view of the perceptible horizon to 
the east of the church is presented in figure 3. The x-axis shows 
the azimuth and the y-axis the altitude (in degrees and grads) of 
the horizon. 
Picture 2 is the photographic documentation of the horizon. 
Picture 2. Photographic panorama of the eastern part of the 
horizon 
3.5 Determination of the path of the sun 
The determination of the apparent diurnal path of the Sun, as 
seen from this monument and for a given date, was done using 
the SkyMap Pro 8 software (digital almanac & virtual 
planetarium, Marriot (2001)). Necessary input data are: 
- The astronomical coordinates <E>, A of the church (determined 
with satisfactory accuracy from the GPS measurements of the 
geodetic network). 
- The date (any date between 4713 BC and 8000 AD) and the 
time interval between successive points of the position of the 
Sun in the sky. 
A local ephemeris of the Sun was produced, listing altitude and 
azimuth of the Sun, accurate to about 2 arcseconds (Meeus, 
1991), as a function of local time. 
The church of the "Transfiguration of our Lord" celebrates on 
August 6 th and the chapel of Saint John celebrates on January 
7 th each year. As already mentioned, the first building was 
erected in 1360 and contained the holy altar of today and the 
chapel. The extension of the building was done in 1388. 
Therefore, the calculation of the path of the Sun was made for 
these particular dates and years. 
Figure 4 combines all available data, showing the path of the 
Sun and the azimuths of the examined lines superimposed on 
the diagram of the perceptible horizon. The rectangular insets in 
the figure show, in magnification, the intersection of the three 
characteristic lines and the resulting accuracy of the orientation. 
AZIMUTH (deg rees) 
Figure 4. The diagram of the perceptible horizon towards the 
East and the apparent paths of the Sun 
The combined error of the orientation of the main axis, 
represented by the dark area in the middle of the inset, is about 
V.2 and the combined error of the orientation of the line 
inscribed in the flat marble stone is about 20', due to its short 
length. The magnitude of the combined errors depends on the 
errors of the azimuth of the lines, of the path of the Sun and of 
the line of the perceptible horizon. 
4. DISCUSSION 
As it is apparent from the diagram in figure 4