new on the date of the katholikon of daphni monastery....

ON THE DATE OF THE KATHOLIKON OF DAPHNIMONASTERY. A NEW APPROACH BASED ON ITS

ORIENTATION

GEORGE PANTAZIS National Technical University of Athens School of Rural and Surveying Engineering

Department of TopographyAthens, Greece

email: [email protected]

MARIA PAPATHANASSIOU National and Kapodistrian University of Athens Faculty of Mathematics

Department of Algebra and GeometryAthens, Greece

email: [email protected]

Received: 21 - 11 - 2004Accepted: 26 - 4 - 2005 *to whom all correspondence should be addressed

ABSTRACTThe exact date of the foundation of the Katholikon of Daphni monastery is unknown. Based on

the stylistic data of its mosaic decoration the archaeologists suggest that its mosaics date to the endof the eleventh century, which is either a terminus ante quem for the construction of the Katholikonor the mosaic decoration is contemporary to this construction.

In this paper we attempt to determine the foundation date of the Katholikon of Daphni, on thebase of its astronomical orientation and by applying the general astrogeodetic method elaborated byone of us (G. Pantazis) in this case. As results from our investigation, the Katholikon, which issacred to the Virgin Mary, was very likely founded on the day of the celebration of the Dormitionof the Virgin in 1153, i.e. in August 15, 1153 (±8years). If it is so, both the church and its famousmosaic decoration date circa half a century later than it is generally accepted by the archaeologists.

KEYWORDS: Geometric documentation, astronomical observations, azimuth, Perceptible horizon,diurnal path of the Sun.

63

Mediterranean Archaeology and Archaeometry, Vol. 5, No 1, pp. 63-72Copyright © 2005 MAA

Printed in Greece. All rights reserved

THE DAPHNI MONASTICCOMPLEX HISTORICAL DATA

The famous Daphni monastic complex(Fig. 1) is situated in the middle distance(c. 10km) between Athens and Eleusis, andon the left side of the ancient ≤sacred road≤to Eleusis. It is built on the place of anancient sanctuary dedicated to Apollo, lateralso to Athena, Demeter and Kore,according to Pausanias (Description ofGreece, Attica, ch.37, 6-7). In Pausanias’time (c. 150) there was a surrounding wallenclosing at least one temple and one gallery(or another building with columns), asthere are many drums of columns andcapitals doric and ionic. The ancientsanctuary survived at least during two andhalf centuries after Pausanias, i.e. until theedicts against pagan religion issued byemperor Theodosius I and his successors.

Some prechristian remains have beenused in the buildings of the monasticcomplex. On the other hand, rectangularstone blocks of the ancient surrounding wallhave been used in the Byzantine fortresswall.

The best saved side of the latter is itslower part along the National Road, which isthe same northern side of the ancient wall,

while its upper parts and the towers, builtwith common stones and in a different styleof stonework, are part of restoration worksand completion of the surrounding wall inByzantine times. According to thearchaeological evidence, the Byzantinesurrounding wall was a square with a side ofone hundred meters. Its main entrance wasat the West Side and not at the east one as itis today.

Archaeological evidence shows furtherthat in the seventh century at the center ofthis enclosure an Early Christian ‘Basilica’was built possibly as the ‘Katholikon’, i.e.the main church, of the early Byzantinemonastery (Kambouroglou 1920). ThisBasilica is not saved but in the eleventhcentury a new church was built almost atthe same place. This latter is the finestByzantine monastic church of the district ofAthens.

The domical method of constructiongoverns the plan of Byzantine churches,which are all distinguished by a centralsquare nave, covered with a dome onpendentives. Short arms on each side form aGreek cross, and the filling in of the anglesbrings the plan nearly to a square. In earlyexamples the dome is supported by semi-domes. In later examples, the churches aremuch smaller and the dome is raised upon ahigh drum with, occasionally, additionalsmaller domes rising at a lower level. At thewest end is usually a narthex, or entranceporch, which forms an entrance vestibule,frequently crowned with domes. At the eastend, opposite the entrance, is the apse forthe altar in the sanctuary, which is screenedoff by the characteristic ‘iconostas’ (screenof icons, i.e. pictures), with its three doors,and there were also lateral ritual chapels(Banister 1961).

The Katholikon of Daphni is a slenderconstruction bathed in light because of itslarge dome on a squat barrel, supported by

64 65G. PPANTAZIS - M.PAPATHANASSIOU ON THE DATE OF THE KATHOLIKON OF DAPHNI MONASTERY

squinches and eight pillars (i.e. a regularoctagonal plan). This type of dome, whichallowed space that might be used for alarger chamber – the diameter of domes onpendentives being generally smaller- wasmuch admired in Greece in the eleventhcentury (Grabar 1966).

The Katholikon of Daphni has one out ofthe three important mosaic decorations inGreece, the other two being the church ofHosios (the Blessed) Lucas in Phokis andthat of the New Monastery in the island ofChios. Although we know nothing abouteither date or their origin, according to A.Grabar the theoretical place occupied byDaphni in the history of Byzantine paintingcan be found thanks to stylistic similaritiesbetween various details. Namely, in Daphniwe discover the future style of theComnenian period in the second stage of itsformation. So it is reasonable to date themosaics of Daphni to the end of the eleventhcentury, as suggested by G. Millet (Grabar1966, 127).

On the northern side of the Katholikonwas a long building, the Refectory of themonastery, almost always the next mostsplendid building in a monastery after theKatholikon. Here the monks eat togetherand this meal taken in common and servedimmediately after the main religiousservice, is regarded as its continuation.

Earthquakes in 1886, 1889 and 1894produced great damages in the narthex ofthe Katholikon, as whole parts of itcollapsed. The works of restoration underthe supervision of the French architectTroump included the reconstruction of thenarthex, of the north west chapel and of thewalls of the upper floor, as well as that of thedome according to the initial plan. The lastearthquake of September 1999 producedmore serious damages and until now isgoing on works for the restoration of thebuilding and especially for the conservationof its famous mosaics.

METHODOLOGYIn order to determine the date of the

foundation of the Katholikon, we shouldfirstly calculate its exact orientation by thefollowing steps:ñ Geometric documentation of the

Katholikon and digital drawing of itsplan.

ñ Astronomical observations for thedetermination of the astronomicalazimuth of any direction.

ñ Geometric determination of the mainaxis of the monument and itsastronomical azimuth.

ñ Geometric determination of the profileof the perceptible horizon, as seen froma specific position inside the monument.

ñ Reconstruction of the apparent diurnalpath of the Sun as seen from themonument, in specific dates.

In the following paragraphs we explaineach one of the above mentioned steps.

GEOMETRIC DOCUMENTATION First of all by using the GPS system the

geographic coordinates (Ê= latitude,Ï=longitude) of the place of the monument(Ê = 38Æ 00’ 46”N, Ï = 23Æ 38’ 10”E)were measured. Both are necessary for thecalculation of the astronomical azimuth andthe reconstruction of the apparent diurnalpath of the Sun as seen at the place.

Further a polygonometric networkconsisting of 31 points had been establishedinside and outside the monument (Figure2) (Project ‘Development of modernTopographic and digital Photogrammetricmethods for the geometric documentationand the total architectural digital drawing ofByzantine monuments, Application at theDaphni Holy Monastery’, NTUA 1999).

Its ‘elements’ (namely the distancesbetween selected points and the anglesformed by these line segments) weremeasured by using the total station TC

Fig. 1: The Daphni monastic complex

1600, the accuracy of which in measuringangles is ±3” and in measuring distances is± 3mm ± 3ppm.

All the detail points of the building werecarefully measured by using a reflectorlesstotal station with a laser pointer, in order tomark the position of each point with greatprecision. The accuracy of thedetermination of the coordinates X, Y ofeach point of the monument is ± 3mm sothat we can draw the monument’s digitalplan in a scale 1:50. All characteristicgeometric elements of the Katholikon ofDaphni monastic complex are displayed inthe following digital plan (Fig. 3).

DETERMINATION OF THEASTRONOMICAL AZIMUTH

The astronomical azimuth of the side ofthe polygonometric network, which isdefined by the points S1 and S3, has beendetermined by means of astrogeodeticobservations of the Pole Star (Polaris,aUMi), using the hour angle method.

These observations have been done witha system of a high precision digital totalstation, Leica TDM 5000 connected to aTrimble 4000DL GPS receiver, providingaccurate UTC time, placed at the point S1 infront of the central apse of the Katholikon.

This system, with the appropriate software,allows the determination of theastronomical azimuth of a direction in shortfieldwork time and with high accuracy(Lambrou 2003).

Three sets of measurements were carriedout. The table 1 gives the calculated valuesof the astronomical azimuth of each set andthe corresponding uncertainties.

The mean value of the astronomicalazimuth is determined by using weights andassuming that the standard deviation of theunit weight is ÛÔ = ±0.3”.

To the final determined uncertaintymust also be added:1. The influence of the difference ‰Ê

between the astronomical and thegeodetic latitude used for thedetermination of the astronomicalazimuth. Taking into account that thedifference ‰Ê at the place of themonument is about ±10”, this increasesthe uncertainty by an amount of ±0”.1.

2. The influence of the difference ‰Ïbetween the astronomical and thegeodetic longitude used for thedetermination of the astronomicalazimuth. Taking into account that thedifference ‰Ï at the place of themonument is about ±20”, this increasesthe uncertainty by an amount of±0.”2.10-3 (Lambrou 2003).The final value of the astronomical

azimuth of the direction S1-S3 and itsuncertainty is:

AS1–S3 = 310Æ 7’ 16”.9 ± 0”.2


DETERMINATION OF THE MAINAXIS OF THE MONUMENT.

The Katholikon of the Daphni complexis a symmetric building in respect to itsmain longitudinal axis. The basic points ofthis axis are determined by the digital planof the monument, after its documentation.These points are the following (Fig. 4):ñ Points 1 and 2 define the middle of the

west entrance.ñ Points 3,4,5,6 and 7 define the middle of

the distances between five pairs ofcolumns.

ñ Point 8 defines the middle of the westside of the altar. At this point the prieststands during the Holly Service.

ñ Point 9 defines the middle of the altar.ñ Finally, point 10 defines the middle of

the narrow window at the central apse.

180 180

240 240

140

220

140

220

200

220

160

180

200

S2

S1

S25

S3

S4

S26

S5

S6

S7

S8

S9

S10 S17

S24

S12 S13 S22

S18 S19

S20

S14

S15 S21

S31

S30

S16

S28 S11

S27

S23

S29

D

S

A

N

Fig. 2: The polygonometric network

Fig. 3:The plan of the Katholikon of Daphni monastic complex

Table 1: The value of the astronomical azimuth.

Fig. 4: The points of the main longitudinal axis ofthe church.


The coordinates of the above points inthe arbitrary reference system are (table 2):

The final longitudinal axis of themonument is the best fitting line to thoseten points according to the formula Y = · . X + b + u

The parameters ·, b, u are calculated bymeans of the least square method and theastronomical azimuth of this line isdetermined with the correspondingaccuracy:

A = 94Æ 6’ 44” 0’.6The astronomical azimuth of the

calculated longitudinal axis of themonument will be used for its orientation.

DETERMINATION OF THEPROFILE OF THE PERCEPTIBLEHORIZON.

The perceptible or conventional horizonextending in front of a monument plays a

very important role in the investigation ofthe meaning of the monument’s orientation.This is due to the fact that the apparentpositions of the celestial bodies at the timeof their rising or setting as seen from themonument depend on the profile of theperceptible horizon in respect to themonument.

The profile of the perceptible horizon(skyline) at a specific position on the earthis defined as the projection of the outline ofeither hills, mountains or buildings situatedat the direction of view of an observerstanding at this point against the celestialsphere and celestial bodies (Sun, stars). Inthe case of a monument the direction of viewcoincides with that of its characteristic axis(Pantazis 2002).

In order to determine the profile of aperceptible horizon, it needs first tocalculate the coordinates of the specificposition – point, to find a reference directionand then measure the horizontal andvertical angles having this point as vertex.

The perceptible horizon of theKatholikon of Daphni Monastery is the wallbuilt on the east of the church. The studyand the analysis of historical sources andother related documents lead to theconclusion that the east side of the enclosuresaved until now was the same as that of itsnorth side (Bouras 1998). Consequentlyboth had the same height, namely that ofthe northern wall, ca. 5.00m.

The results of the measurements areillustrated in a diagram (Fig. 6) where the x– axis shows the azimuth (Az) and the y –axis shows the altitude (˘) of each point ofthe profile. The dashed line shows theoriginal profile of the east wall of theenclosure, as seen from the middle of thealtar.

The photographic documentation of thehorizon profile is illustrated in Fig. 5.

The total error in the determination ofthe profile of the perceptible horizon is Ûhor

= ±1’.2

DETERMINATION OF THE PATHOF THE SUN

In order to determine the apparentdiurnal path of a celestial body, as seen fromthe monument’s place, in a given date, weused the Sky map Pro8 software - a digitalalmanac and virtual planetarium (Marriot2001). Our data were the following:ñ The celestial body (the Sun) whose path

must be calculated.

ñ The astronomical coordinates º, § of themonument’s place.

ñ The date (any date between 4713 B.C.and 8000 A.D.).The apparent diurnal path of the Sun, is

calculated for August 15 – celebration day ofthe ‘Dormition of Virgin Mary’ - during fourhundred years, namely from 900 to 1300A.D., and is illustrated in a diagram wherethe x-axis shows the azimuth (Az) and they-axis the altitude (˘).

THE DATE OF THE KATHOLIKONOF DAPHNI MONASTERY

Thus the series of successive diagramsdrawn for the 15 August shows that thediurnal path of the Sun for the year 1153A.D. passes through the point at whichintersect the direction of monument’s mainlongitudinal axis defining its astronomicalazimuth and the profile of the percrptiblehorizon (Fig. 7). Moreover, as shown in thisdiagram there is no other day or year inwhich the Sun’s path passes through this

Table 2: The coordinates of the points of the mainlongitudinal axis.

Fig. 5: The photographic panorama of the eastern part of the horizon.

Fig. 6: The profile of the east wall.


point of intersection. Consequently, itbecomes obvious that the Sun’s path for the15th August 1153 A.D. is unique, namely theonly one which passes through this point.

ACCURACY OF THE DATEThe final accuracy of the determination

of the foundation date of the church can becalculated if they are known: ñ The total error of the methodology.ñ The annual change of the diurnal path of

the Sun for a specific date (d sun)According to the formula:Date uncertainty = ± Û total / dSun

ñ The error of the methodology dependson:

ñ The error of the determination of theastronomical azimuth of the mainlongitudinal axis, which is ±0’.6.

ñ The error of the determination of theprofile of the perceptible horizon, whichis ±1’.2.The error of the determination of the

diurnal path of the Sun, which is ±2”.

The striped area ABCDA in the figure 8corresponds to the total error of themethodology, which is Ûtotal =±73’.

The annual change of the apparentdiurnal path of the Sun for August 15th

from the monument’s place is dSun= 10”Consequently the date uncertainty is:

practically ±8 years

CONCLUSIONSAn accurate determination of the

orientation of a monument can be made bymeans of modern digital total stations inwhich a combination of geodetic andastronomical methods and procedure areused.

It is possible to determine approximatelythe foundation year of the monument (date)as well as to identify the saint to whom itwas sacred.

In the case of the Katholikon of Dapnhihaving as data:m The digital plan of the monument;m The main longitudinal axis of the

monument (determined by a geometricmethod) and the value of its astronomicalazimuth.

m The profile of the perceptible horizon;m The geographic coordinates (latitude

and longitude) of the place of themonument.

m The diurnal path of the Sun drawn forthe place of the monument in a specialdate; we find that the accurate value ofits orientation is 94Æ 6’ 44” with an

accuracy of ±0.6’; consequently it facesSouth – East. Further we arrive at theconclusion that the Katholikon ofDaphni is oriented to the Sun and itdates in 1153 A.D. ±8years, whichmeans that it has been built sometimebetween the years 1145 A.D. and 1161A.D. Moreover, as in 15 August the diurnal

path of the Sun, the azimuth of the mainlongitudinal axis of the monument and theprofile of the perceptible horizon meet atthe same point, it is confirmed that theKatholikon of Daphni Monastery is sacredto the Dormition of Virgin Mary.

Fig. 7: The diagram of the perceptible horizon towards East, the apparent path of the Sun and the mainlongitudinal axis.

Fig. 8: The total error of the methodology for the orientation of theKatholikon

72 G. PPANTAZIS - M.PAPATHANASSIOU

REFERENCES

Athanasopoulos, D. (2003) The orientation of the Katholikon of Daphni Monastic complex.Unpublished diploma dissertation (in Greek), NTUA, School of Rural and SurveyingEngineering, Athens.

Bouras, C. (1998) The Daphni Monastic Complex Reconsidered, Athens.

Fletcher, B. (196117) A history of architecture on the comparative method, London.

Grabar, A. (1966) Byzantium.Byzantine art in the middle ages, London.

Kambouroglou, D. (1920) The Daphni, Athens.

Labakis, G. (1889) Christian Archaeology of the Daphni Monastic Complex, Athens.

Lambrou, E. (2003) Development of a Methodology for astrogeodetic Determinations, using DigitalGeodetic Instruments. Unpublished PhD dissertation (in Greek), NTUA, School of Ruraland Surveying Engineering.

Marriott, C. (2001) Skymap Pro Version 8.

Pantazis, G. (2002) Investigation of monuments orientation using Geodetic and Astronomical methods:Application at Meteora. Unpublished PhD dissertation (in Greek), National TechnicalUniversity of Athens, School of Rural and Surveying Engineers.

Troump, E. (1896) Imprimerie Generale Achard Et C ie, Marseille.

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