Since the beginning of the 20th century, several academics have researched the possible astronomical functions of some of Cusco’s constructions and of those in the surrounding areas. Nevertheless, the authors, whose contributions were of great importance and gained recognition (at least in their time) were the Germans Roberto Lehmann-Nitsche and Rolf Müller¹. But in the 70s, it was Anthony F. Aveni and R. T. Zuidema who contributed in a more significant way to the development of studies in this field, presenting a series of proposals about the geographical location of some of these places designed to make astronomical observations that have been mentioned in historical sources. The structures to which these two scholars have paid special attention were the sucancas of the Picchu hill, which could be seen, according to an anonymous chronicler, on the horizon west of Cusco; and the Coricancha temple. Another topic that has been studied by these authors is the possible astronomic role of some of the ceques (Zuidema 1977;1981; Aveni 1981)².

Zuidema postulated that the Incas were particularly interested in observing eight critical moments of the ‘route’, or the apparently annual displacement, of the Sun:

Fig. 2. The eight critical moments of the „route” or apparent annual displacement of the Sun, observed from the laтιтude of Cusco (Zuidema 2010).

Osiem tzw. „krytycznych” momentów w rocznej wędrówce Słońca po horyzoncie, obserwowanych na szerokości geograficznej Cusco (Zuidema, 2010).

Zuidema and Aveni’s works served as reference points for the investigations addressed later by other researchers, among which we can highlight Brian Bauer and David Dearborn. In 1995, both the authors published a valuable study enтιтled Astronomy and Empire in the Ancient Andes, in which they summarised a large part of what was known by then on the astronomical knowledge reached by the Incas (Bauer and Dearborn 1995). They conducted field prospections around Cusco, as well as studies of the historical sources, with the purpose of analysing, in detail, the hypotheses formulated by Aveni and Zuidema. In several points, the conclusions reached by Bauer and Dearborn differ significantly from the postulates of Aveni and Zuidema. In this study, we will follow the course drawn by Bauer and Dearborn, tackling in detail the topic of possible astronomical observations carried out in the main temple of Coricancha in Cusco, because of their particular importance for the structure and the functioning of the calendar-ceremonial system of the Inca Empire.

The Coricancha (Qurikancha)

This name is attributed to the main temple of Inka cult, located in the heart of Cusco, on a small hill at the junction of two streams (now covered). Its exact geographical coordinates are 13° 31′ 12.3″ S, 71° 58′ 30.9″ W, elevation 3391 m asl (Google Earth).

Before moving to the main topic of this article, that is, to the discussion about the possible astronomical functions of Coricancha, we must ask a question of particular importance, namely: to what extent the compound, as we see it today, corresponds to the form that Coricancha had, for example in 1530 AD, it means before the arrival of the Spaniards?

Without going into the details of this profusely debated subject4, let us remember some basic facts. The first historical news about this temple comes from 1533, in the context of the richness of its decoration in gold (in particular, the frieze of this metal), which was looted by the Spaniards5. In spite of this, eyewitnesses underline that even in mid-1537 the whole temple was apparently structurally intact, so it could, for example, serve as a prison for the brothers Pizarro captured by Diego de Almagro ‘El Viejo’ and his followers6.

The first somewhat detailed description of Coricancha dates from the early 1540s, from the chronicle of Pedro Cieza de León is as follows:

This temple had in circuit more than four hundred steps, all surrounded by a strong wall, all the building of excellent stonework with perfectly processed stones, precisely placed and settled, some of the stones were very large and impressive; they had no mortar of earth or lime, but only the bitumen with which they usually make their buildings, and these stones are so well carved, that it does not seem to be a seam or a joint between them. (…) The stones seemed to me to be something black and coarse and very excellent. There were many doors, and the facades very well carved; in the middle of the wall, a gold ribbon two hands wide and four fingers high. The facades and doors were covered with plates of this metal.

Further in were four houses, not very large, carved in this manner, and the inside and outside walls were plated with gold, as was the carpentry, too, and the roof was made with straw that served as tiles. There were two seats in that wall, which the sun illuminated on rising, and the stones [of the seats] were spottily perforated and in the holes, many precious stones and emeralds were embedded. In these seats [only] the kings sat, and if someone other did, he was punished with death.7

There, for the first time, an information appeared about a type of solar observations that had been realized in the temple for ceremonial events: ‘… two seats in that wall, which the sun illuminated on rising …’.

Bartolomé de las Casas, apparently based on the information of Cieza de León, presents a slightly different interpretation of this device:

In a part of the temple there was a piece as an oratory, to the part of the East where the Sun rises, with a large wall, from which came a roof six feet wide, and on the wall there was a niche where the image of the Sun was put, in the mornings, when the sun is rising. (…) and after noon they pᴀssed the image to the opposite part, in another lace, so the setting Sun faces the effigy.8

Inca architectural elements, which were hidden by the colonial constructions, have been uncovered. At the same time, a partial anastylosis of the Inca structures reconstructed several missing parts of the original walls.

To evaluate the importance of these interventions, just compare the pH๏τos of the famous niche in the east wall of the so called ‘Enclosure of the Stars’ in 1944 with its current appearance (Fig. 4), after the aforementioned restoration works.

Anyway, according to both archaeological and historical evidence, it seems that the external appearance of this complex would not be much different from other Cusco palaces: a complex consisting of a number of sheds or rectangular buildings, covered with straw, located around a central patio. It was surrounded by a polished stone wall. The number of structures located inside the enclosure is still to be established. According to the current research, it appears that there were all together nine buildings, and of these, all, but one, were connected directly with the central patio (Fig.18) 10.

The temple had a rectangular form, except for the western enclosure wall, which was curved, and higher than the others, because it rested on the side of a hill, giving it a balcony shape (Fig. 5 and 18).

Fig. 5. The curved wall of the ‘balcony’ of the Coricancha (pH๏τo Jacek Kościuk).

Fragment inkaskich murów Coricancha – zakrzywiona ściana tzw. „balkonu” (zdjecie Jacek Kościuk).

In summary, the current form of Coricancha has been profoundly altered since the Inca times. Although the general layout and part of the walls of the enclosures as well as the famous curvilinear balcony are undoubtedly authentic, in other parts we are confronted with the presence of restoration effects and contemporary anastylosis. Therefore, any study of archaeo-astronomic character must be carried out with extreme caution and, preferably, based on undoubtedly pre-Hispanic vestiges.

Regarding the historical references about the disposition of certain elements within the Coricancha, which could be ᴀssociated with astronomical observations of some kind, the only existing information is that about the ‘… two seats on that wall, which the sun illuminated on rising…’.

The hypothesis on the astronomical-calendric function of the Coricancha (Qurikancha)

The hypothetical astronomical function of Coricancha and the result of studies by different authors, particularly those mentioned in the introduction, have been summarized as follows by Ian Farrington

It is clear that certain solar observations must have been made from Qorikancha, particularly of the sunrises an

10 This is what Farrington proposes, summarizing the existing evidence (Farrington, 2013: 166). Previously Gasparini and Margolies postulated that the Coricancha was formed by seven rectangular buildings: two larges on the south and north sides, two mediums on the west side, two smalls on the east side and one additional to the north-west (Gasparini, Margolies, 1977).d sunsets thought to be critical to the inkas, such as solstice, zenith, and anti-zenith. Various scholars have speculated about what was observed. For example, Zuidema (1982: 214) argued that both the June solstice sunrise and the heliacal rise of Pleiades could have been viewed above the alcove wall from the doorway between R-3 and R-4. The December solstice sunrise could have been observed from the southern terrace. In terms of sunsets, Bauer and Dearborn (1995: 77−78) provided evidence that the December solstice sunset behind Killke mountain could have been viewed from the corridor between R-3 and R-4 as well as from Intipampa (Farrington 2013, p.).

In their first studies, Zuidema and Aveni postulated a special role of the so-called ceques or 41 symbolic lines that came from the Coricancha and its vicinity. They considered these perfectly straight lines, visualized on the ground by successive sanctuaries or huacas (Fig. 6).

Some of those lines were supposed to mark a specific orientation for astronomical observations at the horizon (Zuidema 1982b; 206)11. Aveni and Zuidema suggested that from the Coricancha, with the help of the ceques lines, several solar phenomena could be observed, possibly a sidereal one.

Fig. 6. The distribution of the 41 lines or ceques, according to R.T. Zuidema (Zuidema, 2010).

Rozkład 41 linii zwanych ceques, wg interpretacji R.T. Zuidemy (Zuidema, 2010).

We can summarize their hypotheses in a few points.

point (origin) and the point established by the intersection of the heavenly body (in this case, the sun) with the line of the horizon. This angle is calculated clockwise. Therefore, the established point of 66° 44′ on Cusco’s horizon would be the place of the sunrise more or less around the 25^th of May Gregorian style (which would be the 15^th of May according to the Julian calendar in the 16^th century). This date would be of great importance in the Cusco’s calendar according to the above-mentioned scholars12. There is, however, no proof of the existence of any sucanca located on this part of the eastern horizon of Cusco, but the corridor axis corresponds, more or less, to the direction of the Ceque An-5 (Zuidema; ceque III, 2b).

3. This last alignment would be the one in the direction of the heliacal rising of the Pleiades – that is, when they appear in the sky, after being invisible since May, one hour before sunrise – between the 6^th−9^th of June according to the Gregorian calendar (27^th−30^th May, Julian style).

According to Zuidema, this relation is reinforced by the roles and attributions of the Ceque An-5 and, especially, of one of its huacas: Susumarca (An-5:8)13. We think that the first postulate, that the sunset was visible from Coricancha during the December solstice, is plausible because the sector of the horizon in which the sunset happens on the aforementioned date is undoubtedly visible from the temple, and it seems to match the location of one of the sucancas: [Cu–13:3] ‘The third (huaca) Chinchicalla is a big hill, with two markers, that when reached by the Sun meant it was time to sow’ (Rowe 1979). Nevertheless, even though Zuidema gave a very detailed debate and analysis of all the historical sources about this huaca (Zuidema 2011: 148ff.), we lack archaeological evidence about the precise location of these ‘markers’, as well as the distance between them.

At this point, it is essential to ask the following question: what kind of supposed astronomical observations postulate Zuidema and Aveni for Coricancha? It is obvious that the practical observation of celestial phenomena, requires some, even rudimentary, devices, such as a gnomon or properly planned and oriented buildings. It should also be noted that, when discussing devices used for tracking the movement of celestial bodies, two different categories of arrangements are considered:

Those, due to religious and ceremonial reasons, aimed at an approximate orientation towards the rising or setting of the sun (or another celestial body) at some important moment in its annual transition across the horizon. In these cases, precision of astronomical observation is not so important but rather creating a visual effect for the mᴀsses of the faithful gathered in spacious plazas in the main ceremonial centres (Aveni 1981; Ziółkowski 2015).

Those, which may be called ‘precise astronomical instruments’, were intended for the use by a few priest-astronomers, as mentioned in some sources (Sarmiento de Gamboa, Anónimo 1906: 151−152).

Recently, two such ‘precise astronomical instruments’ located within the perimeter of the Archaeological Park of Machu Picchu, namely Intimachay and the Mirador de Inkaraqay, were unveiled. (Dearborn, Schreiber and White 1987; Ziółkowski, Kościuk, Astete 2013; Astete, Ziółkowski, Kościuk 2018).

Looking at the evidence referred so far by Zuidema and Aveni, it is very difficult to decide which of the aforementioned categories they postulate for the case of Coricancha. We don’t precisely know the place, inside of the Coricancha’s perimeter, where such observations of the sun could have been made. With respect to this point, Zuidema tried to compare the historical data that were available with the position of the Incan structures inside the Coricancha. Taking this analysis as a basis, he proposed the hypothesis that a window might have existed in the curved side of the perimeter wall of the Coricancha, from where the sunset might have been visible during the winter solstice from a structure called Inticancha (Zuidema 2011:134ff.)14.

With these limitations, the only way to establish the more or less exact dates of the sun’s transit through the aforementioned corridor would be by observing the shadow projected by the jambs of its eastern door at sunrise. However, this would have been an approximate orientation, much less precise than the one that could have been obtained with the astronomical equipment of Inkaraqay and Intimachay mentioned above.

Leaving aside, for the time being, the technical issue of the alleged observations and their practical goal, let us come back to the main matter, i.e. the orientation of these parts of the temple. In 2011 and 2012, as part of the architectonic documentation project of the Coricancha carried out by a group from the Centre of Pre-Columbian Studies at Warsaw University, a 3D scan of the whole ceremonial complex was done18. Based on that data, a plan of the whole Coricancha had been prepared and referenced to geographical North through 15 observations of the Sun disc made from the main court of the temple using a theodolite with a digital display. When it comes to the orientation of the Coricancha’s structures, these new measurements differ widely from Zuidema and Aveni’s ideas. To make it clearer, the debate about this critical topic is presented in several points.

The most significant difference is within the corridor of the western buildings19. This pᴀssageway is not oriented towards an azimuth of 66° 44′ but of 67° 06′. This difference of almost 22 MOA means that the line postulated by Aveni and Zuidema doesn’t point to the sunrise on the 25^th May and 18^th July but on the 23^rd May and 19^th July20. Therefore, the time that lapses between the successive sun pᴀssages (at its rises) through the corridor axis, an event that was very important to Zuidema (Zuidema 2010: 131ff.) changes from 55 to 57/58 days. Digressing slightly, let us try to answer a basic question, which is: where are all these very significant differences coming from, at least in the archaeo-astronomical studies, between the results of Zuidema and Aveni and ours? Could an expert in archaeo-astronomy such as Aveni have been wrong in making observations about the sun? The answer is: no; his measurements, which served him as a reference, are accurate, they are almost the same as ours. The problem is down to the drawings that our colleagues used. That is:

All this has some important consequences, because, as has been previously stated, the two key points of all the quipu-calendar model, namely the date – May 25^th – as well as the time span of 55 days25, lose their relevance26. In short, this theoretical model remains without any archaeo-astronomical basis.

Fig. 11. Coricancha. Schematic reconstruction of the view towards the eastern wall of the patio and the horizon. In light grey – according to A.F. Aveni and R.T. Zuidema. In black and colour– according to J. Kościuk and B. Ćmielewski. Setting aside the difference in the orientation of 22 MOA between the two estimations, the corridor between R-3 and R-4 could not be used for precise astronomical observations (prepared by J. Kościuk, B. Ćmielewski, M. Ziółkowski).

Coricancha. Schematyczna rekonstrukcja widoku w kierunku wschodniej ściany patio i horyzontu. Linie jasno szare: według A.F. Aveniego i R.T. Zuidemy; linie czarne: według J. Kościuka i B. Ćmielewskiego. Pomijając różnicę w orientacji rzędu 22 minut kątowych między obiema estymacjami, korytarz pomiędzy budynkami R-3 i R-4 nie mógł służyć do precyzyjnych obserwacji astronomicznych (opracowanie J. Kościuk, B. Ćmielewski, M. Ziółkowski).

The seats of the Inca (and the Sun)

The critical review of the hypotheses formulated about the possible function of Coricancha as a certain type of astronomical observatory gives somewhat disappointing results: either there are conjectures without a tangible archaeological basis, or, in the case of the hypothesis of ‘quipu-calendar’ the supporting arguments turned out to be reʙuттable.

Let us then go back to the only historical reference, related directly to some device inside Coricancha, oriented towards the sun: the two ‘seats of the Inca’ (or, alternatively, of the effigy of the sun). As we have mentioned in the introductory part of this paper, the reference in question comes from two chroniclers of the 16^th century: Pedro Cieza de León and Bartolomé de las Casas. Both authors speak of a wall, provided with two seats or niches, which were illuminated by the sun at a certain moment of the day. The difference between these testimonies is that Cieza de León speaks of two seats facing the rising sun: ‘two seats in that wall, which the sun illuminated on rising’.

On the other hand, de las Casas talks about niches on both sides of a wall, one illuminated at the sunrise while the other at the sunset: ‘… and on the wall, there was a niche where the image of the Sun was put, on the mornings, when the sun is rising. (…) and after noon they pᴀssed the image to the opposite part’.

Now let us go back to Coricancha: is there an architectonic element, similar in structure and function to the transversal wall (with niches) of ‘Cuerpo de Guardia’? Let us remember that a special, portable, object of worship was kept in the Coricancha, which reflected the sun’s rays: it is the figure called Punchao, the principal effigy of the solar cult of the Inca Empire. Punchao fell into the hands of the Spaniards in 1572 during the final attack on the last Inca redoubt of Vilcabamba and was later sent to Spain. Fortunately, we have a description, although short, of this effigy: ‘The idol punchau is made of casting gold (…) it had a way of small shields of gold around it, so when the rays of the Sun reflected from them, they [the worshipers] could never see the idol but the radiance …)’27. The information about the ceremonial importance of the radiance, produced by this solar image at the moment of being illuminated by the rays of the sun is confirmed by other sources28.

Fig. 14. The image of Punchao represented in a drawing by Guamán Poma de Ayala, enтιтled Pressure of Tupa Maru Inqa, infant, king. He is held prisoner with his crown by Captain Martin García de Loyola (Guamán Poma, fol. 449 [451]). The king walks barefoot, with his symbols of power. Another Spanish takes a small statue, above which an aureole of rays is represented. It indicates, that this is an effigy of the Sun, protector of the Inca dynasty. From the description in the letter of Francisco de Toledo (see in the text) it turns out that this was certainly the figure of the Punchao.

Przedstawienie Punchao na grafice Guamán Poma de Ayala zatytułowanej Uwięzienie Tupa Amaru Inqi, infanta i króla. Prowadzi go uwięzionego i z koroną kapitan Martín García de Loyola (Guamán Poma, fol. 449 [451]). Król idzie boso dzierżąc symbole swojej władzy. Jeden z Hiszpanów niesie mały posążek nad którym widać aureolę światła wskazująca że jest to wyobrażenie Słońca – protektora inkaskich dynastii. Opis zawarty w liście Francisco de Toledo (patrz w tekście) potwierdza że jest to przedstawienie Punchao.

With this evidence in memory, we now return to Cusco and the Coricancha. Are there elements within this temple similar to those described by Spanish chroniclers? Trying to answer this question we must remember that only two buildings (Fig. 18; R2 and R3) are extant (although partially reconstructed) to the degree, which allows us to interpret their detailed layout. For another two (R 1 and R4) the northern perimeter walls are missing and their exact plan can be deducted only by analysing still preserved foundations (R4) or comparison with dimensions of the neighbouring one (R1). The only remains for other five structures (R-A ÷ R-E) are partially preserved foundation walls – just enough to propose the general outline and position of these buildings, but nothing to judge about details of their exterior and interior arrangement.

The most inspiring description of Pedro Cieza de León tells us about ‘… two seats in that wall, which the sun illuminated on rising …’. The only walls, which are eastwardly orientated are the ones of R-3 and R-4 forming ca. 30.25 m long section (Fig. 18). Its left (southern) part corresponds to R-3, while the right part (belonging to R-4) is only partially preserved. In the centre of the former one, a niche is extant with evident traces of fittings (Fig. 4) meant to receive covering by gold plates, well attested by Spanish chroniclers. Oscar Ladrón de Guevara

We postulated the existence of similar observation system in the case of the observatory at El Mirador de Inkaraqay (Astete, Ziółkowski, Kościuk, 2016/2017, pp. 20−21).

Fig. 16. E-W section across R-3 building with the simulation of sun rays on the day of the June solstice. A – the theoretical direction of the sun’s rays at the moment of rising above the horizon, B – the actual direction of sunlight taking into account the existence of roofs over R-1 and R-2. Angular data according to Table 1. (Prepared by J. Kościuk).

Przekrój W-Z przez budynek R-3 z symulacją padania promieni słonecznych w czasie przesilenia czerwcowego. A – teoretyczny kąt padania pierwszych promieni słonecznych w momencie wschodu słońca nad linią horyzontu. B – faktyczny kąt padania pierwszych promieni słonecznych biorący pod uwagę dachy nad budynkami R-1 i R-2. Dane kątowe według Tabeli 2. (Opracowanie J. Kościuk).

Fig. 17. Theoretical reconstruction of Punchao placed in the niche of the eastern façade of the so called ‘Enclosure of the Stars’. (Prepared by J. Kościuk. Fragment of Oscar Ladrón de Guevara Aviles reconstruction used as a background)

Teoretyczna rekonstrukcja figurki Punchao umieszczonej w niszy na wschodniej elewacji tzw. „Enclosure of the Stars”. (Opracowanie J. Kościuk. Fragment rekonstrukcji autorstwa Oscara Ladrón de Guevara Aviles użyty jako tło).

On the other hand, it seems very likely that the niche in the R-3 facade (and the alleged second one, in the R-4 façade), both covered with gold plates, served to achieve already mentioned radiation effect, so desired from the ceremonial point of view. Looking for places which might fit Pedro Cieza de León description of ‘… two seats…’ this might be the best choice. Perhaps not inside the niches, but rather in front of them since the niches are too narrow and too shallow for humans to seat comfortably in29. What might, however, fit well into the seats in the niches, is mentioned above the statue of Punchao – the effigy of Sun attested by many sources as being kept in Coricancha (Fig. 17).

The most spectacular effect of Punchao and niches radiating in sun-light will be when sun rays are nearly perpendicular to the wall surface. The normal to the wall in question is at the azimuth 66° 41′ 25″ (Fig. 11), so the niches will be in full, perpendicular sun-light for at least one month before and one month after the June solstice, roughly one hour after the astronomical sun rise due to R-1 and R-2 roofs obscuring the eastern horizon.

Still remains the critical analysis of the second account – that of Bartolomé de las Casas describing ‘… a niche where the image of the Sun was put, in the mornings, when the sun is rising. (…) and after noon they pᴀssed the image to the opposite part, in another lace, so the setting Sun faces the effigy…’. Although the existence of similar niches is attested by the quoted above Ingapirca example (Fig. 13), there is no room for such the arrangement within the perimeter of Coricancha (Fig. 18).

Let us now consider the second possibility, i.e. the observation of a specific part of the night sky from inside of the room R-3. Of course, the observed section of the sky changed, depending on the place where the observer stood (or rather sat) inside of the room. Reconstructing the situation at the beginning of June 1500 AD, we note that an observer, sitting at the foot of the inner western wall of the R-3 room, a little bit S of the axis of the window, could have seen, close to the inner left border of the window, the rising Pleiades at a height of about 10 degrees above the horizon, it means, above the roofs of buildings on the eastern side of the patio. However, the problem what could be observed through this window in the night sky, requires further analysis.

Conclusions

Let us then return to the question already asked in the тιтle of this paper: are there evidences that accurate astronomical observations have been performed within the Coricancha Inca compound? And if so, of what kind?

We can answer this question in points:

5. The only existing original architectonic element, that can be used for more precise observations, is the window in the niche in the façade of the building R-3. It should be noted that a window so small in size could not be placed by builders in such a special place without a precise and specific purpose. The observation function seems very likely here. Two, not mutually exclusive, hypotheses can be considered: it was either for gnomonic observations of the Sun’s rays falling into the room at sunrise, or observations from within the building R-3 of a specific fragment of the night sky. However, both hypotheses will require further research to determine, what kind of event and/or celestial bodies were indeed subject to observation.

Final remarks

What we have presented in the present paper is only part of a multidisciplinary study on Coricancha, whose results we hope to publish soon. However, it seemed important to present to the public an alternative view of the supposed astronomical function of this temple, a hypothesis extant for many years in the literature of the subject, and widely accepted without prior critical evaluation of its bases.

But it is to be emphasised that our predecessors, with the means available at that time, made a careful study, formulating an interesting hypothesis about the Inca sky-lore and calendric. If with the pᴀssage of time, the new data are forcing us to review the previous postulates, this does not reduce the importance of the scientific contribution of the aforementioned scholars. They opened a research path, which others are now following.

Acknowledgements

The research described above was carried out in several phases between 2011 and 2017. In the years 2011−2013, laser scanning of the entire complex and the basic archival and bibliographic query were financed under the grant of the National Science Centre of Poland31 for the research project ‘Qorikancha – a complex historical and architectural study of the former Temple of the Sun in the capital of the Inca state, Cusco (Peru)’ headed by architect Sławomir Święciochowski, PhD, ᴀssociate researcher of the Centre for Precolumbian Studies of the University of Warsaw (OBP UW). In subsequent years, i.e. 2014−2017, the researches were sponsored within the BST funds of the OBP UW. The research team also used the infrastructure and equipment of the Centre for Andean Studies of the University of Warsaw in Cusco (CEAC) as well as of the Laboratory of 3D Laser Scanning and Modeling of Wroclaw University of Science and Technology (LabScan3D) – both sponsored under the SPUB grants by the Ministry of Science and Higher Education of Poland.

We would like to thank the Community of the Dominican Friars in Cusco, and especially the then Prior of the Qorikancha-Santo Domingo convent, Fray Luis Enrique Ramirez Camacho, for their comprehensive help. We are also extremely grateful to Mr César Ladrón de Guevara for the release of the highly valuable plans and pH๏τos of Coricancha, from his Fathers’, Oscar Ladrón de Guevara, private archive. Finally, last but not least, we would like to thank Professor Anthony F. Aveni for providing us with information about the fieldworks in Coricancha carried out by him and late Professor Tom Zuidema in 1976 and 1980.

31 Grant number N527 228140 (contract no. 2281/B/T02/2011/40 – ‘Qorikancha –kompleksowe studium historyczno-architektoniczne dawnej Świątyni Słońca w stolicy państwa Inków -Cusco (Peru)’.

Annex. Preliminary observations on Coricancha metrology

As a conclusion of a methodological nature, it is important to underline the importance of new technologies, such as 3D laser scanning, particularly for the study of complex architectural structures like the Coricancha Temple. Beside precise measurements giving a good starting point to verify earlier surveys, it results in the abundant amount of data which might be used also for metrological studies.

table 2. Comparison of Coricancha main walls dimensions. Porównanie długości głównych ścian świątyni Coricancha.

A According to the results of our 3D laser scanning project. Please note that N2 + E + S1 + W2 = 286.91 ≈ 400 single steps (of ca. 72 cm) mentioned by Pedro Cieza de León in his description of Coricancha (Cieza, II p., Cap. XXVII: 105−107) B Farrington 2013, p. 170.

Fig. 18. Coricancha enclosure dimensions according to 3D laser survey. Lettering corresponds with Farrington naming convention (prepared by J. Kościuk).

Wymiary muru obwodowego Coricancha według wyników laserowego skanowania 3D. Oznaczenia literowe zgodne z konwencją nazw przyjętą przez I. Farringtona. (Opracowanie J. Kościuk).

According to the archaeological and historical data, “it is estimated that the temple enclosure dimensions were north side, 74.3 m (46r); west, 85.6 m (53r); and east, 41.9 m (26r)” (Farrington 2013, p. 170).

At this point, we must admit that there must be apparently a confusion between dimensions of particular walls given by Farrington. The following table (Table 2) and the plan (Fig. 18) illustrate the differences we noticed. The plan is based on an original drawing of Oscar Ladrón de Guevara (Fig. 9) kindly provided to the Authors by his son D. César Ladrón de Guevara and adjusted according to the results of 3D laser scanning project done in 2011−201432. It should be stated however that results presented in Table 2 depend greatly on the way the measurements were taken – at the foot of the wall, at a certain height above the ground or on the foundation level.

Following the presented above measurements of different parts of Coricancha, we are tempted to summarize these observations from the metrological point of view. Although our general study on Coricancha metrology is still not finished, some primary observations can be already offered, especially that they might be useful for any further archaeo-astronomical studies on Coricancha where not all the walls and details are fully preserved.

To begine, we can analyse the already quoted Coricancha main walls dimensions (Table 2). In his Cusco publication, Farrington gave dimensions of main Coricancha walls both, in meters and rikra (Farrington 2013, p. 170). Following these data, one arrives at the averaged rikra length of 1.614 m (Tabele 3). Using an analogous procedure in relation to our measurements we get rikra of 1.649 m. At this point, however, we must remind that none of these measurements was taken on the foundation level where possibly one could trace the original measurement units used by Inka builders. This may explain differences in reconstructing the length of the original measuring unit (rikra) – so, these results should be not considered as conclusive.

table 3. Estimation of rikra length based on dimensions of Coricancha main walls. Estymacja miary rikra na podstawie długości głównych ścian świątyni Coricancha.

A – Farrington 2013, p. 170. B – According to the results of after mentioned 3D laser scanning project.

Fig. 19. Estimation of quanta for Coricancha main walls.

Estymacja quanta dla głównych ścian Coricancha.

32 The project has been executed in 2011 by Janusz Janowski and Marta Bury of the Insтιтute of Archaeology of the University of Warsaw with Leica ScanStation 2 facilitated by the Insтιтute of Archaeology of the University of Warsaw and completed in 2012−2014 by Jacek Kościuk and Bartłomiej Ćmielewski from the Department of History of Architecture, Art, and Technology of the Wroclaw University of Science and Technology (Poland) with Leica ScanStation C10.

It is intriguing, that rikra equal to 1.649 m corresponds with our reconstruction of rikra length based on niches spacing and dimensions of original (not reconstructed) walls of Coricancha, where a much larger set of measurements has been analysed33. The cosine quantogram method (Kendall 1974; Pakkanen 2001) was used for these estimations (Fig. 19). Two local maxima of cosine quantogram function were detected. The first (10.3 cm) is corresponding with incaic unit yuku, the second (20.5 cm) fits well with another unit – k’apa.

Since the system of ancient incaic units seems to be based on multiplication by factor 2 (Agurto 1987; Baudin 2003; Rostworowski 1978; Rowe 1946), therefore we can attempt to reconstruct the whole system using the first two items of the series. The length of rikra reconstructed in this way will be around 1.64 m (Table 4).

table 4. Reconstruction of rikra length based on cosine quantogram estimation for Coricancha main walls. Rekonstrukcja miary rikra metodą cosine quantogram na podstawie długości głównych ścian świątyni Coricancha.

table 5. Reconstruction of yuku length based on dimensions of the so called „Enclosure of the Stars” niches. Rekonstrukcja miary yuku na podstawie wymiarów nisz w tzw. „Enclosure of the Stars”.

Fig. 20. Estimation of quanta for the so called ‘Enclosure of the Stars’ niches.

Estymacja quanta dla nisz tzw. „Sali Gwiazd”.

33 This study is however still in progress and will be published separately.

Further on, we can continue with already mentioned, far more precise34 measurements of the niches in the east wall of the so called ‘Enclosure of the Stars’. Using 25 measurements of both, the eastern and the western niches we are ending with the average length of yuku as 10.5 cm (Table 5). This, can be also verified by cosine quantogram method. The result of 10.49 cm (Fig. 20) confirms our previous estimation.

Using again multiplication by factor 2, the length of reconstructed in this way rikra will be around 1.68 m (Tabele 6) – the value already suggested by Maria Rostworowski de Dies Canseco (Rostworowski, 1978).

table 6. Reconstruction of rikra length based on cosine quantogram estimation for the so called ‘Enclosure of the Stars’ niches (Fig. 4).

Rekonstrukcja miary rikra metodą cosine quantogram na podstawie wymiarów nisz w tzw. „Enclosure of the Stars” (Fig. 4).

To sum up all this information we can conclude that the most likely length of rikra was between 1.64 and 1.68 m. Dividing these values in succession by 2, we will get lengths for the remaining units of the metrological system which might have been used by Coricancha builders (Table 6).