ASTROSIM

In preparation of the Lower Austrian County Exhibition at Heldenberg in 2005 featuring the Middle Neolithic circular ditch systems (Kreisgrabenanlagen, KGA) - the oldest Middle European monuments (approx. 4850/4750 - 4550/4500 BC) - all known Austrian KGAs have been magnetically prospected by the applicants. The acquired magnetic data were combined with aerial photographs, digital terrain models (DTM), cadastral maps etc. By the means of a Geographical Information System (GIS) for the subsequent combined archaeological interpretation and archiving. This digital archive, a comprehensive and comparable data-base will be used for the planned project. Selected archaeological interpretation maps derived from the over 40 sites have been used already to verify and extend archaeo-astronomical hypotheses on the function of the KGAs. A new hypothesis presented by the applicants describes the orientation of entrances of many of the KGAs towards rising and setting points of certain stars. A systematic observation of these stars at certain times of the year could have been used for calendrical purposes. Due to the lack of accurate horizon profile data, however, this hypothesis and the existing hypotheses on solar and lunar orientations of the KGA could not be verified so far. In the course of this planned proposed project, the archaeo-astronomical tools developed so far will be refined and extended towards an interactive GIS-based toolbox. In a first step we plan to survey accurate horizon profiles of all KGA sites in the field. These data shall be compared to profiles computed from the digital elevation models in order to assess the difference in data quality between surveyed and computed data. The extended data-base will be the input for a detailed archaeo-astronomical analysis. Beside that, empirical astronomical observations of heliacal risings of certain stars shall be performed. In this project we intend to build virtual reconstruction models of all monuments in combination with the DTMs. The results of the analysis of these virtual models will be used for a simulation of the middle Neolithic sky to visualise and to verify the developed hypotheses in the virtual world. This project could be an Austrian contribution of high public interest to the UNESCO International Year of Astronomy 2009. In extension to the scientific dissemination of the project results we therefore plan to present the expected fascinating results to the large public by the means of various activities as well.

Adherents of the popular belief in widespread astronomical practice by the Neolithic inhabitants of Central Europe must accept a largely astronomy-free result for the orientation of the entrances into the Neolithic Circular Ditch Systems (Kreisgrabenanlagen, KGA) of Lower Austria.The main subject of the ASTROSIM project (P 21208-G19; 2008-12) was a detailed investigation of the entrance orientation of the KGAs in Lower Austria. These early monumental buildings (4800 4500 BC), built by several culture groups in Neolithic Central Europe, consisted of one or more ring ditches enclosing one or more wooden palisade rings. The entrances are frequently described as having been orientated towards certain sunrise/sunset or moonrise/moonset directions, indicating a ritual or calendrical function connected with systematic celestial observation. In 2005 a preliminary analysis even indicated a possible connection with a few stellar objects, but the final clarification had to wait for this project. Given their large extents, most of the KGAs could have been documented only by geomagnetic surveys. For this project, researchers created a series of 3D virtual reconstructions based on the magnetograms and on a digital elevation model. In addition, the real landscape horizons were surveyed and documented on-site with panorama photographs. An appealing astronomical simulation environment was created by adding a plugin to an open-source desktop planetarium program. The virtual reconstructions could now be explored interactively, and possible locations for observation could be investigated. It turned out, however, that the stellar orientation previously suggested can no longer be supported the measured horizon line too often does not provide the necessary altitude. But the horizon altitudes also contradict some other earlier results associating entrances with the sun or moon. On the other hand, with the virtual models reconstructed in a larger digital elevation model, it became evident that we can find a simple explanation for most of the entrances, as leading up or down the sloping terrain, and in other cases the entrances are on the contour line (perpendicular to the slope line). This result removes any necessity for postulating celestial observation at those sites!With stellar and lunar candidates rejected, in a few sites, solar orientation can still be assumed. The strongest result was found for the site Pranhartsberg 2, where the north-western entrance follows the direction towards summer solstice sunset, maybe even further enhanced by two posts. This entrance does not follow the usual surface slope pattern, while in a few other sites, solar and slope patterns almost coincide.The methods and software developed will be applied towards similar archaeo-astronomical questions, and virtual models for both KGAs at Pranhartsberg will be made available online in 2013. The functions and purposes of KGA still remain enigmatic.