AstroArch is a part of the Human of Dawn Project (THOD). The idea for this project was born to the begining of the new Millennium. The AstroArch development was started autumn 2017 and the first working development version was finished in February 2018. Since beginning 2020 the tool is available for download as freeware.
Horizon profile is AstroArch's most powerful graphical representation of ancient sites. The tool allows you fast and easy to create beautiful realistic panorama views with all important astronomical events. The horizon profil is also the prehistoric calendar of the investigated ancient site.
I have had the idea for a software for archaeologists and archaeoastronomers for a long time after I was repeatedly confronted with missing, outdated or complicated tools in this area.
The archaeoastronomical research is often associated with many difficult steps that are very time consuming and demanding. Some researchers use planetarium programs to simulate prehistoric events, which was often not easy for me and now I know that the planetarium programs should be used with great care because they are not error-free for prehistoric times (BC), but that becomes a big topic in another article.
At some point years ago, when I was searching the Internet, I came across the Horizon program, which was programmed by Andrew Smith. At first, I found the program too complicated for me because I had hardly dealt with GIS, cartography, radar data from NASA etc. at the time. So, the program fell into oblivion. At some point, after reading dozens of articles and books on GIS, SRTM, and other geological terms, I was beginning to feel familiar with everything. In the meantime, I have dealt with a few web tools for generating horizon profiles (or panoramas) and expanded my knowledge, e.g. the pages of HeyWhatsThat, Ulrich Deuschle and PeakFinder. The integration of horizon profile is now also part of many sundial design programs.
So, in summer 2017 I came back to the Horizon program with a certain know-how and in the end I was able to get the program up and running and generate the first horizon profile of my city environment. Horizon is an excellent program with great 3D graphics (written in C++) and has greatly influenced my development. After some time of use, I soon found some things annoying (speed, limited possibilities for calculating from the ephemeris back in the past, only up to 1800 AD, limited user environment, management of data and settings, etc.). So, the idea came to develop a new tool that combines the best features of various programs that are used in archeoastronomy.
The development of AstroArch started in autumn 2017 and the first working development version was finished in February 2018. The software is written in Object Pascal with Delphi. Development often faced failure for half a year. The problem was that there are hardly any programs or components in Pascal in the GIS area that could make my life easier. On the Internet you can find tons of help resources programmed in C ++, C # and Python. Using such resources is dragging in a huge amount of installations and knowledge that I didn't like. The use and porting (source code) of these resources in other languages, such as Basic or Pascal, is not an easy thing.
Despite the difficulties, I was able to successfully finish programming the program core within six months with the option of reading SRTM data, such as with a resolution of 3" (90m), but also with 1" (30m).
After that, the development proceeded rapidly. Above all, the astronomical calculations, ephemeris of the sun, moon, planets and associated sky events, such as sunrise and sunset, various twilights, equinoxes, solstice, lunar standstill etc. Very soon I found that the whole calculation was unusable and could not be used suitable for prehistoric research, since the calendar only went up to 1900 or 1800. The reason for this was that the calculations depended on the computer date and not on the Julian date (JD). So, I had to reinvent everything again.
At that time, I also discovered that most (99%) online calculators incorrectly calculate the Julian Date Before Christ (BC). Some planetarium programs have also this error. As already mentioned, however, this will be discussed in detail in another article.
Sun 2000BC to 6000AD Earth 2000BC to 6000AD Moon 1600AD to 2300AD Venus 2000BC to 6000AD Mars 2000BC to 6000AD Jupiter 0001BC to 4000AD Saturn 0001BC to 4000AD Uranus 0001BC to 4000AD Neptune 6000BC to 8000AD
AstroArch main window.
The program name selection was an important issue when completing the first public version. During the development of the program core, the name was “SRTM Reader”, because at the beginning the greatest difficulty was reading out the height data. The program name was "The Archaeoastronomer" for a short time, but I was not satisfied with it because it was too long and somewhat fragmented. I create short list of possible names as follows:
The name selection was difficult for me, but after a few conversations with the beta testers, the favorite among the possible names was AstroArch. The name is short, easy to remember, sounds melodic and consists of the two meaningful words - astronomy and archeology, which are also contained in the word archeoastronomy.
The program logo (above left) was created from a real area (the village Bankia near Tran city, Bulgaria, my grandpa's birthplace) with coordinates lat: 42° 51'41.22 "N, lon: 22° 40'43.14" E, elv: 642m whose horizon profile was simulated with AstroArch.
As already mentioned, the AstroArch program uses data from the Shuttle Radar Topography Mission (SRTM) and precise astronomical calculations based on Variations Seculaires des Orbites Planetaires (VSOP87). This enables the generation of a realistic profile of the horizon with great accuracy and many astronomical events can be precisely presented in the same coordinate system.
Schematic representation of the SRTM project (left), precision of the data and the calculations (middle) and example for the use of the altitude data (right).
The current version of AstroArch is an advanced classic Windows program with all the trimmings that make it such. Above all, the user has full control over the program, e.g. manage huge amounts of data (including SRTM) through convenient data management for the object position and description (Location Manager), the management of the brightest stars (Stars Manager) and the BSD5 (Brigth Star Catalog 5th Edition) and Hipparcos star catalogs, manage object categories, such as the orientation diagram measurement data.
The user can refine and optimize his work by means of numerous parameter settings. He can import or export various data quickly with a click, e.g. object or stars positions. Preferred files format is CSV.
The program comes with a thousand object positions from all over the world, as well as with a variety of orientation data cited in the most famous books and articles on archaeoastronomy.
All program elements use the same conventions (icon symbolism, control via mouse, keyboard, context menus and key combinations). A large number of the user parameters are configurable and can be saved in the program settings dialog.
The program settings dialog. The meaning of the settings is often self-explanatory.
All of this makes the user interface very flexible and customizable. If the user has already gotten to know all the functions for control in a manager, he can also get on with other managers directly. If the user is already familiar with a graphical window for analysis, he can find his way in all other windows. In general it can be said that the program has an intuitive user interface and control that requires a minimal learning time.
In the program settings dialog there are to fin mainly settings for program folders for various data, such as SRTM files, manager files, files for import and export, main window topics, background colors for managers, researcher name, as well as a few settings regarding program start, visibility of user interface components etc.
Further settings can be found under calculations, orientation diagrams, orientation histograms. These settings are assigned here because they are not directly assigned to a project (see program standalone functions).
There are two types of features in the program. Features that need a new or existing project and features (standalone) that don't necessarily need an open project file. Nevertheless, both types can be useful to each other. If a project is open, the assigned object with its object name, description, characteristics and coordinates can be automatically adopted in another task, which saves the user time for multiple entries and reduces possible errors when typing.
Stand Alone Features include all data managers for object positions, object categories, star catalogs, such as orientations and associated orientation diagrams and histograms, declination diagram analysis or various calculation types, as well as calendars, precession, etc.
The AstroArch toolbar for quick access to the most important program functions. Move the mouse over the buttons to show explaining text about the feature.
The Location Manager window. If the user has selected a location, it can be adopted from here in a new project. The notice can be shown/hidden. With a double click or an entry, the user can edit the selected category. Locations with missing SRTM data are listed in the column for file names with red colored text, otherwise in black. Add or edit individual location entries. The user can decide how the display text of the location should look.
This manager is the most important part of data management. Therefore it is best if the user deals with it first. The Location Manager can manage large quantities of objects and their characteristics. Part of it is the download of the corresponding SRTM (HGT) data, which will later be used for calculations of the horizon profile.
Once a location has been identified, it can be used anywhere in the project and so to speak it is the business card of the project. The location contains the input data necessary to generate the horizon profiles from the SRTM (GIS) data, but also the input data necessary for the calculation of astronomical events and astronomical object’s position (ephemeris).
The location data can also be used for global representation of the objects in order to show various common characteristics (distribution by countries, continents, etc.).
The Location Manager has many functions that simplify data management and save time. The user can add new locations to edit or delete them later (see below).
AstroArch automatically creates a name for the user of the SRTM file as soon as geographical latitude and longitude have been entered for the location. This can then be downloaded manually. If the file does not exist, the file name will be colored in red, otherwise in black.
All functions are available via the main menu "Location" or via the context menu (right mouse click) or via buttons from the right sidebar. An important parameter of an object is its category (e.g. dolmen, menhir, cromlech, etc.). The category manager enables you to manage the list of categories. The idea for these managers came after I saw that there is no uniform list of categories worldwide. There is a category specification by Andy Burnham on the megalithic portal (www.megalithic.co.uk). The category manager allows the user to define their own category and then apply it.
The category manager with intuitive management (add, edit or delete data). The notice can be shown/hidden. With a double click or Enter the user can edit the selected category.
Another useful function of the Location Manager is the location search. This allows you to quickly find a specific object. The function is very helpful especially if you have to manage a hundred or a thousand locations. When the searched location has been found, the user can edit it (button pencil) or use it to create a new project (button + Prj). Otherwise, the location you are looking for can also be conveniently created as a new location (the + button).
The location search window (left) and adding easy and fast new proect using selected location (right).
The Location Manager also has import/export routines that allow it to import long location lists, e.g. from the megalithic portal. The import format is described in the user guide. The export function enables the user to exchange his data with other users. This rule applies to every import/export of data in the program.
It should be mentioned here that AstroArch has a download manager that can be started in a separate task and allows the user to download all available SRTM files (vary between 15000 and 250000). Depending on the Internet access speed and server load, the download can take between 2 and 4 days. The total file size varies between 30 and 60 GB for HGT files with a resolution of 90 and 30 m.
The Star Manager (left). With the assignment of a certain color, the star on the horizon profile can later be recognized by the assigned color. In the manager it is quickly possible to interpolate the colors to selected stars. Add and edit the data from a star (right). There is a possibility that the user can determine how the star name should appear.
The Star Manager contains the coordinates and the visual brightness of the brightest 25 stars. The user can add further stars to this list (e.g. from the BSC5 or Hipparcos Catalog) or define the center of zodiac signs or e.g. the Pleiades. A color can be assigned to each star, which can lead to easier identification later on the horizon profile. All coordinates are coordinated at epoch 2000.
The viewing (left) can be filtered accordingly from the settings dialog (right), e.g. by certain zodiac signs, by star magnitude or rectangular coordinate regions defined by right ascension and declination.
The Bright Star catalog (also Yale "Catalog of Bright Stars") is an astronomical catalog of bright stars. It contains all the stars visible to the naked eye (9111 in total). The Bright Star catalog therefore contains all stars that are brighter than 6.5 mag and was published in 1930 in its first edition. The fourth edition was published in 1982 as the last printed version, the 5th edition (BSC5) has only been available online or as an electronic version since 1991 and contains the equatorial coordinates as well as for the standard epoch J1900 and J2000.
Individuals or groups of selected stars can be added to the Star Manager by confirming with the (+ SM) button.
The viewing (left) can be filtered accordingly from the settings dialog (right), e.g. by certain zodiac signs, by star magnitude or rectangular coordinate regions defined by right ascension and declination.
The Hipparcos catalog is a high-precision star catalog based on measurements by the Hipparcos satellite, which was active from 1989 to 1993. The catalog consists of 99900 stars with a coordinate precision up to 0.002 “. The viewer allows the user to view the data of individual stars and, if desired, to transfer them to the Star Manager. Otherwise, a part of the stars is used as a realistic sky representation when calculating simulations. In the catalog you can find the own movements of the stars (in right ascension and declination), which are important for the precise calculation of precession.
Output window with all available data from the selected star (left: BSC5, right:Hipparcos.
Add and edit the data of an object. The user can also assign a specific color to each measurement. Each Data measurement can be described/commented on.
The orientation manager manages the measurement data of the observers from an observation location defined with its geographic coordinates (latitude, longitude). The coordinates, the azimuth, the height above the mathematical horizon and the converted declination are recorded as measurement data. The managing data are the basis for the generation of orientation diagrams and histograms. The user can individually assign or interpolate colors to a selected group of measurements at the click of a mouse. This function is available above the context menu.
The sidebar can be used to call up orientation diagrams and histograms directly, as well as import or export data in CSV format (e.g. made available by other AstroArch users). A notice can be recorded for individual measurement data, with which the data is well documented and recorded.
General settings for the manager (this also applies to all other managers) can be made in the program settings (e.g. colors for even and odd lines, background color for the grid and the notice area).
The user can collect measurement data for each object that he analyses, both individual and common files (e.g. for an entire country, a continent, worldwide, etc.). AstroArch comes with a rich collection of measurement data for orientation diagrams quoting from the specialist literature (books and articles).
This calculator made it possible to use the Julian date to calculate the corresponding date and time according to the Julian-Gregorian calendar and vice versa to determine the corresponding Julian date from a given calendar date without errors, i.e. the calculator correctly calculates the date for negative JD values (e.g. 10000BC). The calculator takes into account the astronomical year 0.
There is no year zero in the traditional Christian time calculation used by the historians, but in the astronomical calendar there is a zero year. In the traditional system, the years are counted with ordinal numbers before and after the birth of Christ: the year 1 before the birth of Christ ends on December 31 (1 BC), the next day, January 1, begins the year 1 after Christ Birth (1 AD). The astronomical annual count, on the other hand, uses natural numbers expanded by zero and negative numbers, the so-called whole numbers. The 0 contained in this series of numbers becomes the year 1 BC, the number -1 the year 2 BC.
Left: In the traditional system, the years from “Christ's birth” are counted starting with 1, once in the past and once in the future. The system consists of two independent chronologies based on natural numbers. The years 2 BC, 1 BC, 1 AD, 2 AD of the historical annual census are called -3, -2, −1, 0, 1, 2, 3 in astronomical counting. Right:Explanation of various calendars with time scale and example calculations closer to the year 0.
AstroArch make easy the calculation of the sun equinoxes and solstices. Similar to the sun solstices the user can compute the lunar standstill over large time interval in tabular form.
The calculation of the solstices includes the azimuths of the sun by rising and setting, information that is very helpful.
The term "lunar standstill" introduced by the archaeoastronom Alexander Thom, in his 1971 book Megalithic Lunar Observatories. The calculation of the lunar standstills includes the azimuths of the moon by by rising and setting, information that is very helpful. The columns Extremum help additional fast determination of the major and minor standstills
Catalogs and star charts always refer to a standard epoch. Newer catalogs or new versions of older catalogs generally use the standard epoch J2000.0, because since 1984 the IAU has recommended using this standard epoch. Older catalogs can still use older standard epochs - mostly J1950.0 but also J1900.0. In this case the star positions must be corrected. The corrections in precession and nutation provided for this will be dealt with in a later chapter.
The catalogs usually also contain information about the self-movement of a star. For practical reasons, it is split into catalogs, but into a component of self-movement in the direction of right ascension and a component in the direction of declination. If the epoch of the catalog and the point in time at which the star position is required is closer to one another, then the inherent movement in the two components can be regarded as constant if the difference between the two epochs does not span more than a few decades. Otherwise, one has to take into account that due to the precession, the components change over time.
AstroArch provides a calculator that can quickly calculate the precession of the selected stars from the Star Manager over the millennia. To do this, it uses the best calculation method (J. Vondrak, N. Capitaine, and P. Wallace, A&A 2011), which has a higher precision from 200000BC to 200000AD.
Various variants of the precession calculation are possible, such as changes over long-time intervals.
The calculations that are otherwise used in the Horizon Profile are now available in tabular form, as is already known from Almanac. The user can choose between different coordinate systems (ecliptic, equatorial or heliocentric), calculation intervals (hourly, daily, monthly or yearly), as well as format of the coordinates.
Extensive settings for the custom appearance of the ephemeris are available.
To be able to use a analysis functions, a project must be created. The non-standalone functions currently include the horizon profile, the elevation model, the ephemeris calculation, elevation model and the star map. To be able to use these functions, the user needs an existing project that must be opened or newly created. AstroArch contains some archaeoastronomical projects that can be very helpful in the first steps of program learning.
After opening an existing project or creating a new one, the user has the option to change extensive settings. If no changes have been made, all features with default values can be used and set later as required, accessible from the respective analysis window.
This feature is the heart of all graphical representations and the information rich. It combines two different technologies. Together they represent a visible horizon profile and the ephemeris calculations of different celestial objects and events. Such merging of different data (SRTM altitude and ephemeris data) into a common coordinate system excludes possible errors.
In this way, AstroArch has so far replaced the usual workflow of using GIS software, such as ArcGIS, QGIS etc. to generate a horizon profile and then import it into the planetarium program, e.g. Celestia, Stellarium, Sky Chart etc. This saves time-consuming studying of various software products from the field of GIS and astronomy.
The user has the option of setting this analysis extensively. All generated data is available in tabular form. The chart can also be zoomed. The coordinates of each object or horizon profile (azimuth and height) can be read with the mouse pointer.
The user has full control over all relevant parameters and is free to design the display as he wishes and to have more fun researching.
Extensive settings to design the horizon profile as desired.
The AstroArch calculates the profile of the visible horizon using two methods: the simple profile (see the first image below) and the profile with a deep view (see the second image below). The second method creates a feeling of three-dimensionality. The available elevation data can also be used to create a precise 3D profile. However, this is associated with very sophisticated programming techniques and will be further developed later. The method I use for spatial simulation is many times faster and more efficient than 3D graphics and does not require any programming resources. Interpolation can also be used to better display the profile, if the observation location is in a kind of cavity and the visible horizon is relatively close.
Above: Simple display of the horizon profile with the visible path of the sun and Sirius (Alpha Orion, Betelgeuse); Middle: Another additional display of the legend with the names of objects and events; Below: additional view (line of sight), the diagram of the visible line in a certain direction;
The next two pictures show the comparison of the simulated visible horizon profile with the real one (Sofia, Bulgaria). The slight difference arose because I did not know the exact geographical coordinates of the picture that I found it on the Internet and could only roughly estimate it.
AstroArch can generate 360° horizon panorama with rectangular projection in PNG format with different resolution (from 512 up to 4096 pixels). For export could be used 3 arcsec or 1 arcsec resolution of the SRTM file. The sky area color is set as transparent for the PNG file. The south direction is in the middle, the east most left, the nord most right. The generated file is compatible for both SkyChart and Stellarium programs.
This feature enables the user to create a relief map from a current SRTM file. It is for informational purposes only. The user has the option of changing the view through various settings, e.g. the color palette, showing/hiding from the object center, as well as reading out geographic coordinates with the mouse pointer.
Bulgaria, Sofia, North Park. Left: The elevation model uses a setting called "false colors". The purpose is to give a clear overview of the relief of the selected geographical area. This example uses a setting that displays the elevation pattern (the shaded area) of the area in which the visible horizon profile is created. Right: Realistic representation of the elevation model. It turned out that rendering the relief with this palette is not trivial and requires fairly sophisticated programming techniques and additional tools for designing palettes. This is also the case in professional GIS programs. There is room for improvement with regard to this graphical representation.
The star map is currently of a purely informative nature. The chart provides the user with an easy-to-use map in horizontal coordinates (azimuth and height). The equatorial coordinates can be calculated since the date, time and geographical longitude are known. The simulations can be saved as animated GIF or video.
Sky Chart (left) can simulate the sky for certain time intervals and selected step. The Sky Chart settings (right) give the possibility e.g. to show/hide individual zodiac signs.
The orientation diagram is one of the most used representations when analysing archaeo-astronomical sites. It is a simple graphical tool for the distribution of measurement data from certain prehistoric objects or systems. The diagram shows the azimuths in polar coordinates. The user can also show/hide various events, such as solstice and equinox, etc. AstroArch uses vector graphics, which makes it possible to scale/zoom the orientation diagrams. Many other functions are available from the window and context menu. If no data is available, the user can generate a set of random data to try out this tool analysis.
When I started to be interested in archeoastronomy, there was only one DOS program for generating orientation diagrams, the use of which was quite complex. There wasn't even an Excel sheet for archaeo-astronomical research for over 30 years. Therefore I am very proud that I give the user the opportunity to offer a modern and flexible feature for this purpose, with easy management of the measurement data, a wide set of options for presenting and exporting the graphics.
The orientation diagram (left). The user can select a white or black graphic background as desired. Various options to design the orientation diagram as desired (right), e.g. display section, length of lines, show/hide events and change their display color.
The orientation histogram is another tool for displaying the measurement data from a prehistoric object or a site. It is very helpful to recognize atypical distributions of the measurement data. Everything that has been said in the orientation diagrams can be repeated for the orientation histograms.
The orientation histogram (left). Custom graphic display as a bar or curve, with or without a grid. Various options to design the orientation histogram as desired (right), e.g. display section, show/hide events, grid, plot type and change their display color. If data is missing, random data can be generated for test purposes.
The current AstroArch freeware version is only the beginning of the development. Due to lack of time and the great desire for approval, I have not yet been able to finish programming many planned features, such as declination diagrams, statistical calculation of the probability of whether a prehistoric object is used for astronomical observations, simulations of various events with video or animated GIF export options, search for possible events for a specific direction of observation or observation region over the millennia, implement NASA ephemeris model DE431 (from 13200BC to 17191AD), analysis of archaeoastronomical objects using geographic maps (e.g. Google Maps) with the use of transparent templates for various events, such as solstice, equinox, etc., broad set of simple astronomical and geographic calculations, such as sky charts with positions of selected objects, twilight diagrams, moon phase calendars, positions of Jupiter moons, ephemeris diagram and much more.
Irrespective of this, an archaeoastronomical software development kit (SDK) consisting of a few DLLs with associated wrapper for Delphi, Visual Basic, C #, C ++ and extensive application examples will be developed. This will enable users to develop their own archaeoastronomical tools and realize their own ideas.
Below you can download latest program release. AstroArch is a portable version and requires no installation. It is packed as zip file. Simple unpack the file to your wish folder and run the program. Enjoy!
Download AstroArch freeware for Windows
At this point I would like to thank everyone who has inspired and accompanied me through the development of AstroArch and who supported the creation of a unique tool for archaeo-astronomical research, which is simple, extensive, fast and time-saving at the same time.
Acknowledgments --------------- NASA's SRTM Project - project that helped me in the first steps in GIS Horizon by Andrew Smith - program that inspired me to write my own - the AstroArch SkyChart by Patrick Chevalley - program that told me a lot about astronomical computing JPL's Development Ephemeris - models that made possible archaeoastronomical studies deep into the past Neoprogrammers by Jay Tanner - showed me how easy and fast it is to perform accurate ephemeris calculations VSOP 87 Theory by Pierre Bretagnon - one of the most common used planetary models in the astronomical programs Megalithic Portal by Andy Burnham - portal that helped me to understand and structure better the prehistoric places Jean Meeus, Peter Duffet-Smith - their books helped me to make the first steps in the astronomical calculations Pencho Markishki (IA BAS) - for the accompanying helpful tips and guidance during programming process
Ivan Krastev successfully completed his education as a physicist at the University St. Kliment Ohridski of Sofia, Bulgaria (1989). His master's thesis is in the field of optics and spectroscopy. He lives in Austria, Moedling near Vienna since 1991 and has been working as a software developer in the IT industry for over 25 years. Ivan is the developer of MODAS (Modern Optical Design and Analysis Software), popular worldwide among amateur astronomers and telescope makers. From 2003 to 2012 Ivan was owner and editor of the journal ATMLJ (Amateur Telescope Maker Letters Journal) and for almost 10 years successfully reported to hundreds of readers worldwide on topics such as classic optics, optical calculations and design, astronomical calculations, history of optics, astronomy, sundials and antique telescopes. AstroArch is his latest software development.
Austria, 2340 Moedling, Friedrich-Lehr Str. 4-6/2/10, Ivan Krastev
AstroArch Tool for archaeoastronomical Research