StandingStones Viewer Introduction Locations Background Samples More Maths Calculator Panorama Stellarium About
Esguan

www.StandingStones.org

Introduction

www.standingstones.org is a resource site for people who want to study Archaeoastronomy for Stone Circles, Standing Stones, Stone Rows and Henges.

www.StandingStones.Org providers a viewer to display the historic rising and setting points of the Sun and Moon - Viewer Tour and Viewer

Most of the source data for the site is sourced from the Megalithic Portal and would like to thank the Megalithic Portal for use of this data.

Viewer

w3images/CastleRigg.jpg

Locations

Background

Archaeoastronomy (also spelled archeoastronomy) is the study of how people in the past have understood the phenomena in the sky, how they used these phenomena and what role the sky played in their cultures.

www.StandingStones.Org has a viewer to display the historic rising and setting points of the Sun and Moon - Viewer

The viewer has data accumulated from around 4000 sites across the UK and Ireland and many others from the rest of Europe including many Stone Circles, Standing Stones, Stone Rows and Henges.
The viewer images are based largerly on the SRTM (Shuttle Radar Topography Mission) data. LIDAR data is used for sites within England and Wales with missing areas filled with SRTM data. The SRTM data is also augmented with the Ordinace Survey (OS) based 50m map data. For UK Latitudes above 60 degrees (Shetland is mainly north of this) then OS data only is used.
For Scandinavia data for locations north of 60 degrees is from the VIEWFINDER PANORAMAS site and I would like to thank Jonathan de Ferranti for use of this data
The SRTM data is easier to process and generally produces cleaner results than the OS data although the SRTM data sometimes can vary from actual maximum heights by around 20m due to an average being taken across a tile (For instance, the SRTM tile for the summit of Snowdon is 20m below the top). The OS data is composed of 10M contour lines so provides better accuracy on steep slopes while the SRTM data is probably more useful on less steep terrain and hence both are used in conjunction. Spot heights where shown are from the OS data.

More details on most of the sites can be found at The Megalithic Portal.
Another useful reference site for many sites is The Modern Antiquarian.
Studies of the Stones Rows of Britain The Stones Rows of Great Britain.
Megalithomania.com includes all sorts of historic and prehistoric sites across Ireland, including Neolithic, Bronze Age, Early Christian and Medieval monuments although now only available on the internet archive. Megalithomania.com.
Lunar sites Scotland. It is interesting to compare the site in the Thom's long solstitial alignments article with the same sites in the StandingStones Viewer (Ballochroy and Kintraw)
mega-what.com provides accurate surveys the Whole Horizon around some sites - useful comparison site

Sample Images

The following are example images taken from a small group of Standing Stones in Anglesey (Druid Farm, SH416751, 53.24921, -4.375564) and shows how the location could have been used to observe the sun and moon at different positions.
The Winter Solstice rising of the sun over Snowdon
w3images/Druid Farm Solstice Rise.jpg
Major Lunar Standstill (-E-I) rising over Trum Y Ddysgl
w3images/Druid Farm Moon -e-i Rise.jpg

More Info

The goal of the viewer is to show the view from a monument and overlay the rising and setting positions of the Sun and Moon.
The site attempts to make study of these sites easier and provides a generally accurate representation of what could be observed historically from a site.
For the Sun, the Winter and Summer Solstices, Equinox and Cross Quarter (XQ1, XQ2) positions are shown
For the Moon the Major and Minor Lunar Standstills are shown (+e+i, +e-i, -e+i and -e-i)

Solstice and Equinox Positions

A solstice is an event occurring when the Sun appears to reach its most northerly or southerly position. The Solstices take place in Winter (about December 21) and Summer (about June 21)
An equinox is the moment at which the center of the visible Sun is directly above the Equator. The equinoxes take place in Spring (around 20 March) and Autumn (about 23 September)
The Quarter days fall between the Equinoxes and Solstices. These days marked the midpoint between a solstice and equinox. For the ancient Celts, these signaled the beginning (not middle) of a season

Lunar Standstills and Eclipses

A major Lunar Standstill occurs when the moon stops on a declination of approximately 28.725° north/south.
There is an eclipse season near the March equinox with solar and lunar eclipses at an odd numbered saros.
There is an eclipse season near the September equinox with solar and lunar eclipses at an even numbered saros.
A minor Lunar Standstill occurs when the moon stops on a declination of approximately 18.134° north/south.
There is an eclipse season near the March equinox with solar and lunar eclipses at an even numbered saros.
There is an eclipse season near the September equinox with solar and lunar eclipses at an odd numbered saros.

SRTM and OS OpenData

The Viewer uses SRTM (Shuttle Radar Topography Mission) data published by NASA together with OpenData vector data published by the OS - "Contains OS data © Crown copyright and database right (2019)". For more informtion see OS OpenData acknowledgements.
For Scandinavia data for locations north of 60 degrees is from the VIEWFINDER PANORAMAS site and I would like to thank Jonathan de Ferranti for use of this data

LIDAR Data

The Viewer uses LIDAR data for UK locations which is published by the Environment Agency which is part of DEFRA and the Welsh Government and Natural Resources Wales. A small amount of LIDAR data is available for Ireland Ireland LiDAR Data (most useful around parts of County Meath). The data is provided by the Geological Survey Ireland, Department of Culture, Heritage and the Gaeltacht, Discovery Programme, Transport Infrastructure Ireland, New York University and The Office of Public Works.
At present LIDAR coverage for England and Wales is around 60%, mainly covering river valleys and areas with a higher flood risk. Both 1m and 2m LIDAR data is used and when used together the coverage of England and Wales is becoming quite useful. Most higher land is not mapped which limits the usefulness but hopefully over time the coverage will improve - Environment Agency has announced plans to map England’s entire landscape by 2020 Mission. In the future I hope to add Scottish and potentially other LIDAR datasets as they become available and get to useful levels of coverage.
The UK LIDAR data is published under the Open Government Licence v3.0. (Open Government Licence (OGL)).
The Irish LIDAR is licensed for re-use under the Creative Commons Attribution 4.0 International license. The data is licensed for re-use under the Creative Commons Attribution 4.0 International license. http://creativecommons.org/licenses/by/4.0/
(http://creativecommons.org/licenses/by/4.0/).
An example of where the LIDAR difference makes a significant difference is the view of the -(e+i) moon set over Hog Lowe Pike from Thirteen Stones Hill. The LIDAR based image is processed from the 1m and 2m LIDAR datasets and shows the additional details that are available.
Moon Set over Hog Lowe Pike from Thirteen Stones Hill rendered from LIDAR data.
HogLowePikeLIDARData.jpg
Thirteen Stone Hill Using LIDAR data
Moon Set over Hog Lowe Pike from Thirteen Stones Hill rendered from SRTM and OS Map Data.
HogLowePikeOSSRTMData.jpg

UK LIDAR data coverage for England and Wales is now generally good although not complete - most sites in England and Wales are rendered with LIDAR data and with missing areas filled with SRTM data. Where areas are infilled with SRTM data sometimes noticeable artefacts (they appear as discontinuities or even tears across the landscape) can often be seen although overall the quality and detail obtained from the use of LIDAR data is felt generally worthwhile.
Detail of Moon Set over Harter Fell showings LIDAR coverages (on the left) and infilled SRTM areas on the right.
four-stones-hill_ny48951620_3750_120_detail.png

GPX Data

The Viewer also contains links to GPX files for each location. These files allow you to see where on a map the various rising and setting points of the Sun and Moon are. This allows you to pinpoint a foresight such as mountain or hill where the event occurred.
On Windows 10, you can install a GPX viewer with the following link. Other web based viewers are available such as Ride With GPS.

Using the Viewer

The viewer can take several parameters including the following
name=string - this is a case insenstive search string
country=Country Code (IM GG JE IE FR BE CZ PL DE GR PT NO SE CH ES MT IT DK NL UK XX)
area=County - the area of the country
type=All|Stone Circle|Standing Stones|Standing Stone (Menhir)|Stone Row - Alignment|Henge
grid=None|grid|fgrid - Specify whether to include a grid (1 degree intervals) or a fine grid (10 minute intervals).
res=High|Med|Low - Specify the image resolution (120, 60 or 30 pixels per degree).
label=None|labels - Display spot heights from OS Maps if available.
year=3700|4000|4500|5000 - Select the year - either 1750BC (3750), 2000BC (4000), 2500BC, (4500) or 3000BC (5000).
zoom=5|10|15|20|30|40|60|80|100|120|140|180 - Specify the Zoom Level.
x=0|360 - Specify the image X position in Degrees from 0 (North) to 360.
y=-1|20 - Specify the image Y position in Degrees from horizon (-1 to 20).

A type URL would be something like the following
http://www.standingstones.org/viewer.html? grid=grid&res=High&label=labels& year=5000&area=Gwynedd

Mathematics

Elevation and Azimuth of the Sun/Moon

The formula for calculating the Elevation and Azimuth of the Sun/Moon can be found at the following:
https://astronomy.stackexchange.com/ questions/1855/how-to-get-the-longitude-latitude-from-solar-zenith-azimuth
In order to calcualte the size of the sun and moon when drawing, it is assumed that all orbits are circular.
Equinox positions are calculated at the true equinox and not at half the number of days between solstices. The different between the two approaches means that the ancient equinox positions may well have been somewhat different to the true equinox position. Similarly, the Cross Quarters are calculated based on the astronomical value which may vary slighlty from the ancient values used.

Adjusting for Parallelax

Parallelax for both the sun and moon is calculated although only the values for the moon are significant. Only the mean parallex of the moon is used which at the horizon is about 57′. The Parallelax variation due to the moon's eliptical orbit can vary by around +-3′ but this is not currently displayed
https://en.wikipedia.org/wiki/ Orbit_of_the_Moon

Adjusting for Refraction

The formula for Refraction is the following Sæmundsson equation, taken from the wikipedia page which is accurate to around 0.1′ at 10 °C https://en.wikipedia.org/wiki/ Atmospheric_refraction
refraction.jpg

Adjusting for Moon "Wobble"

The moon has an additional wobble with a 173.3 day period of approximately +-9′ - this is displayed on either side of the moon as a series of dots.

Drawing the Landscape

The main formulas used when calculating what to draw is the Aviation Formulary and Haversine formulas
from: Ed Williams' Aviation Formulary
https://edwilliams.org/avform.htm
Haversine formula is used to Calculate distance (in m) between two points specified by latitude/longitude (in numeric degrees).
https://en.wikipedia.org/wiki/ Haversine_formula
Landscape dip and teresstial refraction
The dip is calculated simply based on distance and curvature of the earth and then adjusted following the R′ = R × 7/6 formula.
https://en.wikipedia.org/wiki/ International_Standard_Atmosphere
https://www.metabunk.org/standard-atmospheric-refraction-empirical-evidence-and-derivation.t8703/#post-205947
https://aty.sdsu.edu/explain/ atmos_refr/horizon.html

OS Grid Conversion

Conversion of spot heights and contours from the grid reference system (OSGB-36) to Lat/Long is using formulation implemented by Thomas, Redfearn, etc and is as published by OS.
The following is a Javascript implementattion of the algorithm that was convered to C#.
wwww.movable-type.co.uk - Convert between Latitude/Longitude & OS National Grid References

Sun Moon Calculator

The following is a screen shot of the Sun and Moon calculator showing some of the maths for the Moel Y Llyn Stone Circle for the distant moon set. Probably not very pretty but very useful for working out bearings, distances, Grid Refs and generally checking results. It now calculates the rising and setting positions of the sun/moon assuming a rise or set over the sea.
SunAndMoonCalculator.jpg
SunAndMoonCalculator.zip - ZIP of the calculator
In order for the calculator to access height data, this must be stored within a folder called "%appdata%\SRTM Data\". The SRTM tiles (e.g. N27W013.SRTMGL1.hgt.zip) can be downloaded from 30-Meter SRTM Tile Downloader
In additional, for those with Excel, there is a basic calculator written in XLSX EarthNumbers.xlsx - Simple Excel based calculator This calculator is based on the same maths as the rest of the site although the refraction calculations work are somewhat different.

Panorama Landscape Generator

The images on the Stnding Stones web site are produced by a program called Panorama which is now available to download from this link Panorama.zip - ZIP of the program.This program is still a work in progress so there are some rough edges.
Panorama is able to use SRTM, OS 50m data and LIDAR data to draw landscales. Now supports wireframe output.
Multiple command lines options are available:-
-drawJobs (draw cairns, stones etc)
-PosRange <angle> - Draw degrees above horizon
-NegRange <angle> - Draw degrees below horizon
-lidar (Process LIDAR data for locations
-lidarfolder (Location where the LIDAR source data is stored (ZIPs and ASC files)
-lidarcache (Location to save processed binary LIDAR cache data for later use
-lidarrange MaxDistance (Maximum distance (m) from observer to use LIDAR data (default 10000)
-f OutputFilename
-r (replace file)
-country <xx> - short country code, e.g. FR for France
-CountryLong <country> - long country name, e.g. France
-match <sitename>
-region <region>
-hf <height> - Height Filter
-county <CountyFile>
-countyHTML <CountyFileHTML>
-locs (dump location GPX files)
-mr - Create multiple resolutions of images (30, 60 pixels per degree)
-ch - Save Horizon GPX File
-pp - Create Passing Points, where the sun/moon cross the horizon
-labels (spot height labels)
-spots (Add OS spot markers)
-nospots (Don't add OS spot markers)
-contours (Add OS Contours)
-srtm (Use SRTM Data)
-grid (add a grid)
-fgrid (fine grid)
-allgrids (Create files with no grid, grid and fine grid in one go)
-stellarium (Generate Stellarium ZIP file)
-out OutputFolder
-srtmFolder <folder> - SRTM Source folder name, e.g. %USERPROFILE%\Appdata\roaming\SRTM Data
-osFolder <folder> - OS Maps 50M data FOlder e.g. %USERPROFILE%\Appdata\roaming\OS Terrain 50
-p Pixels (pixels per degree - default 120)
-oldcsv <oldcsvfile> - Not really used any more
-json JSONOutFile (Create JSON File)
-max MaxDistance in M
-l Location
-a age
-t (Create Template file)
-tf InputTemplateFilename
-d Description
-h Height
-csv CSVFiles (Bulk process from a list of CSV files)
-threads N (Number of threads to run)
-Solstice - Draw Sun Solstices
-Equinox - Draw Sun Equinox
-xq - Draw Sun Cross Quarters
-Moon+e+i - Draw Moon +e+i
-Moon+e-i - Draw Moon +e-i
-Moon-e+i - Draw Moon -e+i
-Moon-e-i - Draw Moon -e-i
-AllSun - Draw all Sun positions
-AllMoon - Draw all Moon positions
-CacheLIDAR N (Number of LIDAR tiles to cache (400MB per tile, default 4)
-CacheSRTM N (Number of SRTM tiles to cache (26MB per tile, default 12)
-CacheOSMap N (Number of OS Map tiles to cache (few MB each, default 150)
-ColourSea <RGB> - Default is Hex RGB (e.g. 000000) for Black
-ColourSky <RGB> - Default is Hex RGB for Blue
-ColourBase <RGB> - Default is Hex RGB for DarkGreen
-ColourTops <RGB> - Default is Hex RGB for Brown
-ColourDistant <RGB> - Default is Hex RGB for DimGray
-ColourOriginLatitude <latitude> - default 45
-ColourSlopeAdjust <int> - default 20
-ColourMaxDist <metres> - default 10k
-ColourGreenBrownShades <count) - default 40
-ColourGreyCount <count) - default 80
-ColourMaxHeight <height> - max height colour in metres
-ColourMoon <RGB> - Default is Hex RGB for Grey
-ColourSun <RGB> - Default is Hex RGB for Yellow
-ColourSaMText <RGB> - Sun and Moon Text - Default is Hex RGB for Black
-ColourTitle <RGB> - Default is Hex RGB for White
-ColourCairns <RGB> - Default is Hex RGB for Red
-ColourStones <RGB> - Default is Hex RGB for DarkGrey
-ColourSpotHeight <RGB> - Default is Hex RGB for Dark Red
-ColourReticleBackground <RGB> - Default is Hex RGB for White
-ColourReticleMajor <RGB> - Default is Hex RGB for Dark Grey
-ColourReticleMinor <RGB> - Default is Hex RGB for Grey
-ColourReticleHorizontal <RGB> - Default is Hex RGB for Black
-ColourReticleText <RGB> - Default is Hex RGB for Black
-CopyrightNotice <Text> - Change Copyright Notice Text
-DumpHeights <string> - Where string is latitue, longitude, lat Increment, lon Increment, lat Count, lon count (e.g. "53.068053, -4.076761,2.777777777777778e-5,2.777777777777778e-5,100,100")
-MaxJobs <number> - Stop processesing after at most N jobs (the MSFT ZIP library leaks badly so useful to restart after N jobs - for LIDAR sites set N to ~3)
-ProximalInterpolation - Perform Proximal Interpolation rather than Linear (Mincraft mode)
-ObserverHeight <height> - Observer eye height (1.5m)
-SiteTypes = <types> - where default types are "Stone Circle,Ring Cairn,Standing Stone(Menhir),Standing Stones,Stone Row / Alignment,Henge,Multiple Stone Rows / Avenue,Viewpoint"
-BlobStoreURL <URL> - where URL default is "https://standingstonesorg.blob.core.windows.net/"
-ViewGPSURL <URL> - where URL default is "https://gpsvisualizer.com/atlas/map?url="
-ViewImageURL <URL> - where URL default is "http://www.standingstones.org/viewer.html?name="
-MegpURL <URL> - where URL default is "https://www.megalithic.co.uk/article.php?sid="
-StandStonesHost <URL> - where host default is www.standingstones.org

The following is a screen shot of the Panorama UI program showing a couple of example renders of Castlerigg, one part way through and the other after completion. A hopefully useful front end to the command line panorama program.
PanoramaUI1.jpg

PanoramaUI2.jpg

Stellarium

Stellarium is a free open source planetarium for your computer. It shows a realistic sky in 3D like you would see with the naked eye, binoculars or a telescope. http://stellarium.org/
Each site in the Viewer has a Stellarium ZIP file link - this link allows you to download the landscape in a format suitable for input into Stellarium. Within Stellarium, hit F4 and then select import landscape to play.
The following is an example image from Stellarium of the Mid Summer Sunset from Raven's Stone, Elgol on Skye
RavensStoneElgol.png
A brief wlakthrough of setting up Stellarium to look at sites
Using Stellarium to view www.StandingStones.org Sites.pdf

Other Stuff

A map of the North Preselis generated my "Stone Circle Detector" program that generates a map of where setting/rising of the sun/moon can be observed for various foresights.
preselinorth.gpx Map
A map of the Anglesay generated my "Stone Circle Detector" program that generates a map of where setting/rising of the sun/moon can be observed for various foresights.
angleseysunandmoon.gpx Map

Sometimes the LIDAR and OS Map data heights diverge from each other and where this happens, the rendering can be somewhat off. The LIDAR Check Link below page shows locations where there are OS Map points (either spot heighs or contours) with heights that are 4m or more different than the LIDAR data.
This often occurs when the location is in woodland, at the edge of the sea, in quarries or locations where building work has occurred. Luckily instances where the values for hilltops being significantly out is quite rare.
An example of this is for the Nipstone (52.566630, -2.950539) which seems to have been largely removed by the LIDAR processing - SO39 Map that covers the Nipstone

LIDAR Checks Links

Possible Site of the Original Bluestone Ring Paper

Possible Site of the Original Bluestone Ring - paper by my father by John R. Hoyle
Bluestones for Net publication 3.pdf

About and Copyright

Copyright David Hoyle 2021.
Maps images by Captain Blood - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=930331
By Maximilian Dörrbecker (Chumwa) - Self made, using Northern Ireland - Counties copy|this map by NNW, CC BY-SA 2.5, https://commons.wikimedia.org/w/index.php?curid=7918534
This Serbia map file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license. https://creativecommons.org/licenses/by-sa/3.0/legalcode