Use NASA SRTM data to estimate elevations
Chankillo Solar Observatory Worksheet #2
Get Elevation of Observation Points and Towers
Use NASA Shuttle Radar Topographic Mission (SRTM) online data to obtain approximate elevation for the two observation points and the hill on which the 13 towers rest.
Use longitude and latitude obtained by manually selecting points in Google Earth.
bounding rectangle of the ruins:
lat of northmost tower: -9.560356965861502
lat of southmost tower: -9.562037172307594
lon of west observation point: -78.2296179913435
lon of east observation point: -78.22573325657659
SRTMv4 data for 5-degree rectangle containing the ruins
Download the SRTM file
Files are here: http://www.cgiar-csi.org/data/srtm-90m-digital-elevation-database-v4-1
Enter extremes of the bounding rectangle using the download GUI here http://srtm.csi.cgiar.org/SELECTION/inputCoord.asp
Search returns one file. Download that.
File format
Based on info at ESRI ASCII Raster format,
Row 1 of the data is at the top of the raster, row 2 is just under row 1, and so on.
File header
Data values represent elevation in meters
http://wiki.openstreetmap.org/wiki/SRTM
Each file is a series of 16-bit integers giving the height of each cell in meters arranged from west to east and then north to south
Approximate elevations in m above sea level:
W and E observation points: 175
Crest of hill (average, running North-South) with 13 towers: 208