The header of the ASC file looks like this:
ncols 840
nrows 603
xllcorner 7.553101000000
yllcorner 45.904949789286
cellsize 0.000277927381
NODATA_value -32768
The format is called ASCII ARC file
cellsize very closely matches 1/3600, so I assume it means 1 arc-second, the resolution of ASTER GDEM data so the pixel size is 1 arc second, that is 2pir / (3606060) = 30.92m
The data value is in meters.
The *.prj file looks like this:
GEOGCS["GCS_WGS_1984",
DATUM["D_WGS_1984",
SPHEROID["WGS_1984",6378137,298.257223563]
],
PRIMEM["Greenwich",0],
UNIT["Degree",0.017453292519943295]
]
The format is explained here
ASTER GDM on Matterhorn seems to have a dent in Matterhorn.