Unknown Old Coordinate System of the Phillipines

Question

I am reading a report made in 1979 and the coordinates show N 46,400 and E 47, 600. This is in the Philippines. Would anybody know what the coordinate system was used in this numbers? Thanks.

Answer 1

Best I could find was Luzon 1911 Phillipines Zone V, EPSG:25395. The point would be at least south to the phillipines. Main islands lay about 1000000 metres north. UTM 51N and Pulkovo CM123E are almost nearby.

For more information on Phillipine datums, have a look at:

http://www.asprs.org/a/resources/grids/08-99-phillipines.pdf

According to that, false Northing was at 4° North up to 1962, then set to the equator.

So using the following proj string:

+proj=tmerc +lat_0=4 +lon_0=125 +k=0.99995 +x_0=500000 +y_0=0 +ellps=clrk66 +towgs84=-133,-77,-51,0,0,0,0 +units=m +no_defs

gives the follwing picture: