ST_SetUpperLeft — Sets the value of the upper left corner of the pixel of the raster to projected X and Y coordinates.
raster ST_SetUpperLeft(raster rast, double precision x, double precision y);
Set the value of the upper left corner of raster to the projected X and Y coordinates
SELECT ST_SetUpperLeft(rast,-71.01,42.37)
FROM dummy_rast
WHERE rid = 2;