[OpenLayers-Users] yet another spherical mercator / geographic question

[Andrew Schuh]

I have managed to get all of my data in EPSG900913 believing that would help
me overlay on google imagery but I still have a nagging problem.  I have a
vector data source representing some polygons.  These display very
accurately against google imagery at very high zoom levels, several hundred
meters across in window.  As one zooms out, it becomes just slightly offset
to the south, several hundred miles in window.  Not terrible, but definitely
noticeable to a user, especially when the polygons are sandwiched up against
a river bank.  The basics of the code are below.  Is this an error in my
coding or a limit of what one can do w/ overlaying on the spherical mercator
imagery?

function initmap(){
  var options = {
      projection: new OpenLayers.Projection("EPSG:900913"),
      displayProjection: new OpenLayers.Projection("EPSG:900913"),
      units: "m",
      maxResolution: 156543.0339,
      maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,
20037508.34, 20037508.34),
      numZoomLevels:22
    };

  map = new OpenLayers.Map('map', options);
   var gsat = new OpenLayers.Layer.Google(
                "Google Satellite",
                {type: G_SATELLITE_MAP,
                 sphericalMercator: true }
            );


OpenLayers.loadURL("/rcbra/web/content/maps/DecisionUnits.geojson",
			null,
			this,
			onGeoJsonLoadSuccess,
			onGeoJsonLoadFailure
	);
			      	     

function onGeoJsonLoadSuccess(data) {
	var geojson_format = new OpenLayers.Format.GeoJSON();
	var pizzastores = new OpenLayers.Layer.Vector("GeoJSON Layer");  
        map.addLayer(pizzastores);
        //alert(data.responseText);
        pizzastores.addFeatures(geojson_format.read(data.responseText));
}

function onGeoJsonLoadFailure(data) {
   
}

    map.addLayers([gsat,terraservice]);
    map.addControl(new OpenLayers.Control.ZoomBox());
    map.addControl(new OpenLayers.Control.LayerSwitcher());
    map.addControl(new OpenLayers.Control.MousePosition());
    map.addControl(new OpenLayers.Control.Permalink());
}
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