Setting TimeExtent Parameter for an Image Service Layer...

[GISAdmin1]

Is this the correct way to specify the time of year I would like my imageservicelayer to display?  It does not appear to make a difference.

imageServiceParameters75 = new esri.layers.ImageServiceParameters();
imageServiceParameters75.TimeExtent=173998939;
imageServiceParameters75.bandIds = [3,2,1];
  
imageServiceLayer1975 = new esri.layers.ArcGISImageServiceLayer("http://imagery.arcgisonline.com/ArcGIS/rest/services/LandsatGLS/MSS_Multispectral_1975/ImageServer", {imageServiceParameters:imageServiceParameters75 });
map.addLayer(imageServiceLayer1975);

Thanks in advance,

Mark