I'm using a javascript like this to transfer to another page (a popup that occurs conditionally)

string popupScript = "<script language='javascript'>" +
"window.open('Duplicate.aspx', 'CustomPopUp', " +
"'width=800, height=600, menubar=yes, resizable=no')" +
"</script>";
Page.RegisterStartupScript("PopupScript", popupScript);

My question is how would I get data from the first page to the second one, either in the form of objects, or raw data (like a string [] ) I've done the regular server transfers, but here I don't need to/want to post back so I don't have the serverVariables available