d3 tributary one circle orbiting another on drag

config.json

{"description":"One circle orbiting another on drag","endpoint":"","display":"svg","public":true,"require":[],"fileconfigs":{"inlet.js":{"default":false,"vim":true,"emacs":false,"fontSize":12},"config.json":{"default":true,"vim":false,"emacs":false,"fontSize":12}},"tab":"edit","display_percent":0.7,"play":false,"loop":false,"restart":false,"autoinit":true,"pause":true,"loop_type":"period","bv":false,"nclones":15,"clone_opacity":0.4,"duration":3000,"ease":"linear","dt":0.01,"hidepanel":false}

inlet.js

var svg = d3.select("svg");

var cx = tributary.sw/2;
var cy = tributary.sh/2;
var outr = 200;

var outer = svg.append("circle")
    .attr({
      cx: tributary.sw/2,
      cy: tributary.sh/2,
      r:outr,
      fill: "none",
      stroke: "#1B8600",
      "stroke-width":4
    });

var electron = svg.append("circle")
    .attr({ 
      cx: tributary.sw/2,
      cy: tributary.sh/2,
      r: 15,
      fill: "#067BA8"
    })

var drag = d3.behavior.drag()
    .on("drag", function(){
    var mx = d3.mouse(this)[0];
    var my = d3.mouse(this)[1];
    var omega = Math.atan2(mx -cx,my-cy);
    var nx = outr*Math.sin(omega);
    var ny = outr*Math.cos(omega);
      electron.attr({
        cx:cx+nx,
        cy:cy+ny
      })
    
    })
        
electron.call(drag);