text: // set the dimensions and margins of the graph
  var margin = {top: 20, right: 20, bottom: 50, left: 50},
      width = 960 - margin.left - margin.right,
      height = 500 - margin.top - margin.bottom;
  
  // parse the date / time
  // var parseTime = d3.timeParse("%y");
  // var formatTime = d3.timeFormat("%e %B");
  
  // set the ranges
  var x = d3.scaleLinear().range([0, width]);
  var y = d3.scaleLog().range([height, 0]);
  
  // define the line
  var valueline = d3.line()
      .x(function(d) { return x(d.Year); })
      .y(function(d) { return y(d.Time); });
  
  var div = d3.select("body").append("div")
      .attr("class", "tooltip")
      .style("opacity", 0);
  
  // append the svg obgect to the body of the page
  // appends a 'group' element to 'svg'
  // moves the 'group' element to the top left margin
  var svg = d3.select("body").append("svg")
      .attr("width", width + margin.left + margin.right)
      .attr("height", height + margin.top + margin.bottom)
    .append("g")
      .attr("transform",
            "translate(" + margin.left + "," + margin.top + ")");
  
  
  // ============================= Main =============================
  d3.csv("chandra_proposal/chandra_proposal_data.csv", function(error, data) {
    if (error) throw error;
  
    // format the data
    data.forEach(function(d) {
        // d.Year = parseTime(d.Year);
        // d.Year = +d.Year;
        d.Time = +d.Time;
  
    });
  
    // scale the range of the data
    x.domain([1998,2021]);
  
    // d3.extent(data, function(d) { return d.Year; }));
    y.domain([1, d3.max(data, function(d) { return d.Time; })]);
  
    // add the dots with tooltips
    svg.selectAll("dot")
       .data(data)
     .enter().append("circle")
       .attr("r", 4)
       .attr("cx", function(d) { return x(d.Year); })
       .attr("cy", function(d) { return y(d.Time); })
       .style("fill","turquoise")
       .on("mouseover", function(d) {
         div.transition()
           .duration(200)
           .style("opacity", .9);
         div.html(d.PI_Name + "<br/>" + "<br/>" + d.Title + "<br/><br/>" + d.Time + "ks" + " (" + d.Year +")")
           .style("left", (d3.event.pageX) + "px")
           .style("top", (d3.event.pageY - 28) + "px");
         })
       .on("mouseout", function(d) {
         div.transition()
           .duration(500)
           .style("opacity", 0);
         });
  
    // gridlines in x axis function
    function make_x_gridlines() {
      return d3.axisBottom(x)
      .ticks(5)
    };
  
    // gridlines in y axis function
    function make_y_gridlines() {
      return d3.axisLeft(y)
      .ticks(5)
    };
  
    // add the X Axis
    svg.append("g")
        .attr("class", "grid")
        .attr("transform", "translate(0," + height + ")")
        .call(make_x_gridlines()
            .tickSize(-height)
            .tickFormat(""));
  
    svg.append("g")
        .attr("transform", "translate(0," + height + ")")
        .call(d3.axisBottom(x));
  
    svg.append("text")
        .attr("transform",
              "translate(" + (width/2) + " ," +
                             (height + margin.top + 20) + ")")
        .style("text-anchor", "middle")
        .text("Year");
  
    // add the Y Axis
    svg.append("g")
        .attr("class", "grid")
        .call(make_y_gridlines()
          .tickSize(-width)
          .tickFormat(""));
    svg.append("g")
        .call(d3.axisLeft(y));
        // text label for the y axis
  
    svg.append("text")
        .attr("transform", "rotate(-90)")
        .attr("y", 0 - margin.left)
        .attr("x",0 - (height / 2))
        .attr("dy", "1em")
        .style("text-anchor", "middle")
        .text("Time (ks)");
  
      });