How do I get my LinkButton to open in a separate window / tab?

I'm having trouble making my LinkButton open in a separate window / tab. How do I do this? In my HTML, its the first LinkButton (ID="lnkbtnGoogleMap")

my HTML

                            <asp:DataGrid ID="dgSummary" runat="server" AllowPaging="True" AllowSorting="true"
                                PagerStyle-Mode="NumericPages" PagerStyle-Position="TopAndBottom" PagerStyle-HorizontalAlign="center"
                                PagerStyle-BackColor="#CCCCCC" PagerStyle-NextPageText="Next Page" PagerStyle-PrevPageText="Prev Page"
                                Font-Size="14px" AutoGenerateColumns="False" CellPadding="2" PageSize="10" Width="80%"
                                OnPageIndexChanged="dgSummary_PageIndexChanged" OnSortCommand="dgSummary_SortCommand"
                                OnItemCommand="dgSummary_ItemCommand">
                                <HeaderStyle BackColor="#CCCCCC" HorizontalAlign="Center" Font-Bold="true"></HeaderStyle>
                                <Columns>
                                    <asp:TemplateColumn Visible="false">
                                        <ItemTemplate>
                                            <asp:Label ID="lblPSEQ" runat="server" Text='<%# Eval("PSEQ") %>' />
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:TemplateColumn Visible="false">
                                        <ItemTemplate>
                                            <asp:Label ID="lblCompName" runat="server" Text='<%# Eval("PNAME") %>' />
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <%--<asp:BoundColumn HeaderStyle-Width="425px" HeaderText="Name" DataField="PNAME" SortExpression="PNAME" />--%>
                                    <asp:TemplateColumn HeaderText="Company Name" ItemStyle-Width="100em" HeaderStyle-ForeColor="#034AF3"
                                        ItemStyle-HorizontalAlign="Center">
                                        <ItemTemplate>
                                            <asp:LinkButton ID="lnkbtnGoogleMap" Text='<%# Eval("PNAME") %>' CommandName="GoogleMap"
                                                runat="server" OnClientClick="_blank"/>
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                    <asp:BoundColumn HeaderStyle-Width="400px" HeaderText="City" DataField="PCITY" SortExpression="PCITY"
                                        ItemStyle-HorizontalAlign="Center" />
                                    <asp:BoundColumn HeaderStyle-Width="75px" HeaderText="State" DataField="PSTATE" SortExpression="PSTATE"
                                        ItemStyle-HorizontalAlign="Center" />
                                    <asp:BoundColumn HeaderStyle-Width="400px" HeaderText="Summary Count" DataField="PCOUNT"
                                        SortExpression="PCOUNT" ItemStyle-HorizontalAlign="Center" />
                                    <asp:TemplateColumn HeaderText="Details" ItemStyle-Width="400px" HeaderStyle-ForeColor="#034AF3"
                                        ItemStyle-HorizontalAlign="Center">
                                        <ItemTemplate>
                                            <asp:LinkButton ID="lnkButton" Text="Show Details" CommandName="ShowDetails" runat="server" />
                                        </ItemTemplate>
                                    </asp:TemplateColumn>
                                </Columns>
                            </asp:DataGrid>

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my C#

protected void dgSummary_ItemCommand(object source, DataGridCommandEventArgs e)
    {
        Label lblCompName;
        Label lblPSEQ;

        lblMsg1.Text = string.Empty;

        if (e.CommandName == "GoogleMap")
        {
            iDB2Connection con;
            iDB2DataReader dbr;
            iDB2Command cmd;

            string strSelect;
            string temp;

            rblDetailsSummary.SelectedIndex = 0;
            lblPSEQ = (Label)e.Item.Cells[0].FindControl("lblPSEQ");
            lblCompName = (Label)e.Item.Cells[0].FindControl("lblCompName");

            using (con = new iDB2Connection())
            {
                con.ConnectionString = ConfigurationManager.AppSettings["ConnString"];
                con.Open();

                strSelect = @"SELECT PADDRESS, PCITY, PSTATE, PZIP FROM ais2000d.POLK WHERE PSEQ = " + lblPSEQ.Text.ToString().Trim();
                cmd = new iDB2Command(strSelect, con);
                dbr = cmd.ExecuteReader();

                if (dbr.Read())
                {
                    if (!dbr["PADDRESS"].ToString().ToUpper().Trim().Equals("ADDRESS NOT AVAILABLE"))
                    {
                        lblMsg1.Text = string.Empty;
                        Response.Redirect("http://maps.google.com/?q=" + dbr["PADDRESS"].ToString().Trim() + "+" +
                            dbr["PCITY"].ToString().Trim() + "+" + dbr["PSTATE"].ToString().Trim() + "+" + dbr["PZIP"].ToString().Trim());
                    }
                    else
                        lblMsg1.Text = @"*** NO ADDRESS AVAILBLE! FOR: " + lblCompName.Text.ToString().Trim() +
                            " IN " + dbr["PCITY"].ToString().Trim() + " ***";
                }
            }
        }
    }

Select allOpen in new window