Sundial for Cape Town

Note that the "squares" on the diagram must look square, ie one unit of length horizontally must equal one unit of length vertically.

The data used to create this sundial are listed below, if you want to make your own large "walk-on" sundial. The columns are:

• Time: time at each marker on the timeline.
• Xtime: X (horizontal) offset from 0.0 (centre of graph) of each time marker.
• Ytime: Y (vertical) offset from 0.0 (centre of graph) of each time marker.
• Date: Date of each marker on the date line and analemma ("8")
• Xan: X (horizontal) offset from 0.0 (centre of graph) of each date marker on the analemma.
• Yan: Y (vertical) offset from 0.0 (centre of graph) of each date marker on the analemma; this is equal to the Y offset for the dateline. The X values for the dateline are 0.0.
• Teqn: The offsets of time correction scale at the foot of the analemma, in minutes. -15 means the Sun is 15 minutes late (e.g. in February), so 15 minutes must be added to the time read from the shadow crossing the timeline when standing on the dateline. +15 means the Sun is 15 minutes early (e.g. in early November), so 15 minutes must be subtracted from the time read from the shadow crossing the timeline when standing on the dateline.
• XTeqn: X (horizontal) offset from 0.0 of the time correction at the foot of the analemma. The Y value is set to place it conveniently below the analemma.

       Cape Town Area

        Time       Xtime       Ytime        date         Xan         Yan        Teqn       XTeqn
       05h00       2.237      -0.621       Jan01      -0.040       0.884      -15.00      -0.164
       05h30       2.364      -0.453       Jan15      -0.101       0.807      -10.00      -0.109
       06h00       2.450      -0.278       Feb01      -0.149       0.648       -5.00      -0.055
       06h30       2.494      -0.097       Feb15      -0.154       0.476        0.00       0.000
       07h00       2.495       0.085       Mar01      -0.135       0.285        5.00       0.055
       07h30       2.454       0.266       Mar15      -0.099       0.087       10.00       0.109
       08h00       2.371       0.442       Apr01      -0.044      -0.156       15.00       0.164
       08h30       2.247       0.610       Apr15      -0.001      -0.348                        
       09h00       2.085       0.768       May01       0.033      -0.553                        
       09h30       1.887       0.913       May15       0.040      -0.703                        
       10h00       1.657       1.042       Jun01       0.025      -0.838                        
       10h30       1.398       1.154       Jun15      -0.004      -0.893                        
       11h00       1.115       1.246       Jul01      -0.039      -0.888                        
       11h30       0.814       1.316       Jul15      -0.065      -0.823                        
       12h00       0.498       1.364       Aug01      -0.067      -0.681                        
       12h30       0.174       1.389       Aug15      -0.050      -0.516                        
       13h00      -0.153       1.389       Sep01       0.000      -0.310                        
       13h30      -0.477       1.366       Sep15       0.051      -0.119                        
       14h00      -0.793       1.320       Oct01       0.112       0.107                        
       14h30      -1.096       1.251       Oct15       0.154       0.302                        
       15h00      -1.380       1.161       Nov01       0.179       0.527                        
       15h30      -1.640       1.051       Nov15       0.169       0.687                        
       16h00      -1.872       0.922       Dec01       0.119       0.827                        
       16h30      -2.073       0.778       Dec15       0.055       0.891                        
       17h00      -2.237       0.621                  -0.040       0.884                        
       17h30      -2.364       0.453                                                            
       18h00      -2.450       0.278                                                            
       18h30      -2.494       0.097                                                            
       19h00      -2.495      -0.085