Sundial for Hermanus

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.

        Time       Xtime       Ytime        date         Xan         Yan        Teqn       XTeqn
       05h00       2.251      -0.615       Jan01      -0.040       0.878      -15.00      -0.164
       05h30       2.374      -0.443       Jan15      -0.101       0.802      -10.00      -0.109
       06h00       2.456      -0.264       Feb01      -0.149       0.644       -5.00      -0.055
       06h30       2.496      -0.081       Feb15      -0.154       0.472        0.00       0.000
       07h00       2.493       0.104       Mar01      -0.135       0.283        5.00       0.055
       07h30       2.448       0.287       Mar15      -0.099       0.086       10.00       0.109
       08h00       2.361       0.465       Apr01      -0.044      -0.155       15.00       0.164
       08h30       2.233       0.636       Apr15      -0.001      -0.346                        
       09h00       2.067       0.795       May01       0.033      -0.549                        
       09h30       1.866       0.941       May15       0.040      -0.698                        
       10h00       1.633       1.070       Jun01       0.025      -0.832                        
       10h30       1.372       1.182       Jun15      -0.004      -0.887                        
       11h00       1.087       1.273       Jul01      -0.039      -0.882                        
       11h30       0.784       1.342       Jul15      -0.065      -0.818                        
       12h00       0.467       1.388       Aug01      -0.067      -0.677                        
       12h30       0.143       1.411       Aug15      -0.050      -0.512                        
       13h00      -0.184       1.409       Sep01       0.000      -0.308                        
       13h30      -0.508       1.384       Sep15       0.051      -0.118                        
       14h00      -0.823       1.335       Oct01       0.112       0.106                        
       14h30      -1.124       1.262       Oct15       0.154       0.300                        
       15h00      -1.406       1.169       Nov01       0.179       0.523                        
       15h30      -1.664       1.055       Nov15       0.169       0.682                        
       16h00      -1.893       0.923       Dec01       0.119       0.821                        
       16h30      -2.090       0.775       Dec15       0.055       0.885                        
       17h00      -2.251       0.615                  -0.040       0.878                        
       17h30      -2.374       0.443                                                            
       18h00      -2.456       0.264                                                            
       18h30      -2.496       0.081                                                            
       19h00      -2.493      -0.104