Sundial for London, England

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.

       London Area
        Time       Xtime       Ytime        date         Xan         Yan        Teqn       XTeqn
       05h00      -2.415      -0.506       Jan01       0.040      -0.663      -15.00      -0.164
       05h30      -2.479      -0.255       Jan15       0.101      -0.605      -10.00      -0.109
       06h00      -2.500       0.000       Feb01       0.149      -0.486       -5.00      -0.055
       06h30      -2.479       0.255       Feb15       0.154      -0.357        0.00       0.000
       07h00      -2.415       0.506       Mar01       0.135      -0.214        5.00       0.055
       07h30      -2.310       0.749       Mar15       0.099      -0.065       10.00       0.109
       08h00      -2.165       0.978       Apr01       0.044       0.117       15.00       0.164
       08h30      -1.983       1.191       Apr15       0.001       0.261                        
       09h00      -1.768       1.383       May01      -0.033       0.414                        
       09h30      -1.522       1.552       May15      -0.040       0.527                        
       10h00      -1.250       1.694       Jun01      -0.025       0.628                        
       10h30      -0.957       1.808       Jun15       0.004       0.670                        
       11h00      -0.647       1.890       Jul01       0.039       0.665                        
       11h30      -0.326       1.940       Jul15       0.065       0.617                        
       12h00       0.000       1.957       Aug01       0.067       0.511                        
       12h30       0.326       1.940       Aug15       0.050       0.386                        
       13h00       0.647       1.890       Sep01       0.000       0.233                        
       13h30       0.957       1.808       Sep15      -0.051       0.089                        
       14h00       1.250       1.694       Oct01      -0.112      -0.080                        
       14h30       1.522       1.552       Oct15      -0.154      -0.226                        
       15h00       1.768       1.383       Nov01      -0.179      -0.395                        
       15h30       1.983       1.191       Nov15      -0.169      -0.515                        
       16h00       2.165       0.978       Dec01      -0.119      -0.620                        
       16h30       2.310       0.749       Dec15      -0.055      -0.668                        
       17h00       2.415       0.506                                                            
       17h30       2.479       0.255                                                            
       18h00       2.500       0.000                                                            
       18h30       2.479      -0.255                                                            
       19h00       2.415      -0.506