# 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.
The units for the X and Y distances are metres for a walk-on sundial.
Note that the time- and datelines should be drawn as smooth curves.

```       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

```

since 2002/05/02
www.hartrao.ac.za/other/sundial/sdllon.html
Last updated 2002/05/02 by M Gaylard