Magazine "Zon & Tijd"

The Netherlands′ Sundial Society has been publishing its "Bulletin" for 40 years (1978 - 2017). It is continued under a new title: "Zon & Tijd". The new journal also serves the Sundial Society of Flanders, Belgium, which discontinued its journal "Zonnetijdingen".

Listings in English of the contents from 1998 onward are available here.

A complimentary copy of "Zon & Tijd" is available here:

Bulletin 118, december 2015


Solar declination and equation of time

Table with average daily values of solar declination and the equation of time for the years 2000 - 2099, prepared by Thibaud Taudin Chabot (pdf, 43 kB).


ZW2000 software

The program ZW2000-v2 for Windows was developed by Fer de Vries (zip-file, 1,0 MB).

ZW2000 calculates various types of lines for flat sundials, for any place on earth.

The line pattern will appear on your screen immediately.

The drawings may be saved as DXF and PLT files for further processing.

The program ZW2000 version 2.0 for Windows. Minimum screen resolution 800 x 600.

The program ZW2000 version 2.0 runs on 32 and 64 bit computers.

The program extracts to folder zw2000-v2.

The manual extracts to folder zw2000-v2/manual.

The manual is a .htm document. Start with zw2000.htm.

Note: Fer de Vries passed away in 2015. The software is not supported anymore.

The theory behind the ZW2000 program is described in the article:
A uniform method to compute flat sundials (pdf, 130 KB).



Fer de Vries, Construction of analemmatic sundials (pdf, 400 KB)

Fer de Vries, Construction of bifilar sundials (pdf, 200 KB).

Fer de Vries, Construction of hemispherium (pdf, 190 KB).

J.A.F. de Rijk, Equator Projection Sundials, J. Brit. Astron. Assoc. 1986, vol. 97 (pdf, 312 KB).