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This is Steve Lelievre's personal website. It contains a small collection of bits and pieces relevant to sundials and sundial calculations, in particular some tools for people (i.e. me!) who do sundial-related programming with Excel or Javascript.

If you are interested in sundials generally or want to learn more about them, you will find many helpful resources on the North American Sundial Society website.

Index Sciathericus

A searchable database of the references for articles in sundial society publications.


Solar Data Now

Solar Data Now is a simple tool that shows current solar data for your location. Although it is has a compact screen layout intended for cell phones, it also works on desktop computers.

If you bookmark Solar Data Now on your mobile phone, it will open in a browser tab. If you create a home page icon, it will behave as an app (webapp) on subsequent use: full screen with no browser bar [tested on iPhone; should also work on Android but I don't have access to that type of phone].


Equation of Time and Solar Declination Calculator

The calculator generates annual tables of Equation of Time and Solar Declination data. You have several choices for table layout, and for how the Equation of Time is formatted. Choose any year up to 2099, or get values averaged over a range of years. The options allow you to get the Equation of Time as either the traditonal (solar to mean time) or modern/IAU (mean to solar time) version, optionally adjusted to a standard time zone. Some other minor options are provided.


You may also be interested in my ±1 minute version of an Equation of Time table.


Wedge Calculator

Calculates the wedge needed when a sundial is moved from the original design location to a new home.


Sun Position Graphs

Plots showing relationships of Solar Altitude, Azimuth, and Hour Angle.


Excel gmath library

The gmath library is an Excel add-in. It adds a set of extra functions to Excel for doing some of the routine calculations and conversions often needed by dialists.


Javascript gPlot.js and gMath.js libraries

The gPlot.js library wraps the SVG functions of HTML and Javascript to provide drawing features needed to write online sundial drawing programs. It aims to hide the complexity of the native SVG interface while providing enough functionality for you to place shapes and text in a 2D drawing area, with control of color, dimensions, etc. Circular and elliptical arcs, and compound (multi-point) lines can be drawn. Curved text is also supported.

The gMath.js library is similar to the Excel equivalent but as of 2020-02-25 it only provides trigonometry functions.


Coordinate Converter

A page that does only one specialist thing - it converts coordinates given in decimal degrees to the standard format used for the NASS registry of sundials.


My recent sundial generator programs

Hevelius Sundial Generator - calculates the dial face of a Hevelius dial (a slightly peculiar portable altitude dial).


Hectemoros Sundial Generator - calculates the faces of a Hectemoros dial (an unusual latitude independent dial).


Others to come when I get time!

Older sundial drawing programs

Here are a couple of my older sundial programs. They generate PDFs using an external Javascript library. I plan to re-implement using SVG (using mygPlot.js and gMath.js libraries, of course!)

A Foster-Lambert sundial that shows the time remaining before sunset.

This program draws the parts needed. It assumes you will get them laser cut from a sheet of material such as Baltic Ply. See my article "A Foster-Lambert Dial Showing Hours To Sunset" in The Compendium 20(2), June 2017, pp.16-20.


A Solar Decliner vertical sundial that shows the time remaining before sunset.

This program draws a dial face intended to be printed on vellum inserted in the front of a deep frame with a mirror at the back. The sundial is operated by turning the frame. See my article "An Hours To Sunset, Solar Declining dial using a mirror in a box" in The Compendium 22(2), June 2017, pp.14-18.


A horizontal dial with a movable circular scale, showing either Civil Time or Time to Sunset.

This program draws a dial face from which a movable ring is cut out. Depending on the option selected, the resulting dial will either show Civil Time (clock time) or the length of daylight remaining.