The data in this graph are collected from a Hot Little Therm digital thermometer, from the people at Spiderplant using their software and kali, a Sun SPARCstation 20. Kali normally samples the temperature every 5 minutes.
The graph is automatically generated by cron, using the Ploticus Data Display Engine and a ksh shell script, plottemps that johan wrote.
The graphs are in PNG format, a very good format publishing images on the web for several reasons: