The PHD Guiding software from Stark Labs (http://www.stark-labs.com) is a popular, free package for telescope autoguiding on Macs and PCs. The goal of this project is to bring PHD Guiding to Linux.

The core routines of PHD Guiding are supplied here. What is missing, by and large, is support for hardware. Most camera makers do not supply Linux drivers and much work is needed here. Likewise, support for guide output devices (e.g., ShoeString GPUSB, GC USBST4, etc.) is needed.

Finally, of course, by opening up the core guide routines for PHD Guiding, we open ourselves up to improvement as PHD's developer (Craig Stark) can only do so much by himself.

At the moment, the project need not be extended beyond Linux as Windows and OS X versions exist, are free, and are mature. Bug fixes and enhancements to the core routines will, of course, be patched into those releases (which will still be done via the Stark Labs website).