OS:  
- Windows 64 bit
- Max OS X 64 bit
PHD2 is telescope guiding software that simplifies the process of tracking a guide star, letting you concentrate on other aspects of deep-sky imaging or spectroscopy.
- Easy-to-use, “push here dummy” guiding for beginners
- Sophisticated guiding and analysis tools for experienced users
- Extensive support for commonly-used equipment
- Easy upgrade/co-installation with PHD1, including many new features
- Available for Windows, Mac, and Linux
- Extensive online help and responsive product support