NOTE: A 60 minute combined audio and data format CD "Auroral Chorus : Music of the Magnetosphere" is included with EACH RECEIVER ordered. This CD is the original/first 'Auroral Chorus' CD, and was not previously released. Also on this CD (dual format - data and audio) is the WR-3 Listening Guide in HTML for web browsers, and the common PDF (Adobe Acrobat Reader) format, and other files as well. Happy Listening!