The IRIS SACPZ web service returns the poles and zeros of the selected instrument responses in SAC ASCII format.

Metadata may be selected based on network, station, location or channel names in addition to time.

Web service clients that use ws-sacpz can be found at the Clients list. In particular the FetchData script will request SAC Poles and Zeros from ws-sacpz and write them to channel-specific files.

More information