High-speed Tap Pipeline

The high-speed tap (HST) pipeline acquired raw, complete CCD frames directly from the camera using a secondary data pathway that is available only on the ground. Having this independent data pathway allows a direct check on the fidelity of the flight processing electronics and software.

The CCD frame data emerging from the camera high-speed tap were captured by the ACIS EGSE workstation and written to disk as FITS images. Software running on the ACIS EGSE processed these images to correct for bias and to extract events, producing FITS event lists. This process and the format of the high-speed tap event lists are described in Section 3.2.

The high-speed tap was used in all phases of ACIS calibration at the XRCF. During the ACIS-2C calibration only high-speed tap data was available because the 2C camera did not support the event extraction and telemetry formatting functions of the flight ACIS experiment. An archive of event lists is maintained by the Calibration Group at the AXAF Science Center and is available on the web athttp://asc.harvard.edu/cal/.