This header file contains telemetry values for engineering data (i.e., quantities recorded in orbit), for example, this file will contain temperature readings taken at various parts of the instrument. The SHP file also contains data used for spacecraft operation (i.e., the Data Group 2 keywords), such as target name, position and velocity of the telescope, right ascension and declination of the target, the reference object, the sun, and the moon. SHP files are identified by the extensions ``.SHH'' and ``.SHD''.
The telemetry values in the SHP file differ from the command values in the UDL file in that SHP values are observed values and may include quantities that are not controllable. For example, the command value for the high voltage setting of Detector #1 (VHIVOLT1 in the UDL file) is a digital instruction sent to the instrument electronics controller; the telemetry value (VHVPSM1 in the SHP file) is the actual measured voltage of Detector #1. However, quantities such as temperature are not controllable-these values will appear only in the SHP file.
