Instrument-Specific Software

High Speed Photometer


Software for the High Speed Photometer is located in the
hsp package, including the calibration task calhsp. The hsp package includes tasks that can be used to calibrate the High Speed Photometer, monitor the instrument's health, and reduce its data. The tasks are grouped below, based on their relation to the Routine Science Data Processing (RSDP), which is automatically performed at STScI on all science data received from the spacecraft. RSDP-related tasks include algorithms to generate the calibration coefficients for high voltage and gain factors, detector efficiency, dark signal, dead time, etc., as well as the calibration algorithm (calhsp), which applies all these correction factors to the observational data. Tasks not related to RSDP include those used to monitor the instrument's health (warm-up time determination, detector linearity verification, etc.), calibrate the polarimeter, locate the apertures, and other general tasks (spacecraft velocity and position determination, polynomial fitting and evaluation, etc.).

RSDP-Related Calibration Software

The Routine Science Data Processing is performed at STScI to calibrate all HSP observations in a consistent manner. The main purpose of the STSDAS calibration software is to provide the calibration parameters needed for RSDP; Table 6.10 summarizes these parameters. For each parameter, the table lists the primary STSDAS task that generates the parameter, and the name of the calibration data base table (if any) that is used to store the parameter. A complete definition of the calibration data base tables can be found in the Calibration Data Base Data Design document.*1



HSP Calibration Parameters Required by RSDP

Aperture sizes (CCP0) and dark aperture translations (CCP9) are not quantities that are calibrated with observational data. The rest of the above quantities, except paired-pulse correction (CCP8), have the identical formula in RSDP processing. They are expressed as a third-order, bi-dimensional polynomial function of temperature and time:

Where:

X is a calibration quantity,

X0 is the base value of X,

t is the observation epoch,

t0 is the reference epoch,

T is the temperature, and

T0 is the reference temperature.

Thus, sixteen coefficients are needed for each set-up combination (for example, in the case of analog gain factor, each detector ID and gain setting combination has 16 polynomial coefficients) in each relation. Paired-pulse correction is calibrated only as a linear function of temperature for each set-up combination (detector ID, voltage, and threshold setting).

Non-RSDP-Related Calibration Software

In addition to those calibration parameters needed by RSDP (described above), several HSP calibration parameters are needed to make full use of the instrument's other functions, and to monitor its performance. These additional parameters are described in Table 6.11.



Additional Calibration Parameters (Non-RSDP) for HSP

Non-RSDP tasks in this package can be put into four groups. The first group performs polarimetry calibrations, the second locates the aperture center, the third monitors instrument health, and the fourth performs miscellaneous functions.

RSDP-Related Calibration Software
Non-RSDP-Related Calibration Software

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