NAME

voltfac -- Calculate high voltage factors.

USAGE

voltfac intable outtable type refhv

DESCRIPTION

This task determines high voltage factors for a set of data points, acquired by observing the same target through the same aperture and the same detector, but with different high voltage settings. It is also assumed that these data are obtained at approximately the same temperature and time.

High voltage factors are calculated by dividing observed count rates (corrected for dark signal, etc.) obtained at various high voltage settings by count rates obtained at the reference voltage setting.

Before actually performing the calculations, the raw digital count rates must be corrected for the dead time, dark signal, and pre-amp noise using the following equation:

        scaled digital count rate = raw digital count rate /
                (1. - raw digital count rate * dead time)
                - dark signal - pre-amplifier noise

Similarly, analog data is corrected as follows:

        scaled analog count rate = (raw analog DN - CVC offset) /
                (gain factor) - dark signal - pre-amplifier noise

PARAMETERS

intable [file name]

Name of the input table. The following columns are needed:

'DETECTOB'      Detector ID (int).
'APERTOBJ'      Aperture name (char*10).
'VOLTAGE'       High voltage setting (real).
'VGAIND'        Gain setting (real).
'THRESH'        Discriminator threshold setting (real).
'DET_TEMP'      Detector temperature (real).
'DEA_TEMP'      DEA temperature (real).
'EPOCH'         Epoch of observation (double).
'PTSRCFLG'      Point source flag (char*1).
'TRGTNAME'      Target name (char*20).

For digital data, the following columns are also needed:

'DOBJ'		Digital count rate (real).
'DOBJ_ERR'	Mean error of digital count rate (real).

For analog data, the following columns are also needed:

'AOBJ'          Analog reading (real).
'AOBJ_ERR'      Mean error of analog reading (real).

outtable [file name]

Name of the output table to be created by voltfac; this table will have the following columns:

'TYPE'          Data type (char*8).
'DET_NUM'       Detector ID (int).
'VOLTAGE'       High voltage setting (real).
'HVFACT'        High voltage factor (real).
'HVFACT_ERR'    Error of high voltage factor (real).
(temp_key)      The temperature; the actual column name 
		is passed from the 'temp_key'
		parameter (real).
'EPOCH'         Epoch (double).
'APER_NAME'     Aperture name (char*10).
'TRGTNAME'      Target name (char*20).

type [string, allowed values = analog | digital]

Input data type.

refhv [file name]

Name of the reference high voltage table, which has the following columns:

'DET_NUM'       Detector ID (int).
'VOLTAGE'       The reference high voltage setting (real).

(cal_tables = "") [string]

Pset name for calibration file parameters. Parameters can be individually changed from the command line or can be edited as a group using :e from eparam or from the cl, eparam cal_tables or simply cal_tables. Details about these parameters are available by typing "help cal_tables".

(save = no) [boolean]

Save the scratch table containing intermediate calibration corrections?

If this parameter is set to "yes", a message will be sent to the terminal and the logfile.

(temp_key = "DET_TEMP") [string]

Column name of the temperature in the input table.

EXAMPLES

1. Calculate high voltage factors from the input data table xvoltfac$input putting the results in the output table yvoltfac$output while saving the intermediate result in another local table whose name will be announced to the user. Digital data is used. The reference high voltage table is xvoltfac$refhv.

hs> voltfac "xvoltfac$input" "yvoltfac$output" "digital" "xvoltfac$refhv" 
    save=yes temp_key="DET_TEMP" 

BUGS

REFERENCES

SEE ALSO