Section 5. High Speed Photometer

Calibrations that may be applied to High Speed Photometer (HSP) files include (1) nonlinearity correction due to dead time in digital data, (2) dark signal subtraction, (3) current-to-voltage converter (CVC) offset subtraction for analog data, (4) pre-amplifier signal subtraction, (5) division of high voltage factor due to the detector’s different efficiency at different high voltage setting, (6) division of gain factor due to the detector’s different current gain at different gain setting for analog data, and (7) division of detector efficiency due to possibly slight difference in different apertures sharing the same filter. The reference tables described in this document are used to supply these calibration quantities.

In addition, when an extended target is observed, the count rate per unit area may be preferred, and thus an aperture area reference table is needed. Also, each detector has designated spots used to calibrate the dark signals. A cross-reference table between these dark apertures and regular apertures is also used to carry out the calibration of HSP.

5.1 HSP Reference Relations and STSDAS Tables

5.1.1 Aperture Areas Table: <unique name>.CV0

The aperture areas table contains the names and areas of all the HSP’s apertures and is used by the HSP calibration. The aperture names are the same as those used to retrieve data from the .CV4 and .CV9 tables; thus every aperture retrieved from the . CV0 table must have an entry in the . CV4 table and one in the .CV9 table. The .CV0 table is loaded only from the project data base tape.

Format: Each entry contains an aperture name and an aperture area, which is used to convert HSP count rates into count rates per square arc-second. Additionally, there is a POINTER field that is a dummy field and is not used to hold data.

Table 5-1 shows the structure of the aperture areas table.

Table 5-1. HSP Aperture Areas Table, <unique name>. CV0

Column Name	Data Type	Units	Description
APER_NAME	CH*10	–	Name of aperture (SOGS aperture naming convention)
POINTER	I	–	Not used
APER_SIZE	D	arcsec2	Aperture area

5.1.2 High Voltage Factor Table: < unique name>.CV1

The high voltage factor table contains the coefficients and base values used in computing the high voltage detector characteristic (H) for the HSP calibration.

Format: Each set of base values and coefficients corresponds to a particular HSP detector high voltage setting (command value) and data type. In each set there are a base value, a reference time, a reference temperature, and 16 polynomial coefficients. Additionally, there is a POINTER field that is a dummy field and is not used to hold data.

Selection Scheme: Records are selected on the basis of detector number, type (ANALOG or DIGITAL), and high voltage setting.

Restrictions: In the high voltage factor table, there should be entries for the three standard voltage settings (corresponding to photoelectric current gains of 0.5E+6, 1.0E+6, and 2.0E+6) for each detector and data type (ANALOG/DIGITAL).

The STSDAS table produced is called <unique name>.CV0; Table 5-2 shows its structure.

Table 5-2. HSP High Voltage Factor Table, <unique name>. CV1

Column Name	Data Type	Units	Description
DET_NUM	I	digital number	Detector number, 1-5
TYPE	CH*7	none	ANALOG, DIGITAL
VOLTAGE	I	digital number	High voltage setting (command value)
POINTER	I	–	Not used
BASE_VALUE	R	none	Base value of the characteristic scaling polynomial
BASE_TEMP	R	deg Celsius	Base temperature of the characteristic scaling polynomial
BASE_TIME	D	MJD	Base time of the characteristic scaling polynomia l(Modified Julian Date)
A00	D	none	0,0th coefficient of the characteristic scaling polynomial
A01	D	day-1	0,1st coefficient of the characteristic scaling polynomial
A02	D	day-2	0,2nd coefficient of the characteristic scaling polynomial
A03	D	day-3	0,3rd coefficient of the characteristic scaling polynomial
A10	D	deg-1	1,0th coefficient of the characteristic scaling polynomial
A11	D	deg-1 day-1	1,1st coefficient of the characteristic scaling polynomial
A12	D	deg-1 day-2	1,2nd coefficient of the characteristic scaling polynomial
A13	D	deg-1 day-3	1,3rd coefficient of the characteristic scaling polynomial
A20	D	deg-2	2,0th coefficient of the characteristic scaling polynomial
A21	D	deg-2 day-1	2,1st coefficient of the characteristic scaling polynomial
A22	D	deg-2 day-2	2,2nd coefficient of the characteristic scaling polynomial
A23	D	deg-2 day-3	2,3rd coefficient of the characteristic scaling polynomial
A30	D	deg-3	3,0th coefficient of the characteristic scaling polynomial
A31	D	deg-3 day-1	3,1st coefficient of the characteristic scaling polynomial
A32	D	deg-3 day-2	3,2nd coefficient of the characteristic scaling polynomial
A33	D	deg-3 day-3	3,3rd coefficient of the characteristic scaling polynomial

5.1.3 Gain Factor Table: <unique name>.CV2

The gain factor table contains the coefficients and base values used to compute the gain detector characteristic (G) for the HSP calibration.

Format: Each set of base values and coefficients corresponds to a particular HSP detector and a gain setting (command value). In each set there are a base value, a reference time, a reference temperature, and 16 polynomial coefficients.

Selection Scheme: Records are selected on the basis of detector number and gain setting.

Restrictions: In the gain factor table, for each detector there should be entries for each of the five gain settings (0, 2, 3, 6, and 7).

Table 5-3 shows the structure of the HSP gain factor table.

Table 5-3. HSP Gain Factor Table, <unique name>. CV2

Column Name	Data Type	Units	Description
DET_NUM	I	digital number	Detector number, 1-5
VGAIND	I	digital number	Gain setting: 0, 2, 3, 6, 7
BASE_VALUE	R	DN/(counts/sec)	Base value of the characteristic scaling polynomial
BASE_TEMP	R	deg Celsius	Base temperature of the characteristic scaling polynomial
BASE_TIME	D	MJD	Base time of the characteristic scaling polynomial
A00	D	none	0,0th coefficient of the characteristic scaling polynomial
A01	D	day-1	0,1st coefficient of the characteristic scaling polynomial
A02	D	day-2	0,2nd coefficient of the characteristic scaling polynomial
A03	D	day-3	0,3rd coefficient of the characteristic scaling polynomial
A10	D	deg-1	1,0th coefficient of the characteristic scaling polynomial
A11	D	deg-1 day-1	1,1st coefficient of the characteristic scaling polynomial
A12	D	deg-1 day-2	1,2nd coefficient of the characteristic scaling polynomial
A13	D	deg-1 day-3	1,3rd coefficient of the characteristic scaling polynomial
A20	D	deg-2	2,0th coefficient of the characteristic scaling polynomial
A21	D	deg-2 day-1	2,1st coefficient of the characteristic scaling polynomial
A22	D	deg-2 day-2	2,2nd coefficient of the characteristic scaling polynomial
A23	D	deg-2 day-3	2,3rd coefficient of the characteristic scaling polynomial
A30	D	deg-3	3,0th coefficient of the characteristic scaling polynomial
A31	D	deg-3 day-1	3,1st coefficient of the characteristic scaling polynomial
A32	D	deg-3 day-2	3,2nd coefficient of the characteristic scaling polynomial
A33	D	deg-3 day-3	3,3rd coefficient of the characteristic scaling polynomial

5.1.4 Pre-amp Table: <unique name>.CV3

The pre-amp table contains the coefficients and base values used in computing the pre-amplifier detector characteristic (E) for the HSP calibration. The PRE AMP detector characteristic (E) is the contribution to the digital count rate or analog current from the electronics.

Format: Each set of base values and coefficients corresponds to a particular HSP detector and data type. In each set there are a base value, a reference time, a reference temperature, and 16 polynomial coefficients.

Selection Scheme: Records are selected on the basis of detector number and data type

(ANALOG or DIGITAL).

Restrictions: In the pre-amp table, there should be an entry for each detector and data type

(ANALOG/DIGITAL). Table 5-4 shows the structure of the HSP pre-amp table.

Table 5-4. HSP Pre-amp Table, <unique name>. CV3

Column Name	Data Type	Units	Description
DET_NUM	I	digital number	Detector number, 1-5
TYPE	CH*7	none	ANALOG, DIGITAL
BASE_VALUE	R	none	Base value of the characteristic scaling polynomial
BASE_TEMP	R	deg Celsius	Base temperature of the characteristic scaling polynomial
BASE_TIME	D	MJD	Base time of the characteristic scaling polynomial
A00	D	none	0,0th coefficient of the characteristic scaling polynomial
A01	D	day-1	0,1st coefficient of the characteristic scaling polynomial
A02	D	day-2	0,2nd coefficient of the characteristic scaling polynomial
A03	D	day-3	0,3rd coefficient of the characteristic scaling polynomial
A10	D	deg-1	1,0th coefficient of the characteristic scaling polynomial
A11	D	deg-1 day-1	1,1st coefficient of the characteristic scaling polynomial
A12	D	deg-1 day-2	1,2nd coefficient of the characteristic scaling polynomial
A13	D	deg-1 day-3	1,3rd coefficient of the characteristic scaling polynomial
A20	D	deg-2	2,0th coefficient of the characteristic scaling polynomial
A21	D	deg-2 day-1	2,1st coefficient of the characteristic scaling polynomial
A22	D	deg-2 day-2	2,2nd coefficient of the characteristic scaling polynomial
A23	D	deg-2 day-3	2,3rd coefficient of the characteristic scaling polynomial
A30	D	deg-3	3,0th coefficient of the characteristic scaling polynomial
A31	D	deg-3 day-1	3,1st coefficient of the characteristic scaling polynomial
A32	D	deg-3 day-2	3,2nd coefficient of the characteristic scaling polynomial
A33	D	deg-3 day-3	3,3rd coefficient of the characteristic scaling polynomial

5.1.5 Efficiency Table: <unique name>.CV4

The efficiency table contains the coefficients and base values used in computing the efficiency (relative sensitivity) detector characteristic (R) for the HSP calibration.

Format: Each set of base values and coefficients corresponds to a particular HSP aperture and detector. In each set there are point and extended base values, a reference time, a reference temperature, and 16 polynomial coefficients.

**Selection Scheme: Records are selected on the basis of detector number and aperture name. Table 5-5 shows the structure of STSDAS table <unique name>.CV4.

Table 5-5. HSP Efficiency Table, <unique name>. CV4

Column Name	Data Type	Units	Description
APER_NAME	CH*10	None	Aperture name identifier
DET_NUM	I	digital number	Detector number, 1-5
VGAIND	I	digital number	Gain setting: 0, 2, 3, 6, 7
BASE_VALUE_P	R	none	Point source base value of the characteristic scaling polynomial
BASE_VALUE_E	R	none	Extended source base value of the characteristic scaling polynomial
BASE_TEMP	R	deg Celsius	Base temperature of the characteristic scaling polynomial
BASE_TIME	D	MJD	Base time of the characteristic scaling polynomial
A00	D	none	0,0th coefficient of the characteristic scaling polynomial
A01	D	day-1	0,1st coefficient of the characteristic scaling polynomial
A02	D	day-2	0,2nd coefficient of the characteristic scaling polynomial
A03	D	day-3	0,3rd coefficient of the characteristic scaling polynomial
A10	D	deg-1	1,0th coefficient of the characteristic scaling polynomial
A11	D	deg-1 day-1	1,1st coefficient of the characteristic scaling polynomial
A12	D	deg-1 day-2	1,2nd coefficient of the characteristic scaling polynomial
A13	D	deg-1 day-3	1,3rd coefficient of the characteristic scaling polynomial
A20	D	deg-2	2,0th coefficient of the characteristic scaling polynomial
A21	D	deg-2 day-1	2,1st coefficient of the characteristic scaling polynomial
A22	D	deg-2 day-2	2,2nd coefficient of the characteristic scaling polynomial
A23	D	deg-2 day-3	2,3rd coefficient of the characteristic scaling polynomial
A30	D	deg-3	3,0th coefficient of the characteristic scaling polynomial
A31	D	deg-3 day-1	3,1st coefficient of the characteristic scaling polynomial
A32	D	deg-3 day-2	3,2nd coefficient of the characteristic scaling polynomial
A33	D	deg-3 day-3	3,3rd coefficient of the characteristic scaling polynomial

5.1.6 Dark Count Table: <unique name>.CV5

The dark count table contains the coefficients and base values used in computing the dark count characteristic (D) for the HSP calibration.

Format: Each set of base values and coefficients corresponds to a particular HSP dark aperture, a high voltage setting (command value), and data type. In each set there are a base value, a reference time, a reference temperature, and 16 polynomial coefficients. Additionally, there is a POINTER field that is a dummy field and is not used to hold data.

Selection Scheme: Records are selected on the basis of dark aperture name, data type (ANALOG or DIGITAL), and high voltage setting (command value).

Restrictions: In the dark count table, there should be entries for the three standard voltage settings (corresponding to photoelectric current gains of 0.5E+6, 1.0E+6, and 2.0E+6) for each dark aperture and data type (ANALOG/DIGITAL).

Table 5-6 shows the structure of the STSDAS table <unique name>.CV5.

Table 5-6. HSP Dark Count Table, <unique name>. CV5

Column Name	Data Type	Units	Description
APER_NAME	A33	D	deg-3 day-1
TYPE	CH*10	D	deg-3 day-2
VOLTAGE	CH*7	None	deg-3 day-3
POINTER	I	NONE	Dark aperture name identifier
BASE_VALUE	I	digital number	ANALOG, DIGITAL
BASE_TEMP	R	–	High voltage setting (command value) Not used
BASE_TIME	R	Counts/sec	Base value of the characteristic scaling polynomial
A00	D	deg Celsius	Base temperature of the characteristic scaling polynomial
A01	D	MJD	Base time of the characteristic scaling polynomial
A02	D	none	0,0th coefficient of the characteristic scaling polynomial
A03	D	day-1	0,1st coefficient of the characteristic scaling polynomial
A10	D	day-2	0,2nd coefficient of the characteristic scaling polynomial
A11	D	day-3	0,3rd coefficient of the characteristic scaling polynomial
A12	D	deg-1	1,0th coefficient of the characteristic scaling polynomial
A13	D	deg-1 day-1	1,1st coefficient of the characteristic scaling polynomial
A20	D	deg-1 day-2	1,2nd coefficient of the characteristic scaling polynomial
A21	D	deg-1 day-3	1,3rd coefficient of the characteristic scaling polynomial
A22	D	deg-2	2,0th coefficient of the characteristic scaling polynomial
A23	D	deg-2 day-1	2,1st coefficient of the characteristic scaling polynomial
A30	D	deg-2 day-2	2,2nd coefficient of the characteristic scaling polynomial
A31	D	deg-2 day-3	2,3rd coefficient of the characteristic scaling polynomial
A32	D	deg-3	3,0th coefficient of the characteristic scaling polynomial

5.1.7 Time Bias Table: < unique name>.CV6

The time bias table contains the time biases that are used to correct the integration time for internal instrument delays.

Format: Each entry contains a time bias for a particular HSP data format (BYTE, WORD, LWRD, ALOG, or ALL) and for a particular instrument mode (SCP, ARS, SSP1, or SSP2).

Selection Scheme: Records are selected on the basis of data format and instrument mode. Restrictions: For each instrument mode there should be entries for each of the five data formats. Table 5-7 shows the structure of the HSP time bias table.

Table 5-7. HSP Time Bias Table, <unique name>. CV6

Column Name	Data Type	Units	Description
DATA_FMT	CH*4	none	Data format
MODE	CH*4	none	Instrument mode
TIME_BIAS	I	clock count	Internal instrument delay added to integration times

5.1.8 CVC Offset Table: <unique name>.CV7

The CVC offset table contains the coefficients used in computing the current-to-voltage converter (CVC) offset detector characteristic (I) for the HSP calibration.

Format: Each set of base values and coefficients corresponds to a particular HSP detector and analog gain setting (command value). In each set there are a base value, a reference time, a reference temperature, and 16 polynomial coefficients.

Selection Scheme: Records are selected on the basis of detector number and gain setting.

Restrictions: In the CVC offset table, for each detector there should be entries for each of the five gain settings (0, 2, 3, 6, and 7).

Table 5-8 shows the structure of the HSP CVC offset table.

Table 5-8. HSP CVC Offset Table, <unique name>. CV7

Column Name	Data Type	Units	Description
DET_NUM	I	digital number	Detector number, 1-5
VGAIND	I	digital number	Gain setting: 0, 2, 3, 6, 7
BASE_VALUE	R	digital number	Base value of the characteristic scaling polynomial
BASE_TEMP	R	deg Celsius	Base temperature of the characteristic scaling polynomial
BASE_TIME	D	MJD	Base time of the characteristic scaling polynomial
A00	D	none	0,0th coefficient of the characteristic scaling polynomial
A01	D	day-1	0,1st coefficient of the characteristic scaling polynomial
A02	D	day-2	0,2nd coefficient of the characteristic scaling polynomial
A03	D	day-3	0,3rd coefficient of the characteristic scaling polynomial
A10	D	deg-1	1,0th coefficient of the characteristic scaling polynomial
A11	D	deg-1 day-1	1,1st coefficient of the characteristic scaling polynomial
A12	D	deg-1 day-2	1,2nd coefficient of the characteristic scaling polynomial
A13	D	deg-1 day-3	1,3rd coefficient of the characteristic scaling polynomial
A20	D	deg-2	2,0th coefficient of the characteristic scaling polynomial
A21	D	deg-2 day-1	2,1st coefficient of the characteristic scaling polynomial
A22	D	deg-2 day-2	2,2nd coefficient of the characteristic scaling polynomial
A23	D	deg-2 day-3	2,3rd coefficient of the characteristic scaling polynomial
A30	D	deg-3	3,0th coefficient of the characteristic scaling polynomial
A31	D	deg-3 day-1	3,1st coefficient of the characteristic scaling polynomial
A32	D	deg-3 day-2	3,2nd coefficient of the characteristic scaling polynomial
A33	D	deg-3 day-3	3,3rd coefficient of the characteristic scaling polynomial

5.1.9 Dead Time Table: < unique name>.CV8

The dead time table contains the coefficients and base values in computing the dead time (tau), which is used for paired-pulse corrections in HSP calibration.

Format: Each set of base values and coefficients corresponding to a particular HSP detector, high voltage setting (command value), and pulse amplifier/discriminator (PAD) threshold setting (command value). In each set there are a base value, a reference temperature, and one

coefficient.

Selection Scheme: Records are selected on the basis of detector number, high voltage setting, and PAD threshold setting.

Restrictions: In the dead time table, there should be entries for the three standard high voltage settings (corresponding to photoelectric current gains of 0.5E+6, 1.0E+6, 2.0E+6) for each detector and PAD threshold setting(s) (usually one).

Table 5-9 shows the structure of the HSP dead time table.

Table 5-9. HSP Dead Time Table, <unique name>. CV8

Column Name	Data Type	Units	Description
DET_NUM	I	digital number	Detector number, 1-5
VOLTAGE	I	digital number	High voltage setting (command value)
THRESH	I	digital number	PAD threshold setting (command value)
BASE_VALUE	R	sec	Base value of dead time
A1	R	sec/deg	Dead time temperature dependence coefficient
BASE_TEMP	R	deg	Celsius Temperature zero point used in temperature dependence

5.1.10 Dark Aperture Table: <unique name>.CV9

The dark aperture table contains the corresponding dark aperture names for each of the regular HSP aperture names. The dark aperture names are later used to calibrate HSP dark counts.

Format: Each regular HSP aperture name has a corresponding dark aperture name. Each image dissector tube (IDT) has three dark apertures, and the photo-multiplier (PMT) has one dark aperture name.

Selection Scheme: Records are selected on the basis of aperture name and detector number.

Restrictions: The dark aperture table may contain aperture names that refer to the same aperture as another name. In this case, the redundant names are eliminated by setting both to the same name.

Table 5-10 shows the structure of the dark aperture table.

Table 5-10. HSP Dark Aperture Translation Table, <unique name>. CV9

Column Name	Data Type	Units	Description
APER_NAME	CH*10	none	Regular aperture name
DET_NUM	I	digital number	Detector number
DARK_APER	CH*10	none	Dark aperture name