Section 4. High Resolution Spectrograph

The calibration of HRS data consists of the following steps:

1. Bad or suspect data are identified u sing the data quality initialization file, < unique name>.R5H.

2. Raw counts are converted to count rates by dividing each data point by the exposure time.

3. Diode nonlinearities are removed by applying a paired-pulse or dead time correction using coefficients stored in the table <unique name>.CMG.

4. The nonuniformities are removed by using the diode response for each diode stored in reference file <unique name>.R0H. 5. Photocathode granularities are removed by first mapping each data point from detector coordinates to photocathode coordinates using coefficients in tables <unique name>.CZ1 and < unique name>.CZ2. The photocathode response applied is obtained from the reference file <unique name>.R1H.

6. Vignetting correction corrects for both light loss due to vignetting and low-frequency sensitivity variations across the photocathode. The vignetting file has a name of the form <unique name>.R2H.

7. Wavelengths are determined for each point using the dispersion coefficients in table <unique name>.CZ6, correcting for thermal effects using coefficients in table < unique name>.CZ7. For the echelle spectra, the spectral order is computed using the parameters in table < unique name >.CZ5. If necessary, an incidence angle offset is added to the wavelengths. The offset is computed using coefficients stored in table < unique name>.CZ8. A velocity correction is done to convert to heliocentric wavelengths, and a vacuum-to-air correction is performed for wavelengths above 2000 Angstroms.

8. The background is smoothed by a median filter, a mean filter, or a low-order polynomialwith filter widths and polynomial order specified in table < unique name >.CZ3. If the background is a sky spectrum, it is normalized to the object spectrum aperture before subtraction from the gross spectrum using relative aperture sizes also stored in this table. The background is corrected for scattered light using coefficients specified in table <unique name>.CZB. Alternatively, the background can be computed based upon a count rate model instead of data acquired during the observation. The count rate model is specified in table < unique name>.CZE. An ancillary file needed to use the count rate model that is used to issue warnings when the observation is near the SAA is specified in the image <unique name>.R6H.

9. A ripple correction is performed for data taken with an echelle using coefficients in tables <unique name>.CZ9 and <unique name>.CZA.

10. The net flux is converted to absolute flux units using the sensitivity values stored in reference files <unique name>.R3H and <unique name>.R4H.

4.1 HRS Reference Files

The HRS reference files are composed of a FITS header file and a binary data file. Although the header files do follow the FITS conventions, the header listings in this section do not adhere precisely to these conventions. In the header listings contained in this section, beware of the following:

The single quotes required around character strings have been omitted.

Numerical values have not been right justified.

The third column in the listing denoting the variable type is additional information, not part of the FITS header itself.

4.1.1 Diode Response Files (DIO): <unique name>.R0H

Nonuniformities in diode responses for HRS detectors require science data to be normalized using data from the diode response files.

Format: Diode response data files contain a single group of normalization data with 512 entries corresponding to the 512 diodes of each HRS detector. Diode responses are stored in REAL*4 format.

Flags and Indicators: The diode response data file is selected on the basis of the DETECTOR keyword. Restrictions: The HRS calibration software will reject any inappropriately sized groups. The following listing shows a sample diode response image header.

SIMPLE  = F                 / image conforms to the fits standard                   L1
BITPIX  = 32                / bits per data value                                   I2
DATATYPE= REAL*4            / datatype of the group array                           CHR
NAXIS   = 1                 / number of data axes                                   I2
NAXIS1  = 512               / words per group                                       I2
GROUPS  = T                 / image is in group format                              L1
GCOUNT  = 1                 / number of groups                                      I2
PCOUNT  = 0                 / number of group parameters                            I2
PSIZE   = 0                 / bits in the group parameter block                     I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= DIODE RESPONSE    / diode response file set                               CHR
HEADNAME=                   / reference file set header filename                    CHR
DATANAME=                   / reference file set data filename                      CHR
DATE    =                   / date this file was written                            CHR

                            / HRS DATA REDUCTION KEYWORDS
DETECTOR=                   / detector: 1,2                                         I2
     / HRS DATA QUALITY KEYWORDS
USEAFTER=                   / use this file for obs. taken on/after this date       CHR
PEDIGREE=                   / data source (INFLIGHT,GROUND,MODEL,DUMMY) & date      CHR
DESCRIP =                   / description of reference data                         CHR

END
                            [Listing Version 01  6-JUN-1995]

4.1.2 Photocathode Response Files (PHC): < unique name>.R1H

Nonuniformities in the responses of the photocathodes of the HRS detectors require science data to be normalized using data from the photocathode response files.

Format: Photocathode response files contain multiple groups of responses. Each group contains the responses for a particular line position. Within the group, responses are ordered by equally spaced sample positions determined by the keywords SAMPBEG and SAMPOFF. Photocathode responses are stored as REAL*4 values.

Flags and Indicators: The photocathode response data file is selected on the basis of the GRATING keyword.

The following listing shows a sample image header from a photocathode response data file.

SIMPLE  = F                 / image conforms to the fits standard                   L1
BITPIX  = 32                / bits per data value                                   I2
DATATYPE= REAL*4            / datatype of the group array                           CHR
NAXIS   = 1                 / number of data axes                                   I2
NAXIS1  =                   / words per group                                       I2
GROUPS  = T                 / image is in group format                              L1
GCOUNT  =                   / number of groups                                      I2
PCOUNT  = 1                 / number of group parameters                            I2
PSIZE   = 32                / bits in the group parameter block                     I2
PTYPE1  = LINE_POS          / line position                                         CHR
PDTYPE1 = REAL*4            / datatype of parameter 1                               CHR
PSIZE1  = 32                / number of bits in parameter 1                         I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= CATHODE RESPONSE  / photocathode response file set                        CHR
HEADNAME=                   / reference file set header filename                    CHR
DATE    =                   / date this file was written                            CHR

                            / HRS DATA REDUCTION KEYWORDS
GRATING =                   / grating, echelle or mirror in use                     CHR
APERTURE=                   / aperture name SSA, LSA                                CHR
SAMPBEG =                   / first response sample number                          R4
SAMPOFF =                   / response sample number offset                         R4

                            / HRS DATA QUALITY KEYWORDS
USEAFTER=                   / use thisfile for obs.taken on/afterthis date          CHR
PEDIGREE=                   / data source(INFLIGHT,GROUND,MODEL,DUMMY)&date         CHR
DESCRIP =                   / description of reference data                         CHR

END
                                                     [Listing Version 01  26-AUG-1997]

4.1.3 Vignetting Files (VIG): <unique name>.R2H

The removal of vignetting and wavelength-dependent photocathode variations is done using data from the vignetting files.

Format: Vignetting correction files contain multiple groups of responses. Each group contains the responses for a particular carrousel position and line position. Within the group, responses are ordered by equally spaced sample positions determined by the keywords SAMPBEG and SAMPOFF. Data in the vignetting correction data files are stored in REAL*4 format.

Flags and Indicators: The vignetting response data file is selected on the basis of the GRATING keyword.

The following listing shows a sample HRS vignetting response file.

SIMPLE  = F                 / image conforms to the fits standard                   L1
BITPIX  = 32                / bits per data value                                   I2
DATATYPE= REAL*4            / datatype of the group array                           CHR
NAXIS   = 1                 / number of data axes                                   I2
NAXIS1  =                   / words per group                                       I2
GROUPS  = T                 / image is in group format                              L1
GCOUNT  =                   / number of groups                                      I2
PCOUNT  = 3                 / number of group parameters                            I2
PSIZE   = 96                / bits in the group parameter block                     I2

                            / GROUP PARAMETERS: PODPS CALIBRATION
PTYPE1  = CAR_POS           / carrousel position                                    CHR
PDTYPE1 = REAL*4            / datatype of parameter 1                               CHR
PSIZE1  = 32                / number of bits in parameter 1                         I2
PTYPE2  = LINE_POS          / line position                                         CHR
PDTYPE2 = REAL*4            / datatype of parameter 2                               CHR
PSIZE2  = 32                / number of bits in parameter 2                         I2
PTYPE3  = APERTURE          / aperture name: SSA, LSA                               CHR
PDTYPE3 = CHARACTER*4       / datatype of parameter 3                               CHR
PSIZE3  = 32                / number of bits in parameter 3                         I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= VIGNETTING        / vignetting calibration file set                       CHR
HEADNAME=                   / reference file set header filename                    CHR
DATANAME=                   / reference file set data filename                      CHR
DATE    =                   / date this file was written                            CHR

                            / HRS DATA REDUCTION KEYWORDS
GRATING =                   / grating, echelle or mirror in use                     CHR
SAMPBEG =                   / first response sample number                          R4
SAMPOFF =                   / response sample number offset                         R4

                            / HRS DATA QUALITY KEYWORDS
PEDIGREE=                   / data source (INFLIGHT,GROUND,MODEL,DUMMY) & date      CHR
DESCRIP =                   / description of reference data                         CHR

END                                                  [Listing Version 01  6-JUN-1995]

4.1.4 Absolute Sensitivity Files (ABS): <unique name>.R3H

The absolute sensitivity scale files contain data that are used to perform HRS absolute flux calibration. These files are used in conjunction with the HRS wavelength net files that specify the wavelength net (grid) used for interpolation of absolute sensitivity scale values.

Format: Absolute sensitivity files contain two groups of data that correspond to the large and small apertures of the HRS. Because the HRS wavelength net files contain the wavelength net corresponding to these sensitivity values, it is not assumed that the spacing between wavelength values is uniform. Data in the absolute sensitivity files are stored in REAL*4 format.

Flags and Indicators: The absolute sensitivity data file is selected on the basis of the GRATING keyword.

Restrictions: The HRS calibration software will reject any inappropriately sized groups. The following listing shows a sample HRS absolute sensitivity file.

SIMPLE  = F                 / image conforms to the fits standard                   L1
BITPIX  = 32                / bits per data value                                   I2
DATATYPE= REAL*4            / datatype of the group array                           CHR
NAXIS   = 1                 / number of data axes                                   I2
NAXIS1  =                   / words per group                                       I2
GROUPS  = T                 / image is in group format                              L1
GCOUNT  = 2                 / number of groups                                      I2
PCOUNT  = 1                 / number of group parameters                            I2
PSIZE   = 32                / bits in the group parameter block                     I2

                            / GROUP PARAMETERS: PODPS CALIBRATION
PTYPE1  = APERTURE          / aperture name: SSA, LSA                               CHR
PDTYPE1 = CHARACTER*4       / datatype of parameter 1                               CHR
PSIZE1  = 32                / number of bits in parameter 1                         I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= ABSOLUTE FLUX     / absolute flux calibration file set                    CHR
HEADNAME=                   / reference file set header filename                    CHR
DATANAME=                   / reference file set data filename                      CHR
DATE    =                   / date this file was written                            CHR

                            / HRS DATA REDUCTION KEYWORDS
GRATING =                   / grating, echelle or mirror in use                     CHR

                            / HRS DATA QUALITY KEYWORDS
USEAFTER=                   / use this file for obs. taken on/after this date       CHR
PEDIGREE=                   / data source (INFLIGHT,GROUND,MODEL,DUMMY) & date      CHR
DESCRIP =                   / description of reference data                         CHR

END

                                  [Listing Version 01  6-JUN-1995]

4.1.5 Wavelength Net Files (NET): <unique name>.R4H

The wavelength net files contain data that are used to perform HRS absolute flux calibration. These data provide the nonuniform interpolation net (grid) used to compute an absolute sensitivity scale from data in the HRS absolute sensitivity files.

Format: Wavelength net files contain two groups of data that correspond to the large and small apertures of the HRS. Because the HRS absolute sensitivity files contain the absolute sensitivities corresponding to the wavelength net values, these two sets of files have exactly the same structure. Data in the wavelength net files are stored in REAL*4 format.

Flags and Indicators: The wavelength net data file is selected on the basis of the GRATING keyword.

Restrictions: The HRS calibration software will reject any inappropriately sized groups. The following listing shows a sample HRS wavelength net file.

SIMPLE  = F                 / image conforms to the fits standard                   L1
BITPIX  = 32                / bits per data value                                   I2
DATATYPE= REAL*4            / datatype of the group array                           CHR
NAXIS   = 1                 / number of data axes                                   I2
NAXIS1  =                   / words per group                                       I2
GROUPS  = T                 / image is in group format                              L1
GCOUNT  = 2                 / number of groups                                      I2
PCOUNT  = 1                 / number of group parameters                            I2
PSIZE   = 32                / bits in the group parameter block                     I2

                            / GROUP PARAMETERS: PODPS CALIBRATION
PTYPE1  = APERTURE          / aperture name: SSA, LSA                               CHR
PDTYPE1 = CHARACTER*4       / datatype of parameter 1                               CHR
PSIZE1  = 32                / number of bits in parameter 1                         I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= WAVELENGTH NET    / absolute flux wavelength net file set                 CHR
HEADNAME=                   / reference header file name                            CHR
DATANAME=                   / reference data file name                              CHR
DATE    =                   / date this file was written                            CHR

                            / HRS DATA REDUCTION KEYWORDS
GRATING =                   / grating, echelle or mirror in use                     CHR

                            / HRS DATA QUALITY KEYWORDS
USEAFTER=                   / use this file for obs. taken on/after this date       CHR
PEDIGREE=                   / data source (INFLIGHT,GROUND,MODEL,DUMMY) & date      CHR
DESCRIP =                   / description of reference data                         CHR
END
                            [Listing Version 01  6-JUN-1995]

4.1.6 Data Quality Initialization Files (QIN): <unique name>.R5H

The HRS data quality initialization files contain a priori information concerning the effect of the HRS’s diode arrays on the quality of output data values.

Format: Data quality initialization data files contain a single group of data with 512 entries corresponding to the 512 diodes of each HRS detector. Data quality initialization values are stored in REAL*4 format.

Flags and Indicators: The data quality initialization file is selected on the basis of the DETECTOR keyword.

Restrictions: The HRS calibration software will reject any inappropriately sized groups. The following listing shows a sample HRS data quality initialization file.

SIMPLE  = F                 / image conforms to the fits standard                   L1
BITPIX  = 32                / bits per data value                                   I2
ATATYPE= REAL*4            / datatype of the group array                           CHR
NAXIS   = 1                 / number of data axes                                   I2
NAXIS1  = 512               / words per group                                       I2
GROUPS  = T                 / image is in group format                              L1
GCOUNT  = 1                 / number of groups                                      I2
PCOUNT  = 0                 / number of group parameters                            I2
PSIZE   = 0                 / bits in the group parameter block                     I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= DQ INIT           / data quality initialization file                      CHR
HEADNAME=                   / reference header file name                            CHR
DATANAME=                   / reference data file name                              CHR
DATE    =                   / date this file was written                            CHR

                            / HRS DATA REDUCTION KEYWORDS
DETECTOR=                   / detector: 1,2                                         I2

                            / HRS DATA QUALITY KEYWORDS
USEAFTER=                   / use this file for obs. taken on/after this date       CHR
PEDIGREE=                   / data source (INFLIGHT,GROUND,MODEL,DUMMY) & date      CHR
DESCRIP =                   / description of reference data                         CHR
END

                                        [Listing Version 01  6-JUN-1995]

4.1.7 SAA Model 7 Contour File (SAA): <unique name>.R6H

The SAA Model 7 contour file contains an image of the SAA Model 7 contour as defined by the HST PDB.

Format: The SAA Model 7 contour file contains a single group of data with dimensions of 360 entries by 180 entries sto red in INTEGER format. The 360 entries represent geographic longitude covering a range of -180 degrees to +180 degrees; the 180 entries represent geographic latitude covering a range of -90 degrees to +90 degrees. The file contains only the values of 0 and 1. The value 0 denotes regions outside of the SAA; 1 denotes regions within the SAA, including the boundary.

Flags and Indicators: Other than the invocation of the background count rate model via the BMD_CORR keyword, there is no selection criterion for this file.

Restrictions: The HRS software will reject any inappropriately sized groups. The following listing shows a sample HRS SAA Model 7 contour file.

GROUPS  = T                 / image is in group format                              L1
GCOUNT  = 1                 / number of groups                                      I2
COUNT  = 0                 / number of group parameters                             I2
PSIZE   = 0                 / bits in the group parameter block                     I2

                            / HRS DATA DESCRIPTOR KEYWORDS
INSTRUME= HRS               / instrument                                            CHR
FILETYPE= SAA Contour Mask  / SAA Contour Mask file                                 CHR
HEADNAME= saahfile.r6H      / reference header file name                            CHR
DATANAME= saahfile.r6d      / reference data file name                              CHR
DATE    = 26/11/96          / date this file was written                            CHR

PEDIGREE= MODEL             / source of reference file                              CHR
ESCRIP = SAA Contour Model 7 from PDB for Model BKGD correction                     CHR
USEAFTER= 24/04/90          / use file for obs. taken on/after this date            CHR

END

4.2 HRS Reference Relations and STSDAS Tables

4.2.1 Line Mapping Parameters Table: <unique name>.CZ1

The line mapping parameters table contains the coefficients of the line mapping function that relates Y-deflection to line position on the photocathode.

Format: Records of line mapping coefficients are organized, for each detector value, by Y- deflection.

Selection Scheme: Data records are selected on the basis of detector. Table 4-1 describes the HRS line mapping parameters table.

Table 4-1. HRS Line Mapping Parameters Table, <unique name>. CZ1

Column Name Data Type Units Description
DETECTOR I D line units/deflection units
YDEF I Detector number, 1-2
L0 D deflection units line units Y-deflection
ERROR_L0 D line units Zeroth order coefficient of the line mapping function
A ERROR_A D line units/deflection units Error associated with l0

4.2.2 Sample Mapping Parameters Table: <unique name>.CZ2

The sample mapping parameters table contains the coefficients of the sample mapping function that relates Y-deflection and diode position to sample position of the photocathode.

Format: Records of sample mapping coefficients are organized, for each detector value, by Y- deflection. The calibration software interpolates sample mapping coefficients using Y- deflection. Fields are provided for estimates of error in the sample mapping coefficients. These estimates, which are for documentation purposes only, are not used by calibration software.

Selection Scheme: Records are selected on the basis of detector.

Table 4-2 describes the structure of the sample mapping parameters table.

Table 4-2. HRS Sample Mapping Parameters Table, <unique name>. CZ2

Column Name Data Type Units Description
DETECTOR I Detector number, 1-2
YDEF I deflection units Y-deflection
S0 D sample units Zeroth order coefficient of the sample mapping function
ERROR_S0 D sample units Error associated with s0
B D sample units/deflection units First order coefficient of the sample mapping function (dx)
ERROR_B D sample units/deflection units Error associated with b
C D ample units/deflection units2 Second order coefficient of the sample mapping function (dx)
ERROR_C D sample units/deflection units2 Error associated with c
E D sample units Sample position increment
ERROR_E D sample units Error associated with e

4.2.3 Detector Parameters Table: <unique name>.CZ3

The detector parameters table contains the miscellaneous calibration parameters that are functions of detector.

Format: Each set of detector parameters consists of such items as the positions of X and Y null deflections, scale factors for the deflection calibration corrections, diode offsets used to compute effective channel numbers of background diodes, mean and median filter widths and tolerances used to relate bins of data to gross spectra, and corresponding background data.

Selection Scheme: Records are selected on the basis of detector. Table 4-3 describes the structure of the detector parameters table.

Table 4-3. HRS Detector Parameters Table, <unique name>. CZ3 (1 of 2)

Column Name Data Type Units Description
DETECTOR I deflection units Position of null deflection in the Y-direction
DXNULL I sample units Sample position at the center of the photocathode
DYNULL I mm/sample Conversion factor from sample units to millimeters
S0 D units Scale factor for the X null deflection component of the deflection
C I calibration correction ZXDCAL
NXSCALE I Scale factor for the X proportional (plate scale) component of the
PXSCALE I diodes deflection calibration correction ZXDCALP
C1 I diodes Diode position offset set used to compute the effective channel number
C2 I diodes for background diodes to the left of the main diode array
SKY_MNFWIDTH I diodes Diode position offset set used to compute theeffective channel number
SKY_MDFWIDTH I diodes for background diodes to the right of the main diode array
INT_MNFWIDTH I diodes Width of the mean filter used in smoothingbackground data obtained as
INT_MDFWIDTH D deflection units sky from another aperture (diode number)
YT0L1 D deflection units Width of the median filter used in smoothingbackground data obtained as
YT0L2 D deflection units sky from another aperture (diode number)
YT0L3 D Width of the mean filter used in smoothingbackground data obtained as
MIN_DIO D interorder data (diode number)
MIN_PHC D Width of the median filter used in smoothingbackground data obtained as
MIN_ECH D interorder data (diode number)
MIN_ABS D .125 sec Y-deflection tolerance used to determine the binsassociated with a gross
DELTA_T D minutes spectrum
PERIOD D Y-deflection tolerance used to associate a grossspectrum
AP_RATIO I with an interorder spectrum
INT_ORDER Detector number, 1-2 Y-deflection tolerance used to associate a grossspectrum with the
I deflection units Position of null deflection in the X-direction specified background diodes of an interorder spectrum

4.2.4 Wavelength Ranges Table: <unique name>.CZ4

The wavelength ranges table contains the valid wavelength range for each HRS grating and echelle mode.

Format: Each record specifies a range of valid wavelengths associated with a grating and echelle mode.

Selection Scheme: Records are selected based on the grating/echelle mode. Table 4-4 shows the structure of the HRS wavelength ranges table.

Table 4-4. HRS Wavelength Ranges Table, <unique name>. CZ4

Column Name Data Type Units Description
GRATING CH*9 Grating/echelle mode
LOWER D Å Lower bound of a range of wavelengths
UPPER D Å Upper bound of a range of wavelengths

4.2.5 Spectral Order Constants Table: <unique name>.CZ5

The spectral order constants table contains the constants used to determine the spectral order of an HRS observation when an echelle mode is used.

Format: Records of data are indexed by the grating and echelle mode (E-A or E-B) and contain the constants needed to compute the spectral order.

Selection Scheme: Records are selected on the basis of grating/echelle mode. Restrictions: Grating/echelle modes are limited to E-A and E-B.

Table 4-5 describes the structure of the spectral order constants reference table.

Table 4-5. HRS Spectral Order Constants Table, <unique name>. CZ5

Column Name Data Type Units Description
GRATING CH*9 Grating/echelle mode: E-A, E-B
CAP_A D Å Constant A used to compute the spectral order
LIT_A D deflection units Constant a used to compute the spectral order
CAP_B D encoder units Constant B used to compute the spectral order
LIT_B D deflection units/ Å Constant b used to compute the spectral order
CAP_C D encoder units Constant C used to compute the spectral order
LIT_D D deflection units/ Å Constant d used to compute the spectral order

4.2.6 Dispersion Constants Table: <unique name>.CZ6

The dispersion constants table contains dispersion constants and a corresponding calibration temperature value that are used to generate an HRS wavelength scale.

Format: Records of dispersion constants and the calibration temperature associated with them are stored as a tabular function of grating mode and carrousel position. For the particular grating and echelle mode of the observation, interpolation in the carrousel position is performed during calibration to adjust these constants to the carrousel position of the observation.

Selection Scheme: Records are selected based on the grating/echelle mode. Table 4-6 describes the HRS dispersion constants table.

Table 4-6. HRS Dispersion Constants Table, <unique name>. CZ6 (1 of 2)

Column Name Data Type Units Description
GRATING CH*9 Grating/echelle mode
CARPOS I Carrousel position
ZRIUTA D deg Celsius RIU A temperature
ZRIUTB D deg Celsius RIU B temperature
ZDETT1 D deg Celsius Detector 1 temperature
ZDETT2 D deg Celsius Detector 2 temperature
ZDEBTF D deg Celsius DEB front post AMPS temperature
ZDEBTR D deg Celsius DEB rear post AMPS temperature
ZPABT1 D deg Celsius Detector 1 pre-amp assembly box temperature
ZPABT2 D deg Celsius Detector 2 pre-amp assembly box temperature
ZMEBT1 D deg Celsius Main electronic box 1 temperature
ZMEBT2 D deg Celsius Main electronic box 2 temperature
ZFIAT D deg Celsius Fixture interface A temperature
ZFIBT D deg Celsius Fixture interface B temperature
ZFICT D deg Celsius Fixture interface C temperature
ZCST D deg Celsius Carrousel stator temperature
ZCST1 D deg Celsius Detector 1 spectral calibration lamp temperature
ZCST2 D deg Celsius Detector 2 spectral calibration lamp temperature
ZHVPST1 D deg Celsius Detector 1 HVPS temperature
ZHVPST2 D deg Celsius Detector 2 HVPS temperature
ZDT11 D deg Celsius Detector 1 detector shield temperature
ZDT12 D deg Celsius Detector 2 detector shield temperature
ZDRT D deg Celsius Digicon radiator temperature
ZOBBT D deg Celsius Optical bench bulkhead temperature
A0 D sample units Dispersion constant
A1 D sample units/Å Dispersion constant
A2 D sample units/Å 2 Dispersion constant
A3 D sample units Dispersion constant
A4 D sample units/Å Dispersion constant
A5 D sample units/Å Dispersion constant
A6 D sample units/Å 2 Dispersion constant
A7 D sample units/Å 3 Dispersion constant

4.2.7 Thermal Constants Table: <unique name>.CZ7

The thermal constants table contains the observation temperature mnemonic and the scaling factor for each grating/echelle mode. These data are used in performing a thermal motion correction for the 0th order dispersion constant.

Format: Each record contains an observation temperature mnemonic that also serves as the name of a keyword appearing in the Standard Header Packet (SHP) header files. For a given grating/echelle mode, the calibration code selects the appropriate temperature mnemonic and retrieves the corresponding keyword temperature value from the SHP header factor included in this relation and used to adjust the low-order wavelength coefficient for temperature effects.

Selection Scheme: Records are selected on the basis of the grating/echelle mode. Table 4-7 shows the structure of a thermal constants table.

Table 4-7. HRS Thermal Constants Table, <unique name>. CZ7

Column Name Data Type Units Description
GRATING CH*9 Celsius
TOBS CH*8 Grating/echelle mode
TC D sample units/deg Observation temperature name to be used for thermal correction: ZRIUTA,

4.2.8 Incidence Angle Constants Table: <unique name>.CZ8

The incidence angle constants table contains the constants needed to perform the incidence angle correction.

Format: The records of this table consist of values for two parameters (a and b) associated with a different grating mode. Each record is also labeled with a carrousel position and order number associated with a grating mode. Interpolation in carrousel position for these constants is carried out when an exact match in this table is not found.

Selection Scheme: Records are selected on the basis of aperture, grating mode, and spectral order.

Restrictions: All possible spectral orders for the echelle modes are expected in this table since interpolation in the spectral order is not performed. Table 4-8 describes the incidence angle constants reference table.

Table 4-8. HRS Incidence Angle Constants Table, <unique name>. CZ8

Column Name Data Type Units Description
APERTURE CH*3 Aperture (SC1, SC2, or LSA)
GRATING CH*9 Grating/echelle mode
CARPOS I encoder units Carrousel position
SPORDER I Spectral order associated with constants a and b
A D Å Constant a
B D Å/sample units Constant b

4.2.9 Echelle Interpolation Constants Table: <unique name>.CZ9

The echelle interpolation constants table contains constants used in the echelle ripple correction. Format: Records contain the constants used to compute the normalized grating efficiency that are indexed by spectral order and carrousel position. Interpolation is performed in the carrousel position.

Selection Scheme: Records are retrieved on the basis of grating mode and spectral order.

Restrictions: Records for all possible spectral orders must be present in this table as interpolation in spectral order is not performed.

Table 4-9 describes the structure of the echelle interpolation constants table.

Table 4-9. HRS Echelle Ripple Interpolation Constants Table, <*unique name*>. CZ9

Column Name Data Type Units Description
GRATING CH*9 – G rating/echelle mode
CARPOS I encoder units Carrousel position
SPORDER I Spectral order associated with constants a and b
A D Constant a
B D Constant b

4.2.10 Echelle Non-interpolation Constants Table: < unique name>.CZA

The echelle non-interpolation constants table contains constants used in the echelle ripple correction. These constants are not interpolated.

Format: Each record contains those constants used to compute the normalized grating efficiency that rely solely upon the grating/echelle mode.

Selection Scheme: Records are retrieved based on the grating/echelle mode. Table 4-10 describes the structure of the echelle non-interpolation constants table.

Table 4-10. HRS Echelle Non-interpolation Constants Table, <unique name>. CZA

Column Name Data Type Units Description
GRATING CH*9 Grating/echelle mode
F D mm Focal length
BETA D deg Echelle blaze angle
DELTA D deg Half-angle between collimator and cross-disperser
CPNORM I encoder units Echelle center carrousel position
RO I encoder units C onstant used in the computation of angle THETA

4.2.11 Scattered Light Coefficients Table: < unique name>.CZB

The scattered light coefficients table contains the coefficients for determining the contribution of scattered light to the background.

Format: Records contain four scattered light coefficients and are organized by aperture, grating/echelle mode, and spectral order. The four coefficients a_scat, b_scat, c_scat, and d_scat are used in the following equation to determine the background spectrum:

math:

B(i) = 0:5 * [a_{scat} * U(i) + b_{scat} \* L(i)] - c_{scat} \* N(i) + d_{scat} \* N

where

N(i) = O(i) - 0.5 \* [U(i) + L(i)] B(i) is the background spectrum

U(i) is the upper interorder count rate per diode

L(i) is the lower interorder count rate per diode

N(i) is the net on-order count rate per diode

O(i) is the gross object spectrum count rate per diode

N is the average net on-order count rate per diode averaged over all science diodes

i is the science diode light subtraction index

Selection Scheme: Records are selected on the basis of aperture, grating/echelle mode, and spectral order.

Table 4-11 shows the structure of the HRS scattered light coefficients table.

Table 4-11. HRS Scattered Light Subtraction Coefficients Table, <unique name>.CZB

Column Name Data Type Units Description
APERTURE CH*3 Aperture (LSA or SSA)
RATING CH*9 Grating/echelle mode
SPORDER I Spectral order
A_SCAT R Scattered light coefficient a
B_SCAT R Scattered light coefficient b
C_SCAT R Scattered light coefficient c
D_SCAT R Scattered light coefficient d

4.2.12 Global Wavelength Coefficients Table: < unique name>.CZC

The global wavelength coefficients table contains the values for the global coefficients solution to determining the wavelength scale of an observation. The coefficients for temperature and time correction factors to the wavelength scale, based on the global coefficient solution, are also included.

Format: Records of global coefficient, temperature, and time constants are indexed by grating mode. Each record contains the necessary information to determine the dispersion coefficients used to calculate the wavelength solution for a given observation.

Selection Scheme: Records are selected on the basis of grating mode.

Table 4-12 shows the structure of the HRS global wavelength coefficients table.

Table 4-12. HRS Global Wavelength Coefficients Table,<unique name>. CZC

Column Name Data Type Units Description
GRATING CH*9 Grating/echelle mode
MCENTER I Central order of the grating
F00 D sample units Global coefficient
F01 D sample units Global coefficient
F02 D sample units Global coefficient
F10 D (sample units)/ Å Global coefficient
F11 D (sample units)/ Å/(encoder units) Global coefficient
F12 D (sample units)/ Å/(encoder units)2 Global coefficient
F20 D (sample units)/ Å2 Global coefficient
F21 D (sample units)/ Å2/(encoder units) Global coefficient
F22 D (sample units)/ Å2/(encoder units) 2 Global coefficient
F40 D (sample units)/ Å Global coefficient
F41 D (sample units)/ Å/(encoder units) Global coefficient
F42 D (sample units)/ Å/(encoder units)2 Global coefficient
F50 D (sample units)/ Å Global coefficient
F51 D (sample units)/ Å/(encoder units) Global coefficient
F52 D (sample units)/ Å/(encoder units)2 Global coefficient
ZRIUTA D deg Celsius RIU a temperature
ZRIUTB D deg Celsius RIU b temperature
ZDETT1 D deg Celsius Detector 1 temperature
ZDETT2 D deg Celsius Detector 2 temperature
ZDEBTF D deg Celsius DEB front post amps temperature
ZDEBTR D deg Celsius DEB rear post amps temperature
ZPABT1 D deg Celsius Detector 2 pre-amp assembly box temperature
ZMEBT1 D deg Celsius Main electronic box 1 temperature
ZMEBT2 D deg Celsius Fixture interface a temperature
ZFIBT D deg Celsius Fixture interface b temperature
ZFICT D deg Celsius Fixture interface c temperature
ZCST D deg Celsius Carrousel stator temperature
ZSCT1 D deg Celsius Detector 1 spectral cal-lamp temperature
ZSCT2 D deg Celsius Detector 2 spectral cal-lamp temperature
ZHVPST1 D deg Celsius Detector 1 HVPS temperature
ZHVPST2 D deg Celsius Detector 2 HVPS temperature
ZDT11 D deg Celsius Detector 1 detector shield temperature
ZDT12 D deg Celsius Detector 2 detector shield temperature
ZDRT D deg Celsius Digicon radiator temperature
ZOBBT D deg Celsius Optical bench bulkhead temperature

4.2.13 Photocathode Blemish Location Table: < unique name>.CZD

The photocathode blemish location table contains the locations of known blemishes in each of the HRS detectors caused by scratches, pits, and other microscopic imperfections in the detector window and photocathode.

Format: Each entry defines the location of one blemish. Blemishes are defined by a rectangle region bordered by the lower and upper line position and smaller to larger sample position. The data quality flag that should be assigned to the calibrated spectra by calhrs is found in the column EPSILON.

Selection Scheme: Records are selected based on the detector used and the line and sample position of the observed spectrum.

Table 4-13 shows the structure of the HRS photocathode blemish location table.

Table 4-13. HRS Photocathode Blemish Locations Table, <unique name>. CZD

Column Name Data Type Units Description
DETECTOR I Detector number
LINE1 D line units Starting lower line position of the blemish
LINE2 D line units Ending upper line position of the blemish
SAMPLE1 D sample units Starting lower sample position of the blemish
SAMPLE2 D sample units Ending upper sample position of the blemish
EPSILON I Data quality flag associated with the blemish
DEPTH D % Maximum depth of blemish

4.2.14 HRS Background Count Rates Table: <unique name>.CZE

The FOS BLUE detector predicted mean background count rates are stored as a function of geomagnetic latitude and longitude. The header keywords, D1SCALE and D2SCALE, are multiplicative scale factors used to adjust the background count rate model to the appropriate HRS detector. D1SCALE adjusts to the HRS Side 1; D2SCALE adjusts to the HRS Side 2. The mean background count rate at the time and position of the observation is interpolated from this table and used as the background spectrum during calibration.

Format: Records of background count rates are organized by detector, geomagnetic latitude, and geomagnetic longitude.

Selection Scheme: All records and the header keywords that represent scaling factors are selected.

Table 4-14 shows the structure of the background count rates table, < unique name>.CZE, as a function of geomagnetic position.

Table 4-14. HRS Background Count Rates Table, <unique name>. CZE

Column Name Data Type Units Description
FOS_DETECTOR BACK_RATE I*8 count/s
BLUE CH*4 Reference FOS detector:
GM_LAT I*4 degrees Geomagnetic latitude
GM_LONG I*4 degrees Geomagnetic longitude

The scaling factor header keywords are D1SCALE and D2SCALE.

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