9.2 Raw data files (ERD and Compact Status)

There are two files in this section: SWER  SWS Edited Raw Data and SSTA  SWS Compact Status.

9.2.1 SWS Edited Raw Data

 

Headers

The ERD files contain primary headers described in Table 9.1. In this table example information is used to fill the header.

Most keywords are self explanatory. Those that are not include:

TMRATE

The Telemetry Rate can only be 32, indicating 32 kbps.

EOHAAOTN

This can take the values S01, S02, S06 or S07, for the appropriate AOT.

ATTUTCS

This should be close in value to EOHAUTCS. If the observation contains micro-slews (e.g. SWS aperture changes) this value will refer to the first pointing.

ATTOTFTH

AOT on target flag. When the pointing is within this accuracy of the target the on target flag is set.

ATTTYPE

Can be set to ``T'' for solar system tracking, ``P'' for fine pointing (single target) or ``R'' for a raster  operation.

Time keys

The various time keys, referred to by TREFUTK, TREKITK and TREFITKU, are described in section 3.2 of the ISO Satellite Data User manual.

 

Header keyword Contents Comment

SIMPLE  = T

BITPIX  = 8

NAXIS  = 0

EXTEND  = T

ORIGIN  = 'ESA ' European Space Agency

TELESCOP = 'ISO ' Infrared Space Observatory

INSTRUME = 'SWS ' Instrument used

COMMENT   SWS Edited Raw Data

FILENAME = 'SWER23300209' File name in ISO archive

DATE  = '26/09/95' Creation date 95/269

FILEVERS = '0377 ' Version ID in ISO archive

OLPVERS  = 'LATEST ' SOC OLP system version

OBJECT  = 'NGC6543 ' Target ID as given by proposer

OBSERVER = 'SWS ' Proposer ID in ISO Mission DB

EQUINOX  = 2000.0 Equinox

TMRATE  = 32 Telemetry rate in Kbps (Kbits/sec)

EOHAUTCS = '96130004435' Approx. UTC of start of observation

EOHAUTCE = '96130013951' Approx. UTC of end of observation

EOHAAOTN = 'S06 ' AOT name

EOHAPLID = 'SWS_EE2 ' Proposal ID

EOHAOSN  = '09 ' Observation sequence number

EOHAPSN  = '00 ' Pointing sequence number

EOHAPCAT = '4 ' Proposal category

EOHACIND = ' ' Calibration indicator

EOHATTYP = '003 ' Target type

AOTVERS  = '95118180436' AOT-to-OCT logic version

ATTUTCSL = '96130004411' UTC of start time of slew to intended target

ATTUTCS  = '96130004421' UTC of time of first arrival at intended target

ATTOTFTH = 10.0 On-target flag threshold (arc secs)

ATTRA  = 303.56 Intended Right Ascension of instrument viewing, in degrees

ATTDEC  = 28.0 Intended DEClination (with ATTRA), in degrees

ATTTYPE  = 'R ' Type of attitude operation (P/R/T)

ATTRNPTS = 1 Number of points per line of the raster

ATTRNLNS = 1 Number of lines in whole raster pointing

ATTRDPTS = 0 Distance (arcsecs) between adjacent points

ATTRDLNS = 0 Distance (arcsecs) between adjacent lines

ATTRORIE = 0 ORIENTation flag (0 or 1)

ATTRROTA = 0.0 ROTATE of raster pattern (degrees)

ATTGUIDE = 150002 Guide star reference number

ATTSAANG = 92.6 Solar aspect angle (degrees)

ATTERROR = 0 CONTINGEncy flag(0=success; 1=target not acq'd)

TREFUTC1 = 231986675 UTC (whole seconds since 01-01-1989)

TREFUTC2 = 4101430 UTC (remaining fraction of second)

TREFUTK  = 1781286624 ISO Uniform Time Key (UTK)

TREFITK  = 1781286624 ISO INSTRUMENT Time Key (ITK)

TREFITKU = 0.04166666666667 ITK unit length in seconds

 

Records

The ERD file contains records with the fields described in Table 9.2. The fields are defined in the FITS file binary header.

 

Field name Number Format Comment

GPSCTKEY  1 I*4 Instrument time key

GPSCRPID  2 I*1 Raster point ID

GPSCFILL  1 I*2 Filler

SWERDR5  12 I*2 5-micron array readouts

SWERDR10  12 I*2 10-micron array readouts

SWERDR20  12 I*2 20-micron array readouts

SWERDR35  12 I*2 35-micron array readouts

SWERDRFP  4 I*2 FP detector readouts

SWERHK1  1 I*2 SW scanner - actual position (if mode = 0,1)

SWERHK2  1 I*2 SW scanner - LVDT  output (if mode = 0,1)

SWERHK3  1 I*2 SW scanner motor current (if mode=1)

SWERHK4  1 I*2 SW scanner DAC output (if mode=1)

SWERHK5  1 I*2 LW scanner - actual position (if mode = 0,2,3)

SWERHK6  1 I*2 LW scanner - LVDT  output (if mode = 0,2,3)

SWERHK7  1 I*2 LW scanner motor current (if mode=2)

SWERHK8  1 I*2 LW scanner DAC output (if mode=2)

SWERHK9  1 I*2 Last received internal command (if mode=3)

SWERHK10  1 I*2 Temp. sensor FP cal. source (if mode=3)

SWERHK11  1 I*2 Fabry-Pérot main current

SWERHK12  1 I*2 Fabry-Pérot correction current 1

SWERHK13  1 I*2 Fabry-Pérot correction current 2

SWERSLHK  1 I*2 Slowly commutated Housekeeping (HK)

SWERIRC  1 I*2 Internal readout counter

SWEREXEC  1 I*2 ``Execute'' flags

 

Notes:

1

Twenty-four records are generated each second.

2

The five SWERDR   fields contain the detector readouts, whereas the thirteen SWERHK   fields allow the wavelength falling on each detector to be calculated.

3

The two GPSCRPID fields should always contain ``1''s for SWS, as SWS does not have a raster  mode.

4

The selection of which of fields SWERHK1  to SWERHK10  contain valid information is mode-dependent. The ``mode'' can be 0, 1, 2 or 3, with a normal default value of 0. A change in mode implies the start of a new measurement period, and the value of the mode is contained in the corresponding Compact Status field called SSTAHKMD .

5

Whereas all other fields repeat at the rate of 24 Hz, SWERSLHK  repeats at 0.5 Hz and the meaning of any individual readout depends on the accompanying value of SWERIRC .

6

SWERIRC   begins at 1 (for the first readout cycle of a new format), then increments up to 48. It is derived from the ``SWS internal frame counter'' and indicates the sequence of information in SWERSLHK .

7

SWEREXEC   is extracted from the more significant byte of the SWS internal frame counter. Because the flags are telemetered at a rate of 12 Hz, they appear only in ERD records for which SWERIRC is a multiple of 2; the flags are set to zero for the intervening records. The more significant byte of SWEREXEC is always set to zero, i.e. the sign bit for the flags is not extended.

9.2.2 SWS Compact Status

Headers

The CSH files primary header, filled with example information, is described in Table 9.3.

Header keyword Contents Comment

SIMPLE  = T /

BITPIX  = 8 /

NAXIS  = 0 /

EXTEND  = T /

ORIGIN  = 'ESA ' / European Space Agency

TELESCOP = 'ISO ' / Infrared Space Observatory

INSTRUME = 'SWS ' / Instrument used

COMMENT   / SWS Compact Status

FILENAME = 'SSTA26400248' / File name in ISO archive

DATE  = '09/07/95' / Creation date 95/190

FILEVERS = '0298 ' / Version ID in ISO archive

OLPVERS  = 'OLP_21 ' / SOC OLP system version

VERS1  = '0298/SCSH264' / Version ID of each input file

EQUINOX  = 2000.0 / Equinox

TMRATE  = 32 / Telemetry rate in Kbps (Kbits/sec)

EOHAUTCS = '96166223020' / Approx. UTC of start of observation

EOHAUTCE = '96166223818' / Approx. UTC of end of observation

EOHAAOTN = 'S07 ' / AOT name

EOHAPLID = 'MPEWARM1' / Proposal ID

EOHAOSN  = '48 ' / Observation sequence number

EOHAPSN  = '0 ' / Pointing sequence number

EOHAPCAT = '1 ' / Proposal category

EOHACIND = ' ' / Calibration indicator

EOHATTYP = '2 ' / Target type

AOTVERS  = '94350161513' / AOT-to-OCT logic version

ATTUTCSL = '96166222532' / UTC of start time of slew to intended target

ATTUTCS  = '96166222627' / UTC of time of first arrival at intended target

ATTOTFTH = 10.0 / On-target flag threshold (arc secs)

ATTRA  = 302.66 / Intended Right Ascension of instrument viewing, in degrees

ATTDEC  = 27.8 / Intended DEClination (with ATTRA), in degrees

ATTTYPE  = 'P ' / Type of attitude operation (P/R/T)

ATTGUIDE = 150002 / Guide star reference number

ATTSAANG = 115.9 / Solar aspect angle (degrees)

ATTERROR = 2 / CONTINGEncy flag(0=success; 1=target not acq'd)

TREFUTC1 = 235175420 / UTC (whole seconds since 01-01-1989)

TREFUTC2 = 8505250 / UTC (remaining fraction of second)

 

TREFUTK  = 1857816480 / ISO Uniform Time Key (UTK)

TREFITK  = 1857816480 / ISO INSTRUMENT Time Key (ITK)

TREFITKU = 0.04166666666667 / ITK unit length in seconds

 

Records

The Compact Status file contains records with the fields described in Table 9.4. The records are defined in the binary header of the FITS file.

 

Field name Number Format Comment

CSGPUKST  1 I*4 UTK  start time

CSGPUKEN  1 I*4 UTK end time

CSGPIKST  1 I*4 ITK  start time

CSGPIKEN  1 I*4 ITK end time

CSGPUTST  2 I*4 UTC  start time

CSGPUTEN  2 I*4 UTC end time

CSGPOSN  1 I*1 Observation Sequence Number

CSGPFILL  15 I*1 Spare

SSTASHUT  1 I*2 Shutter position (0=closed, or 1/2/3)

SSTAGAIN  6 I*2 Nominal gain in each of the bands (1/4/16)

SSTACALS  4 I*2 Calibration source status

SSTARESP  2 I*2 Reset pulse interval in frames (SW/LW)

SSTAHKMD  1 I*2 House keeping mode

SSTAFPS  1 I*2 FP selection (1=FP1, 2=FP2)

SSTASPAR  9 I*2 Spare

 

The four elements of SSTACALS are:

1

Grating calibrator

2

Flusher

3

FP calibrator

4

Diffuse calibrator

A zero in a SSTACALS field indicates that the respective calibrator is off. 1 indicates it is on low, 2 that it is on high.