Subsections

• A.2.1 Edited Raw Data (ERD)
  • A.2.1.1 Headers
  • A.2.1.2 Records
• A.2.2 Compact Status History (CSH)
  • A.2.2.1 Headers
  • A.2.2.2 Records

A.2 Raw Data Files

Two files are described in this section: the SWS Edited Raw Data (ERD) and the SWS Compact Status (CSH).

A.2.1 Edited Raw Data (ERD)

These files are normally named swer*.fits, where `*' is an eight-digit number generated from the revolution the observation was made, the order the observations were performed in that day and the order it appeared in the proposal.

A.2.1.1 Headers

The ERD files contain primary headers described in Table A.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 AOTs 1, 2, 6 and 7, or S90 to S99 for calibration/post-He observations. This is copied from the field of the same name in the EOHA file for the observation, see the ISO Handbook Volume I, [17] for an explanation of this file.

EOHAPCAT

indicates the proposal category as entered by the user in PGA. The categories were European GT, NASA GT, ISAS GT, OT or Calibration, and these are coded in EOHAPCAT as numbers 1 to 5 respectively. This is copied from the field of the same name in the EOHA file for the observation.

EOHATTYP

indicates the scientific category as entered by the user in PGA. The categories were Solar System, Interstellar Matter, Stellar Physics, Extragalactic Systems or Cosmology, and these are coded in EOHATTYP as numbers 001 to 005 respectively. This is copied from the EOHASCAT field in the EOHA file for the observation.

ATTUTCS

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

is the AOT on target threshold in arcsec. 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, TREFITK and TREFITKU, are described in the ISO Handbook Volume I, [17].

VERSn

indicates the version numbers of the various files used to generate this product.

Table A.1: ERD primary headers

Header keyword		Contents		Comment
SIMPLE	=	T	/	file does conform to FITS standard
BITPIX	=	8	/	number of bits per data pixel
NAXIS	=	0	/	number of data axes
EXTEND	=	T	/	FITS dataset may contain extensions
COMMENT	FITS (Flexible Image Transport System) format defined in Astronomy and
COMMENT	Astrophysics Supplement Series v44/p363, v44/p371, v73/p359, v73/p365.
COMMENT	Contact the NASA Science Office of Standards and Technology for the
COMMENT	FITS Definition document #100 and other FITS information.
ORIGIN	=	'ESA '	/	European Space Agency
TELESCOP	=	'ISO '	/	Infrared Space Observatory
INSTRUME	=	'SWS '	/	Instrument used
COMMENT	SWS Edited Raw Data
FILENAME	=	'SWER67801301'	/	File name
DATE	=	'2001-12-14'	/	Creation date 2001/348
FILEVERS	=	'2690 '	/	Version ID (derived from creation date)
OLPVERS	=	'OLP_101 '	/	SOC OLP system version
CALGVERS	=	'CALG_71 '	/	SOC OLP CAL-G files version
USERNAME	=	'PIPEPAR'	/	Product not catalogued
VERS1	=	'2518/EOHA678'	/	Version ID of each input file
VERS2	=	'2518/EOHI678'	/	Version ID of each input file
VERS3	=	'1120/APPH678'	/	Version ID of each input file
OBJECT	=	'HR7001 ALPHA-LYR'	/	Target ID as given by proposer
OBSERVER	=	'SWS_CAL '	/	Proposer ID in ISO Mission DB
EQUINOX	=	2000.0	/	Equinox
TMRATE	=	32	/	Telemetry rate in Kbps (Kbits/s)
EOHAUTCS	=	'97266235847'	/	Approx. UTC of start of observation
EOHAUTCE	=	'97267011121'	/	Approx. UTC of end of observation
EOHAAOTN	=	'S06 '	/	AOT name
EOHAPLID	=	'SWS_678 '	/	Proposal ID
EOHAOSN	=	'01 '	/	Observation sequence number
EOHAPSN	=	'00 '	/	Pointing sequence number
EOHAPCAT	=	'5 '	/	Proposal category
EOHACIND	=	' '	/	Calibration indicator
EOHATTYP	=	'001 '	/	Target type
AOTVERS	=	'03.70 '	/	AOT-to-OCT logic version
TREFCOR1	=	275443127	/	UTC of 1st reference time
TREFPHA1	=	678.40749	/	Orbital phase at TREFCOR1
TREFCOR2	=	275445304	/	UTC of 2nd reference time
TREFPHA2	=	678.43275	/	Orbital phase at TREFCOR2
TREFCOR3	=	275447481	/	UTC of 3rd reference time
TREFPHA3	=	678.45801	/	Orbital phase at TREFCOR3
ATTUTCSL	=	'97266235519'	/	UTC of start time of slew to intended target
ATTUTCS	=	'97266235820'	/	UTC of time of first arrival at intended target
ATTOTFTH	=	10.0	/	On-target flag threshold (arc secs)
ATTRA	=	279.23442	/	Intended Right Ascension of instrument viewing
ATTDEC	=	38.78350	/	Intended Declination (with ATTRA)
ATTTYPE	=	'P '	/	Type of attitude operation (P/R/T)
ATTGUIDE	=	101570	/	Guide star reference number
ATTSAANG	=	96.8	/	Solar aspect angle (degrees)
ATTERROR	=	0	/	Contingency flag(0=success; 1=target not acq'd)
TREFUTC1	=	275443127	/	UTC (whole seconds since 01-01-1989)
TREFUTC2	=	951300	/	UTC (remaining fraction of second)
TREFUTK	=	1437003072	/	ISO Uniform Time Key (UTK)
TREFITK	=	1437003072	/	ISO INSTRUMENT Time Key (ITK)
TREFITKU	=	0.04166666666667	/	ITK unit length in seconds (= 1/24)
END

A.2.1.2 Records

The ERD file contains records (24 per second) with the fields described in Table A.2.

Table A.2: Records in the ERD file

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. The five SWERDR fields contain the detector readouts, whereas the thirteen SWERHK fields allow the wavelength falling on each detector to be calculated.
2. The two GPSCRPID fields should always contain `1's for SWS, unless a SSO is being tracked.
3. The selection of which of fields SWERHK1 to SWERHK10 contain valid information is mode-dependent. The `mode' can be 0 (default), 1, 2 or 3. 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 SSTAHKMD. In practice the mode is completely ignored and the only SWERHK information that is used is the actual positions of the scanners: SWERHK1 and SWERHK5.
4. Whereas all other fields repeat at the rate of 24 Hz, SWERSLHK repeats at 0.5 Hz. The meaning of any individual readout depends on the accompanying value of SWERIRC.
5. 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.
6. SWEREXEC is extracted from the more significant byte of the SWERIRC. They appear only in ERD records for which SWERIRC is a multiple of 2, as the flags are telemetered at a rate of 12 Hz, and are set to zero for the intervening records. The more significant byte of SWEREXEC is always set to zero, e.g. the sign bit for the flags is not extended.

A.2.2 Compact Status History (CSH)

These files are normally named ssta*.fits.

A.2.2.1 Headers

The CSH files primary header are very much the same as the ERD headers. No new keywords need to be explained.

A.2.2.2 Records

The Compact Status file contains records with the fields described in Table A.3. The records are defined in the binary header of the FITS file.

Table A.3: Records in the CSH 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$^1$	4	I*2	Calibration source status
SSTARESP	2	I*2	Reset 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

1. The four elements of SSTACALS are:
   1: Grating calibrator, 2: Flusher, 3: FP calibrator and 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.