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12.3 SPD product types

12.3.1 Rationale behind product design

PHT generates per detector an SPD record for each signal per chopper plateau or for each raster point. There are 7 separate SPD products:

1.: - C100 SPD data
2.: - C200 SPD data
3.: - P1 SPD data
4.: - P2 SPD data
5.: - P3 SPD data
6.: - PHT-SS SPD data
7.: - PHT-SL SPD data

In order to retain the information on the actual observing conditions, each SPD record contains additional information to identify the operating conditions under which the data were collected. Within an SPD file, the type of record is determined by:

spacecraft viewing direction (e.g. in case of raster maps)
chopper viewing direction (CFOV, offset position, or FCS)
aperture
filter

Within one AOT, data of different types can be archived inside the same SPD file. Examples:

For chopped measurements, each on-source and background plateau is stored as a separate record in the same SPD file
Data from each raster position within a raster map are stored in separate records in chronological order in the same SPD file.
Multi-filter AOT's produce one SPD file per detector. Data from different filters for a given detector are stored as a series of records ordered chronologically inside the same SPD file.
In case of multi-aperture photometry with PHT04, one SPD file is created. The aperture measurements are stored as series of records ordered chronologically inside the same SPD file.
In case of oversampled maps with PHT32, each map position can yield several records corresponding to the number of chopper plateaux collected on that position.

12.3.1.1 General SPD header items I

The following header keywords are included in all PHT SPD products.


FIELD		T	 	 Description				Comment
DETECTOR	C		 Detector subsystem 		 
NMEAS 		I		 Number of measurements 		 
CALSEQU 	I		 Calibration sequence 		 
PTOREXT 	C		 Point(P) or Extended(E) 		 
FPCMODE 	C		 Focal plane chopper mode 		 see Table 12.2
FPCAMP 		I		 Chopper amplitude(arcsec)		 
FPCNSTEP	I		 Number of chopper steps 		 only if chop mode
FPCINCR 	I		 Increment between steps (arcsec)	 only if chop mode
DARKPn 		R		 dark current 				 for pixel n, both keywords -
DARKUPn 	R		 dark current uncertainty 		 -repeated for each pixel

Notes:

the dark currents (DARK..) are given in signal units of V/s.
FPC modes: `ST' = staring, `RE' = rectangular, `SW' = sawtooth, `TR' = triangular,`CB' = chop between FCS1 and FCS2.

12.3.1.2 Filter dependent SPD header items

The following header keywords are repeatedly given for each filter m:


FIELD		T		Description				Comment
FILTERm 	C		 Filter 		 		filter name
EXFLUXm 	R		 Expected source flux (Jy or MJy/sr) 	Jy if PTOREXT=P
UNCFLXm 	R		 Uncertainty (Jy or MJy/sr) 		Jy if PTOREXT=P 
MXBACKm 	R		 Maximum background (¹⁰log MJy/sr) 		 
CALP1Fm 	C		 Cal used in SPD calculations 		see notes below 
CALDATE 	C		 Date default calibration file 		in `dd/mm/yy'
CHC1Pm 		R		 Chopper correction 		 	only if chopped mode
CHU1Pm 		R		 Chopper correction uncertainty 	only if chopped mode
A0RIm 		R		 Reset interval corr. offset, A0 (V/s) 		 
A0RIUm 		R		 Uncertainty in A0 (V/s) 		 
A1RIm 		R		 Reset interval corr. slope, A1 		 
A1RIUm 		R		 Uncertainty in A1		 
CALPnFm 	C		 Calibration used in SPD 		present if npix>1
CALDATE 	C		 Date default calibration file 		in dd/mm/yy
CHCnPm 		R		 Chopper corrections 		 	only if chopped mode
CHUnPm 		R		 Chopper correction uncertainty 	only if chopped mode
TRS1Sm 		I		 Selected TRS for FCS1 		 
POW1Sm 		R		 Selected power for FCS1 		 
POW1Mm 		R		 Measured power for FCS1 		 
CALPOW1 	R		 In-band power on detector for cal (Watts)		 
RESPDEF 	L		 TRUE if default responsivity is used.		 
CALPOLm 	I		 CHWI position 		 		see section A.1
CALTYPm 	I		 Type of processing for cal measurement number of cal. measurements
RS1PnFm 	R		 Responsivity (A/W) for first cal. 	for pixel n
RU1PnFm 	R		 Uncertainty (A/W)		 	for pixel n
RS2PnFm 	R		 Responsivity (A/W) for second cal.	for pixel n
RU2PnFm 	R		 Uncertainty 		 		for pixel n

Notes:

CALP1F can have the following values: single, first, second, both, and default, depending on the calibration method in the AOT and the quality of the FCS measurements.
EXFLUX, UNCFLX, and MXBACK were the initial estimates from the observer entered in PGA.
for AOT PHT32 there is no one-to-one match between the keyword description and the AOT parameter as given by the observer in the ISO proposal generation aids (PGA): EXFLUX= maximum unsaturated surface brightness, UNCFLX= minimum surface brightness flux.

12.3.1.3 General PHT related SPD header items II

The following header keywords are appended after all filters have been listed:


FIELD		T	 	 Description				Comment
SATLIMn 	R		 Saturation limit 		 	in Volts for pixel n
FITDRn 		L		 Drift fit flag 		 	always T (no fitting implemented)
MINDEG 		I		 Min points for deglitcher  	 	see section 7.3.4-
MAXERR 		R		 Max error if points < MINDEG	 	-for signal deglitching 
NITERATE	I		 No. of iterations of deglitcher 		 
NLOCAL 		I		 No. of local points used by deglitcher 		 
NSTEP 		I		 Deglitcher step size 		 
NSIGMA 		R		 Deglitcher: rms from local median 		 
NBAD 		I		 Deglitcher: badness count limit 		 
CALFCS 		I		 FCS used for cal calculations 		FCS 1 or 2 
RDITER 		I		 Ramp deglitch: no. iterations 		see section 7.2.8-
RDFSIG 		R		 Ramp deglitch: sigma for detection 	-for ramp deglitching
RDMINP 		I		 Ramp deglitch: min. readouts in ramp 		 
DRALPHA 	R		 Drift removal: significance level 	see section 7.3.5 - 
DRMINPTS	I		 Drift removal: min. points		-for drift recognition 
READAUTO	I		 Readouts with automatic data reduction 		 
READSUSP	I		 Readouts flagged as suspicious 		 
READOFFT	I		 Readouts off-target 		 
READCOP 	I		 Readouts with chopper off position 		 
RAMPSAT 	I		 Ramps saturated 		 
RAMPDEGL	I		 Ramps deglitched 		 
RAMPPCT 	I		 % ramps accepted 		 
RAMPUSET	I		 % time for accepted ramps 		 
RAMPINVD	I		 Bad cycles 		 
RAMPFROP	I		 First ramps ignored 		 
RAMPZSG 	I		 Zero signals on plateau 		plateaux with no accepted signals 
PLATNORP	I		 Plateaux with no good ramps 		 
PLATDROP	I		 Plateaux dropouts due to gaps 		 
USEDRS 		L		 Use destructive readouts? 		always `F' for OLP7
DISCNDRS	I		 Discard 1st NDRs of ramps 		number of read-outs removed
									see section 7.2.2

12.3.1.4 Product specific SPD header items: PHT05 and PHT25

The following keywords are only present in SPD products from absolute photometry observations PHT05 and PHT25.


FIELD		T		Description				Comment
MEASPW1 	R 		FCS1 heating power (mW)		 
POWFCS1 	R 		Power from FCS1 (W) 		 
RESPRn 		R 		ratio Actual/Default responsivity	for pixel n
CALPn 		R 		FCS measurement signal in V/s		for pixel n 
CALUPn 		R 		uncertainty in V/s 		 	for pixel n 
CALQPn 		R 		FCS quality		 		for pixel n 
COLDPn 		R 		Cold FCS measurement signal in V/s	for pixel n 
COLDUPn 	R 		Uncertainty in V/s 		 	for pixel n

12.3.2 Product PPxS

PHT-P1/2/3 Standard Processed Data where x = 1,2, or 3

HEADER
Product specific header entries:


CALAPER		I		Aperture used for FCS calibration (CHW position)

RECORD
record length: 68 bytes


FIELD		N	T	Description			Comment
GPSCTKEY	1	I*4	Instrument time key		 
GPSCRPID	2	I*1	Raster point ID		 	points and lines
GPSCFILL	1	I*2	Filler		 
PPxSKYID	1	I*2	Keyword identifier 		 
PPxSMNUM	1	I*2	Measurement number		 
PPxSSPAR	1	I*2	Spare		 
PPxSFILT	1	I*2	CHW3 position 			value: 1 - 14, see A.1
PPxSAPER	1	I*2	CHW2 position		 	idem
PPxSPOLZ	1	I*2	CHW1 position		 	idem
PPxSNDRS	1	I*2	Number of destructive readouts 	per chopper plateau
PPxSCSTP	1	I*2	Chopper step number 		see 7.3.3
PPxSDWEL	1	I*4	Chopper dwell time in 2^-7 s 	commanded time
PPxSMEAS	1	I*4	Measurement time (secs) 		 
PPxSCPOS	1	I*4	Chopper position (arcsec) 		 
PPxSMNPW	1	R*4	Mean or fitted power		in W
PPxSMNPU	1	R*4	Uncertainty		 	in W 
PPxSMDPW	1	R*4	Median power		 	in W
PPxSQ1PW	1	R*4	1st quartile of power		in W
PPxSQ3PW	1	R*4	3rd quartile of power		in W
PPxSPLEN	1	I*4	Chopper plateau length in 2^-7s	effective time-
					 			-after discarding signals
PPxSNSIG	1	I*4	No. of valid signals on the plateau		 
PPxSFLAG	1	I*1	Status flag		 	see section 12.3.12
PPxSFILL	3	I*1	Filler

12.3.3 Product PC1S

PHT-C100 Standard Processed Data

HEADER
Product specific header entries:


STATPIX		I		Pixel used in statistics

RECORD
Record length: 300 bytes


FIELD		N		T		Description			Comment
GPSCTKEY	1		I*4		Instrument time key		 
GPSCRPID	2		I*1		Raster point ID		 	points and lines
GPSCFILL	1		I*2		Filler		 
PC1SKYID	1		I*2		Keyword identifier 		 
PC1SMNUM	1		I*2		Measurement number		 
PC1SSPAR	1		I*2		Spare		 
PC1SFILT	1		I*2		CHW3 position 			value: 1 - 14, see A.1
PC1SAPER	1		I*2		CHW2 position		 	idem
PC1SPOLZ	1		I*2		CHW1 position		 	idem
PC1SNDRS	1		I*2		Number of destructive readouts 		 
PC1SCSTP	1		I*2		Chopper step number 		see 7.3.3
PC1SDWEL	1		I*4		Chopper dwell time in 2^-7 s 	commanded time
PC1SMEAS	1		I*4		Measurement time (secs) 		 
PC1SCPOS	1		I*4		Chopper position (arcsec) 		 
PC1SMNPW	9		R*4		Mean or fitted power		in W
PC1SMNPU	9		R*4		Uncertainty		 	in W
PC1SMDPW	9		R*4		Median power		 	in W
PC1SQ1PW	9		R*4		1st quartile of power		in W
PC1SQ3PW	9		R*4		3rd quartile of power		in W
PC1SPLEN	9		I*4		Chopper plateau length in 2^-7s	effective time-
										-after discarding signals
PC1SNSIG	9		I*4		No. of valid signals on the plateau
PC1SFLAG	9		I*1		Status flag		 	see section 12.3.12
PC1SFILL	3		I*1		Filler

12.3.4 Product PC2S

PHT-C200 Standard Processed Data

HEADER
Product specific header entries:


STATPIX		I		Pixel used in statistics

RECORD
Record length: 152 bytes


FIELD		N		T		Description			Comment
GPSCTKEY	1		I*4		Instrument time key		 
GPSCRPID	2		I*1		Raster point ID		 	points and lines
GPSCFILL	1		I*2		Filler		 
PC2SKYID	1		I*2		Keyword identifier 		 
PC2SMNUM	1		I*2		Measurement number		 
PC2SSPAR	1		I*2		Spare		 
PC2SFILT	1		I*2		CHW3 position 			value: 1 - 14, see A.1
PC2SAPER	1		I*2		CHW2 position		 	idem
PC2SPOLZ	1		I*2		CHW1 position		 	idem
PC2SNDRS	1		I*2		Number of destructive readouts 		 
PC2SCSTP	1		I*2		Chopper step number 		 
PC2SDWEL	1		I*4		Chopper dwell time in 2^-7 s
PC2SMEAS	1		I*4		Measurement time (secs) 		 
PC2SCPOS	1		I*4		Chopper position (arcsec) 		 
PC2SMNPW	4		R*4		Mean or fitted power		in W
PC2SMNPU	4		R*4		Uncertainty		 	in W
PC2SMDPW	4		R*4		Median power		 	in W
PC2SQ1PW	4		R*4		1st quartile of power		in W
PC2SQ3PW	4		R*4		3rd quartile of power		in W
PC2SPLEN	4		I*4		Chopper plateau length in 2^-7 s	effective time-
							 			-after discarding signals
PC2SNSIG	4		I*4		No. of valid signals on the plateau
PC2SFLAG	4		I*1		Status flags		 	see section 12.3.12

12.3.5 Product PSSS

PHT-SS Standard Processed Data

HEADER
Product specific header entries:


FIELD		T	Description				Comment
CALDATE 	C	 Date cal defaults generated		 
PTOREXT 	C	 Point(P) or Extended(E)		 
LAMBDAd 	C	 Central wavelength of pixel (m)		 
LUNCd 		C	 Uncertainty (m)		 
RESPPd 		C	 Point source srf (V/s)/Jy		if point source
RPUNCd 		C	 Uncertainty (V/s)/Jy)		 	if point source
RESPEd 		C	 Extended source srf (V/s)/(MJy/sr)	if extended source
REUNCd 		C	 Uncertainty (V/s)/(MJy/sr)		if extended source

note:
d=1,...,64
srf=spectral response function

RECORD
Record length: 1892


FIELD		N		T		Description			Comment
GPSCTKEY	1		I*4		Instrument time key		 
GPSCRPID	2		I*1		Raster point ID		 	points and lines
GPSCFILL	1		I*2		Filler		 
PSSSKYID	1		I*2		Keyword identifier 		 
PSSSMNUM	1		I*2		Measurement number		 
PSSSSPAR	3		I*2		Spare		 
PSSSPOLZ	1		I*2		CHW1 position			value: 1 - 14, see A.1
PSSSNDRS	1		I*2		Number of destructive readouts 		 
PSSSCSTP	1		I*2		Chopper step number 		 
PSSSDWEL	1		I*4		Chopper dwell time in 2^-7 s	commanded
PSSSMEAS	1		I*4		Measurement time (secs) 		 
PSSSCPOS	1		I*4		Chopper position (arcsec) 		 
PSSSMNPW	64		R*4		Mean or fitted signal		in V/s
PSSSMNPU	64		R*4		Uncertainty		 	in V/s
PSSSMDPW	64		R*4		Median signal		 	in V/s
PSSSQ1PW	64		R*4		1st quartile of signal		in V/s
PSSSQ3PW	64		R*4		3rd quartile of signal		in V/s
PSSSPLEN	64		I*4		Chopper plateau length in 2^-7 s	 effective time-
							 			-after discarding signals
PSSSNSIG	64		I*4		No. of valid signals on the plateau
PSSSFLAG	64		I*1		Status flags		 	see section 12.3.12

12.3.6 Product PSLS

PHT-SL Standard Processed Data

HEADER
Product specific header entries are the same as for product PSSS

RECORD
Record length: 1892


FIELD		N		T		Description			Comment
GPSCTKEY	1		I*4		Instrument time key		 
GPSCRPID	2		I*1		Raster point ID		 	points and lines
GPSCFILL	1		I*2		Filler		 
PSLSKYID	1		I*2		Keyword identifier 		 
PSLSMNUM	1		I*2		Measurement number		 
PSLSSPAR	3		I*2		Spare		 
PSLSPOLZ	1		I*2		CHWI position 		 
PSLSNDRS	1		I*2		Number of destructive readouts 		 
PSLSCSTP	1		I*2		Chopper step number 		 
PSLSDWEL	1		I*4		Chopper dwell time in 2^-7 s	commanded
PSLSMEAS	1		I*4		Measurement time (secs) 		 
PSLSCPOS	1		I*4		Chopper position (arcsec) 		 
PSLSMNPW	64		R*4		Mean or fitted signal		in V/s 
PSLSMNPU	64		R*4		Uncertainty in mean signal	in V/s 
PSLSMDPW	64		R*4		Median signal		  	in V/s 
PSLSQ1PW	64		R*4		1st quartile of signal		in V/s 
PSLSQ3PW	64		R*4		3rd quartile of signal		in V/s 
PSLSPLEN	64		I*4		Chopper plateau length in 2^-7 s	effective time-
										-after discarding signals
PSLSNSIG	64		I*4		No. of valid signals on the plateau
PSLSFLAG	64		I*1		Status flags		 	see section 12.3.12

12.3.7 Product PPxA

PPxA (where x=1,2,3) contains the SPD of the FCS measurements obtained with detector P1, P2 or P3. PPxA products are also referred to as Cal A files (see section 5.7.2). The product of a chopped measurement contains 1 record per chopper plateau. In case a cold FCS measurement is selected in the absolute photometry AOT PHT05, the first record contains the cold FCS measurement and the second record contains the results of the heated FCS measurement.

RECORD
Record length: 84


FIELD	 N  T	 Description				Comment
GPSCTKEY 1  I*4  Instrument time key
GPSCRPID 2  I*1  Raster point ID			points and lines
GPSCFILL 1  I*2  Filler
PPxAQFLG 1  I*2  Quality flag
PPxAKYID 1  I*2  Keyword identifier
PPxAMNUM 1  I*2  Measurement number
PPxASPAR 1  I*2  Spare
PPxAFILT 1  I*2  CHW3 position 				value: 1 - 14, see A.1
PPxAAPER 1  I*2  CHW2 position		 		idem
PPxAPOLZ 1  I*2  CHW1 position		 		idem
PPxASTAT 1  I*2  FPC state (0 = CFOV, 1 = FCS1, 2 = FCS2)
PPxADWEL 1  I*4  Commmanded chopper dwell time in 2^-7 s 
PPxACPOS 1  R*4  Chopper position (arcsec)
PPxAFCS1 1  R*4  Measured FCS1 power (mW) 
PPxAFCS2 1  R*4  Measured FCS2 power (mW) 
PPxATEMP 1  R*4  Detector temperature (K)
PPxAFILR 1  R*4  Filler
PPxABIAS 1  R*4  Measured bias voltage (V) 
PPxAMNSG 1  R*4  Mean or fitted signal (V/s) 
PPxAMNSU 1  R*4  Uncertainty(V/s) 
PPxAMDSG 1  R*4  Median signal (V/s) 
PPxAQ1SG 1  R*4  1st quartile of signal (V/s) 
PPxAQ3SG 1  R*4  3rd quartile of signal (V/s) 
PPxAPLEN 1  I*4	 Chopper plateau length in 2^-7 s 	 effective time
							after discarding signals
PPxANSIG 1  I*4  No. of valid signals on the plateau
PPxAFLAG 1  I*1  Status flag
PPxAFILI 3  I*1  Filler

Note: FPC state (PPxASTAT) cannot be zero for these measurements.

12.3.8 Product PCxA

PCxA (where x=1 or 2) is a Cal A product which contains the SPD of the FCS measurements obtained with the C100 or C200 detector arrays. In case a cold FCS measurement is selected in the absolute photometry AOT PHT25, the first record contains the cold FCS measurement and the second record contains the results of the heated FCS measurement.

RECORD
Record length: 316 for x=1, 180 for x=2


FIELD		N	T	Description				Comment
GPSCTKEY 	1 	I*4 	Instrument time key
GPSCRPID 	2 	I*1 	Raster point ID				points and lines
GPSCFILL 	1 	I*2 	Filler
PCxAQFLG 	1 	I*2 	Quality flag
PCxAKYID 	1 	I*2 	Keyword identifier
PCxAMNUM 	1 	I*2 	Measurement number
PCxASPAR 	1 	I*2 	Spare
PCxAFILT 	1 	I*2 	CHW3 position 				value: 1 - 14, see A.1
PCxAAPER 	1 	I*2 	CHW2 position		 		idem
PCxAPOLZ 	1 	I*2 	CHW1 position		 		idem
PCxASTAT 	1 	I*2 	FPC state (0 = CFOV, 1 = FCS1, 2 = FCS2)
PCxADWEL 	1 	I*4 	Commanded chopper dwell time in 2^-7 s 
PCxACPOS 	1 	R*4 	Chopper position (arcsec)
PCxAFCS1 	1 	R*4 	Measured FCS1 power (mW)
PCxAFCS2 	1 	R*4 	Measured FCS2 power (mW)
PCxATEMP 	1 	R*4 	Detector temperature (K) 
PCxAFILL 	1 	R*4 	Filler
PCxABIAS 	1 	R*4 	Measured bias voltage (V)
PCxAMNSG 	j 	R*4 	Mean or fitted signal (V/s)
PCxAMNSU 	j 	R*4 	Uncertainty (V/s)
PCxAMDSG 	j 	R*4 	Median signal (V/s)
PCxAQ1SG 	j 	R*4 	1st quartile of signal (V/s)
PCxAQ3SG 	j 	R*4 	3rd quartile of signal (V/s)
PCxAPLEN	1	I*4	Chopper plateau length in 2^-7 s		 effective time
									after discarding signals
PCxANSIG 	1 	I*4 	No. of valid signals on the plateau
PCxAFLAG 	j 	I*1 	Status flags
PCxAFILL 	k 	I*1 	Filler

For product PC1A the parameters j and k are 9 and 3, respectively; for product PC2A both j and k are 4.

Note: FPC state (PCxASTAT) is the cannot be zero for these measurements.

Also for the product PC2A replace PC1A with PC2A above.

12.3.9 Product PPxD

PPxD (where x=1,2,3) contains the SPD of the dark measurements obtained with detector P1, P2 or P3. These measurements are only obtained with AOT P05.

RECORD
Record length: 24


FIELD		N	T	Description			Comment
GPSCTKEY 	1 	I*4 	Instrument time key
GPSCRPID 	2 	I*1 	Raster point ID			points and lines
GPSCFILL 	1 	I*2 	Filler
PPxDDARK 	1 	R*4 	Dark current (V/s) 
PPxDDUNC 	1 	R*4 	Uncertainty (V/s) 
PPxDFLAG 	1 	I*1 	Status Flag 
PPxDNSIG 	1 	I*4 	No. of valid signals on the plateau
PPxDFILI 	3 	R*4 	Filler

12.3.10 Product PC1D

PC1D contains the SPD of the dark measurements obtained with detector C100. These measurements are only carried out for AOT P25.

RECORD
Record length: 128


FIELD		N	T	Description			Comment
GPSCTKEY 	1 	I*4 	Instrument time key
GPSCRPID 	2 	I*1 	Raster point ID			points and lines
GPSCFILL 	1 	I*2 	Filler
PC1DDARK 	9 	R*4 	Dark current (V/s) 
PC1DDUNC 	9 	R*4 	Uncertainty (V/s) 
PC1DNSIG 	9 	I*4 	No. of valid signals on the plateau
PC1DFLAG 	9 	I*1 	Status Flag  
PC1DFILI 	3 	I*1 	Filler

12.3.11 Product PC2D

PC2D contains the SPD of the dark measurements obtained with detector C200. These measurements are only carried out for AOT P25.

RECORD
Record length: 60


FIELD		N	T	Description			Comment
GPSCTKEY 	1 	I*4 	Instrument time key
GPSCRPID 	2 	I*1 	Raster point ID			points and lines
GPSCFILL 	1 	I*2 	Filler
PC2DDARK 	4 	R*4 	Dark current (V/s) 
PC2DDUNC 	4 	R*4 	Uncertainty (V/s) 
PC2DNSIG 	4 	I*4 	No. of valid signals on the plateau
PC2DFLAG 	4 	I*1 	Status Flag

12.3.12 Pixel status flag

The pixel status flag in the SPD products gives an indication of the data processing quality for each detector pixel. The status flag is one byte of information, the coding of the decimal value of the byte is given in Table 12.3. All success and warning codes are even; all failure (do not process further) codes are odd.

**Table 12.3:** Coding of the pixel status flag
Decimal
Value	Description
	normal (pixel ok)
1	calibration measurement saturated
2	plateau partly affected by drift
3	all ramps on plateau rejected
4	plateau data affected by residual drift
5	zero standard deviation
6	not used
7	zero signal for plateau

Next: 12.4 AA product types Up: 12 Product Descriptions Previous: 12.2 ERD product types

ISOPHOT Data Users Manual, Version 4.1, SAI/95-220/Dc