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Subsections



D.1 Attitude and Orbit Control System (AOCS)

This file contains raw AOCS data copied from telemetry frames 4, 12, 20 and 28, each of identical layout, used for the derivation of the pointing information included in the IIPH (see Section D.12) and IRPH (see Section D.13) files.

D.1.1 Primary header

The AOCS file contains a primary header with the fields described in Table D.1. In this example non-mandatory fields are filled with example values.


Table D.1: AOCS primary header.
Keyword Value Description
SIMPLE = T /
BITPIX = 8 /
NAXIS = 0 /
EXTEND = T /
ORIGIN = 'ESA ' / European Space Agency
TELESCOP = 'ISO ' / Infrared Space Observatory
COMMENT   Raw AOCS frames
FILENAME = 'AOCS01700101' / File name in ISO archive
DATE = '09/07/95' / Creation date
FILEVERS = '0298 ' / Version ID in ISO archive
OLPVERS = 'OLP_21 ' / SOC OLP system version
CALGVERS = 'CALG_31 ' / SOC OLP CAL-G files version
USERNAME = 'PIPELINE' /
VERS1 = '1082/EOHA017' / Version ID of each input file
VERS2 = '1082/EOHI017' / Version ID of each input file
VERS3 = '1082/APPH017' / Version ID of each input file
EQUINOX = 2000.0 / Equinox
TMRATE = 32 / Telemetry rate in Kbps (Kbits/sec)

D.1.2 Records

The AOCS file contains records described in Table D.2.

Table D.2: AOCS records.
Keyword Number Format Description
GEPRTKEY 1 I4 UTK time key
GEPRQUAL$^1$ 1 I4 Frame quality
AOCSFRAM$^2$ 256 I1 Frame 4, 12, 20 or 28


Notes:
1.
The 32-bit integer GEPRQUAL gives the quality of the telemetry frame from which AOCSFRAM was extracted. The most significant bit (bit 31) refers to frame 0, the least (bit 0) to frame 31. A bit set to 1 shows the corresponding frame is bad and should be ignored. e.g. if bit 27 is set to 1, then frame 4 is bad. It is recommended that the AOCSFRAM should be ignored for any non-zero GEPRQUAL.
2.
Frames 4, 12, 20 or 28 (the AOCS frames) all have the same layout.

The AOCSFRAM record is described in Table D.3.

Table D.3: Description of AOCSFRAM field.
Keyword Number Format Description
HEADER 10 I1 Frame header
TKEY 1 I4 AOCS time, TUNIT=0.5s
LAYOUT 1 I2 Frame layout information
ATTQUAT 4 I4 Integer-coded attitude quaternion
FSSX 1 I2 FSS X output data
FSSY 1 I2 FSS Y output data
GYRDATA 4 I2 GYR1-4 output rate data
SASDATA 1 I2 SAS channels 1-9 output
RWSSPD 4 I2 RWL 1-4 speeds (tachometer output)
TORQREQ 3 I2 RWS & RCS torque requests
WDSTAT 1 I2 Watch Dog status word
PDUADIG 1 I2 Branch 1 RCS relay status
PDUBDIG 1 I2 Branch 2 RCS relay status
PDUAMEMR 1 I2 Contents of PDUA memory
PDUBMEMR 1 I2 Contents of PDUB memory
ACCHW 1 I2 ACC H/W status word
AOCSSTAT 1 I2 AOCS status word
MODSDAT 1 I2 Mode specific data
INHISTAT 1 I2 Inhibit status
SCOMSTAT 1 I2 Single word command status
MCOMSTAT 1 I2 Multiple word command status
RMCSTAT 1 I2 RMC status
STRY$^1$ 1 I2 STR output Y-coordinate of guide star
STRZ$^2$ 1 I2 STR output Z-coordinate of guide star
STRMAGG$^3$ 1 I2 STR output magnitude of guide star
STRSTAT1 1 I2 STR mode status information
STRHC 1 I2 STR health check status
STRHK1 1 I2 STR housekeeping data
REGULAR 20 I1 Regular TM buffer
STRHK2 1 I2  
STRYOUT2 1 I2  
STRZOUT2 1 I2  
STRMAG2 1 I2  
STRYOUT3 1 I2  
STRZOUT3 1 I2  
STRMAG3 1 I2  
STRYOUT4 1 I2  
STRZOUT4 1 I2  
STRMAG4 1 I2  
RASPOID 2 I2 Raster point ID
E_ATTIT 3 I4 Integer-coded attitude error vector
HSSENDOR 1 I2  
GSTARIN 1 I2  
IRREGULA 98 I1 Irregular TM buffer
TRAILER 2 I1 Frame trailer


Notes:
1.
STRY refers to the position of the star's image on the CCD. It is measured in Star-Tracker instrumental units of 1/7$\mu $m, which correspond to approximately 0.24 $^{\prime \prime}$. The maximum and minimum values are 30106 and $-$30106.
2.
STRZ refers to the position of the star's image on the CCD. It is measured in Star-Tracker instrumental units of 1/7$\mu $m, which correspond to approximately 0.24 $^{\prime \prime}$. The maximum and minimum values are 22378 and $-$22378.
3.
This is the visual magnitude of the star, with magnitude 2.0 represented as 0 and 8.0 represented at 120. The resolution is approximately 0.05 mag.


next up previous contents index
Next: D.2 ISO Operational Guide-Star Up: D. Satellite Files Previous: D. Satellite Files
ISO Handbook Volume I (GEN), Version 2.0, SAI/2000-035/Dc