ISOCAM Interactive Analysis User's Manual Version 5.0 - ISO - ESA

220 CHAPTER 19. ADVANCED SLICING
19.6.2.3 Problems with STD files
Since they were mostly produced on VAX/VMS you may have problems to read them under
UNIX. If this occurs, x slicer will inform you of this kind of problem. What you have to do is:
• Log onto a VAX system.
• Begin an IDL session.
• Restore the STD file.
• Save it again, using the /XDR keyword.
• FTP it to your UNIX system (do not forget the BIN command. . . )
Or, more simply, slice it directly on your VAX system. . .
Otherwise, except for pointing information, STD is the internal format that is used by
x slicer for the data representation. Therefore, no problem should occur.
19.6.3 Slicing ERD files
Edited Raw Data files (ERD) were preferred to Standard Processed Data files (SPD) for historical
reasons – mostly because the pipeline has made the least alterations to ERD with respect
to the telemetry.
To slice an ERD properly you also need:
• an IIPH file
• aCSTAfile
• and sometimes, an IFPG file
19.6.3.1 IIPH files
IIPH files are Instantaneous Instrument Pointing History files: they contain the information
about the RA, DEC and ROLL angle of the satellite during the observation as well as information
about satellite jitter. They are calculated for the prime instrument.
IIPH files have evolved as the pipeline software (OLP) has been refined. In the distant past
it was possible to accidentally receive an IIPH file from another instrument while CAM was
prime – see Section E.2. Now that OLP has been scientifically validated these problems should
no longer exist. A brief history of OLP. . .
• Up to version 2.41, OLP did not specify the instrument for which the IIPH was computed.
• Version 2.43 and later specified the instrument for which the IIPH was computed.
• Version 4.1 and later filtered the RA, DEC and ROLL values.
• Version 6.1 and later provides improved values of RA, DEC and ROLL, namely CRA,
CDEC and CROLL.
Moreover, it is in the IIPH that x slicer reads the crucial information about how the observation
went (was it OK, or was the Target not acquired, etc. . . ). If you have the misfortune to
see on your screen a message like the one of Figure 19.2, two possible reasons are: