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

19.6. ADVANCED SLICING WITH X SLICER 221
Figure 19.2: x slicer’s dreaded message!
• ATTERROR = 1: The target was not acquired. Your observation is lost.
• ATTERROR = 2: Due to a break in the telemetry down-link system, the IIPH file will
contain uncorrected data from the star-trackers. All your RA, DEC and Roll will be false,
but your images should be OK.
For normal observations, both these problems should be spotted during the quality checking
process – affected data would not be distributed by ESA.
19.6.3.2 IFPG files
The Instrument Focal Plane Geometry file contains the rotations that allow transformation of
the pointing information given in an IIPH from one instrument to another – this may be useful
if you wish to attempt to work on non-scientifically validated data (see Section E.2). Since the
focal plane of ISO will not change during the mission, it has been written to a CDS (Calibration
Data Set). The IFPG file is therefore no longer useful, use the CDS instead.
19.6.3.3 CSTA files
CSTA files are Compact STAtus files. They contain a summary of the CAM CONFIGURATION.
This information can be used to check that the observation was properly done. Since the x slicer
displays what is in the data, you can do that job too. Therefore, you may omit it when slicing,
especially if you know what should be in the data.
19.6.3.4 ORBIT files
This file is used to calculate the position and speed of ISO with respect to the Earth. The position
may be useful if you are observing very nearby solar system objects because of the parallax.
Though the speed is useful for the ISO spectrometers, the spectral resolution of ISOCAM’s CVF
mode is of the order of λ/50 and so is not affected by ISO’s speed. You may therefore omit the
ORBIT file.
19.6.4 Slicing TDF
TDF files are Telemetry Distribution Files. They contain CAM telemetry for the prime and
parallel mode 2 . TDF files are used by instrument experts only, and can be accessed at the ISO
Data Centers at VilSpa, Saclay or Orsay. Telemetry was delivered only during PV phase by
ESA.
2 If CAM is parallel, the TDF also contains the telemetry of the prime instrument.