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

20.18. HOW TO SAVE SPOILED OBSERVATIONS 269
20.18 How to save spoiled observations
The data of some observations are spoil and therefore resists standard CIA data reduction. The
most common reasons are:
1. telemetry drops
2. bad raster point IDs
3. target not acquired
4. bad QLA flag
5. bad CSH flag
6. strong saturation
CIA provides the functionality to recover some of these observations. However, only experienced
CIA users should try these steps!
telemetry drops Short telemetry drops, affecting only a few readouts, will normally go unnoticed.
For longer telemetry drops, were the data for one or more SCDs is missing, the
following actions can be taken:
• raster observations: Calling get sscdraster with the option /nocheck will permit
you to continue with the data reduction.
CIA> raster_pds = get_sscdraster(sscd, /nocheck)
Alternatively, sscd clean will fake empty SCDs so that get sscdraster is tricked
into believing the raster is complete.
CIA> cleaned_sscd = sscdclean(sscd)
CIA> raster_pds = get_sscdraster(cleaned_sscd, /nocheck)
• CVF observations: CIA data reduction is not affected by telemetry drops.
• Beam-Switch observations: With most beam-switch observations consisting only of
one on and one off-position, the observation is quite likely lost. If there are more on/off
positions, use get sscdstruct on the “cleaned” dataset, e.g. a dataset containing no
spurious SCDs any more, and combine the results of on/off positions manually.
• Polarization observations: It will depend on the redundancy of the observation,
whether the observation is lost. If there are sufficient observations with all polarizors,
use get sscdstruct on the “cleaned” dataset, and combine the results manually.
badrasterpointIDsSome observations are affected by an invalid [0,0] raster-point ID. sscd clean
will remove these SCDs so you can progress with your data reduction. However, the final
mosaic will contain holes — in the example below 39 readouts for the three pointings with
the raster-point IDs [26,2], [25,2] and [24,2] are merged in one SCD, SCD #35.