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How to avoid saturation for C05

In order to allow observations of relatively bright sources to coexist with the parallel mode, a change has been made to the details of the AOT-to-OCT logic, to allow the observer to control the instrument set-up before and after the actual observation. This is done by adding dummy observations with the desired observing configurations to the beginning and to the end of a concatenated chain of observations.

For polarimetric imaging C05 the implementation is such that you may now specify in your observation template file (``polar.dat'') a new entry for the key word: SEQ_RESET. In case the target would cause saturation while arriving in ISOCAM parallel mode you must use:

SEQ_RESET = DARK

This flag will automatically create two dummy observations. First a dummy off-source position some 5 arcmin North from the desired pointing position of the target. At this dummy off-source position the instrument will go into the optical configuration as specified for the ON source position. Then it will move to the ON source position and perform the C05 observations. At the end of the polarization measurements the system will be forced to return to the OFF source position. The move from OFF to ON and back to OFF will be done by suppressing the automatic transition to parallel / standby mode, so that no saturation will happen due to the parallel mode configuration.

If you set SEQ_RESET to DARK the observations will be about 430s more expensive than without this procedure. For SEQ_RESET=DARK you have to add  430s to the total target dedicated time (TDT). However, if you fail to take this precaution when necessary, your observation is likely to be suppressed during routine screening of schedules.

If you do not need this OFF-ON-OFF procedure you should specify

SEQ_RESET = PARALLEL


next up previous contents
Next: Calibration Up: Saturation Previous: Overview of saturation effects


Thu Jan 16 18:15:16 MET 1997