The Useable Modes

The ESAS method for creating model background spectra and images relies on data from the unexposed (to the sky) corners of the detectors. This means that, for the PN, one can only process data from the Full Frame or Full Frame Extended modes. For the other modes, the corner data are not recorded.

For the MOS detectors, CCDs 2 through 7 always operate in Full Frame mode, providing ESAS-compatible imaging for all observations, at least for the outer CCDs. ESAS can also process the Large and Small Window modes for MOS CCD 1 but for typical observations with bright sources the results may not be particularly useful due to the broad wings of the PSF. It is generally a good idea to deselect the central CCD if it is in a window mode. If the central CCDs are operated in timing mode they must be deselected in mosspectra (and other tasks where relevant). We should also note that in window mode there may be interference noise that appears in other chips. We have not yet studied its effect, so be aware of it and be careful.