There are two IDL routines that were used for cleaning SOHO/CDS data from cosmic rays, and they are found to give good results for EIS data. The routines are:

clean_exposure - works on 2D images (i.e., exposure images)

new_spike - works on 3D data-cubes, making use of neighbouring exposure comparisons to help flag CRs

Both routines do a good job of removing of CRs, with clean_exposure slightly more thorough than new_spike, but new_spike is less likely to remove real data (high velocity events were sometimes partially flagged as CRs by clean_exposure).

A wrapper routine called eis_despike is used to call new_spike for EIS data. It is called as, e.g.,

IDL> eis_despike, wd, wd_clean, swtch=spikes

where wd is the original data window, wd_clean is the cleaned window, and spikes is an array containing the locations of the spikes.

If you worried about whether real data are being flagged as CRs, then use the routine eis_spike_viewer.

If you find an example where real data has been removed then please contact Peter Young.

Peter Young