Despiking

After we have extinction corrected the map and taken out noisy bolometers, we need to despike the data. This is done with the SURF task despike2, which takes a small portion from each end of a scan and computes the rms-variations for each bolometer and then does a standard sigma clip. If you want to be conservative, use 4 sigma. This does a reasonable job, but large spikes (extending over several seconds in time) are not detected and these will have to be removed manually using sclean or dspbol. It is often necessary to run despike2 a second time after scan_rlb, because even with the same sigma threshold, the rms is now smaller and one finds a fair amount of residual spikes missed in the first round.