Spacing between reference scans in band 3 in SWS06 was reduced from 8000 sec (effectively disabling reference scans) to 1000 sec. The purpose was to monitor baseline changes during long scans, to alleviate fringing problems. These reference scans were disabled again from revolution 590. The effect of this was detrimental in some cases, potentially helpful in some other cases (but only for users willing to use OSIA, since reference scans are treated as normal data by the pipeline).