Spitzer Documentation & Tools

Purpose and Description

Some Long High (LH) data exhibit "bowing" of spectral orders, which results in mismatches between orders and non-physical tilts. This is usually caused by a time- and position-dependent dark current on the LH array.

The dark_settle software takes a set of IRS basic calibrated data (BCD) images and subtracts off a time-dependent, row-dependent smoothed background. The algorithm is based on the assumption that, in the absence of settling, each BCD would have an interorder flux of zero. For a given row of a given BCD, dark_settle computes a robust interorder mean, smoothed along the column. It then subtracts this mean from all the data in the row. In this way, the interorder region for each row is set to zero.