10 APPENDIX 2: Limiting Which Orders IRCLEAN_MASK Examines (/getFmask, ORDERS=)
Under getFmask=1 (hierarchical iterative rogue finding method), you can force IRSCLEAN to detect rogues only in specific spectral orders using the ORDERS keyword in conjunction with /getFmask. You may find this useful if the combination of signal, noise, and background varies from order to order and you need to tune your rogue-finding to order-to-order variations. Note that the procedure for detecting rogue pixels here is different than the standard approach. The noise will be measured in each order independently , and rogue pixels will be detected using a thresholded multiple of the noise level in the order. [The default algorithm without setting ORDERS measures the noise level in either the interorder regions (droop.fits, rsc.fits, f2ap.fits, bcd.fits) or all orders together (coa2d.fits,bksub.fits) and searches for rogue pixels in the whole array at once.]
Set ORDERS equal to an IDL vector listing the order numbers to examine. Each order in the list will be analyzed separately to look for rogue pixels, and the discovered rogues will be combined into the found mask.
We show the order numbers for IRS arrays in Figure 10.1. Note: the IRS peakup sub-arrays are designated short low “orders” 4 (Red Peakup) and 5 (Blue Peakup). The keyword /PeakUp must be set to find rogues in the peakup sub-arrays (see below), with or without using the ORDERS= functionality.
Figure 10.1 IRS Orders. We show the default order masks in white. Wide order masks accessible via keyword /wide_omask are shown in gray. Although not officially numbered in the IRS pipeline, the peakup sub-arrays are labeled Short-Low orders 4 (Red) and 5 (Blue) in IRSCLEAN.
