CALIBRATED MICAS SHORT-WAVELENGTH INFRARED SPECTRA
OF BORRELLY REDUCED TO NORMALIZED I/F

Following is a description of the files you will find in this directory. If you have questions or 
difficulty with them, contact lsoderblom@usgs.gov (phone 928-556-7018, fax 928-556-
7014).

IR_streak_1_32b_bot_sc.cub
IR_streak_2_32b_bot_sc.cub
These are single band ISIS-format image cubes. The first cube is derived from the Borrelly 
observation IR_streak_1.pds, a MICAS SWIR frame with an exposure time of 28.0s that 
successfully scanned across the nucleus. The second is derived from IR_streak_2.pds, a 
subsequent 19.7s exposure that missed the nucleus but gives a good estimate of solar stray 
light. The following processing was done to these cubes: 1) reformat to remove dummy 
pixels, 2) model and removed electronic ghosts (a form of residual image that travels from 
quadrant to quadrant during readout), 3) model and remove dark current (using 
IR_streak_2.pds; this is done on a per pixel basis and uses the top half or flush frame and the 
expose frame for the model), 4) remove non-linearity of the detector response, 5) remove gain 
differences between quadrants, and normalize by exposure time. The result is linearized DN/s 
with background removed. Note stray-light is not yet removed. 


IR_streak_32b_bot_sc_dif_nois_shear_cvt0.cub
This is an ISIS-format image cube that contains one band. It was derived from ISIS cubes 
IR_streak_1_32b_bot_sc.cub and IR_streak_2_32b_bot_sc.cub by the following steps: 1) 
subtract cube 2 (linearized stray light measured in IR_streak_2.pds) from cube 1 (linearized 
swath across Borrelly nucleus from IR_streak_1.pds), 2) remove spike noise (used a 3x3 box; 
set value to nul if it exceeded the standard deviation of the box), 3) shear image to remove 
small (1 degree ) misalignment between the spectral dispersion direction and the down-line or 
sample direction on the detector, 4) convert all nulls (whether due to saturation or despiking 
or voids introduced in the shear) to 0. 

IR_streak_32b_bot_sc_dif_nois_shear_cvt0.asc
This is an ascii formatted file containing all samples (1-256) for lines 57-120 of the ISIS cube: 
IR_streak_32b_bot_sc_dif_nois_shear_cvt0.cub. Remember that the value zero is to be 
interpreted as non-valid or null data.


NormalizedBorrellySWIRspectra.xls
This is a standard Microsoft Excel workbook that performs the following steps to the ascii 
data file, IR_streak_32b_bot_sc_dif_nois_shear_cvt0.asc: 1) convert sample number to 
wavelength, 2) convert linearized DN/s to I/F by dividing by the product of the MICAS SWIR 
spectral response (generated from inflight observation of Arcturus) and a solar radiance 
spectrum taken from the Galileo NIMS data library, 3) normalize the I/F spectra to unity at 
2.359 microns (a continuum wavelength for which all spectra have valid data).