The DATACUBE package offers two ways to create passband images: first we may use (as before) the squash shell script, this time specify more restrictive limits, e.g.
% squash -i ifu_file -o out -l 5490 -u 5690 -p
would create a two-dimensional passband image, collapsing a 200 Å-wide section of the spectral axis.
Figure: The passband script.
Alternatively, we may choose to generate our passband image interactively using the passband shell script.
%passband NDF input file: ifu_file Input NDF: File: ifu_file.sdf Shape: No. of dimensions: 3 Dimension size(s): 59 x 110 x 961 Pixel bounds : 1:59, 1:110, 1:961 Total pixels : 6236890 Collapsing: White-light image: 59 x 110 Left click to extract spectrum. Extracting: (X,Y) pixel : 32,71 NDF array analysed : DATA Pixel sum : 47734.279694 Pixel mean : 49.671466903226 Standard deviation : 62.703311643991 Minimum pixel value : -21.781915 At pixel : (31) Co-ordinate : (4697.297) Maximum pixel value : 916.4472266 At pixel : (174) Co-ordinate : (5526.027) Total number of pixels : 961 Number of pixels used : 961 (100.0%) Zoom in (yes/no): yes Left click on lower zoom boundary. Left click on upper zoom boundary. Zooming: Lower Boundary: 5237.92 Upper Boundary: 5756.03 Left click on lower boundary. Left click on upper boundary. Passband: Lower Boundary: 5498.83 Upper Boundary: 5561.82 Collapsing: White-light image: 59 x 110 Wavelength range: 5498.83--5561.82 Angstrom Plotting: Left: White-light image. Right: Passband image (5498.83--5561.82 Angstrom) %
Here the script presents us with a white-light image and prompts us to click on it to select a good signal-to-noise spectrum, it then asks us whether or not we want to zoom in on a certain part of the spectrum. Let us zoom, and then the script allows us to interactively select a region to extract to create a passband image. It then plots this next to the white-light image for comparison.
Alternatively we can again we can make direct use of the collapse application, upon which both the squash and passband have been built, as shown below.
% collapse in=ifu_file out=out axis=3 low=5490 high=5560
The IFU Data-Product Cookbook