Tutorial 5 - Operations on Datacubes

Smoothing

specex-smooth can be used to perform spatial and/or spectral smoothing of a datacube. For example, to perform a spatial smoothing with a gaussian kernel of standard deviation (sigma) of 0.5”

specex-smooth ADP.2023-09-01T12_56_41.595.fits --spatial-sigma 0.5arcsec

In this picture the orignal cube is shown on the left and the smoothed one, resulting from the previous command, is shown on on the right

The spatial sigma can be also different for the two spatial axes

specex-smooth ADP.2023-09-01T12_56_41.595.fits --spatial-sigma 0.5arcsec, 0.25arcsec

and also pixel units are supported

specex-smooth ADP.2023-09-01T12_56_41.595.fits --spatial-sigma 2,3

The cube can be smoothed also along the spectra axis using a sigma in either physical units

specex-smooth ADP.2023-09-01T12_56_41.595.fits --wave-sigma 2

or pixel unit

specex-smooth ADP.2023-09-01T12_56_41.595.fits --wave-sigma 1angstrom

And, of course, spatial and spectral smoothing can be applied at the same time

specex-smooth ADP.2023-09-01T12_56_41.595.fits --spatial-sigma 0.5arcsec,0.3arcsec --wave-sigma 1angstrom

Making Cutouts

specex-cutout can be used to extract cutouts from a datacue.

For example, the following command extracts a cutout centered on Ra=16.3867 and Dec=-24.6464 and size 6”x4” and with a rotation of 45°

specex-cutout --verbose --center 16.3867deg,-24.6464deg --size 6arcsec,3arcsec --angle 45deg ADP.2023-09-01T12_56_41.595.fits

To make a square cutout, the second value for --size can be omitted. Pixel units also are acceped:

specex-cutout --verbose --center 250,100 --size 50 ADP.2023-09-01T12_56_41.595.fits