The naco_spc_wavecal recipe



Wavelength calibration using arc lamps


naco_spc_wavecal – NACO spectrocopy wavelength calibration from lamp images.

The files listed in the Set Of Frames (sof-file) must be tagged: NACO-raw-file.fits CAL_ARC_SPEC NACO-spectrum-model.fits SPC_MODEL NACO-arc-lines.fits SPC_ARGON

The input frames are split into groups with identical values of ‘ESO DET DIT’, ‘ESO INS OPTI1 ID’, ‘ESO INS CWLEN’ and ‘ESO SEQ SPECMODE’.

Furthermore, each input frame must have a value of ESO INS LAMP1 ST that is false for off-frames and true for on-frames.

Products: ARC_MAP: Primary HDU with the wavelength map, i.e. the pixel values are wavelengths. The first extension is a single-row table with the polynomial coefficients of the 2D dispersion relation, lambda = P(x, y).

ARC_IMAGE: Primary HDU with the difference image of the lamp-on and -off image. The first extension is the distortion corrected image, were all the arc-lines are straight. The dispersion in the distortion corrected image is given by the central dispersion, lambda = P(512.5, y).



Create an object for the recipe naco_spc_wavecal.

import cpl
naco_spc_wavecal = cpl.Recipe("naco_spc_wavecal")



The recipe can produce a number of predefined plots. Zero means that none of the plots are produced, while increasing values (e.g. 1 or 2) increases the number of plots produced. If the plotting fails a warning is produced, and the recipe continues. The default behaviour of the plotting is to use gnuplot (with option -persist). The recipe currently produces 1D-plots using gnuplot commands. The recipe user can control the actual plotting-command used by the recipe to create the plot by setting the environment variable CPL_PLOTTER. Currently, if CPL_PLOTTER is set it must contain the string ‘gnuplot’. Setting it to ‘cat > my_gnuplot_$$.txt’ causes a number of ASCII-files to be created, which each produce a plot when given as standard input to gnuplot (e.g. later or on a different computer). A finer control of the plotting options can be obtained by writing an executable script, e.g., that executes gnuplot after setting the desired gnuplot options (e.g. set terminal pslatex color) and then setting CPL_PLOTTER to The predefined plots include plotting of images. Images can be plotted not only with gnuplot, but also using the pnm format. This is controlled with the environment variable CPL_IMAGER. If CPL_IMAGER is set to a string that does not contain the word gnuplot, the recipe will generate the plot in pnm format. E.g. setting CPL_IMAGER to ‘display - &’ will produce a gray-scale image using the image viewer display. (int; default: 0) [default=0].


Force the computation (bool; default: False) [default=False].

The following code snippet shows the default settings for the available parameters.

import cpl
naco_spc_wavecal = cpl.Recipe("naco_spc_wavecal")

naco_spc_wavecal.param.plot = 0
naco_spc_wavecal.param.force = False

You may also set or overwrite some or all parameters by the recipe parameter param, as shown in the following example:

import cpl
naco_spc_wavecal = cpl.Recipe("naco_spc_wavecal")
res = naco_spc_wavecal( ..., param = {"plot":0, "force":False})

See also

cpl.Recipe for more information about the recipe object.

Bug reports

Please report any problems to Lars Lundin. Alternatively, you may send a report to the ESO User Support Department.