This file describes the data model for the WaveCalib
.
The images are written to disk as a multi-extension FITS file prefixed by WaveCalib
in the Calibrations/
folder. See calib-naming
for the naming convention.
You can print a set of simple diagnostics to the screen with the pypeit_chk_wavecalib script, e.g. :
$ pypeit_chk_wavecalib Calibrations/WaveCalib_A_1_MSC03.fits
N. SpatID minWave Wave_cen maxWave dWave Nlin IDs_Wave_range IDs_Wave_cov(%) measured_fwhm RMS
--- ------ ------- -------- ------- ----- ---- --------------------- --------------- ------------- -----
0 35 6422.5 7753.8 9053.2 0.325 48 6508.325 - 9047.930 96.5 3.5 0.046
1 93 6310.0 7641.4 8940.8 0.325 49 6336.179 - 8931.145 98.6 3.6 0.036
2 140 6440.8 7772.1 9071.5 0.325 47 6508.325 - 9047.930 96.5 3.6 0.049
3 184 6301.2 7632.6 8932.0 0.325 50 6306.533 - 8931.145 99.8 3.6 0.037
4 243 6257.1 7588.5 8887.9 0.325 49 6268.229 - 8821.832 97.1 3.6 0.034
SpatID
is the spatial position of the slit/order.minWave
,maxWave
,Wave_cen
,dWave
are, respectively, the minimum wavelength value, the maximum wavelength value, the central wavelength, and the wavelength dispersion of the calibrated arc spectra. All the values are in Angstrom.Nlin
,IDs_Wave_range
,IDs_Wave_cov(%)
are, respectively, the number, the wavelength range, and the spectral coverage of the identified and fitted arc lines.measured_fwhm
is the measured arc lines FWHM (in binned pixels of the input arc frame), i.e, the approximate spectral resolution. Note that this not necessarily thefwhm
used to identify the arc lines during the wavelength calibration, seewvcalib-fwhm
.RMS
is the RMS of the wavelength solution (in pixels).
At present, the only way to visually examine the quality of this step is by viewing the PNG file generated by the code. ../qa
describes how to access them.
There is 1 PNG file generated per slit. Here is an example from the shane_kast_red
spectrograph.
What you hope to see in your QA is:
- On the left, many of the blue arc lines marked with IDs
- In the upper right, an RMS < 0.1 pixels
- In the lower right, a random scatter about 0 residuals
Wavelength solutions are amongst the most challenging part of data reduction. See wave_calib
for extensive details on how PypeIt performs wavelength calibration and related issues.
Internally, the image is held in pypeit.wavecalib.WaveCalib
which subclasses from pypeit.datamodel.DataContainer
.
The datamodel written to disk is: