The wavelength day calibration consists in using the MIDI heated
blackscreen and taking 3 exposures through different narrow-band
filters [NeII], [SIV] and [ArIII] (having central wavelengths
accurately measured in the laboratory by the manufacturer). An extra
exposure is taken through a polycarbonic foil that has several
absorption lines in its N-band spectrum. Exposures without filters and
with closed shutter are also taken to process the exposures with
filters. From the spectra obtained through the filters a fit of the
lambda(X) function is performed. The procedure is performed for each
setup (PRISM or GRISM, and SCI_PHOT or HIGH_SENS). The MIDI HIGH_SENS mode
uses 2 windows on the detector (R1 and R2). The MIDI SCI_PHOT mode uses 4
windows (R1 to R4)
We monitor here the stability of the dispersion by plotting the
wavelength of a spectral channel given by the lambda(X) function
computed by the reduction of the calibration data. The selected
spectral channels corresponds to the expected central wavelength of the
three narrow-band filters.
Click on any of the plots to see a close-up version.
The latest date is indicated on top of the plot.
data points belonging to the latest date are specially marked
statistical averages are indicated by a solid line, and thresholds by broken lines
outliers are marked by a red asterisk. They are defined as data points outside the
"aliens" (= data points outside the plot Y limits) are marked by a red arrow (↑ or ↓)
you can download the data for each parameter set if the 'Data downloads' link shows up