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.
If applicable, the latest values from Paranal ops logs are plotted as blue dots. More information about those values, including a download option, is available in the OPS column.
The latest date is indicated on top of the plot, data points belonging to that 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