High Resolution CCD Spectra Reduction: Temporal Changes of the Flat-field
Compensation
A. Kucera(1),
A. Hanslmeier(2),
J. Ryb'ak(1),
H. Wohl(3)
1 - Astronomical Institute, Slovak Academy of Sciences, SK-05960 Tatranská Lomnica, Slovakia
2 - Institut for Geophysics, Astrophysics and Meteorology, Universitätsplatz 5, A-8010 Graz, Austria
3 - Kiepenheuer-Institut fur Sonnenphysik, Schoneckstr. 6, 79104 Freiburg,
Germany
A new method suitable for long time series of high resolution CCD spectra
reduction is presented. The method allows to compensate the temporal changes
of the instrument conditions which leads to temporal changes of the flat
field matrix. Sometimes it is impossible to make the flat-field measurements
during long simultaneous observations with satellites (SOHO, TRACE).
The method splits the flat-field matrix into two components. The first
one, connected with CCD camera is stable in time and is correct for all
spectra. The second one varies and reflects temporal changes of the
conditions in spectrograph. Description of the method and it's application
to real high resolution CCD spectra is presented and discussed.
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