Electronic Spectra Processing -- (Reticon or CCD)

• CCD The basic reduction of data from electronic detectors is done here. The data from the Ondrejov observatory Reticon (acquisited by the local RETICON program) are used directly, data from foreign instruments have to be already one-dimensional and first converted to SPEFO format (see File utilities). In both cases all types of files are requested -- *.OFF for offset (i.e. bias) data, *.FF for flat field, *.CML for calibration light exposure and *.STA for stellar spectrum. The specific point of using the Reticon Ond submenu is following: Just the pixels 95-1790 (out of 1872) are considered good and just one offset file is requested
  • Flat select First bias file is selected (for foreign instrument several may be averaged), than one or more flat field data (also may be averaged).
  • Derive disp Two comparison line exposures (before and after the stellar exposure) are requested. Than the comparison line list *.CMP for the same grating angle is chosen. Than the line identification begins. The comparison lines from particular *.CMP list are identified interactively in either oscilloscopic or automatic mode with the chosen polynomial fit order. The wavelength-zoomed comparison lines are displayed and their approximate center position has to be marked by moving of vertical line (see Fig. 1 ) together with their identification number according to *.CMP list. Then the enlarged line together with its mirror profile is shown that may be interactively shifted until their exact match is reached (see Fig. 2). The amount of the displayed mirrored profile may be changed interactively too (see Fig. 1). After identification of at least three lines the estimate of the dispersion curve fit is calculated and the next lines may be identified automatically. The badly defined line may be rejected. After the line list has been exhausted, the dispersion curve is displayed with possibility of the rejection of points with large errors. (See Fig. 3) The protocol of comparison line measurement *.CMF is finally produced.
  • Star reduce The stellar spectrum *.STA file is chosen together with the corresponding *.OFF bias. The result of the processing is the wavelength-calibrated unrectified intensity file *.UUI.