Make aperture trace information with standard star frames

Spectra of a standard star or a point source are used to trace the aperture on the detector array. APALL task is used for tracing and extracting apertures (Massey, Valdes, & Barnes, 1992). The traced data is saved in a `database' directory and referred for setting `references' parameters of each task. Figure 31 shows an example of a setting of several main parameters necessary to trace apertures of point source spectra. In order to check whether the trace is done successfully, apertures are extracted as images by setting the ``strip'' for the `format' option of the APALL and then checked whether the continuum of a standard star or a point source is a straight line with the same Y coordinates such as upper image shown in Figure 44. If the trace is done satisfactory, the frame used by the APALL task can be set as a reference frame. The trace data, then, is applied to the median flat frame by setting the frame name for the `references' parameter. At this point, the widths of apertures should be adjusted to fit the widths of the entire slit length if the apertures were traced by using a narrow width around the continuum peak of a point source. Figure 32 shows an example setting of several main parameters of the APALL task to adjust the width of apertures.

Figure 31: Several main parameters of the APALL task to make the aperture data from point source spectra of Traceref.imh. The paremeters with itelic are critical.

Figure 32: Several main parameters of the APALL task to adjust the widths of apertures which are determined by llimit and ulimit. These limit parameters are adjusted to show all spectrum area along the slit length.

Figure 33: A parameter set for the APNORMALIZE task. The parameters with italic are critical.