The cal_lines program is used to determine which calibration lamp lines are to be used at a given wavelength selected for observation. The narrow spectral range of CSHELL usually prevents observing a calibration lamp in the same order as your object spectral line(s). CSHELL has three discharge lamps: Argon, Krypton, and Xenon. The Xenon lamp is mounted behind one of the other lamps, so its lines are fainter. The following steps illustrate how to use cal_lines:
1. Start up an xterm on an IRTF computer using your guest account.
2. Call the program and include the desired central wavelength (e.g. cal_lines 2.298).
3. Select several brighter lines that span a large part of the array (shortward and longward of the target line column).
The output consists of seven columns. Starting from the left they are waveno, line(vac. um), obs(um), order, CVF(um), col, and ADU(5s). The fifth column, labeled CVF(um), is used by the CSHELL XUI for observing the calibration lines. The third column, labeled obs(um), is used when determining the calibration dispersion and zero point.. These tasks are described in more detail here. The ADU(5s) column shows relative intensities. The actual number of counts will be a third to a fifth as much, depending on what slit is used (assuming 5 second integration times). This is due to changes in the lamp intensities since CSHELL commissioning.
LAST UPDATE: February 1, 2010