Is there a way to get apall to produce a text file output of the extracted spectrum
in columns of "flux" "wavelength" and "error"?If not, is there a way to get splot to do this?If not, is there any other way to get a text version of the spectrum?Thanks in anticipationNick

Hi,Currently IRAF spectra are images. To convert to text, particularly a 1D spectrum, use the task wspectext. It will give you wavelength (provided there is a wavelength calibration otherwise it would be pixels) and flux. Errors are not generally computed though APALL does provide an associated spectrum with errors assuming a standard CCD Poisson model.For APALL the output spectrum is the sum across the aperture. So depending on the width of the aperture and any background subtraction, the counts may be higher than the individual pixel values in the 2D image.The logic of apall is that you mark the spectrum at some point in the 2D image. It has to have keywords or parameters to know the dispersion direction. See the package parameters (i.e. epar apextract). It defines a aperture of a width set by the parameters at that point which is assumed to be the same at all points along the dispersion. The trace step then allows tracing the position of the spectrum at other points along the dispersion as they drift due to distortions and alignment. Finally the pixels are summed across the aperture using partial pixel weighting at the edges.Typically you would say yes to each step: find, edit, trace, accept trace, write aperture information to a file in the database subdirectory, and do the extraction. Any question about review the spectrum can be no because you will likely look at it in SPLOT.I'm sorry for the very brief responses. I am leaving on vacation right now for a week and had to get last minute things done.I hope this helps.Yours,
Frank Valdes