About the photometric calibration of IUE high resolution spectra: quantification of the order overlap for the SWP camera.

In order to quantify the errors in the IUE line profiles caused by the order overlap, the authors have compared line depths in IUE and Copernicus spectra. The excess line depth in IUE spectra suggests that the amount of order overlap is about 32% at 1150 Å and decreases to zero at about 1400 Å, for spectra extracted with the recent version of IUESISPS (the IUE standard extraction software). The transfer of a spectral feature from one order to the next is below the 5% level. Based on these results, a correction technique is described.