10 MORE WAYS TO MASSAGE YOUR DATA

This chapter covers a number of procedures for massaging your data. With few exceptions (e.g., COADD), they are general and may be used with data other than IUE data. The dereddening routines and CRSCOR expect spectral data with wavelengths but the other routines will accept any vectors representing an independent and a dependent variable in lieu of wavelengths and fluxes. However, wavelengths and fluxes will be referred to in this text.

Corrections to the wavelength vector or conversion to velocity or frequency units can be done easily using some simple IDL commands. The IUE calibration and the IUEDAC software use Åthe wavelength units.

 

Table 10.1: Wavelength Unit Conversions

Expression	Definition
W=W-4.5	Shifts wavelength scale by 4.5 Å.
INVLAM=10000./W	Inverse wavelength in $\lambda^{-1}$.
FREQ=2.998E18/W	Converts wavelength (Å to frequency (Hz).
VEL=(W/W0-1.) * 2.998E5	Converts wavelength (Å to velocity in km s-1with respect to rest wavelength W0.