Response Files

The response function is specified in grism response files, which are simple three columns ASCII files containing the wavelength (in $\mu$), the inverse sensitivity (in DN/s per mJy), and the error estimate for the inverse sensitivity (again in DN/s per mJy). These files are derived from calibration data and are regularly updated on the ST-ECF NICMOS homepage . The user can change which response file is used to calibrate extracted spectra by simply editing the grismspec.dat file in $CALNICC_BASE/calib directory. Please note that the response files are computed using a particular set of flatfields and should therefore be applied to spectra extracted using the same set of flatfields. Calnic C and NICMOSlook can additionally apply the appropriate units conversion to convert from mJy to 10^-15 erg/s/cm²/Angstrom. Which units are used in the actually output is determined by the PUNITSW parameter in the $CALNICC_BASE/calib/calnicc.setup file.