Grism Flux Calibration Files


Sensitivity Calibration Files Cycle 7

  • The inverse sensitivity curves in units of DN/sec/Jy for the NICMOS grism mode are given below. They apply to observations taken before the NCS cryocooler was installed. We recommend to use these response curves for all pre-NCS observations no change in time has been established.
  • Response curves were derived taking into account the pixel response function. These response curves should be used for all purposes, even when PRF correction in the spectral extraction is not used. Older response curves should not be used anymore.
  • The inverse sensitivity curves were derived by first using NICMOSlook to extract the spectra from the background subtracted images of G191-B2B and P330 and comparing them to models of the spectrum as given by Colina & Bohlin 1997, 113, 1138 (for the Solar Analog p330), and Bohlin & Colina & Finley 1995, AJ 110, 1316 and Bohlin 1996, AJ 111, 1743 (for the White Dwarf G191-B2B). The model for P330 was rescaled to match groundbased observations by M. Rieke (1999, in preparation). The throughput derived from the two standards differs by about 3%, we use the average of the two.
  • The G096,G141,and G206 grisms have been calibrated in DN/s per Jy.
  • Click on ASCII to download a simple text file containing the inverse sensitivity for the chosen grism in DN/s per Jy as a function of wavelength (in micron)
  • Click on the plot to view an EPS file of the response for each grism.
  • The following calibration files can be directly used by the grism extraction software NICMOSlook. They are already included in the distribution of the software and do not need to be retrieved separately.
  • The second order response files were constructed using spectra for which both a first and a second order spectra were available. The uncertainty of the second order G141 flux calibration was observed to be within 20%. Due to the low signal to noise data available for the G096 second order spectra, the uncertainty of the flux calibration of the 2nd order is estimated to be 50%.



    1st order:        G096 response curve G096 ASCII file        G141 response curve G141 ASCII file        G206 response curve G206 ASCII file
    2nd order:        G096 2nd order response curve G096 ASCII file        G141 2nd order response curve G141 ASCII file        G206 2nd order response curve G206 ASCII file
    This page was last updated September 20, 2002