It was decided at the Cambridge meeting last week to adjust the NIS calibration based on a reanalysis of the original lab calibration, and on the comparison with the Woods sounding rocket data. This has now been done, and has been put online. The following adjustments were made: NIS-1: The wavelength dependence was adjusted to match the latest results of the lab calibration. The curve was then adjusted upwards so that the efficiency at 368A was increased by a factor of 2.3 over the original calibration curve, based on the comparison with the Woods rocket. NIS-2: A new calibration curve based on the comparison with the Woods rocket was installed. Two databases are affected, efficiency.db* and wave_eff.db*. Both databases need to be refreshed in order to correctly pick up the new calibration. You can still obtain the old calibration curve by passing the keyword DATE_USED to GET_EFFICIENCY and GET_WAVE_EFF. Any value of DATE_USED between 23-Nov-1996 and 23-Dec-1998 will return the old calibration. This allows you to calculate a correction factor to be applied to data analyzed using the old calibration. For example WAV1 = PIX2WAVE('N1', INDGEN(1024)) GET_EFFICIENCY, date_obs, 'N1', EFF1 GET_EFFICIENCY, date_obs, 'N1', OLD_EFF1, DATE_USED='1-Jan-1998' GET_WAVE_EFF, date_obs, 'N1', COEFF1 GET_WAVE_EFF, date_obs, 'N1', OLD_COEFF1, DATE_USED='1-Jan-1998' CORRECTION = POLY(WAV1, EFF1*COEFF1) / POLY(WAV1, OLD_EFF1*OLD_COEFF1) To simplify the process, the keyword WAVELENGTH has now been added to the GET_EFFICIENCY routine, so that GET_WAVE_EFF and POLY no longer have to be called by the user. This simplifies the above to WAV1 = PIX2WAVE('N1', INDGEN(1024)) GET_EFFICIENCY, date_obs, 'N1', EFF1, WAVE=WAV1 GET_EFFICIENCY, date_obs, 'N1', OLD_EFF1, DATE_USED='1-Jan-1998', $ WAVE=WAV1 CORRECTION = EFF1 / OLD_EFF1 Bill Thompson ---------------------------------------- PS It's been pointed out to me that the business about deriving a correction factor for already calibrated data is a little confusing. It should be pointed out that the correction factor defined above needs to be *divided* into the data.