***** File IUECAL.ASC This file contains information on the files needed to calibrate Net Flux Data of low resolution extracted spectra for the IUE final archive. The NEWSIPS absolute calibration, sensitivity degradation correction, THDA sensitivity correction, and exposure gain correction can be extracted from the comments in the IDL procedure NEWCALIB (below) developed by the project. (For a full description on how to calibrate an IUE net spectrum, you are referred to the NEWSIPS manual Chapter 10.) ;***************************************************************************** ;+ ;*NAME: ; ; NEWCALIB December 21, 1993 ; ;*CLASS: ; ; Spectral Calibration ; ;*CATEGORY: ; ; NEWSIPS ; ;*PURPOSE: ; ; To apply the NEWSIPS absolute calibration, sensitivity degradation ; correction, THDA sensitivity correction, and exposure gain ; correction to NEWSIPS low dispersion spectral data. ; ;*CALLING SEQUENCE: ; ; NEWCALIB,HD,WAVE,FLUX,ERROR ; ;*PARAMETERS: ; ; HD (REQ) (I) (1) (S) ; FITS header as an IDL string array ; ; WAVE (REQ) (I) (1) (R) ; Wavelength vector. ; ; FLUX (REQ) (IO) (1) (R) ; Net flux in IUE flux units on input, ; absolutely calibrated flux on output. ; ; ERROR (OPT) (IO) (1) (R) ; Input error estimates (such as those generated by GEX routines) ; calibrated the same way as flux vector on output. ; ;*EXAMPLES: ; NEWCALIB,HD,W,F,E ; ;*SYSTEM VARIABLES USED: ; ; !iuer.dat ; ;*INTERACTIVE INPUT: ; ; None. ; ;*SUBROUTINES CALLED: ; ; PARCHECK ; IFITSRD ; QUADTERP ; SENSCOR ; DAATECONV ; ;*FILES USED: ; ; !iuer.dat SWPLSENS.FIT (I) ; SWPLSEN2.FIT (I) ; SWPLSEN3.FIT (I) ; LWRLSENS.FIT (I) ; LWPLSENS.FIT (I) ; LWPLSEN2.FIT (I) ; Data sets containing the NEWSIPS sensitivity degradation ; correction tables and THDA sensitivity correction coefficients. ; See FITS header of particular file for more information. ; ; !iuer.dat SWPLABS.FIT (I) ; LWRLABS.FIT (I) ; LWPLABS.FIT (I) ; Files containing the inverse sensitivity functions ; See particular FITS file header for more information. ; ;*SIDE EFFECTS: ; ;*RESTRICTIONS: ; ; - This procedure should only be used with NEWSIPS data. ; - If the APERTURE keyword = 'BOTH', NEWCALIB will use ; the value stored in the keyword EXTAPER. This is the ; only way NEWCALIB knows which aperture-dependent corrections ; are needed. ; ;*NOTES: ; ; The inverse sensitivity function is interpolated using ; QUADTERP, which uses a quadratic interpolation at all ; intervals. NEWSIPS software uses a linear interpolation ; at the first and last bin. This causes some small differences ; in the calibrated fluxes in the first and last 10 angstroms ; interval. ; ; Calibration files were created by programs FITSSDC.PRO and ; FITSCAL.PRO (not implemented). ; ; The wavelengths listed in the degradation correction files are ; the starting wavelength of each bin rather than the average ; wavelength. Since all bins are 5 angstroms, NEWCALIB adds 2.5 ; to all wavelength vectors before any interpolation is performed. ; (Before this change, NEWCALIB produced fluxes 3-5% different than ; those derived by NEWSIPS. Now values agree (except at the extremes) ; to within 0.3%.) ; ; ;*PROCEDURE: ; ; Tables containing the inverse sensitivity function and ; degradation correction coefficients are read. Corrected flux ; (and optional error vector) is calculated as: ; ABNET = FNET * ABS_INTERP * SENSCOR * TCORR * TEFF * GAIN ; where ; FNET = net flux ; ABS_INTERP = interpolated inverse sensitivity function ; (e.g., swplabs.fit) ; SENSCOR = 1.0 / (NS1 + NS2*DATE) ; NS1,NS2 = degradation corr. coefficients (e.g., swplsens.fit) ; DATE = observation date (from fits keyword apl+dateobs) ; TCORR = 1.0 + TCDEFF * (THDA - TREF) ; THDA = THDA at end of exposure (from fits keyword thdaend) ; TCDEFF = temp correction coefficient stored in sensitivity ; degradation file (e.g., lwplsens.fit ) ; TREF = reference temp (from sens. degradation files) ; TEFF = 1.0/ effective exposure time ; GAIN = non-standard UVC voltage gain correction factor ; ; The absolute flux is in erg/sec/cm2/A. ; ;I_HELP nn ; ;*MODIFICATION HISTORY: ; ; written by R. Thompson 12/21/93 (based on calib.pro) ; 3 Feb 1994 LLT change name of error flags from "e" to "error" since ; "e" was used for the extension headers of the ; calibration files. ; 12 Mar 1994 LLT Calibrate input error vector. ; 14 Mar 1994 RWT make error optional & update prolog ; 13 Apr 1994 RWT make error optional again ; 01 Sep 1994 RWT handle double aperture headers (i.e. aper='BOTH') ; and modify values searched to determine trail mode ; 26 OCT 1994 RWT add LWP calibrations, use new JD-OBS keyword for ; observation date, and correct trail mode check ; for degradation correction ; 02 NOV 1994 RWT modify date calculation to use apl+DATEOBS keyword ; 07 NOV 1994 RWT rename calibration files ; 18 Nov 1994 LLT use !iuer.dat ; 4 May 1995 RWT modify for SWP set 2 calibrations ; 18 Sep 1995 RWT modify for LWP set 2 calibrations, correct typo ; to allow gain correction when readgain = high, & ; include gain corrections for non-standard LWR UVC ; voltage. ; 1 May 1997 RWT modify for LWR ; 6 May 1997 RWT modify to use new format LWRSENSL.FIT file ; and shift senscor wavelengths by half an interval ; (for all cameras) ; 9 May 1997 RWT prevent SWP & LWP small aperture spectra from using ; trailed senscor table ; 20 May 1997 RWT add SWP post-1993 sens degrad ;- ;*****************************************************************************