;+ ; NAME: ; EIS_LTDS ; ; PURPOSE: ; Calculates the long-term decrease in sensitivity (LTDS) of the ; EIS LW channel, and returns the correction factor to be ; multiplied to the EIS radiances for data that ; have been previously calibrated with the ground calibration. ; ; If the EIS data had been calibrated with the old ; /correct_sensitivity keyword (which implemented an exponential ; sensitivity decay equally for all lines), then the user should ; give the /UNDECAY keyword, which "uncorrects" this correction ; factor. ; ; CATEGORY: ; ; Hinode EIS Data analysis SW ; ; CALLING SEQUENCE: ; print, eis_ltds('14-Sept-2010 00:00:00.000',[171,195,211,255,284]) ; ; INPUTS: ; date: a valid string with one single date. ; wavelengths: an array of EIS wavelengths (Angstroms) ; ; KEYWORD PARAMETERS: ; QUIET: If set, then no informational messages will be printed. ; ; UNDECAY: If an EIS file had previously been calibrated using the ; /correct_sensitivity option to eis_prep, then setting ; the /undecay return will yield the correction factor ; to go from this calibration to the GDZ calibration. ; ; OUTPUTS: ; The function returns the correction factors at the input wavelengths ; ; OPTIONAL OUTPUTS: ; The routine can return via keywords: ; lw_corr: the degradation of the LW channel ; effa_sw: the SW effective areas for the input date ; effa_lw: the LW effective areas for the input date ; ; CALLS: ; rd_tfile to read the ground-based effective areas and a few ; standard IDL/SSW routines. ; ; COMMON BLOCKS: ; None ; ; PROCEDURE: ; ; This programs calculates the EIS effective areas and the long-term ; decrease of the LW channel as described in Del Zanna (2013, ; A&A, 555, A47). ; It returns the correction factor to be ; multiplied to the EIS radiances for data ; that have been previously calibrated with the ground ; calibration (**without any long-term corrections applied to them**). ; ; RESTRICTIONS: ; ; Input Dates must be between 22-Sept-2006 and 14-Sept-2012 ; Wavelengths must be in the EIS ranges ; ; MODIFICATION HISTORY: ; ; Ver. 1, 2-May-2013, Giulio Del Zanna ; Ver. 2, 5-Oct-2013, Peter Young ; corrected minor bug; introduced /quiet keyword; updated ; header; added /undecay keyword. ; Ver. 3, 12-Mar-2024, Peter Young ; fixed bug whereby /undecay was giving incorrect results. ;- function eis_ltds, date, wavelengths, lw_corr=lw_corr,effa_sw=effa_sw,effa_lw=effa_lw, $ quiet=quiet, undecay=undecay ind1=where(wavelengths gt 165 and wavelengths lt 212, n1) ind2=where(wavelengths gt 245 and wavelengths lt 292, n2) if n1+n2 eq 0 then message,'Error, no input wavelengths in the EIS spectral region! ' ; these are the effective areas from the adjusted ground-based calibration eff_lw =rd_tfile('$SSW/hinode/eis/response/EIS_EffArea_A.004',/nocom,/auto,/conv) eff_sw= rd_tfile('$SSW/hinode/eis/response/EIS_EffArea_B.004',/nocom,/auto,/conv) ; these are the spline points for the Del Zanna (2013) calibration: gdz_sw=[165, 171, 174.5, 177.2, 178.1, 180.4, 182.2, $ 184.5, 185.2, 186.9, 188.3, 190, $ 192.4, 192.8, 193.5, 194.7, 195.1, $ 196.6, 197.4, 200, 201.1, 202., $ 202.7, 204.9, 208., 209.9, 211.3] gdz_eff_sw=[0.000174973/1.5, 0.000255772/1.5,0.00158207/1.5, 0.00476608/1.55, $ 0.00705735 /1.5, 0.0168637/1.45, 0.0316499/1.4, $ 0.0647319/1.35, 0.0779082/1.35, 0.115240/1.4, 0.150199/1.45, 0.194897/1.25, $ 0.255993/1.13, 0.264945/1.1, 0.279607/1.05, 0.298884/1.02, 0.302737*1., $ 0.301859/1.05, 0.287675/1.15, 0.174608*1.05, 0.119586/1.0, 0.0838537 /1.,$ 0.0635698/1., 0.0332376/1.0 ,0.0189209/1., 0.0133581/1., 0.0105513/1.] gdz_lw=[245., 252., 255, 257., 259, $ 263. , 265., 268., 270., $ 272. , 274. , 277., 281., 286., 292] gdz_eff_lw=[0.022673*0.8, 0.03908*0.75, 0.05065*0.78, 0.0588 *0.8, 0.06738*0.85,$ 0.0861*0.9, 0.09551*0.95, 0.106984*1.0, 0.110764*1.02, $ 0.10944*1.03, 0.1026*1.03, 0.084775*0.9, 0.05718*0.87, 0.0333*0.85, 0.01679*0.85]/1.1 ; these are the values interpolated over the wavelength grid of the ; ground calibration: effa_sw= interpol(gdz_eff_sw , gdz_sw, reform(eff_sw[0, *]),/spline) effa_lw= interpol(gdz_eff_lw , gdz_lw, reform(eff_lw[0, *]),/spline) ; convert input time into TAI: Xtime=ANYTIM2TAI(date) xtime_save=xtime ; this is the reference time Xtime_ref=ANYTIM2TAI('22-Sept-2006 21:36:00.000') ; this is the last time for which the long-term correction can be ; applied for: Xtime_last=ANYTIM2TAI('14-Sept-2012 00:00:00.000') corrections=fltarr(n_elements(wavelengths))+1. if xtime lt Xtime_ref then BEGIN IF NOT keyword_set(quiet) THEN print,'% EIS_LTDS: input time before launch date! Set correction factor(s) to 1' return,corrections ENDIF if xtime gt Xtime_last then begin IF NOT keyword_set(quiet) THEN print,'% EIS_LTDS: input time is after 14-Sept-2012 - the correction for the LW channel is given assuming no degradation after that date.' xtime=Xtime_last endif ; coefficients for the long-term decrease of the LW channel: coeff1=[1.0326230, -5.2495791e-09, 1.2055185e-17] ; decrease lw_corr=poly(Xtime - Xtime_ref, coeff1) ; print, 'EIS LW long-term decrease: ', lw_corr ; apply the long-term decrease to the LW channel: effa_lw=lw_corr*effa_lw ; calculate the correction factor for radiances previously calculated ; if n1 gt 0 then corrections[ind1]=$ interpol(reform(eff_sw[1, *]), reform(eff_sw[0, *]),wavelengths[ind1],/spline)/$ interpol(effa_sw, reform(eff_sw[0, *]),wavelengths[ind1],/spline ) if n2 gt 0 then corrections[ind2]=$ interpol(reform(eff_lw[1, *]), reform(eff_lw[0, *]),wavelengths[ind2],/spline)/$ interpol(effa_lw, reform(eff_lw[0, *]),wavelengths[ind2],/spline ) ; ; For about 2 years, the recommended calibration option for eis_prep ; was to use the keyword /correct_sensitivity. This applied an ; exponential sensitivity decay to all lines, with a decay time of ; 1894 days. The /undecay keyword allows this old correction to be ; undone. ; ; PRY, 12-Mar-2024 ; I changed xtime_last to xtime_save. ; /undecay was not being correctly applied because xtime_last was not the ; observation time, but the time at which gthe Del Zanna calibration ; ceases to be time-sensitive. ; The results are now consistent with eis_recalibrate_intensity. ; IF keyword_set(undecay) THEN BEGIN tref_tai=anytim2tai('22-sep-2006 21:36') dt_days=(xtime_save-tref_tai)/86400. decay_factor=exp(-dt_days/1894.0) IF NOT keyword_set(quiet) THEN print,'% EIS_TLDS: the output correction factor applies to data that has previously been corrected with a universal exponential decay of 1894 days.' ; corrections=corrections*decay_factor ENDIF return,corrections end