FUNCTION hsi_qe_depress, runid, TABLE_IDS=meas_rids, TABLE_QEDS=meas_qeds
;
; Look up the QE_DEPRESS value for a measurement
; based on the runid.
;
; 4/15/99 dd
; 5/3/99 dd  Updated values based on HSI post-XRCF flat field data
; 5/8/99 dd Updated values based on fit to cum counts, etc. from
;           hsi_snoop_anal output.

; - - - - MEASURED DATA - - - - 
; Manually created lookup table from various "measured" data:

; 106463 = 1.0 is first Phase C HSI exposure

; 106720 = 1.0 is first Phase C HSI exposure at nominal CA5 location
;   (could there have been degradation earlier?  new MCP?)

; NOT INCLUDED:
; 106859 = 0.989 is first grating-related HSI exposure...  assume
;   a low level of degradation from the initial SFs, etc.
;   (e.g. 106738 is in focus near degraded location.)

; 107545 = 0.988 : This test, D-IXH-PI-3.002, gives -1.2% the QE from
;                 earlier test, with 1 sigma = 1.7% error bar.
;                 (hsi_qe_change did the analysis.)

; NOT INCLUDED
; 108577 = 0.95 C-K dispersed image, could go up to 0.9 maybe...

; 110212 = 0.83 B-K beauty: clear measurement ~ 0.83 with other parameters
;                   fixed according to flat field results, well corrected
;                   by a simple gaussian depression...

; NOT INCLUDED
; 111402 = 0.685 HIREFS, looks OK, near end of HSI use, the 0.69 value is 
;          close to the end-of-life value

; 111804 = last HSI exposure at XRCF, so qed = 0.685, from Ian Evans
;          flat field data sets.

meas_rids = [0.0,      106463.0, 106720.0, $
	107545.0, 110212.0, $
	111804.0, 1.E6]
meas_qeds = [1.0,      1.0,      1.0, $
	0.988,    0.83,$
	0.685,    0.685]

; - - - - - - VALUES TO USE - - - -
; The above measured values are combined with cumulative count
; information in hsi_snoop_anal.pro.  The resulting analysis
; gives a qed value for each HSI file...  Assuming linear
; interpolation a small runid-to-qed-value table is produced
; (by hsi_snoop_anal)
; and encoded here for correction use:
;
; Some of the runids have significant changes within them, from
; iteration to iteration - adjust the runid to keep iterpolation
; working...  see the "; was ..." comments:
rids = [0.0, $
      106463., $
      109042., $    ; was '043, changed to 042
      109043., $
      109044., $
      109045., $    ; was '044, changed to 045
      109634., $    ; was '635, changed to 634
      109635., $
      109659., $
      109798., $
      110302., $
      110398., $
      110609., $
      110680., $
      111085., $
      111089., $
      111199., $    ; was 111200, changed to 111199
      111200., $
      111394., $
      111497., $
      111762., $
      111804., $
      111877., $
        1.E6]
qeds = [1.0, $
     0.998070, $
     0.977875, $
     0.945878, $
     0.945695, $
     0.905977, $
     0.887077, $
     0.862460, $
     0.848599, $
     0.836496, $
     0.820310, $
     0.804850, $
     0.795477, $
     0.779530, $
     0.770629, $
     0.755479, $
     0.750916, $
     0.732781, $
     0.712045, $
     0.703426, $
     0.694432, $
     0.686039, $
     0.686028, $
        0.686]

qed_value = INTERPOL(qeds, rids, runid)

RETURN, qed_value
END