From: JOHN PHILO <JOHN_PHILO@amgengate.amgen.com>
  To  : Borries Demeler/Biophysics <demeler@selway.umt.edu>
  Date: 9 May 1994 14:32:08 U

Re: more on sloping plateau

        Reply to:   RE>>more on sloping plateau
As my follow up to RASMB will hopefully have made clear, I disagree that the
problem Jack and I see has to do with the wavelength.  I have done what you
suggest and gone on both sides of the 280 peak (or wherever the xl-a says the
peak is), and the slope DOES NOT CHANGE SIGN.  Also, as I noted, the effect
is there even with the KNO3 calibration solutions, which have very broad
absorption maxima.  I fully realize and understand that the effects we are
describing make no sense IF YOU ASSUME THE PHOTOMETRIC SYSTEM WORKS PROPERLY.
 That is the whole point:  there is strong experimental evidence that at
least some XL-As have serious photometric problems, but Jack and I have had
tremendous trouble convincing people that this is true, and that we have done
all the controls to prove it.