From wilhelm@linax2.mpae.gwdg.de Tue Nov 18 16:46:03 2003
Date: Fri, 8 Oct 1999 11:38:04 +0100
From: wilhelm@linax2.mpae.gwdg.de
Reply-To: sumer-soft@esa.nascom.nasa.gov
To: sumer-soft@esa.nascom.nasa.gov
Subject: SUMER-SOFT: SUMER Calibration; detector A

Subject: SUMER Calibration: Detector A (2nd order, below 584 A)

Dear colleagues,

we have repeatedly mentioned that the SUMER radiometric calibration of
detector A at very short wavelengths would need more work. We used
the opportunity of an invited SUMER talk at the forthcoming NEWRAD99
conference in Madrid to go through the data again. Based on the different
behaviour of the detectors in this range, we re-assessed both the Ne VII
465 A observations and the Si XII lines at 499 A and 520 A. It appears to be
very likely that the 2nd order Ne VII line was severely blended by the 1st order
H I Ly 6 line. Werner Curdt could, on the other hand, produce a consistent
data set for Si XII, which did not support the crossing of the KBr and bare
curves resulting from the earlier Ne VII evaluation. We have therefore not
considered the Ne VII line for the evalution of the detector A sensitivity
any longer. The position of the Si XII lines was adjusted the provide
a reasonable continuation of the sensitivity at longer wavelengths.
Although this situation is not completely satisfactory, the resulting good
agreement with detector B - treated separately by Udo Schuehle - is
encouraging. I have put the new calibration in the SUMER contrib directory
today, but as usual the old calibration is still available by employing
the epoch keyword.
Philippe Lemaire is working on the recent star observations. We will
keep you inform on any impact this may have on the long-wavelength calibration.
   
With best regards,
Klaus Wilhelm