From wilhelm@linax1.mpae.gwdg.de Tue Nov 18 16:46:19 2003
Date: Tue, 14 Mar 2000 08:50:17 GMT
From: wilhelm@linax1.mpae.gwdg.de
Reply-To: sumer-soft@esa.nascom.nasa.gov
To: sumer-soft@esa.nascom.nasa.gov
Subject: SUMER-SOFT: SUMER Radiometry

Subject: SUMER Calibration (Wavelength Input Error)

Dear colleagues,

Luca Teriaca directed my attention to an error related to the input format
of the wavelength in RADIOMETRY.PRO. Correct results were obtained
with floating point numbers, but an error in one of the sub-routines
(vignetting correction) led to deviations for integer inputs. For the 1" slits
the error in 1st order was between - 2% at 800 A and - 8% at 1600 A
in a monotonic fashion. In 2nd order, the error was always smaller than 3%.
The corresponding values for the 0.3" slits were -3%, -14% and 4%.
No error occurred for the 4"-wide slit.
 
I hope that most of the applications have used floating
point inputs in the past, but you might want to check your calibration results.
Although the error is smaller than the uncertainty levels of the calibration,
it is rather unfortunate that it could hide for so long.

With best regards,
 
Klaus Wilhelm  

Appendix:
---------
Modifications of RADIOMETRY.PRO on 13 March 2000 
---------------------------------------------------

Change control:

; Corrected wavelength input format                  (||||) 13 March 2000, KW
;-------------------------------------------------------------------------------

pro vignetting,slit,wavelength,diffr_cor,slit_width
;-------------------------------------------------------------------------------
wavelength=float(wavelength) ;                                              ||||