Front Page
 Scientific Ops
  » Latest
  » Science
  » Calibration
  » Operations
  » Past Issues

CDS Calibration Update
23 March 2006
CDS Calibration Update - Giulio Del Zanna

GIS Status Report
23 March 2006
GIS Status Report - Paul Kuin

GIS Calibration Update
September 17, 2003
GIS Calibration Update - Carl Foley

Book Announcement - The Radiometric Calibration of SOHO
January 20, 2003
The Radiometric Calibration of SOHO - Anuschka Pauluhn

CDS NIS Wavelength Calibration - O V 629.7 A Line
January 20, 2003
CDS NIS wavelength calibration - Dave Pike and Jeff Payne

CDS Radiometric Calibration
Friday November 9, 2001

This year there have been two meetings in Bern to discuss the radiometric intercalibration of SOHO instruments. CDS's contribution to those meetings has necessitated a careful review of the state of CDS's own calibration and its implementation in the standard software.

Although the calibration has been under continual review since launch, recent significant progress suggested than we are ready for a new release, which will both update and rationalise the calibration.

Bill Thompson has been refining the NIS detector corrections (the narrow and wide slit burn-in) and their effect as a function of time. As well as updating these corrections in the software he has published an intensity correction (GET_WIDTH_CORR), which should be used to correct fitted line intensities. Previous rocket data have also been reanalysed recently using the latest corrections and this will result in a small change in the NIS absolute calibration.

Also, the report of an extensive calibration project by Del Zanna et al. (2001) has been accepted for publication. This provides detailed checks on the shape (as a function of wavelength) of the NIS calibrations and also cross-references NIS to GIS, thereby suggesting a significant update to the GIS absolute calibration. It also confirms previous estimates of second-order calibrations. Their suggested GIS update agrees with an assessment of the GIS calibration derived from a comparison with SUMER data by Pauluhn et al (2001) which, independently, had shown the need for a factor of two revision in the GIS calibration. As a result of all this work, we believe we are now able to converge on a consistent calibration for all CDS detectors.

Some of the detailed analysis still has to be done, but we are hoping that the new calibrations will be incorporated into the standard software before the end of the year.

For anyone interested, the grisly details of what is being proposed and discussed are available in a summary of the Bern discussions.
-- Dave Pike

Irradiance Study
Monday, 10 September 2001

Measuring Irradiance with CDS, and Implications for the CDS Calibration - William Thompson

Items for the newsletter should be sent to the editor, Andrzej Fludra at

From the CDS Operations Management Team in the Space Science & Technology Department at CCLRC Rutherford Appleton Laboratory
Site maintained by John Rainnie.
Last revised on Wednesday (22/Mar/2006) at 16:19.