Solar Physics

, Volume 276, Issue 1, pp 491–499

Long-Term Evolution of the Photometric Calibration of the STEREO Heliospheric Imagers: I. HI-1

Article

DOI: 10.1007/s11207-011-9874-7

Cite this article as:
Bewsher, D., Brown, D.S. & Eyles, C.J. Sol Phys (2012) 276: 491. doi:10.1007/s11207-011-9874-7

Abstract

The aim of this paper is to determine whether the photometric response of the STEREO HI-1A and HI-1B Heliospheric Imagers has evolved or degraded during the mission to date. This is done using the methodology of Bewsher et al. (Solar Phys.264, 433, 2010) to calculate the photometric calibration factor, μ, over the four complete STEREO heliocentric orbits between the start of the science mission operations in April 2007 and June 2011, and to evaluate whether this parameter has undergone any significant variation. It is shown that the photometric response of the instruments has remained stable to within ∼ 1%. The value of μ across different parts of the field of view is also determined to evaluate the validity of the calibrated large-scale flatfield determined by Bewsher et al. (Solar Phys.264, 433, 2010). Based on the results, new revised values for the photometric calibration factor and conversion factors for diffuse sources are presented.

Keywords

Instrumentation and data management Instrumental effect 

Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Jeremiah Horrocks InstituteUniversity of Central LancashirePrestonUK
  2. 2.Space Science and Technology DepartmentSTFC Rutherford Appleton LaboratoryDidcotUK
  3. 3.Laboratorio de Procesado de ImagenesUniversidad de ValenciaValenciaSpain