Straylight-Rejection Performance of the STEREO HI Instruments     

J.-P. Halain  C. J. Eyles  A. Mazzoli  D. Bewsher  J. A. Davies  E. Mazy  P. Rochus  J. M. Defise  C. J. Davis  R. A. Harrison  S. R. Crothers  D. S. Brown  C. Korendyke  J. D. Moses  D. G. Socker  R. A. Howard  J. S. Newmark 《Solar physics》2011,271(1-2):197-218

The SECCHI Heliospheric Imager (HI) instruments on-board the STEREO spacecraft have been collecting images of solar wind transients, including coronal mass ejections, as they propagate through the inner heliosphere since the beginning of 2007. The scientific use of the images depends critically on the performance of the instruments and its evolution over time. One of the most important factors affecting the performance of the instrument is the rejection of straylight from the Sun and from other bright objects located both within and outside the HI fields of view. This paper presents an analysis of the evolution of the straylight-rejection performance of the HI instrument on each of the two STEREO spacecraft over the three first years of the mission. The straylight level has been evaluated and expressed in mean solar brightness units, in which such scientific observations are usually quoted, using photometric conversion factors.  相似文献   

On-Orbit Degradation of Solar Instruments     

A. BenMoussa  S. Gissot  U. Schühle  G. Del Zanna  F. Auchère  S. Mekaoui  A. R. Jones  D. Walton  C. J. Eyles  G. Thuillier  D. Seaton  I. E. Dammasch  G. Cessateur  M. Meftah  V. Andretta  D. Berghmans  D. Bewsher  D. Bolsée  L. Bradley  D. S. Brown  P. C. Chamberlin  S. Dewitte  L. V. Didkovsky  M. Dominique  F. G. Eparvier  T. Foujols  D. Gillotay  B. Giordanengo  J. P. Halain  R. A. Hock  A. Irbah  C. Jeppesen  D. L. Judge  M. Kretzschmar  D. R. McMullin  B. Nicula  W. Schmutz  G. Ucker  S. Wieman  D. Woodraska  T. N. Woods 《Solar physics》2013,288(1):389-434

We present the lessons learned about the degradation observed in several space solar missions, based on contributions at the Workshop about On-Orbit Degradation of Solar and Space Weather Instruments that took place at the Solar Terrestrial Centre of Excellence (Royal Observatory of Belgium) in Brussels on 3 May 2012. The aim of this workshop was to open discussions related to the degradation observed in Sun-observing instruments exposed to the effects of the space environment. This article summarizes the various lessons learned and offers recommendations to reduce or correct expected degradation with the goal of increasing the useful lifespan of future and ongoing space missions.  相似文献   

Transition-Region Blinkers – II. Active-Region Properties     

Parnell  C.E.  Bewsher  D.  Harrison  R.A. 《Solar physics》2002,206(2):249-271

The distribution and general properties of events identified in an active region that have the same characteristics as quiet-Sun blinkers are discussed and named `active-region blinkers'. The events are identified using an automated scheme `BLinker Identification Program' (BLIP) which was designed for and tested on quiet-Sun blinkers. Like quiet-Sun blinkers, the active-region events are most easily identified in the 629 Å emission line from Ov although evidence for them is also found in other extreme UV lines emitted from Hei, Oiii and Oiv. Unlike quiet-Sun blinkers, however, they may also have coronal signatures in the lines Mgix and Mgx. Their properties are very similar to those of quiet-Sun blinkers with mean lifetimes of 16–19 min, mean areas of 2.4–4.3×10⁷ km² and mean intensity enhancements factors of 1.8–3.3. Their global frequency of 7–28 s^–1 is about 42%–700% higher than that for quiet-Sun blinkers. The blinkers discussed here are found above both active-region (plage) magnetic fields, as well as above the umbra and penumbra of a sunspot.  相似文献