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Intercomparison of the LASCO-C2, SECCHI-COR1, SECCHI-COR2, and Mk4 Coronagraphs |
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| Authors: | Richard A Frazin Alberto M Vásquez William T Thompson Russell J Hewett Philippe Lamy Antoine Llebaria Angelos Vourlidas Joan Burkepile |
| Institution: | 1. Dept. of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, 48109, USA 2. Instituto de Astronom??a y F??sica del Espacio, (CONICET-UBA) and FCEN (UBA), CC 67 ?C Suc 28, Ciudad de Buenos Aires, Argentina 3. Adnet Systems, Inc., NASA Goddard Space Flight Center, Code 671, Greenbelt, MD, 20771, USA 4. Dept. of Computer Science, University of Illinois, Urbana, IL, 61801, USA 5. Laboratoire d??Astrophysique de Marseille, UMR6110, CNRS/Universit?? de Provence, 38 rue Fr??d??ric Joliot-Curie, 13388, Marseille Cedex 13, France 6. Naval Research Laboratory, Code 7663, Washington, DC, 20375, USA 7. High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO, 80307, USA |
| Abstract: | In order to assess the reliability and consistency of white-light coronagraph measurements, we report on quantitative comparisons between polarized brightness pB] and total brightness B] images taken by the following white-light coronagraphs: LASCO-C2 on SOHO, SECCHI-COR1 and -COR2 on STEREO, and the ground-based MLSO-Mk4. The data for this comparison were taken on 16?April 2007, when both STEREO spacecraft were within 3.1° of Earth??s heliographic longitude, affording essentially the same view of the Sun for all of the instruments. Due to the difficulties of estimating stray-light backgrounds in COR1 and COR2, only Mk4 and C2 produce reliable coronal-hole values (but not at overlapping heights), and these cannot be validated without rocket flights or ground-based eclipse measurements. Generally, the agreement between all of the instruments?? pB values is within the uncertainties in bright streamer structures, implying that measurements of bright CMEs also should be trustworthy. Dominant sources of uncertainty and stray light are discussed, as is the design of future coronagraphs from the perspective of the experiences with these instruments. |
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