Lessons learned from the SOHO/LASCO-C2 calibration

Antoine Llebaria; Philippe L. Lamy; Maurice V. Bout

doi:10.1117/12.506159

4 February 2004 Lessons learned from the SOHO/LASCO-C2 calibration

Antoine Llebaria, Philippe L. Lamy, Maurice V. Bout

Author Affiliations +

Proceedings Volume 5171, Telescopes and Instrumentation for Solar Astrophysics; (2004) https://doi.org/10.1117/12.506159
Event: Optical Science and Technology, SPIE's 48th Annual Meeting, 2003, San Diego, California, United States

Abstract

The LASCO-C2 coronagraph onboard the SOHO solar probe have been providing for the last seven years an unprecedented long sequence of coronal images at high cadence (about 75 images/day). The LASCO-C2 calibrations included the determination of the geometric characteristics (attitude, distortion) as well as the photometric and photopolarimetric responses. Such calibrations needed resort to a complementary set of approaches including optical-modelling, pre-flight measures and in-orbit measures and monitoring. In this paper we discuss about the specific contribution of each of them, the example of radiometric calibration of LASCO-C2 is dominated by the strong vignetting induced by the occultors. The occultors fully mask the extended circular area centered on the Sun image. Due to operational constraints the vignetting function has been obtained using a complementary set of approaches: 1) ray tracing, 2) the geometric convolution of diaphragms, 3) the measure of uniform sources in laboratory, 4) the measures in orbit of the stars and F-corona. Finaly the relationship of radiometry with geometric calibrations, strylight calibration and the log term stability monitoring is discussed.

Citation Download Citation

Antoine Llebaria, Philippe L. Lamy, and Maurice V. Bout "Lessons learned from the SOHO/LASCO-C2 calibration", Proc. SPIE 5171, Telescopes and Instrumentation for Solar Astrophysics, (4 February 2004); https://doi.org/10.1117/12.506159

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

;

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE