Sixty‐five coronal mass ejections have been identified in a systematic examination of white‐light coronal images obtained between March and September 1980 by the coronagraph/polarimeter flown on the solar maximum mission spacecraft. These ejections were more uniformly distributed in position angle (or “projected” solar latitude) than the similar events observed during the Skylab mission in 1973–1974; 27% of the solar maximum mission mass ejections were centered at positions more than 45° from the solar equator. The average rate of occurrence of the observed mass ejections for the entire solar maximum mission epoch, based on the assumption that one coronagraph image per spacecraft orbit is sufficient for detection, was 0.9±0.15 per 24‐hour day. Application of the same sampling assumption to the Skylab data set leads to a rate of 0.75 per 24‐hour day and thus a change in this rate from the Skylab era (on the declining phase of sunspot cycle 20) to solar maximum mission (near the maximum of sunspot cycle 21) of only ∼20%.

The application of Unno's (1956) solution of the transfer equation for polarized radiation to the determination of the vector magnetic field is investigated. An analysis procedure utilizing non-linear least squares techniques is developed that allows one to automate the reduction of measured spectral profiles of the Stokes parameters to determine the field angles, strength as well as other parameters. The method is applied to synthetic spectra generated using a model solar atmosphere and yields results of remarkably high accuracy. The influence of additional factors upon determination of the vector field are also considered. These factors include effects of: asymmetric profiles, magneto-optical effects, magnetic field gradients, unresolved field elements, scattered light, and instrumental noise.

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The High Altitude Observatory Coronagraph/Polarimeter, to be flown on the National Aeronautics and Space Administration's Solar Maximum Mission satellite, is designed to produce images of the solar corona in seven wavelength bands in the visible spectral range. The spectral bands have been chosen to specifically exclude or include 'chromospheric' spectral lines, so as to allow discrimination between ejecta at high (coronal) and low (chromospheric) temperatures, respectively. In addition, the instrument features spectral filters designed to permit an accurate color separation of the F and K coronal components, and a narrow band (5.5 A,) filter to observe the radiance and polarization of the Fe xIv 5303 A. line. The effective system resolution is better than 10 arc sec and the instrument images a selected quadrant (or smaller field) on an SEC vidicon detector. The total height range that may be recorded encompasses 1.6 to more than 6.0R| (from Sun center). The instrument is pointed independently of the SMM spacecraft, and its functions are controlled through the use of a program resident within the onboard spacecraft computer. Major experimental goals include: (a) Observation of the role of the corona in the flare process and of the ejecta from the flare site and the overlying corona; (b) the study of the direction of magnetic fields in stable coronal forms, and, perhaps, ejecta; and (c) examination of the evolution of the solar corona near the period of solar maximum activity. Scientific ObjectivesIt has become increasingly apparent that the ejection of material from near the site of a solar flare represents a major manifestation of the energetic flare process. Indeed, in general the kinetic energy of the mass ejection may exceed the net radiative output over all wavelength bands of the flare by at least a factor of two. This conclusion was reached as a result of rough estimates of the radiative output of some large (>2B) flares when compared with the mass and energy estimates of large interplanetary shocks resulting from such flares (e.g., Hundhausen, 1972). As a result of the observations during the Skylab mission period, the source of the material ejected from the Sun from the large flare process has been clearly identified as having principally a coronal origin (Gosling et al., 1975). Thus, studies of solar flares must include estimates of the energy of the ejection process if the source of the energy is to be specified. The coronal origin for the majority of the ejected mass requires observation of the coronal regions above the flare site -observations which can only be obtained with coronagraphic techniques.The mechanism(s) causing the mass ejections are not yet understood; it is not clear, for example, if the ejections are primarily magnetically or pressure driven.