This is a sequence of 4Kx2K images, cylindrical-equidistant projection, of the Sun that can be mapped to a sphere. The sequence was assembled by combining 304 Ångstrom (extreme ultraviolet wavelength) images from STEREO-A, STEREO-B, and the Solar Dynamics Observatory (SDO). The series covers the time frame shortly after the STEREO spacecraft moved into a position where they had a complete view of the side of the Sun not visible from the Earth (see Sun 360).
The data are sampled in time approximately every three hours. Since each spacecraft is at a slightly different distance from the Sun, the intensity received by each pixel was normalized to correspond to the intensity one astronomical unit from the Sun using the inverse-square law. The flux was also adjusted for the fact that each pixel captures a different fraction of the light due to their different angular size for each spacecraft. The image from each spacecraft is then reprojected using the World Coordinate System (WCS) routines of the SolarSoft library. Masks were made to smooth the transition where datasets overlap. There are a few gaps in the data, especially near the poles of the Sun, that are filled using data from the previous time step.
Note: This sequence is suitable for animation and visualization purposes but NOT for scientific analysis.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 220.127.116.11.0