Welcome to Cor2

The Cor2 coronagraphs are part of the Sun Earth Connection Coronal and Heliospheric Investigation (SECCHI) package onboard the twin STEREO spacecraft. The Cor2 detectors each observe a range from 2 to 15 solar radii.

The STEREO mission is the third in the line of Solar-Terrestrial Probes (STP) and is a strategic element of the Sun-Earth Connections Roadmap. STEREO is designed to view the three-dimensional (3D) and temporally varying heliosphere by means of an unprecedented combination of imaging and in situ experiments mounted on virtually identical spacecraft flanking the Earth in its orbit.

SECCHI coronagraphs mask the solar disk, whose brightness is more than 105 that of the corona. The coronagraph measures the total brightness or polarization brightness integrated over the line of sight through the optically thin corona.

Image Gallery

Daily images are available for Cor2 A and Cor2 B, typically 2 days after they are acquired onboard the spacecraft. These gallery images have a background subtracted to enhance the observed active regions such as streamers and CMEs.


The primary information on Cor2 are part of the general SECCHI webpages, part of the NRL Solar Physics Branch. As the STEREO separation increases, this web page will update with science news.

Region of Overlap from CORs on each spacecraft
Region of Overlap from CORs on each spacecraft