Mk3 K-Coronameter White Light Polarization Brightness Images

Mk3 is a scanning instrument that provides fully calibrated polarization brightness (pB) images of the Sun's white light corona over a full field-of-view from ~1.15 to ~2.45 solar radii. Mk3 operated from Jan 2, 1980 until August 30, 1999 when it was replaced by the Mk4 K-coronameter. Mk3 has a 1-D diode array detector that acquires a radial scan at a fixed angle every 0.5 degrees and builds up a 360-degree view of the Sun (720 scans) every 3 minutes. Images are available in two formats: 1) original scan format known as 'cpb' images and 2) reformatted (recognizable) cartesian coordinate images known as 'rpb'. The original scanned images (cpb) are 16-bit 720 x 128 pixels with 10.007 arcsec pixels at a 3 minute time cadence. Reformatted rpb images are 16-bit 512 x 512 pixels and keep the solar diameter at a fixed number of pixels, taking into account the change in Earth-Sun distance (i.e. variation in apparent solar diameter) over the year. Data are available on the MLSO web page and can be used to identify and measure coronal mass ejections (CMEs) as well as variations in coronal brightness and structure over the solar cycle.