Polarimeter for Inner Coronal Studies (PICS)

The Polarimeter for Inner Coronal Studies (PICS) at the Mauna Loa Solar Observatory (MLSO) records the full solar disk and limb in the neutral emission line of Hydrogen at 656.3 nm known as H-alpha (H) at a 3 minute cadence. Solar limb images are 1534 x 1030 pixels and solar disk images are 1024 x 1024 pixels. All images have a platescale of 2.9 arcseconds per pixel. The limb image field-of-view (FOV) extends out to 2.3 solar radii (4.6 solar radii across) in the low latitude regions and out to 1.5 solar radii (3 solar radii across) over the solar poles. It operated from September 25, 1997 until February 23, 2010. PICS was an upgrade to the older H instrument known as the Digital Prominence Monitor (DPM). PICS has a narrower H bandpass filter than the DPM. This provides significantly sharper disk imaging. PICS also includes improved optics for acquiring solar limb observations.

PICS data products consist of fits and gif formatted images: 1) full disk H images (‘asc’ in the filename), 2) full disk Hwith limb darkening correction applied (‘asl’ in the filename) and 3) H limb images (‘alr’ in the filename). The limb-darkened corrected full disk (asl) images are oriented with solar north up. The uncorrected fits disk images (asc) and limb images (alr) are in the geo-coordinate system. These data can be oriented to solar north up by rotating by [-1*pangle] (see PICS fits header keywords: CROTA1, CROTA2, and SOLAR_P0). Gif images contain annotation indicating the direction of solar north.

All PICs data are available on the MLSO web page and can be used to identify and track solar prominences, filaments and their eruptions, chromospheric waves produced by flares and CMEs, sunspots, active regions and variations in chromospheric structure over the solar cycle.