2013/12/10 by Andrew R. Marble, Marble, Andrew R., Lorraine Callahan +4
Engineering · Medicine · Physics and Astronomy · #CCD and CMOS Imaging Sensors #FOS: Physical sciences #Image Processing Techniques and Applications #Instrumentation and Methods for Astrophysics (astro-ph.IM) #Medical Imaging Techniques and Applications #Solar and Stellar Astrophysics (astro-ph.SR) #astro-ph.IM #astro-ph.SR
paper · pdf · doi:10.48550/arxiv.1312.2909
arxiv created 2013/12/10 · openalex publication_date 2013/12/10 · arxiv updated 2013/12/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The Vector Spectromagnetograph (VSM) instrument on the Synoptic Optical Longterm Investigations of the Sun (SOLIS) telescope is capable of obtaining spectropolarimetry for the full Sun (or a select latitudinal range) with one arcsecond spatial resolution and 0.05 Angstrom spectral resolution. This is achieved by scanning the Sun in declination and building up spectral cubes for multiple polarization states, utilizing a beamsplitter and two separate 2k x 2k CCD cameras. As a result, the eastern and western hemispheres of the Sun are separated in preliminary VSM images by a vertical gap with soft edges and variable position and width. Prior to the comprehensive analysis presented in this document, a trial-and-error approach to removing the gap had yielded an algorithm that was inconsistent, undocumented, and responsible for incorrectly eliminating too many image columns. Here we describe, in detail, the basis for a new, streamlined, and properly calibrated prescription for locating and removing the gap that is correct to within approximately one arcsecond (one column).