Challenges in the Analysis of Images from the Wide-field Imager (WISPR) on Parker Solar Probe

The three-to-five-month elliptical orbit of Parker Solar Probe (PSP), approaching within 10 solar radii of the Sun, will allow the Wide-field Imager for Solar Probe (WISPR) to view the corona with unprecedented spatial resolution from multiple viewpoints. WISPR, located on the ram side of PSP, will image and fly through structures sample by the in situ instruments. WISPR has a wide fixed angular field-of-view (FOV), extending radially from 13.5? to 108? from the Sun and approximately 50? in the transverse direction, but the physical extent of the imaged coronal region varies directly with the distance of the spacecraft from the Sun. To relate and compare features seen in the images to observation by other instruments and spacecraft with other locations and viewpoints, it is first necessary to relate the field-of-view of the WISPR telescopes at any given time to other frames of reference, such as the various Heliographic and Heliocentric coordinate systems. Here we present projections of WISPR images in several frames, made utilizing the World Coordinate System which relies on information in the images’ FITS headers (see W. T. Thompson, 2006, DOI: 10.1051/0004-6361:20054262). Specifically, the projection software uses the SolarSoft Sunpice package ($SSW/sunspice), developed by W. Thompson to obtain the proper SPICE information on spacecraft location, orientation, and the pointing of the WISPR telescopes relative to the spacecraft pointing. The changing size of the FOV relative to the Sun must be considered when analyzing tracks of density features in a sequence of images. We discuss how to create elongation (angle from the Sun as seen by the observer) vs. time images from WISPR and show J-maps created from data on WISPR’s first encounter.