Modeling, Simulation, and Data Analysis Software Development for the Roman Coronagraph Instrument

PI: Gersh-Range, Jessica, DM Telescopes LLC
Coronagraph Community Participation Program

The Coronagraph Instrument (CGI) on the Nancy Grace Roman Space Telescope is critically important to advancing our general understanding of high-contrast imaging in space and meeting the decadal recommendation that the next flagship be a 6m telescope with a coronagraph capable of detecting 25+ Earth-like planets. CGI will demonstrate key coronagraph technologies and operational strategies that have never before been used in space but will be needed. CGI’s success depends on a cooperative team effort among the participating scientists and engineers, the Community Participation Program (CPP). We propose Dr. Jessica Gersh-Range and Prof. N. Jeremy Kasdin (emeritus) as members of the team. Dr. Gersh-Range brings 5+ years of experience on the Roman project, having extensively supported the shaped pupil coronagraph (SPC) mask design efforts, contributed the flight design for the rotated bowtie SPC, and produced polarized Observing Scenario 11 time series simulations for the Hybrid Lyot coronagraph (HLC) and the wide-field-of-view (WFOV) SPC. Prof. Kasdin brings 10+ years of experience on the Roman project, having served on the Science Definition Team, as the CGI Adjutant Scientist, and as co-chair of the Roman Formulation Science Working Group.

We propose to serve the CPP Team and the broader Roman community by using our experience and our already-developed CGI-specific software tools to provide simulated datasets; assist in commissioning; update and/or improve the data analysis software; conduct activities that enable additional imaging modes, ensure the results have long-term value, and prepare for extended use of CGI; and engage the community and communicate results. In particular, our tools include a CGISim-based tool for generating time series datasets in all polarizations for the HLC, bowtie SPC, and WFOV SPC; a completely parametric algebraic model of the Roman pupil that can generate pupils with translation, clocking, and magnification errors by manipulating the individual edges of the struts, central obscuration, and tabs; and a modular set of algorithms for calculating the (Fresnel and Fraunhofer) optical propagation through a coronagraph with or without deformable mirrors (DMs) included and with or without wavefront control.

We propose a work plan shaped by the distinct phases of the period of performance. During the initial pre-launch phase, we propose to: (1) integrate features of our software tools into existing CPP code as needed and produce polarized datasets for testing the data reduction pipeline (topics E, H); (2) update and/or improve the data analysis software by incorporating standard techniques for planet detection and photometry (topics G, H); (3) create a working group that identifies and prepares for potential issues that may degrade CGI’s performance (topics F, G, H, J); and (4) begin preemptively evaluating factors that may lead to a mismatch between the operational and modeled performance (topics F, G, H). During the primary mode commissioning phase, we propose to: (1) update the assumed error values in the coronagraph model to reflect observed behavior (topics E, F, H); (2) produce updated simulated images for the primary observing mode (and additional best-effort and unsupported modes as time permits) to compare against the data and verify that CGI is performing as expected (topics E, F, H); and (3) complete the analysis of factors that may lead to a mismatch between the operational and modeled performance. During the operations phase, we propose to: (1) investigate the effectiveness and potential benefits of restricting the corrected dark hole (DH) area to the spectroscopic slit of the bowtie SPC (topic J); (2) produce updated time series datasets to study what can be learned without digging a DH in the event of significant DM degradation (topics E, H, J); and (3) improve the data analysis software by incorporating additional community-requested algorithms as time permits (topics G, H, I).