Long-term trends in the NICMOS Camera 2 obscuration pattern and aberrations
Phase retrieval measurements of well-exposed NICMOS Camera 2 star images show that long-term changes occurred in coma and the cold mask position over the 1997-1998 lifespan of the instrument. These caused time-dependent variations in the PSF diffraction pattern, notably the shape of the Airy rings and the positions of bands in the diffraction spikes. These effects are evident in both direct and coronagraphic images when two observed PSFs obtained at different times are subtracted from each other. The derived trends have been implemented in Version 5 of Tiny Tim. PSF monitoring programs for NICMOS after the cryocooler is in place should include similar exposures so that any further cold mask shifting can be tracked.
Wide-Field Infrared Survey Telescope–Astrophysics Focused Telescope Assets coronagraphic operations: lessons learned from the Hubble Space Telescope and the James Webb Space Telescope
Abstract. The coronagraphic instrument (CGI) currently proposed for the Wide-Field Infrared Survey Telescope–Astrophysics Focused Telescope Assets (WFIRST-AFTA) mission will be the first example of a space-based coronagraph optimized for extremely high contrasts that are required for the direct imaging of exoplanets reflecting the light of their host star. While the design of this instrument is still in progress, this early stage of development is a particularly beneficial time to consider the operation of such an instrument. We review current or planned operations on the Hubble Space Telescope and the James Webb Space Telescope with a focus on which operational aspects will have relevance to the planned WFIRST-AFTA CGI. We identify five key aspects of operations that will require attention: (1) detector health and evolution, (2) wavefront control, (3) observing strategies/postprocessing, (4) astrometric precision/target acquisition, and (5) polarimetry. We make suggestions on a path forward for each of these items.
Exploring the Textual Alchemy of Legal Gender: Experimental Statutes and the Message in the Medium
This article draws on original empirical research to explore the politics of experimental feminist statutes. It has two main aims. First, it traces how conventional legislative drafting techniques have participated in the wider social creation and continuance of sex/gender norms. It shows how dominant statutory expressions of sex and gender that might otherwise appear timeless have shifted with social change and legal innovation. The article contributes to debates in feminist legal studies, legal anthropology, and legislative drafting by making visible, and analysing the particular power of legislative text, its ‘alchemy’, in expressing and re-creating sex/gender as a social, cultural and political artefact. Second, drawing on this research, the article explores what the Future of Legal Gender project might consider and do when drafting an experimental statute to decertify legal gender. Addressing questions of positionality, believability, legal form and the use of potentially innovative or contested drafting techniques (the singular “they”, the second person), the article explores tensions between legislative drafting and feminist legal method, as well as the benefits for bringing feminist analysis and perspectives to this important aspect of legal practice. Given that legislative drafting does not merely inscribe pre-agreed policy ideas into legal text but helps to shape emerging ontologies of gender, then drafting an experimental statute invites feminists to pay attention to interlinked questions of substance and form in the exploration of prefigurative legal futures.