GeminiFocus July 2017 - Page 23

The new version of GMMPS is a major improvement over its predecessor. Driven by the need to ac- commodate the new GMOS-N detectors, and in particular F-2, the source code was overhauled in many ways to make it more instrument-indepen- dent and modular. These changes come with greater stability, internal consistency checks, many bug fixes, and new features including the following: • Safe placement and proper motion check of acquisition stars; • No more external band-shuffling files; • Slit placement area accurately measured (no more lost slits); • Consistent visualization of band- and mi- cro-shuffling mask designs; • Spectral packing in micro-shuffling mode, allowing for much greater slit density; • Allowing tilted slits in micro-shuffling mode (e.g., for faint strong lensing arcs); • Display of required Phase II parameters for the Observing Tool; • Extensive integrated help web pages, also available online here; • Simpler and more robust source code in- stallation. In addition, accurate mathematical models of both GMOS spectrographs have been inte- grated (see the GMOS WaveMapper item on next page). They predict accurately (within a few pixels) where a certain wavelength will fall onto the detectors — as a function of slit position, central wavelength, and grating. Us- ing these models and full optical throughput curves, the length of the spectra and their location are accurately known in advance, al- lowing users to perform the following tasks (among others): July 2017 • Overlay wavelength grids and display 2nd order contamination (Figure 5); • Display individual wavelengths and atomic line series (optionally redshifted); • Display the wavelength intervals cut out by the detector gaps; • Interactively adjust the central wavelength to preserve spectral features of interest (Figure 6). The new version of GMMPS allows users to design the masks in a more transparent and robust manner, and provides a quantitative and accurate preview of any data obtained. New: WaveMapper — Modeling the GMOS Spectrographs The GMOS WaveMapper is a new and highly useful tool that predicts accurately where a GeminiFocus Figure 5. GMMPS optionally displays a wavelength grid (yellow numbers) for each spectrum, including the wavelength interval (bright blue) cut out by the detector gaps. Second order contamination can also be shown (orange shaded area). Figure 6. The central wavelength (CWL) of GMOS can now be adjusted interactively, guided by the wavelength displays (see Figure 5). Optionally, individual wavelengths and atomic line series can also be shown. 21