This project is to construct and deploy a multiband Parallel Imager for Southern Cosmology Observations for the Magellan telescope. This instrument will make fast, simultaneous, pipelined measurements of brightness, color, and redshift toward faint astronomical sources. The instrument comprises a camera that acquires simultaneous images in four optical passbands along with tightly coupled real-time analysis software to be deployed on the 6.5 meter Magellan telescope. It is designed to address a number of important questions in astrophysics including follow up to surveys by the South Pole Telescope and the Atacama Pathfinder Experiment obtaining images and photometric redshifts of galaxies discovered with these surveys. It will also perform precision photometry of supernovae in order to map out the history of cosmic expansion. These measurements will help to understand the nature of Dark Energy. It would also be used to measure exoplanet transits using the four colors which can constrain planetary orbits and physical parameters.
The instrument will be available to the many users of the Magellan consortium giving broad access to the astronomical community and will heavily involve student participation in the design, construction and deployment of the instrument as well as in its use.
The Parallel Imager for Southern Cosmology Observations (PISCO) is a project to develop an instrument package that will be used on large visual-wavelength astronomical telescopes such as the 6.5 meter diameter Magellan Clay and Baade telescopes and the 3.5 meter diameter telescope at the Apache Point Observatory. PISCO is novel in that it splits the beamed image from the telescope into four different color bands, the standard astronomical bands called g, r, i, and z. This is done with an innovative optical element composed of three thin-film dichroic filters embedded in cubical blocks of fused quartz. This has two principal advantages: since four different bands are exposed to detectors simultaneously, (1) the effect of varying atmospheric opacity (clouds) on the color data is minimized, and (2) obtaining multi-color calibrated pictures is several times faster than instruments that take successive exposures with changes of band filter in between. The software development aspect of the PISCO project has produced a data reduction pipeline that works in real time as the images are obtained. This too speeds up the image acquisition, because the variable length of time (roughly a minute to an hour) needed to obtain useful data on a newly-discovered object can be assessed at the telescope as the observations progress, instead of weeks afterwards as had previously been the case. The scientific motivation for the construction of PISCO is the need to rapidly follow up the thousands of clusters of galaxies that are being discovered and will continue to be discovered by the South Pole Telescope (SPT) Survey, in pursuit of observational data about cosmology. The SPT is a 10 meter diameter submillimeter-wave telescope located at the United States Amundsen-Scott South Pole Station in Antarctica. The SPT is surveying a 2500 square degree area of the sky in the vicinity of the southern pole of the Milky Way at wavelengths of 3 millimeters, 2 millimeters, and 1.3 millimeters. The survey detects several types of objects: (1) brightness and polarization features in the Cosmic Microwave Background radiation due to structure in the very early Universe; (2) far-infrared bright galaxies and active galactic nuclei, some of which are nearby and some of which are very distant but brightened by intervening gravitational lenses; and (3) clusters of galaxies detected by their Sunyaev-Zel'dovich (SZ) effect. Clusters of galaxies are filled with hot (many millions of degrees) inter-galactic plasma gas that scatters Cosmic Microwave Background photons to somewhat higher energy, so that the clusters look like a cooler dark spot in the background. The important thing is this: the effect is independent of distance, so the SPT detects all large clusters within the survey area, regardless of distance. This means, however, that the SPT data does not show the cosmological redshift of the cluster, it only shows that a cluster is in some particular position on the sky, and this is where PISCO comes in: PISCO is designed to rapidly confirm the existence of a cluster and determine a redshift by making the first multi-band images of the galaxies within a cluster. The goal is a complete census of large clusters of galaxies within the SPT survey area, together with determination of their redshift and mass. This result can then be compared to cosmological models of the Universe, to determine properties such as the age of the Universe, the amount of its various constituents (normal matter, Dark Matter, Dark Energy, the number and mass of neutrinos), and the history of the universal expansion. PISCO is capable of significant additions to our knowledge of the Universe, particularly the development of the mysterious Dark Energy. PISCO is also useful for other astronomical projects, for example the atmospheres of planets around distant stars. If the planet is eclipsed by its star from the point of view of the Earth, then its atmosphere can be studied by observing the changes in the color of the star plus planet as the planet emerges minute-by-minute from behind the star. PISCO is uniquely capable of such measurements.
