LSST Charge-Coupled Device Calibration

Abstract

The prototype charge-coupled device created at the Stanford Linear Accelerator Center for the Large Synoptic Survey Telescope must be tested to check its functionality and performance. It was installed into the Calypso telescope in Arizona in November of 2008 for this purpose. Since then it has taken many images of various astronomical objects. By doing photometry on standard stars in these images, we can compare our magnitude results to the known magnitudes of these stars. This comparison allows us to then determine the chip's performance and functional capabilities. Expecting to see first light in 2016, the Large Synoptic Survey Telescope (LSST) is an extremely large ground based telescope that anticipates funding and will be built in Chile. Described as 'Wide-Fast-Deep', the LSST will have an unprecedented wide field of view (ten square degrees for surveys), short exposures (fifteen to thirty seconds and still see faint objects), and the largest digital camera in the world. One of the goals hoped to be achieved with this camera is the measurement of dark matter using strong and weak gravitational lensing. Gravitational lensing occurs when a large cluster of galaxies distorts the light from a galaxy behind this cluster. This causes an arc of light to form around the cluster. By measuring the length of this arc, one can calculate how much matter should be present in the cluster. Since the amount that should be present is vastly greater than the amount of visible matter that can be seen, it is postulated that the difference between these two numbers is made up of dark matter. This is a direct way of measuring the amount of dark matter in the universe. Thousands of galaxy clusters will be seen with LSST, allowing precise measurements of strong lensing effects. Weak lensing is a much smaller effect, distorting the shape of galaxies by only a few percent. The scale of LSST will allow these small effects to be measured with a precision unavailable with current smaller surveys. Some of the other uses for the LSST will be cataloging the entire sky, observing exploding supernovae and near Earth objects, and probing into the nature of dark energy. Since the LSST is such a large project, one organization alone cannot build it. Therefore many organizations have come together, each one working on a specific part of the telescope's construction. Here at the Stanford Linear Accelerator Center (SLAC) the camera is being designed.