LSST Science Missions Drive System Design
Significant progress has been achieved in developing the science case for building a Large Synoptic Survey Telescope and in deriving the scientific requirements for the facility from the science case. A single set of LSST observations will support a wide range of scientific programs. Members of the LSST collaboration have identified four broad topics that drive different aspects of the requirements:
- Nature of Dark Energy
- Requires excellent image quality (FWHM < 0.7arcsec in two of five bands), control of PSF shape, and deep summed images. Requires many short exposures (10-15 sec) to control systematics and to obtain a sufficient depth in the summed images (29th AB per square arcsec, in 5 bands). Photometric redshifts require better than 2% absolute photometric precision. The tracking of image quality and rapid response to changing observing conditions requires simultanous data reduction, with latency not longer than a few minutes.
- Solar System Map
- Requires accurate absolute astrometry to link motion vectors. The same exposures used for dark energy can be organized in a cadence that allows robust and efficient linking of moving objects.
- Optical Transients
- Data processing must enable real time alerts (with latency not longer than a few minutes). The same exposures used for dark energy can be organized in a cadence that minimizes aliasing.
- Galactic Structure
- The separation of stellar populations also drives the requirements on photometric precision (1% internal, 2% absolute); proper motions and parallax measurements drive the requirements on relative astrometry. For a detailed description of how LSST data will impact Asymptotic Giant Branch Star Research, see Ivezic et al. 2006, The Impact of LSST on Asymptotic Giant Branch Star Research, astro-ph/0701507 [PDF].