eLSST CatalogsFor many of these simulations, catalogs of stars, galaxies, and Solar System (moving) objects are necessary. These catalogs are used to feed the image simulations, calibration simulations (both photometric and astrometric calibration), and for database load testing. The catalogs can also be useful for scientific research and for evaluation of LSST detection limits of (for example) high proper motion stars, weak lensing signatures, distant planetesimals, or galactic structure.
Because of the different requirements for different simulations, there are several 'flavors' of catalogs which may be available.
- Simulated base object catalogs - created from our model of the universe (or galaxy, or solar system), these are the base catalogs from which all the other catalogs are derived.
- Instance catalogs: input format for the image simulation.
- Simulated Object catalogs, which are the base catalog but with positions, proper motions, parallax, and magnitudes calculated along with errors in each of these. In some cases, the reported values may be smeared by amounts corresponding to the errors. At the present time, these Object catalogs are derived directly from the base catalogs, *not* by associating together individual measurements into an 'object'. These simulated object catalogs are intended to mimic the LSST Object database.
- Simulated Source catalogs, which come from the base catalogs combined with a version of the Operations Simulation (i.e. these 'sources' correspond to individual measurements of each 'object'), along with a time-varying atmosphere. Each 'source' is intended to mimic the LSST Source database, and thus will contain a position and magnitude along with errors - these positions/magnitudes will incorporate random noise consistent with the expected errors.