Sims 2.3.3 available via `eups distrib install`

A new version of the LSST simulations stack is now available to install with the commands

eups distrib install lsst_sims -t sims


eups distrib install lsst_sims -t sims_2_3_3

This new version will be listed as 2.3.3.sims if you run eups distrib list lsst_sims (note that, because of a change in how eups treats github tags, all future versions of the sims stack will be tagged according to the convention X.Y.Z.sims).

Version 2.3.3 includes the following updates:

  • Uses the ephem software package, rather than pyephem.

  • Uses PALPY version 1.8.0, which fixes a bug in how transformations between mean RA, Dec and geocentric apparent RA, Dec were handled.

  • Fixes a bug in sims_utils that was affecting the way proper motion was applied when transforming between mean RA, DEc and geocentric apparent RA, Dec.

  • Git-LFS is no longer required.

  • Fixes a bug in obs_lsstSim that was preventing users from instantiating LSST camera models when using a copy of the stack which they did not personally install (this was a problem for people using shared stack installations).

  • The CatalogDBObject class (and all of its daughter classes) automatically keeps a cache of all open database connections. Whenever possible, it uses one of these cached connections, rather than opening a new connection to a database.

  • The Sed class automatically caches SED files that have been read from disk. Thus, if your code uses the same SED more than once (perhaps with a different normalization or extinction parameters), you do not need to spend time reading it in more than once.

  • The EBVBase class keeps a cache of all E(B-V) maps read from disk.

  • Adds the method sims_clean_up(), which can be imported from lsst.sims.utils.CodeUtilities, to clean up dataproducts cached by the simulations stack, in the event that memory usage becomes an issue.

  • Adds the method cache_LSST_seds(), which can be imported from lsst.sims.photUtils, to create a binary cache of all of the SEDs in sims_sed_library for speedy loading of LSST SEDs.

  • Adds the method parallelCatalogWriter(), which can be imported from lsst.sims.catalogs.definitions, to simultaneously write multiple InstanceCatalogs from a single database query.

  • Adds the method getImsimFluxNorm(), which can be imported from lsst.sims.photUtils, to rapidly calculate the normalizing magnitude of an SED in the ‘ImSim’ bandpass (this being the used by PhoSim for normalizing SEDs).

  • Adds files to the throughputs repository which contain the LSST filters, but only sampled at wavelengths which have non-zero throughput.

  • Fixes a bug in sims_catUtils which caused PhoSim InstanceCatalogs to be output with the dust extinction parameters in the wrong order (internal extinction should come before Milky Way extinction; this order had been reversed in previous versions of sims_catUtils).

  • sims_GalSimInterface does not precompute a list of SEDs before it starts generating images of objects. The DESC ImSim team discovered that this was significantly slowing down their code.

This version of the sims stack was built against the DM weekly tag w.2017.1. This was necessary to get the bugfix to obs_lsstSim mentioned above.