As we move toward operations, we are also moving towards an “as-measured” set of system throughputs, instead of simply the “requirements” or “expected values” set of system throughputs.
That is - as CCDs are put together into rafts and measured, we will be updating the QE curves, readnoise and so on. We are (or will be) also updating the throughput curves for the lenses, mirrors, and filters as lab measurements are obtained.
The throughput updates in particular are currently tracked for further use in lsst-pst/syseng_throughputs … this is synced with lsst/throughputs as the latter contains the combined throughput curves in formats that are consistent with their use throughout the lsst_sims software.
In general, an update in syseng_throughputs will trigger a corresponding update in the throughputs repo, which then also necessitates an update in:
- lsst/sims_utils : m5_flat_sed
and potentially updates in
- lsst/sims_skybrightness_data (ESO sky background values used to create LSST skybrightness values)
- lsst/sims_skybrightness_pre (the pre-calculated LSST skybrightness values for opsim)
- lsst/sims_skybrightness (potential unit-test updates)
- lsst/sims_galsimInterface (potential unit-test updates)
depending on the extent of the changes in the throughputs curves.
It is worthwhile to note, however, that magnitudes of objects calculated with sims_photUtils will be calculated using the throughput curves ‘setup’ at the time of the calculation. You can choose a particular throughputs version to use, however, and then “setup” the desired version with eups. In general, the recommendation would be to use the most recent set of throughputs.
This announcement brought to you by a recent update in throughputs.
These updates include an increase in u band throughput.