Truth-Match and ForcedSourceOnDiaObject tables are available

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#1

This message is for all @DP0-Delegates, and is just FYI (no action needed).

The “TruthSummary” table containing data from the DC2 simulation has been matched to the DP0.2 Object table, and the results are now available in the “TruthMatch” table. To explore the truth data, it is recommended to use the TAP service with table joins, as demonstrated in DP0.2 tutorial notebook “08_Truth_Tables.ipynb”, and not the Butler. More information about the truth catalog contents, and the matching algorithm, can be found in the DP0.2 data products documentation.

The “ForcedSourceOnDiaObject” table is now available, and contains the results of forced photometry on all difference images at the locations of all DiaObjects. This table is similar to the “DiaSource” table, which contains photometric measurements only for signal-to-noise-ratio > 5 detections in all difference images. It is recommended to use the “ForcedSourceOnDiaObject” table for, e.g., supernova light curves. More information can be found in the DP0.2 data products documentation. The scientific applications of the data in this table are not yet incorporated into any of the tutorial notebooks, but work is in progress.

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Summary, Delegate Assembly, Fri Sep 30
#2

An update regarding DESC DC2 truth data available for DP0 delegates.

Jim Chiang (@jchiang) has put additional parquet-format truth tables in the /projectdirectory, which is shared by all users, in the Notebook Aspect at data.lsst.cloud. Thank you Jim!

This directory contains:

  • SNe/truth_sn_summary_v1-0-0.parquet (46M)
  • SNe/truth_sn_variability_v1-0-0.parquet (247M)
  • stars/truth_star_summary_v1-0-0.parquet (211M)
  • stars/truth_star_variability_v1-0-0.parquet (5.3G)

These truth tables have been publicly released by the DESC, but they are not part of DP0.2. They contain more detailed information about the simulated supernovae (SNe) and stars that were injected into the DP0.2 dataset.

These truth tables have not been, and will not be, cross-matched to the DP0.2 DiaObject table nor available via the TAP service like other DP0.2 catalogs.

Learn more: A notebook demonstrating how to access the data in these parquet files has been added to the “desc_truth” folder of the delegate-contributions-dp02 GitHub repository.

The schema for these tables can be found in the DESC’s DC2 Data Release note (arXiv:2101.04855), in tables B.3 (truth star summary), B.4 (truth SN summary), B.6 (truth star variability), and B.7 (truth SN variability).

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