QUALITY ASSURANCE
QUALITY ASSURANCE...
...is the final analysis which ensures that we are meeting level-1 specifications.
...closes the loop with the observatory by determining which tiles can be forever checked off as ``done'' and which need high or low priority re-scans.
Steps in Quality Assurance of the 2MASS Data:
24hr QA: done when tape reaches IPAC
Nightly Science QA: done when night is fully processed
24hr QA Monitor
Overview: The 24hr QA report (see example for 981007s) shows the quality parameters that are generated by the 24hr processing after a night's data has reached IPAC. In this quick processing, only the darks, responsivities, and calibration scans are generally run.
Checking health of telescope and instrument: The 24hr QA report checks that the telescope pointing, scanning, and focus are within tolerance. The report also checks that the intrument is behaving as expected by checking that the darks and responsivities are within nominal limits.
Checking photometricity of night: The 24hr QA report also determines whether
with default processing the night is photometric or not. This pre-processing allows
us to see if any overrides will be needed in full production processing. Also,
if the night appears to be a disaster photometrically, we can triage the night at this
step and not schedule it for full production processing. The tile manager can also be
immediately notified that these tiles need to be re-observed.
Nightly Science QA
Overview: The nightly science QA report (see example for 971215n)
shows the quality parameters generated by each subsystem in the data
processing pipeline. In this processing, all of the data are run. The report
generates an overall review of the night;
scan-by-scan quality reports on telescope tracking and stepping,
background/seeing/focus, astrometry, photometricity, and extended source processing;
and a report on the preliminary quality scores for each scan. Diagnostic images and
plots are also generated.
Scoring Rules: The rules for the quality scoring of scans are outlined in in the QA Scoring Rules document. This document is our guide to checking that the data meet the level-1 specifications. The quality reviewer uses the preliminary scores generated above as a baseline, then checks the quality reports along with the diagnostic images and plots (for example, the zero point, scan-to-scan photometric overlap, and sensitivity plots) to assign final scores to each scan.
QA Recommendation: The final scores are then justified in a report (see example for 971215n) which is mailed to UMASS. UMASS reviews the report, agrees with the recommendation or requests slight changes to the scoring, and then IPAC generates transaction files which notify the tile manager and the database loader of the scores for each scan.