Quality assessment

The quality assessment is performed in two stages. The initial quality assessment (IQA) is done by a QO just after the observation. It includes a quick check of the currently taken data for seeing, sky transparency, detector noise, etc. The QO will then judge if current conditions are acceptable for the next scheduled OB. If not, the night schedule will be updated instantly. Note that the transparency will be measured directly only on the SDSS fields. Execution of an OB is determined based on the latest available measurement.

The next day after observations, a final quality assessment (FQA) will take place. SAs will double-check the quality of the data, taking into account more factors, and compare with the PIs requests. Each program will have one SA delegated to deal the FQA. Comments will be assigned, and later delivered to the PI (together with other products). When an OB passes the FQA, it is considered completed. Otherwise, it will be repeated. Schedule for the next night will be updated accordingly.

Note that weather may change during observations, so at each stage a tolerance of $0.1''$ for seeing and 20% for transparency will be applied. For example, if the PI asks for seeing $<0.8''$ and transparency $>$0.9, OBs executed under the conditions of seeing $\le0.9'$ and transparency $\ge0.72$ will be considered as completed. To minimize the probability of having the last exposure of an OB taken in significantly worse conditions than the first one, we encourage the PIs to use dithering sequences with small number of positions (recommended number is $\sim 5$). As a general policy, even if only one of the exposures fails to pass the FQA, such an OB will be considered as not completed, and will be scheduled for re-execution. However, when a significant fraction of exposures in an OB are taken under the requested conditions (including the tolerance factors above), QWG may evaluate the OB as completed.