Observations

Scheduling

Before each queue night, a schedule will be produced. OBs will be selected based on the visibility of targets, currently installed filters, time constrains, and priority of programs (based on their Grades and ranks assigned by TAC) and priorities set in Phase 2. In principle, a Grade A target has the highest priority and will be observed if at all possible. Before starting an OB, current weather conditions are checked, and the night schedule can be instantly updated as they change. The scheduler will also take into account the position of targets on the sky, in order to minimize the telescope slew time. The number of filter changes in a night will be minimized. In case of proposals using both broad-band and narrow-band filters, once it becomes impossible to execute narrow-band OBs due to difficulty in installing a particualr filter, the priority of corresponding broad-band OBs may be lowered.

Scheduling for one night will also depend on FQA of the previous nights' data, and will be adjusted on the basis of completeness of programs (especially Grade As). If a program’s completeness is very low, we may ask its PI to relax constraints.

Early execution

OBs that are submitted and accepted well before a new semester begins may have a chance to be executed in the semester that is just coming to an end. If, for example, users send their OBs early December before semester A starts, their execution will be possible for over a month. For the early execution purposes, all Grade ABC programs will be temporarily assigned Grade C. The original Grades will be restored once the new semester begins.

Sukima (gap time)

The “gap time”, or sukima, is a time during classical mode observations when no targets are available (due to weather, visibility, etc.). For HSC classical observations, queue programs may be executed in such cases, and will be given higher priority than classical backup targets. All Grades (ABC) are accepted for sukima, and OBs will be prioritized in the same way as in nomal QM.

Carry over

Normal Program

Starting in S24A, we will no longer carry incomplete Grade A proposals over to next semesters. Please resubmit them if missing data are crucial to the completion of your projects. This measure basically brings Grade A programmes in line with the rest of the HSC queue grades. That is, all normal and filler programmes are considered to be complete at the end of a semester for which telescope time had been allocated, whatever their status of progress at that time may be.

Intensive Program

Intensive programs will not be automatically carried over to next semesters. If the overall completion rate is expected to be significantly low, PIs may submit an equivalent normal program proposal (of the same science goals) in the last semester of the active intensive projects so that, if successful, they can practically be carried over to the following semester (see 6. Notice for Accepted Intensive PIs - Devotion and Complement).

Quality assessment

The quality assessment is performed in two stages. The initial quality assessment (IQA) is done by a QO soon after an OB is complete. It basically constitutes a quick check of seeing, sky transparency, etc. The QO will then judge if the current conditions are acceptable for the next OB. If not, the night schedule will be updated accordingly.

In the days following observations, a final quality assessment (FQA) will take place. The quality of data is double-chekeckd and carefully compared with the initial requests. Comments will be added, and later delivered to PIs (together with other products). When an OB passes FQA (i.e., is good), it is considered complete. Otherwise, it will be rescheduled.

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 ones, we recommend a small number of dither positions (recommended number is \(\sim 5\)). As a general policy, even if only one of the exposures fails to pass FQA, such an OB will be considered as not completed, and will be rescheduled. However, when a significant fraction of exposures in an OB satisfies the initial constraints (plus the tolerance factors discussed above), those OBs may be considered good.