roboscheduler is software that decides which designs to observe next in the SDSS field plan. It uses a set of fields and designs created by robostrategy and the information about the previous observations of those designs. See the robostrategy page for the definitions of fields and design. roboscheduler is described in detail in Donor et al. (in prep)
Within each field, roboscheduler is required to schedule individual designs with a particular cadence. A cadence is defined by:
- Number of epochs and timing of the epochs with respect to each other
- Number of designs (corresponding to back-to-back observations) at each epoch
- Observing conditions (e.g. moon illumination is dark or bright, airmass, etc) for each design
as well as some other more technical information.
While fields are ideally observed when they are directly overhead, some parts of the sky, e.g., the Galactic Center, have too many exposures planned to observe them all directly overhead. robostrategy allocates specific local sidereal times (LSTs) for each field, to ensure fields are observed at reasonable airmass, when they can’t be fit in while directly overhead.
roboscheduler plans the next observation based on each design’s observability (i.e. are at low enough airmass and for which the current sky brightness is satisfactory) and timing in their field cadence, while respecting the LST allocation. A prioritization scheme was developed based on the cadence and LST requirements, discussed in detail in Donor et al. (in prep). For a given time during the night, fields failing any observability constraint are discarded, and then the highest priority field is chosen to be observed.
The roboscheduler code is available on GitHub.