90% of the available observing time with LS4 will be used to conduct a public survey. Alerts for all variables and transients with a >5-sigma detection in difference imaging will be distributed to the public via AVRO packets (using a system similar to one utilized by the Vera C. Rubin Observatory).
The observational strategy for LS4 is set by the LS4 collaboration council in consultation with the LS4 science working groups. There are three major components to the LS4 public survey:
1. Wide, extragalactic 3 day cadence project
The wide survey will discover a large number of extragalactic transients and variables (e.g., supernovae, novae, tidal disruption events, active galactic nuclei) via monitoring in the g, i, and z filters. Sources will be observed in g+i on one night and then i+z 3 nights later (i.e., the 3 day cadence refers to revisit time in the i band).
2. Narrow, extragalactic 1 day cadence project
The narrow survey will discover fast-evolving transients (e.g., orphan afterglows of GRBs, shock breakout from core-collapse SNe, early flashes from thermonuclear survey) via monitoring in the g, i, and z filters. Sources will be observed in g+i on one night and then i+z the following night (i.e., the 1 day cadence refers to revisit time in the i band).
3. Galactic Plane monitoring project
The Galactic survey will monitor high-density star fields to identify transients and variables (e.g., microlensing events, extreme eclipsing binary systems). Sources will be observed in g+i on one night and then i+z two nights later, producing a 2 day cadence.
