By Timo Anguita, young researcher of MAS and  Professor of  Universidad Andrés Bello 

The Large Synoptic Survey Telescope (LSST) is a dedicated ground-based astronomical facility whose goal is to provide a database of high fidelity images and object catalogs that enable a wide range of science investigations. With its 9.6 square degree field of view and effective aperture of 6.7 meters, it will be able to survey the Southern half of the sky every few nights (on average), building up a 10-year, 900-frame movie of the ever-changing cosmos. These observations will support investigations of our Solar System, Galaxy and Universe.

However, exactly how the LSST observations will be taken (the observing strategy or “cadence”) is not yet finalized. As such, in a large community effort, we, the LSST scientific community, have embarked on a an ambitious task to study how different observing strategies will affect all of the different science cases that can be probed by the LSST. For example, one of the main science goals of LSST is to map and measure Dark Energy and Dark Matter in the Universe. This requires a certain number of observations in the same fields, however, if these observations are all done in a certain field over one year or over the 10 years would significantly make a difference for transient phenomena such as supernovae. In this case, changing the observing strategy to high cadence and shorter overall time would mean more scientific output for supernovae without affecting the “Dark” science cases but it will affect slowly varying transients such as slowly varying AGN, which require observing over a longer timescale.

Using realistic simulations of the LSST schedule and observation properties, we have designed and computed diagnostic metrics and Figures of Merit that provide quantitative evaluations of different observing strategies, and have analyzed their impact on a wide range of proposed science projects. This is work in progress and the current results can be seen in a whitepaper called the “Science Driven Optimization of the LSST Observing Strategy”. Timo Anguita, MAS researcher and member of the LSST Science Advisory Committee is one of the authors and editors of the “AGN science” section of the whitepaper. This “living document” is used to communicate the science community and most notably the LSST Science Advisory Committee about the relative merits of the observing strategy choices that could be made, in an effort to maximize the scientific value of the survey. This information will be taken into account when deciding the final observing strategy for the survey.

This scientific community effort is completely open for contributions from all of the LSST scientific community, including any scientist working in Chilean institutions. Details about it can be seen at:

Check out this example of an observing strategy:

Internight cadence considering all filters for a particular observing strategy. Left Panel: two dimensional histogram in the southern sky. Right panel: One dimensional histogram considering every point in the sky

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