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Binary file added whitepaper/figs/opsim_timeline.pdf
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186 changes: 166 additions & 20 deletions whitepaper/introduction.tex
Original file line number Diff line number Diff line change
Expand Up @@ -71,6 +71,11 @@
\section{Synoptic Sky Surveying at Universal Cadence}
\def\secname{intro:baseline}\label{sec:\secname}

\credit{ivezic},
\credit{drphilmarshall},
\credit{michaelstrauss}


The LSST defined a so-called ``baseline cadence'', described in the
\href{http://adsabs.harvard.edu/abs/2008arXiv0805.2366I}{LSST overview
paper} and Chapter 3 of the Science Book. This was used
Expand Down Expand Up @@ -153,32 +158,33 @@ \section{Synoptic Sky Surveying at Universal Cadence}
\section{Evaluating and Optimizing the LSST Observing Strategy}
\def\secname{intro:evaluation}\label{sec:\secname}

The next step is to quantify how well any given realization of the
LSST observing strategy (i.e., an output of \OpSim) supports the (many)
\credit{drphilmarshall}

Given a realization of the LSST observing strategy (i.e., an output of
\OpSim), our first task is to quantify how well it supports the (many)
science projects that LSST will enable. As the algorithms controlling
\OpSim are varied, some projects will benefit, while others may
suffer. By quantifying this for each projects, we can determine which cadence
\OpSim are varied, some projects will benefit, while others may suffer.
By quantifying this for each projects, we can determine which cadence
maximizes the science potential overall of the project.

Therefore, we need
a {\it science-based evaluation of the baseline
LSST observing strategy and its variants}. After simulating a sample
Therefore, we need a {\it science-based evaluation of the baseline LSST
observing strategy and its variants}. After simulating a sample
observing schedule consistent with this strategy (see
\autoref{chp:cadexp}), we then need to quantify its value to each
science team. This is what the LSST Simulations team's ``Metric Analysis
Framework'' was designed to enable: science case investigators can
now design quantitative evaluations of the outputs of \OpSim, to answer
the question, ``how good would that observing strategy be, for my
science team. This is what the LSST Simulations team's ``Metric
Analysis Framework'' was designed to enable: science case investigators
can now design quantitative evaluations of the outputs of \OpSim, to
answer the question, ``how good would that observing strategy be, for my
science?'' These ``metrics'' can be coded against the \MAF API, and
shared among the LSST science community at the
\href{https://sims-maf.lsst.io/metricList.html#contributed-mafcontrib-metrics}{\simsMafContrib}
online repository. All of the \MAF metrics described in this paper can be
found there.
online repository. All of the \MAF metrics described in this paper can
be found there.

Once the fiducial strategy has
been evaluated in this way, then any other strategy can be evaluated
in the same terms, using the same code. We will then be able to %start
optimize the strategy through iterations between \OpSim and \MAF.
in the same terms, using the same code. We will then be able to iterate towards an
science-optimized strategy.

With this program in mind, it makes sense to define {\it one ``Figure
of Merit'' (FoM) per science project}, that captures the value of the
Expand Down Expand Up @@ -229,23 +235,42 @@ \section{Influencing the LSST Observing Schedule}
the findings presented in this paper be taken forward?

In this section we describe the mechanisms by which community input to
the developing observing schedule will be absorbed, and then explain how
the developing observing schedule will be absorbed, and explain how
we will distil the vital information that the project needs from our
\OpSim / \MAF analyses.
\OpSim / \MAF analyses. We then provide a target timeline for the provision of community input.

% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

\subsection{How will the results of our analyses be used?}
\label{sec:\secname:useage}

% Beth to write this, with Andy Connolly and guidance from
% Michael Strauss and the SAC.
\credit{bethwillman}, \credit{connolly}, \credit{ivezic}

Through the end of construction and commissioning, this community
Observing Strategy White Paper will remain a living document that is
{\it the vehicle for the community to communicate to the LSST Project
regarding the Wide-Fast-Deep and mini-survey observing strategies.}
{\it The Project Scientist will synthesize and act on the results
presented in this paper,} with support from the Science Advisory
Committee and Survey Strategy Committee (see below).

As described in the LSST Operations Plan (LPM-181), the observing
strategy will continue to be refined and optimized during operations:
the Survey Scientist will chair a survey evaluation working group that
will evaluate quarterly the current and expected performance of the
survey and scheduler software. This group may include representation
from the Survey Support Scientist, the Pipelines and Data Products
group, the Data Processing group, the Camera team, and science
community. The science community representation may be implemented as a
sub-group of the Science Advisory Committee.

% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

\subsection{Science Case Conclusions}
\subsection{Communicating via Science Case Conclusions}
\label{sec:\secname:caseConclusions}

\credit{ivezic}

In order to consolidate the various constraints on the observing
strategy by different science cases, and provide high signal to noise
data for the project to take forward, each science case will answer ten
Expand Down Expand Up @@ -331,6 +356,127 @@ \subsection{Science Case Conclusions}
\navigationbar


% - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

\subsection{Timeline}
\label{sec:\secname:timeline}

\credit{connolly},
\credit{drphilmarshall}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[ht!]
\includegraphics[angle=0,width=0.9\linewidth,clip]{figs/opsim_timeline.pdf}
\caption{Target timeline for the iterated optimization of the LSST observing strategy through 2020.}
\label{fig:timeline}
\end{figure}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

The intersection between the community and the scheduler development,
and the expected support that can be provided by the Project, is
outlined in \autoref{fig:timeline}. From the point of view of the community, this timeline contains a number of interesting features:

\begin{description}

\item{\textbf{Update of the Baseline Cadence and Exploration of Rolling
Cadences.}} During development of version 1.0 of this white paper, the
Project has been developing an enhanced operations simulator code,
\OpSim~4. This will be used to generate, by September 2017, a new set of
observing strategies, including some that have a ``rolling cadence''
component. This is in response to the results presented in the science
chapters of this paper. Analysis of these simulations would form the
backbone of an updated, version 2.0 of this white paper, with existing
science cases being updated to include quantitative assessment of the
new \OpSim~4 simulations, and new science cases being identified and
investigated.

\item{\textbf{The definition of the Deep Drilling Fields (DDFs) and
associated cadences.}} The September 2017 simulations will all continue
to use the baseline DDF cadence. However, by September 2017, the LSST
will issue a call for proposals to define the cadence and properties of
the currently selected DDFs, and to propose a new set of DDFs. To enable
this, the project will publish the known boundary conditions for
additional DDFs (e.g.\ the definition of a DDF, the current division of
survey time, constraints on the number of filter exchanges that can be
accomplished within a night, the expected range of integration times).
This call will include a request to describe the science objectives of
new DDFs, the position on the sky of these DDFs, the depth required as a
function of filter, the required cadence of observations, and the
metrics that will demonstrate that the DDF observations meet their
science requirements (these metrics do not need to be written within the
framework of \MAF). Delivery of these white papers by the community will
expected by the end of 2017. The LSST Observing Strategy GitHub
repository can support the development and aggregation of these DDF
white papers. The SAC will be asked to make a recommendation to the
project by the end of April 2018 on which DDFs and cadences should be
considered, and the project will respond to these recommendations by
September 2018. The Project's ``SOCS and Scheduler'' team will support
this effort by evaluating the proposed cadences and DDFs. This may be in
the form of simulations (for new cadence proposals) or through an
evaluation of the visibility and properties of the fields relative to
the nominal performance of the LSST system.

\item \textbf{The definition of Figures of Merit (FOMs) for the LSST
survey strategy}. By September 2018 the project will issue a request to
to the community to update this Observing Strategy white paper with
\MAF-coded Figures of Merit, to evaluate both the Wide-Fast-Deep and the
mini-surveys (Galactic plane, Northern Ecliptic Spur, South Celestial
Cap) for their impacts on specific science cases. These FOMs will be
required for the Project to evaluate the efficacy of different survey
strategies on a range of LSST science (e.g.\ the trade-off between a
rolling cadence for supernova classification vs transient detection or
long period variability will need to be explored quantitatively). The
requested delivery date for these \MAF FOMs into the Observing Strategy
White Paper will be April 2019. This will leave time for a Survey
Strategy Committee (see below) to undertake trade studies that
incorporate the community-provided FOMs. Details of the design of the
FOMs (including units, thresholds, speed) will be described at a later
date (prior to September 2018). If Project resources can be allocated to
the process, then the SOCS and Scheduler team will support the writing
of the FOMs with advice and tutorials on the use of \OpSim~4~v1.4, but
the Observing Strategy white paper community will be expected to deliver
their metrics as \MAF code.

\item \textbf{Establishment of a Survey Strategy Committee (SSC)}. Given
the delivery of the FOMs, the project will establish a committee by July
2019 to evaluate competing survey strategy proposals and to propose a
survey strategy for commissioning and operation of the full LSST camera.
This committee will be chaired by the LSST Project Scientist and be
comprised of project and non-project personnel. The SAC will be asked to
make recommendations for committee membership. The SSC will report to
the LSST Director until the end of LSST construction and commissioning.
In December 2019, based on the recommendation made by the SSC, the
project will announce an initial survey strategy and publish a baseline
simulation that reproduces that strategy. If Project resources can be
allocated to the process, then the SOCS and Scheduler team might support
the committee by helping to generate the proposed survey strategies.

\end{description}

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\begin{figure}[t!]
\includegraphics[angle=0,width=0.9\linewidth,clip]{figs/opsim_timeline.pdf}
\caption{Target timeline for the iterated optimization of the LSST observing strategy through 2020.}
\label{fig:timeline}
\end{figure}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

It's important to note that the dates for this timeline are {\it
targets}. Since the deliverables are dependent on the availability of
project resources, these milestones should be considered as those we
could achieve given our best effort. Likewise, given the limited
availability of resources in the SOCS and Scheduler engineering team,
support of community members who wish to use \OpSim v4 will be on a best
effort basis. \OpSim v4 will be delivered as a Docker container and its
use and operation will be documented, but there will be no guarantee of
support for, or timeliness in response to requests for support from,
community users. The solution to this problem is to work together: the LSST Observing Strategy community, represented here by this white paper, is already developing the skills to perform and analyze LSST operations simulations: by learning from each other, we can produce high quality quantitative conclusions for the Project to act upon.



\navigationbar


% --------------------------------------------------------------------

\section{Guidelines for Contributors}
Expand Down