diff --git a/answers.tex b/answers.tex index ca2bee3..1d5eb27 100644 --- a/answers.tex +++ b/answers.tex @@ -54,7 +54,8 @@ \subsection{Filter Balance}\label{sec:filterbalance} \caption{Magnitude limit change, compared to expected magnitude limit with E2V chips coated with Al-Ag-Al. Note: values are reported for chips acquired by two different detector vendors as E2V and ITL for both coating schemes. Positive values indicate deeper limiting magnitudes. }\label{tab:dm5Agx3} \end{longtable} -The SCOC reviewed the largely positive impact of the new throughput on science cases: nearly all MAFs responded positively to the increase in survey depth with some metrics showing improvements as large as 10\% (\eg\ Parallax uncertainty, see \autoref{fig:parallax}; see also \autoref{fig:heatmap} and note the significant improvements between \baseline{3.2} and \baseline{3.3} when the new filter transmission curves were introduced). + +The SCOC reviewed the largely positive impact of the new throughput on science cases: nearly all MAFs responded positively to the increase in survey depth with some metrics showing improvements as large as 10\% (\eg\ Parallax uncertainty, see \autoref{fig:parallax} (see also \autoref{fig:heatmap} and note the significant improvements between \baseline{3.2} and \baseline{3.3} when the new filter transmission curves were introduced). \begin{figure} \centering diff --git a/intro.tex b/intro.tex index 8a35150..c0039fb 100644 --- a/intro.tex +++ b/intro.tex @@ -1,15 +1,13 @@ \section{Introduction} -With an unprecedented engagement of the scientific community at large, the Vera C. Rubin Observatory (hereafter Rubin) has designed a process of incremental improvements on the survey strategy to maximize the overall scientific throughput of the Legacy Survey of Space and Time (LSST). The high-level requirements for the LSST are set by four science pillars: probing dark energy and dark matter, building an unprecedented inventory of the Solar System, mapping the Milky Way and Local Volume, and exploring the transient universe. These requirements are described in \cite{LPM-17} (hereafter Science Requirements Document, or \citetalias{LPM-17}, but significant flexibility in survey cadence remains within these requirements. The optimization of the survey strategy process is aimed at maximizing science for the four science pillars and increase the portfolio of LSST science by tuning the survey strategy and cadence within the SRD requirements (\citetalias{LPM-17}). +With an unprecedented engagement of the scientific community at large, the Vera C. Rubin Observatory (hereafter Rubin) has designed a process of incremental improvements on the survey strategy to maximize the overall scientific throughput of the Legacy Survey of Space and Time (LSST). The high-level requirements for the LSST are set by four science pillars: probing dark energy and dark matter, building an unprecedented inventory of the Solar System, mapping the Milky Way and Local Volume, and exploring the transient universe. These requirements are described in \cite{LPM-17} ---hereafter Science Requirements Document, or \citetalias{LPM-17}---, but significant flexibility in survey cadence remains within these requirements. The optimization of the survey strategy process is aimed at maximizing science for the four science pillars and increase the portfolio of LSST science by tuning the survey strategy and cadence within the SRD requirements (\citetalias{LPM-17}). -As part of this process, the Survey Cadence Optimization Committee (SCOC) was set up by Rubin's Science Advisory Committee in 2018 to solicit review and integrate community feedback at large and make recommendations for the implementation of the LSST survey strategy to the Director of Operations. This document constitutes the third SCOC recommendation, resulting from the phase 3 process of survey design which started in January 2023, after the delivery of the Phase 2 recommendation (\citealt{PSTN-055} ---hereafter \citetalias{PSTN-055}--- and the baseline simulation \texttt{baseline\_v3.0}. This will be the last recommendation leading to the start of LSST. Yet, reviews of the survey strategy will continue throughout the 10-years of LSST with the SCOC reviewing the survey throughput and community feedback and renewing its recommendation on an annual basis. +As part of this process, the Survey Cadence Optimization Committee (SCOC) was set up by Rubin's Science Advisory Committee in 2018 to solicit, review, and integrate community feedback at large and make recommendations for the implementation of the LSST survey strategy to the Director of Operations. This document constitutes the third SCOC recommendation, resulting from the phase 3 process of survey design which started in January 2023, after the delivery of the Phase 2 recommendation (\citealt{PSTN-055} ---hereafter \citetalias{PSTN-055}--- and the baseline simulation \texttt{baseline\_v3.0}. \cite{PSTN-056} (this document) is planned to be the last recommendation for the LSST as a whole before the start of LSST. However, the SCOC will refine the plan for Y1 in particular and the LSST in general in the light of commissioning outcomes and reviews of the survey strategy will continue throughout the 10-years survey with the SCOC evaluating the survey throughput and community feedback and renewing its recommendation on an annual basis. + +The Phase 3 recommendation (\citetalias{PSTN-056}) responds directly to the questions left open in Phase 2 (\citetalias{PSTN-055}) and updates and refines previous recommendations (\citetalias{PSTN-055} and \citetalias{PSTN-053}) The present document generally does not reiterate previous recommendations that have not changed. -The Phase 3 recommendation responds directly to the questions left open in \citetalias{PSTN-055} and updates and refines previous recommendations (\citetalias{PSTN-055} and \cite{PSTN-053}, hereafter \citetalias{PSTN-053}) The present document generally does not reiterate previous recommendations that have not changed. -Finally, to help the reader understand the text that follows, we note that the LSST survey is actually an ensamble of surveys. It includes a main survey, knwon as Wide Fast Deep (WFD) which by SRD requirement should receive more than 825 observations and covered at least 18,000 square degrees, a Galactic Plane (and Bulge) survey. Furthermore, a WFD low-dust region is defined with limits $-70^o \leq \mathrm{Dec} \leq +12.5^o$ for -$\mathrm{RA} \sim 7-18 h$ and $-72^o \leq \mathrm{Dec}\leq +3^o$ -for $0 \lesssim \mathrm{RA} \lesssim 7$ h and $18 h \lesssim \mathrm{RA} \lesssim 24 h$, with the addition of the Virgo cluster \citetalias{PSTN-053}. Special regions in the LSST include the LMC, SMC, and South Celestial Pole and North Ecliptic Spur. Microsurveys can be performed and \citetalias{PSTN-053} committed to perform a twilight Near-Earth-Objects microsurvey in Y1 and to accept further proposals for future microsurveys after the start of LSST. The document is structured as follows. @@ -30,16 +28,22 @@ \section{Introduction} \section{Executive Summary of the Phase 3 recommendation} -Notable updates from previous recommendations, and corresponding changes to the baseline, include: updating system throughputs, expectations for engineering time (particularly in the first year of LSST, Y1), and slew performance; tweaking the filter balance in response to throughput changes; refining observing choices in the Galactic Plane, Bulge, and LMC/SMC/SCP; defining the implementation plan for the ToO program; recommending single visit exposures over visits implemented in ``snaps''; investigating new rolling strategy options; refining the DDF observing plans. + +To help the reader parse the content that follows, we note that the LSST survey is actually an ensemble of surveys. It includes a main survey, knwon as Wide Fast Deep (WFD) which by SRD ``goal'' (minimum) requirement should receive more than 825 (750) observations and covered at least 18,000 (16,000) square degrees, and a Galactic Plane (and Bulge) survey. Furthermore, a WFD low-dust region is defined with limits $-70^o \leq \mathrm{Dec} \leq +12.5^o$ for +$\mathrm{RA} \sim 7-18 h$ and $-72^o \leq \mathrm{Dec}\leq +3^o$ +for $0 \lesssim \mathrm{RA} \lesssim 7$ h and $18 h \lesssim \mathrm{RA} \lesssim 24 h$, with the addition of the Virgo cluster, as of \citetalias{PSTN-055}. Special regions in the LSST include the LMC, SMC, South Celestial Pole (SCP), and North Ecliptic Spur (NES). Microsurveys, or surveys performed with a different cadence from the WFD and that require $<3\%$ of the LSST time can be performed and \citetalias{PSTN-055} committed to a twilight Near-Earth-Objects microsurvey in the first year of LSST, Y1, and to accept further proposals for future microsurveys after the start of LSST. A Target of Opportunity program was recommended for up to $3\%$ of LSST time in \citetalias{PSTN-055}. + +Notable updates from previous recommendations, and corresponding changes to the baseline, include: updating system throughputs, expectations for engineering time (particularly in Y1), and slew performance; tweaking the filter balance in response to throughput changes; refining observing choices in the Galactic Plane, Bulge, and LMC/SMC/SCP; defining the implementation plan for the ToO program; recommending single visit exposures over visits implemented in ``snaps''; investigating new rolling strategy options; refining the DDF observing plans. + \subsection{Note on how to read the SCOC plots} In this document, you will see sky maps measuring quantities (\eg, number of visits) in healpixels. The typical sky pixelization that underlies the metric calculations the SCOC review is 128 sides healpixels (covering an area $\sim 0.2\mathrm{deg}^2$) although for particularly computationally intense MAFs this is turned down to 64 or 32. -The SCOC typically reviews the outcome of MAFs across multiple \opsim\ to compare scientific performance. You will see plots in three styles: +The SCOC typically reviews the outcome of MAFs across multiple \opsim\ to compare scientific performance. You will see plots in the following styles: {\bf Heatmaps}: \autoref{fig:heatmap} - -the divergent color scheme shows improvements in metrics in blue and drops in metrics in red. Note that different heat maps may show different ranges in the color scheme, but the SCOC typically considers changes of more than a few percent to be significant and less than a few percent to be in the noise. One of the \opsim\ is chosen as a comparison and the corresponding column will look neutral in color. +the divergent color scheme shows improvements in metrics in blue and drops in performance in red. Note that different heat maps may show different ranges in the color scheme, but the SCOC typically considers changes of more than a few percent to be significant and less than a few percent to be in the noise. One of the \opsim s is chosen as a comparison and the corresponding column will look neutral in color. \begin{figure} \centering