Subject: lsst requirements

From: Sidney Wolff

Submitted: Thu, 10 Oct 2002 11:50:50 -0700

Message number: 13 (previous: 12, next: 14 up: Index)

requirements for the lsst
From: Sidney Wolff <swolff@sidney-rh.tuc.noao.edu>
To: lsst-general@princeton.edu

The collaborators on the project to build the LSST (the version based on a 
single large-aperture telescope) have been working on a 
requirements document for the project.  We have also developed a list of 
questions that will ultimately have to be answered in developing a plan for 
the project.  This document can be viewed at:



http://www.noao.edu/lsst/sci-reqs.htm


Click on the document labeled LSST Requirements.


This document may be useful to the SWG in defining what questions they should 
address in developing a design reference mission for a large survey 
capability.  


The distinction between the charge to the SWG and the ongoing efforts to 
develop a costed proposal for the single-telescope LSST will be described at 
the meeting by Jeremy Mould.  However, I think Michael described it well when 
he said at the SPIE meeting that the task of the SWG is to tell the NSF 
whether a large survey capability is worth the investment.  In answering this 
question, I hope the SWG will also define what the science priorities of such 
a survey capability should be, how such a project fits into the various 
worldwide efforts to conduct surveys, and how well various design approaches 
meet the science requirements.  All of this is consistent with Michael's 
earlier e-mails to the SWG.


In parallel with the work of the SWG, NOAO is providing funds and working with 
the community to develop a costed proposal for the single-telescope version 
of the LSST so that it will reach a level of engineering maturity that 
enables a decision to be made about its cost effectiveness.



The Web document referred to above summarizes the LSST requirements as we have 
discussed them to date along with a list of open questions.  The items marked 
with a check are ones where there appears to be a fair degree of consensus.  
The ones with bullets remain open.  This is very much a work in progress and 
should be read and discussed as such.



In a discussion at NOAO last week, we highlighted the following as important 
issues needing early definition based on the science to be done with LSST:


Filters:  How many filters must be accessible on what time scales?  
Multi-color surveying will inevitably reduce the area covered in a fixed 
time.  What is the balance between color information and sky coverage?



Delivered image quality:  What is the requirement?  How does the ability to 
achieve the science goals roll off with degraded image quality?



Site characteristics:  What are the requirements for cloud cover, seeing, 
weather patterns, etc?



Cadence of observing:  To what extent can the various science programs be 
supported with a single observing strategy; what is the required cadence 
during the night, month, year, and lifetime of the LSST project?



Cadence of reduction:  What information is required on what time scales?



Astrometric precision:  What is the requirement?



Sidney Wolff

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