Subject: Re: strawman SciReq & DRM

From: Jeremy Mould

Submitted: Fri, 14 Mar 2003 23:07:52 -0700

Message number: 98 (previous: 97, next: 99 up: Index)

For next week's meeting here's an illustrative outline of a Design Reference Mission
based on Dan Eisenstein's lsst-general posting #73. A strawman (with some obvious
blemishes) to start with !

Science Requirements
       
The area of sky imaged at any given time.                7 sq degrees
The depth and dynamic range needed in a single exposure. R=24
The depth and dynamic range needed in stacked exposure.  R=26
The requirements on seeing, PSF, and pixel size.         0.8" DIQ median
The filters needed                                       gri
The need, if any, to stack the data                      For all except NEAs
The photometric accuracy needed (both rel and abs).      0.05 mag relative only
The astrometric accuracy needed (both rel and abs)       .5 mas for //x, 50 mas absolute
The cadence of observations needed        
(very different for moving objects & distant galaxies). 
          2 pointings, each about 25 seconds (with overheads and a CR-split)
The area of sky to be covered.                           4000 sq deg/night
Requirements on the speed of data reduction needed, and the
          nature of the measured quantities.             TBD
Auxiliary data needed (e.g., follow-up spectroscopy,
                observations at non-optical wavebands, and/or 
                a priori calibrating data)               TBD
Specialized data analysis tools needed to carry out the science   TBD


Strawman DRM

Visit schedule              5 per month with #n within 2 nights of #n-1 for some n
Filter changing             2 filters per visit, r first, alternating second 
Area surveyed twice a month 15 / 5 x 4000 / 2 = 6000 sq deg (dark)
Area surveyed weekly        2000 sq deg; 'whole' sky in a year
Area surveyed daily         240 sq deg in a month; 2880 sq deg in a year
Science product SNe         >1000/yr at z=0.1; >1000/yr at z=1
Science product lensing     Omega_m to 1%, w to 1% 95% confidence
Science product NEAs        Need simulations
Science product KBOs        Needs model
Science product astrometry  Whole sky to 50 mas, volume in 10 pc to 5 mas
Science product transient objects ~100 transiting planets/year, 1000 GRBs/yr
Duration of LSST mission    Determined only by the NEA requirement

At 10:22 PM 3/14/2003 -0500, you wrote:
>Yes, feel free to post this to lsst-general; let me just ask you to
>change the ms-word document into ascii (if nothing else, it will be
>readable that way as an archived mail on the web). 


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