Subject: Re: LSST exposure time calculator

From: Alan W Harris

Submitted: Wed, 10 Sep 2003 12:35:16 -0700

Message number: 169 (previous: 168, next: 170 up: Index)

Thanks, nice toy.  I ran a couple calculations to see how asteroid surveys 
go in different fileters.  I adjusted the magnitude threshold according to 
mean colors of asteroids (I'm not sure of the value for I) to correspond to 
uniform detection threshold of an object across various filters:
band  mag   exp,s
  B   24.8   35.8
  V   24.0   13.8
  R   23.6   13.8
  I   23.2   22.5
V+R  24.0    9.8

The last row is a putative V+R band filter, which should reach the V=24.0 
magnitude target in 1/sqrt(2) times less time than either R or V.  As long 
advertized, V and R are about equally effective for asteroid detection, and 
R+V is of course optimum.  Anything outside of the V,R range is not very 
effective.  Images taken in B or I band are probably worth examining for 
asteroids, but won't add much to survey coverage; images in any other band 
will take too long exposure to allow effective detection of moving asteroids.


At 08:36 AM 9/10/2003, Knut Olsen x204 wrote:


>With significant input from Tony Tyson and help from many others, we have
>prepared a web-based exposure time calculator for LSST.  We hope it
>will be useful for calculating the single-exposure and survey depths
>of the LSST Point Design, as well as for exploring the impact of
>changing that design on the science case.
>
>To access the ETC, go to http://www.ctio.noao.edu/lsst/etc/.  We would
>appreciate any and all feedback.
>
>       Knut Olsen and Chris Smith
>
>
>
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*******************************************************************
Alan W. Harris
Senior Research Scientist
Space Science Institute
4603 Orange Knoll Ave.          Phone:  818-790-8291
La Canada, CA 91011-3364        email:  harrisaw@colorado.edu
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