Subject: Re: Meeting dates, and a scientific challenge
From: Alan W Harris
Submitted: Wed, 20 Nov 2002 16:38:52 -0800
Message number: 22
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Dear Mike,
I'll pass on a couple brief comments now, and try to post something more
thorough on the general exploder before the telecon, or certainly before
the January meeting.
At 05:29 PM 11/20/2002 -0500, Michael Strauss wrote:
>Executive summary:
> -We'll have a phonecon, Monday, December 9, 2-4 PM East Coast Time.
> Please send suggested agenda items!
I'll have something to say regarding survey strategy by telecon
time. Also, and related, I can report on the Pan-STARRS workshop I
attended last week in Hawaii. The most interesting issue raised there is
the possibility that a fairly good NEO Hazard survey can be done with less
than all-sky coverage, concentrating on "sweet spots" at 60-90 degrees
elongation from the sun near the ecliptic plane (looking along the Earth's
orbit out to about the Lagrange points). The "good news" is, this might
reduce the amount of time needed to do the NEO survey. The bad news is,
that part of the sky (low solar elongation) is really crappy for any other
purpose, so the NEA survey would become a "divorced" endeavor from anything
else. Or maybe that's not bad news. Anyway, I'm running "quick and dirty"
simulations right now to test the claim and see if I agree with it. I'll
continue doing more detailed simulations over the coming month or two, and
the results will probably be a substantial part of my AAS poster talk.
> -We'll provisionally meet at the AAS 10-1:30, and perhaps 3:30 to
> 5:30, Thursday, January 9; Chris Stubbs will check whether
> a room is available
I suspect we'll need all of that time. I'll be there. I should have
progress to report, including the above survey matters plus some comments
on the NASA and Hawaii studies and how they relate to LSST.
> -What are the scientific drivers for 10-second exposures?
In my opinion, not much with respect to NEO surveys. Trailing loss begins
to set in at about 20 sec. exposures for 1 degree/day motion. Faster
moving NEAs are typically smaller than 250 m diameter at the LSST threshold
magnitude, so losing some sensitivity at >1 deg/day is not a serious
hit. The main driver, in my opinion, is simply to cover the sky fast
enough. However, if the less-than-all-sky strategy mentioned above is
valid, then it may be possible to do the NEA survey with longer exposures
and less sky coverage.
Cheers,
Al
*******************************************************************
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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