[meteorite-list] Progress in the Spaceguard Survey

From: drtanuki <drtanuki_at_meteoritecentral.com>
Date: Thu Apr 22 09:54:03 2004
Message-ID: <3C65AB4E.F271B7A5_at_tkc.att.ne.jp>

List Members:
   Mark my words and write be back in ten if I was wrong. In the next
ten years we will witness a MIE (Multiple Impact Event), unlike seen my
man for some time. My statement is based on research done by
observation.
Dirk Ross....."The Chicken Little"........ in Tokyo

Ron Baalke wrote:

> http://web99.arc.nasa.gov/impact/news_detail.cfm?ID=109
>
> Progress in the Spaceguard Survey
> Alan Harris (JPL) and David Morrison (NASA Ames)
> February 2, 2002
>
> We have now found 587 of the larger (1 km) NEAs. Will we make the
> goal of 90% completeness by 2008?
>
> The Spaceguard Goal as adopted by NASA is to discover 90% of the near
> Earth asteroids (NEAs) larger than 1 km (actually, brighter than
> absolute magnitude H=18) before the end of 2008. This is a summary of
> progress through the end of 2001, with more than 100 new discoveries
> of NEAs brighter than H=18, bringing the total to 587 as of January
> 28, 2002. The total number of known NEAs of all sizes is 1743.
>
> The following table shows the discoveries of total NEAs and of NEAs
> brighter than H=18, listed by month and observing team during 2001.
> The months are actually lunations, full moon to full moon, starting
> with the full moon of January 9, 2001, and ending with the full moon
> of January 28, 2002, a total of 13 "months." The observing groups
> listed are LINEAR (MIT), LONEOS (Lowell Observatory), NEAT-Maui
> (JPL), NEAT-Palomar (JPL; new), Spacewatch-I (Kitt Peak), and
> Spacewatch-II (Kitt Peak; new)
>
> LINEAR LONEOS NEAT-M NEAT-P SW-I SW-II Other | Total
>
> Jan 22 6 1 0 3 0 - - 1 0 - - 0 0 | 27 6
> Feb 19 6 1 0 2 1 - - 1 0 - - 0 0 | 23 7
> Mar 15 5 8 0 4 1 - - 1 0 - - 2 0 | 30 7
> Apr 12 3 6 1 2 1 - - 2 0 - - 0 0 | 22 5
> May 11 3 4 2 7 3 5 1 2 0 - - 0 0 | 29 9
> Jun 9 4 2 1 0 0 5 3 0 0 - - 0 0 | 16 8
> Jul 1 0 5 2 3 0 13 4 0 0 - - 0 0 | 22 6
> Aug 18 4 3 2 7 3 12 1 3 0 - - 0 0 | 43 10
> Sep 47 17 10 2 0 0 7 2 1 0 - - 0 0 | 65 21
> Oct 35 4 0 0 3 0 11 1 4 0 2 0 0 0 | 55 5
> Nov 35 7 3 1 1 0 2 0 1 0 3 0 0 0 | 45 8
> Dec 45 8 2 0 2 1 4 1 1 0 0 0 2 0 | 56 11
> Jan 48 13 1 1 4 0 4 1 3 0 0 0 1 1 | 61 16
> ------------------------------------------------------------|--------
> Tot 317 80 46 13 38 10 63 14 20 0 5 0 5 2 | 494 119
>
> The next table groups the discoveries into 6-month intervals for
> easier comparison with earlier years. It also drops the final
> lunation:
>
> LINEAR LONEOS NEAT SpacewatchOther Total
>
> 01-1 88 27 22 4 28 10 7 0 2 0 147 41
>
> 01-2 181 40 23 7 65 13 15 0 2 0 286 60
> -----------------------------------------------------------------
> Tot 269 67 45 11 93 23 22 0 4 0 433 101
>
> It is particularly notable how much LINEAR's discovery rate picked up
> in the second half of the year. A preliminary look at discovery
> magnitudes suggests this is largely due to reaching to fainter
> magnitude, around visual magnitude V=19.5, while previously the limit
> was near V=19.0. Both NEAT systems are getting down to around V=19.5
> too. It is this improvement in the detection limits that keeps the
> discovery rate so high; without such improvements we would expect a
> drop-off as the survey becomes more complete. The average discovery
> rate for 2002 is 9 per lunation, approximately the same as in 2000
> (10 per lunation)
>
> We can also ask how long it will take at the present discovery rate
> to find 90% of the NEAs brighter than H=18. The present total number
> of discovered NEAs of H </= 18.0 is 587. Taking a nominal value of
> 1000 as the total population, that implies that the survey is now 59%
> complete. It appears that, especially if the discovery efficiency of
> the last 5 months can be sustained, the Spaceguard Survey may be on
> track for 90% completion by 2008 or 2009. However, this statement is
> dependant on what number is assumed for the total population, since
> the discovery rate needed to finish the job depends on the number of
> objects remaining to be discovered. For example, if the total
> population is only 800 (we consider this impossibly low, but is still
> 100 above one of the estimates of two years ago), then 90% completion
> requires discovering only 133 more objects. For an assumed population
> of 1000, we need 313 more discoveries to reach 90%, and for an
> assumed population of 1200, an additional 493 discoveries are needed
> to achieve 90% completion.
>
> We may be still a little shy of the mark for 90% completion by the
> end of 2008, but not seriously so for the nominal population of 1000.
> If there are as many as 1200, then we will have to go deeper (perhaps
> beyond magnitude V=20) to reach the goal in 2008. Or we would need to
> increase sky coverage, for example by adding a telescope at a
> Southern Hemisphere site whose long winter nights (hopefully clear)
> would complement the short and often cloudy summer nights in the US
> Southwest.
>
> Detailed modeling of the survey and analysis of the discovery
> statistics is in preparation by Harris and will be published later in
> the professional literature.
>
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Received on Sat 09 Feb 2002 06:05:51 PM PST