How many Earth-approaching asteroids are there?

The discovery process of Earth-approaching asteroids is formulated as a periodic sampling problem from an urn with replacement. It presumes as unchanging number of such objects over recent historical times, a fixed limiting magnitude/angular speed combination for detection probability, and allows for the possibility of the lack of detection or the lack of sufficient observations to refine an orbit at the first noticed apparition. While simple, the model is sufficiently powerful to show that an estimate of the number of Earth-approaching minor planets is impossible. This conclusion is insensitive to uncertainties in perturbing influences, celestial mechanics, or a model for the distribution of the orbital element sets of these minor planets

Hubble Space Telescope: Fine guidance sensors instrument handbook. Version 2.1

The Fine Guidance Sensors (FGS) are a system of photomultiplier tubes and white light amplitude interferometers (Koester's prism) which are used for the fine guidance of the Hubble Space Telescope (HST). The purpose of the handbook is to provide information to a potential user of the FGS so that he may explore the feasibility of performing various observations. A brief overview is given of how the FGS works, along with an explanation of the instrument in some detail. The procedure for estimating exposure times is explained. The observing modes are described. Some details needed to specify the exposures and observation requirements on the proposal forms are explained. Data reduction procedures are outlined

Minnesota Agricultural Economist 690

Land Economics/Use,

Minnesota Farm Real Estate Sales: 1990-2004

This publication is a snapshot of the Minnesota Farm Real Estate Sales web site (http://www.apec.umn.edu/faculty/sjtaff/salesstudy) as of June 2, 2005. It will be formally "reissued" (the web site will be recaptured) each Spring, as new sales data become available. We no longer distribute a separate farm real estate report in the Minnesota Agricultural Economist (now the Minnesota Applied Economist). The site consists largely of graphs and tables summarizing sales over the past fifteen years. It provides averages at the multi-county region and at the statewide levels of aggregation. Individual transaction data are available for downloading and analysis at Minnesota Land Economics (MLE) web site, located at http://www.apec.umn.edu/landeconomics. Electronic versions of this document are presented in fully navigable portable document format (pdf).Land Economics/Use,

PERSPECTIVES ON THE SALE OF HUNTING ACCESS RIGHTS TO PRIVATE LANDS IN MINNESOTA

Land Economics/Use,

RIM AND CRP: TWO MARGINAL CROPLAND RETIREMENT PROGRAMS

Land Economics/Use,

SUSTAINABLE AGRICULTURE: POLICY REFORM IS NOT ENOUGH

Agricultural and Food Policy, Environmental Economics and Policy,

Minnesota Farm Real Estate Sales: 1990-2008

This report is a summary of the data contained on the farmland sales portion of the Minnesota Land Economics (MLE) web site (http://landeconomics.umn.edu ) as of May 20, 2009. It is formally reissued each Spring, as new sales data become available. We no longer distribute a separate farm real estate report in the Minnesota Agricultural Economist (now the Minnesota Applied Economist: http://www.apec.umn.edu/MnApEc). The present document consists largely of graphs and tables summarizing sales over the past eighteen years. It provides averages at the multi-county region and at the statewide levels of aggregation. Individual transaction data are available for downloading and analysis at the MLE web site. An electronic version of the current report in fully navigable portable document format (pdf) is also available: http://landeconomics.umn.edu/mle/readings/Minnesota_Farm_Real_Estate_Sales .pdf.Land Economics/Use,

COMMUNITY-WIDE FINANCIAL IMPACTS OF PREFERENTIAL ASSESSMENTS FOR FARMLAND PROPERTIES

I estimate the magnitude and the geographic distribution of property tax impacts of the Twin Cities Metropolitan Area's two farmland protection programs. The total 2001 net tax reduction for participating landowners was $12.5 million, ranging from$0.2 million in Ramsey County to $3.2 million in Washington County. These "tax breaks" were necessarily matched by tax increases for all property owners, both participants and non-participants, but the pattern of these "tax shifts" does not match the pattern of tax breaks. Residents in the periphery of the metropolitan area pay more (on a per tax dollar basis) than do residents closer to the core-just the reverse of the pattern of tax breaks. Preferential tax schemes such as these are often touted as "free," because their municipal budget implications are obscured by the complexities of the property tax system. But the full financial effects are very real indeed. Somebody has to pay.Land Economics/Use,

Optimal searches for asteroids

Optimal searches for a fixed object are discussed, and the rigorous analytical results of discrete search theory are presented. The totally optimal, the uniformly optimal, the locally optimal, and the fastest searches are shown to be identical under not too restrictive assumptions. The mathematical formalism is illustrated by an Earth-approaching asteroid search and optimal searches for such objects are explicitly constructed. The approximation that Earth-approaching asteroids are fixed is equivalent to having a very high ( equiv 100 sq degs/hour) search rate. Generalizations to other types of astronomical search are briefly mentioned