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We construct uncertainty intervals for weak Poisson signals in the presence of background. We consider the case where a primary experiment yields a realization of the signal plus background, and a second experiment yields a realization of the background. The data acquisitions times for the background-only experiment,T_bg, and the primary experiment,T, are selected so that their ratio varies from 1 to 25. The expected number of background counts in the primary experiment varies from 0.2 to 2. We construct 90 and 95 percent confidence intervals based on a propagation-of-errors method as well as two implementations of a Neyman procedure where acceptance regions are constructed based on a likelihood-ratio criterion that automatically determines whether the resulting confidence interval is one-sided or two-sided. The first Neyman procedure (due to Feldman and Cousins) neglects uncertainty in the background. In the other Neyman procedure, we account for uncertainty in the background with a parametric bootstrap method. We also construct minimum length Bayesian credibility intervals. For each method, we test for the presence of a signal based on the value of the lower endpoint of the uncertainty interval. When T_bg/T is 5 or more and the expected background is 2 or less, the Feldman Cousins method outperforms the other methods considered., Comment: 12 pages,12 tables, 10 figures. This is the final version of a manuscript that has been accepted for publication by Measurement Science and Technology

We give an overview of the current and future IFU capabilities on the Gemini 8-m telescopes. The telescopes are well-suited to integral field spectroscopy and both telescopes will have optical and near-infrared IFUs within the next few years. Commissioning for the GMOS IFU on Gemini North has begun recently and it is now available to the community. Future integral field instruments will take advantage of wide-field adaptive optics systems., Comment: 6 pages, 3 figures, LaTeX style file included, to appear in the proceedings of Galaxies: The Third Dimension, edited by M. Rosado, L. Binnette, and L. Arias

A common proper motion survey of M dwarf stars within 8 pc of the Sun reveals no new stellar or brown dwarf companions at wide separations (~100-1400 AU). This survey tests whether the brown dwarf ``desert'' extends to large separations around M dwarf stars and further explores the census of the solar neighborhood. The sample includes 66 stars north of -30 degrees and within 8 pc of the Sun. Existing first epoch images are compared to new J-band images of the same fields an average of 7 years later to reveal proper motion companions within a ~4 arcminute radius of the primary star. No new companions are detected to a J-band limiting magnitude of ~16.5, corresponding to a companion mass of ~40 Jupiter masses for an assumed age of 5 Gyr at the mean distance of the objects in the survey, 5.8 pc., Comment: 8 pages, 3 figures, accepted for publication in AJ

A new MKO-NIR infrared filter set is described, including techniques and considerations given to designing a new set of bandpasses that are useful at both mid- and high-altitude sites. These filters offer improved photometric linearity and in many cases reduced background, as well as preserve good throughput within the JHKLM atmospheric windows. MKO-NIR filters have already been deployed with a number of instruments around the world as part of a filter consortium purchase to reduce the unit cost of filters. Through this effort we hope to establish, for the first time, a single standard set of infrared fitlers at as many observatories as possible., Comment: PASP, in press; 32 pages, 11 figures, 3 Tables

We present a description of a new 1--5 $\mu$m filter set similar to the long-used JHKLM filter set derived from that of Johnson. The new Mauna Kea Observatories Near-Infrared (MKO-NIR) filter set is designed to reduce background noise, improve photometric transformations from observatory to observatory, provide greater accuracy in extrapolating to zero air mass, and reduce the color dependence in the extinction coefficient in photometric reductions. We have also taken into account the requirements of adaptive optics in setting the flatness specification of the filters. A complete technical description is presented to facilitate the production of similar filters in the future., Comment: PASP, in press. 16 pages, 4 figures, 3 tables

High angular resolution J, H, K, and L' images are used to investigate the stellar content within 6 arcsec of SgrA*. The data, which are complete to K ~ 16, are the deepest multicolor observations of the region published to date., Comment: 34 pages, including 12 figures