At the present time, several new Gemini instruments are being delivered and commissioned. The Near-infrared Coronagraph has been extensively tested and commissioned on the Gemini-South telescope, and will soon begin a large survey to discover extrasolar planets. The FLAMINGOS-2 near-IR multi-object spectrograph is nearing completion at the University of Florida, and is expected to be delivered to Gemini-South by the end of 2008. Gemini's Multi-Conjugate Adaptive Optics bench has been successfully integrated and tested in the lab, and now awaits integration with the laser system and the Gemini-South AO Imager on the telescope. We also describe our efforts to repair thermal damage to the Gemini Near-IR Spectrograph that occurred last year. Since the last update, progress has been made on several of Gemini's next generation of ambitious "Aspen" instruments. The Gemini Planet Imager is now in the final design phase, and construction is scheduled to begin shortly. Two competitive conceptual design studies for the Wide-Field Fiber Multi-Object Spectrometer have now started. The Mauna Kea ground layer monitoring campaign has collected data for well over a year in support of the planning process for a future Ground Layer Adaptive Optics system.

This paper presents the basic design of the Gemini Near‐Infrared Imager (NIRI) and discusses its capabilities. NIRI offers three different pixel scales to match different operating modes of the Gemini telescope and allows polarimetric and spectroscopic observations. It is equipped with an infrared on‐instrument wave‐front sensor (OIWFS) to allow tip‐tilt and focus correction even in highly obscured regions. The science detector array is an Aladdin II InSb 1024 × 1024 pixel device sensitive from 1.0 to 5.5 μm.

This is the fourth in a series of SPIE papers that chronicle the accomplishments, challenges, and evolution of Gemini's instrumentation program. For the first time we are pleased to report about progress made, on instruments being fabricated as well as results with completed instruments, now steadily producing world-class scientific results at the Gemini Observatory. With the steady arrival of new facility class instruments, we anticipate phasing out our reliance on visitor-instruments, which have enabled our early scientific capabilities at both Gemini-N and Gemini-S. Currently two facility class instruments are operational and six more are due in roughly a year, hence commissioning all of these instruments in Hawaii and Chile will, doubtless be an enormous task for the staff at Gemini in the near future.

A description of:a new 1-5 micron filter. set for infrared photometry is presented. This new Mauna Kea Observatories near-infrared filter set is designed to reduce background noise, improve photometric transformations from observatory to observatory, provide greater accuracy in extrapolating to zero airmass, and reduce the color dependence in the extinction coefficient in photometric reductions. Through this effort we hope to establish a single standard set of infrared filters for ground-based astronomy. A complete technical description is presented to facilitate the production of similar filters in the future.

A new Mauna Kea Observatories near‐infrared (MKO‐NIR) 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 preserving good throughput within the JHKLM atmospheric windows. MKO‐NIR filters have already been deployed within 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 filters at as many observatories as possible.

We present a description of a new 1–5 μm filter set similar to the long‐used JHKLM filter set derived from that of Johnson. The new Mauna Kea Observatories Near‐Infrared 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.

Building instruments suitable for the new 8-10 m class of telescopes has been a major challenge, as specifications tighten, costs, scientific demands, and expectations grow, all while schedules remain demanding. This report provides a top level description of the status of various elements in the Gemini instrument program, and touches on some of the common problems the various teams building Gemini instruments are having. Despite these challenges, Gemini anticipates harvesting great scientific rewards from the combination of its Observatory facilities and exciting complement of scientific instruments.

We discuss the design of the laser guide star system to be implemented with ALTAIR, the Gemini North adaptive optics system. We give an overview of the sodium physics in order to understand why some lasers are more efficient than others to produce bright artificial stars. We present some simulation results which set the laser output power requirement when launching a perfect beam to the sky. Preliminary designs for the beam transfer optics, the laser launch telescope and the safety systems are also presented.

Exploiting instrument platforms like the current generation of 8-10 m class telescopes represents a new era in instrument design, construction, handling, and use. Gemini's instruments are no exception to this revolution. For example, since at least 50% of Gemini's observing time will be queue scheduled, Cassegrain-mounted instruments will effectively remain on-line, ready to be called into service for typically months at a time with minimal delay to match observing programs with changing conditions. Furthermore, effective instrument emissivities of <1% will be needed to take advantage of the very low emissivity of the telescopes. Here we report on the technical status of the Phase I instruments, describe attention being given to the total system performance of the telescopes and instruments, and list some of the considerations going into the Phase II instrument program.

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 this region published to date. The mean locus of the (K,H −K) CMD varies across the field, a result that is attributed to differential reddening with amplitude ∆AV ∼ 15 mag. The reddening variations within 3 arcsec of SgrA* are significantly smaller than this, and the resolved members of the compact star cluster immediately surrounding SgrA* have photometric properties that are not significantly different from objects at larger radii. We find that sources in our field with published 2μm spectra showing either line emission or CO absorption occupy different sequences on the (K, J − K) CMD. The emission line stars, which fall along the most richly populated sequence, have redder J−K colors than stars in the Magellanic Clouds with similar spectroscopic characteristics, and evidence is presented that this is due to excess infrared emission in the spectrum of the GC sources. The photometric properties of the giant branch, which is defined by stars showing CO absorption, are similar to those of the giant branch in Baade’s Window (BW). The mean J −K color and peak K brightness of the red giant branch are both consistent with a metal-rich population having an age ∼ 10 Gyr, while the width of the giant branch on the (K, J −K) CMD is indicative of an age spread ∆log(t) ≤ 1 dex. Therefore, if the inner bulge contains an underlying population of stars with ages in excess of ∼ 10 Gyr, as is the case in BW, then the region within a few arcsec of SgrA* cannot contain a large population of giant branch stars younger than 1 Gyr. We also report the detection of a modest population of faint, blue sources with K ≥ 14. We speculate that these are bright main sequence stars at the distance of the GC, although spectra will be required to confirm this interpretation. Nevertheless, the photometric properties of the largely unresolved compact knot of stars immediately surrounding SgrA* provide indirect evidence to support the presence of a large population of faint blue stars. In particular, we confirm previous studies that measure a relatively blue color for this cluster.

The Gemini Telescopes Project is an international partnership of the U.S., U.K., Canada, Chile, Argentina, and Brazil to build two telescopes, one in the northern hemisphere and one in the south. The telescopes will achieve an unprecedented combination of light-gathering power and image quality over the infrared, optical and ultraviolet spectral regions observable from the ground. The facilities are intended to exploit the best natural observing conditions at the sites to carry out a broad range of astronomical research programs undertaken by the National communities of the partner countries. First light on Gemini-North is scheduled for 1998 and for Gemini-South in the year 2000, with handover to operations in 2000 and 2001 respectively.

A near-infrared survey designed to detect widely separated, very low-mass companions to M dwarfs within 8 pc is described. This survey is unique in that it is sensitive to companions with separations of similar to 100-1400 = AU from primaries and with masses down to the 0.03 M(.) level, thereby sampling rarely explored parameter space. In Phase I of this program, described here, candidate stellar and brown dwarf companions are identified by creating color-magnitude plots of all detected point sources in the fields surrounding primaries and searching for objects that are bright enough to be stellar (M(J) less than or equal to 11) or that fall close to theoretical brown dwarf isochrones like GD 165B (M(J) similar to 13). Common proper motion and spectroscopic checks are used to screen candidates. To date, all candidates for which we have made follow-up observations have been identified as background sources and no new low mass stellar or brown dwarf candidates have emerged from this survey. Phase II of this program will include a search for common proper motion between primaries and all field objects to M(J) similar to 17.5, allowing identification of widely separated substellar components, including objects like GL 229B. (C) 1996 American Astronomical Society.

The CFHT imaging FTS (Maillard 1995) works by coupling the facility Fourier Transform Spectrometer (Maillard and Michel 1982) and "Redeye" infrared camera (Simons et al. 1993) to work as a single instrument. The spatial resolution of images is seeing limited with 0.33 arcsec/pixel sampling. The system is designed to reimage the CFHT f/35 focal plane onto an infrared array through the FTS optics by a special optical interface, creating a pair of complementary images that modulate in intensity as the interferometer is stepped through a scan. The infrared camera records an image at each interferometer step. From the recorded data, spectra at points in the eld can be extracted through straightforward aperture photometry of complementary regions in the eld of view. It is also possible to invert an entire raw data cube, making a four-dimensional processed cube (x, y, , intensity) from which monochromatic images can be extracted and manipulated. Some of the unique advantages of this instrument over other imaging spectrometers in use at observatories include:

A shift and add algorithm was used to combine similar to 3000 L'(lambda(c) 3.8 mu m) images of the Galactic center to create a high resolution image of the IRS 16 region. A final spatial resolution of 0.32 '' was achieved with this technique. This image was used to make new measurements of the relative brightnesses and locations of various point sources in the central parsec, as well as search for an L' counterpart to the radio source Sgr A*. We found a possible counterpart with an L' brightness of 12.1+/-0.4 mag. but cannot conclude with certainty that the object detected is in fact Sgr A*. (C) 1996 American Astronomical Society.

Spectra and finder charts are given for 20 dwarfs having types of M7 or later, and a spectral classification scheme is introduced for types M7 V to M9 V. Three of these dwarfs are later that M9 and have spectra in which VO absorption appears greatly enhanced. First results are also presented for a spectroscopic follow-up of unclassified proper motion targets, begun in an attempt to identify other low-luminosity members of the solar neighborhood.

The Gemini Telescopes are being built to exploit the unique infrared sites of Mauna Kea in Hawaii and Cerro Pachon in Chile. Both telescopes are being designed to deliver 0.1 arcsec images at the focal plane at 2.2 micrometers which will include all tracking and enclosure affects. Beyond 2 micrometers , using fast tip/tilt secondaries these 8 m telescopes will be essentially diffraction limited. In addition the use of protected silver coatings for both the primary and secondary mirrors and efficient in-situ mirror cleaning means the Mauna Kea telescope should be capable of delivering focal plane emissivities of approximately 2%. The baseline design for the Mauna Kea telescope also includes an adaptive optics system capable of feeding a 1 - 2 arcminute corrected field to near infrared instruments mounted at the f/16 Cassegrain focus. Fully exploiting the superb characteristics of the Gemini Telescopes will require a new generation of instruments which will challenge both instrument designers and infrared array technologies. The baseline complement of infrared instruments includes a 1 - 5 micrometers imager, a 1 - 5 micrometers spectrometer, and a mid-infrared (8 - 25 micrometers ) imager. Several optical instruments will also be built under the baseline instrumentation plan.

We have obtained deep J and K' images of four fields in and around the disk globular cluster M71. Our (K, J-K) diagram extends two magnitudes fainter than the main-sequence turn-off (MSTO), which occurs at K similar to 15.5. The near-infrared color-magnitude diagram (CMD) is compared with isochrones from Bergbusch and VandenBerg (1992, ApJS, 81, 163), which were transformed onto the near-infrared observational plane using two different methods. We find that isochrones translated onto the observational plane using relations derived from model atmospheres reproduce the slope of the red giant branch (RGB) on the (K, J-K) diagram from the sub-giant branch (SGB) to a point slightly brighter than the horizontal branch (HB), but do not match the observed color difference between the MSTO and the base of the RGB. On the other hand, models transformed using empirical relations derived from moderately metal-poor globular cluster and solar neighborhood stars closely match the morphology of the CMD near the MSTO. These models suggest that differential comparisons of near-infrared CMD's using, for example, the color difference between the MSTO and the base of the RGB, could be used to detect age differences comparable to what can be achieved at optical wavelengths. We also derive an age for M71 near 16 Gyr, although this conclusion should be considered as tentative given uncertainties in the metallicity of M71 and our knowledge of stellar physics. Finally, we investigate the mass function between 0.9 and 0.6 M. and find it to be relatively flat, in good agreement with what has been computed from observations shortward of 1 mu m.

We discuss deep J and K images of the nearby globular cluster M4. The colour of the RGB locus is consistent with [Fe/H] ~ -1.3, while the main-sequence mass function is flat or decreasing down to 0.2M⊙. Isochrones with ages of at least 16 Gyr are required to fit the CMD near the main-sequence turn-off.

The near-infrared photometric properties of red giant branch (RGB) and horizontal branch (HB) stars in the [Fe/H] approximately -0.3 globular cluster NGC 6553 are investigated using J and H images obtained with the CFHT facility infrared camera. The near-infrared color-magnitude diagram (CMD) of NGC 6553 differs from its optical counterparts in two respects. First, the (H,J-H) diagram does not hook downwards or flatten near the RGB tip. After correcting for differences in distance and reddening, the locus of the NGC 6553 RGB in the (H,J-H) diagram falls redward of the [Fe/H] approximately -0.7 cluster 47 Tuc, and a comparison with isochrones suggests that [Fe/H] greater-than-or-equal-to -0.4, consistent with other metallicity estimates. Second, the NGC 6553 HB is very flat in H, which is different from what is seen at optical wavelengths, where the HB is noticeably tilted. The ratio of supra-HB to zero-age HB stars is similar to what is seen in other metal-rich clusters, but is larger than predicted by evolutionary models.

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° and within 8 pc of the Sun. Existing first-epoch images are compared with new J-band images of the same fields an average of 7 yr later to reveal proper-motion companions within a ∼4′ 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.