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NOAO Newsletter - NOAO Highlights! - September 1999 - Number 59


Gemini North Dedicated! Operations to Begin June 2000

The Gemini North Telescope on Mauna Kea was dedicated 24 June 1999 in a ceremony that brought together scientists and dignitaries from all seven Gemini partner countries. While this was primarily a non-scientific event, it did represent a milestone in the technical development of the Gemini telescopes; the Gemini staff worked hard to provide outstanding and dramatic images to demonstrate the capabilities of the Gemini telescopes.

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Caption: The central region of globular cluster NGC 6934. The image on the left is taken in the V-band using the Gemini North Telescope without Adaptive Optics (Resolution = 0.6" FWHM). The image on the right is taken in the K-band using the Gemini North Telescope plus adaptive optics (Resolution = 0.09" FWHM). (Gemini Observatory, US National Science Foundation and the University of Hawaii Institute for Astronomy)

Almost from the beginning, Gemini has been advertised as an IR-optimized telescope. The truth is that nothing that was done to IR-optimize it has made it any less effective for visible-light observations -- in fact, some of the choices made will significantly enhance its visible-light performance. The two most dramatic requirements related to this optimization are: 1) 50% of the encircled energy at 2.2 m inside a diameter of 0.1" and 2) telescope emissivity less than 4% (with a goal of 2% when silver coatings are in place on the optics; the initial coating on the primary is aluminum). Currently, it appears that both of these requirements will be achieved. (The Gemini North primary mirror puts over 81% of the light at 5500 inside of 0.1" diameter!) In addition, many steps have been taken to minimize dome- and telescope-generated atmospheric turbulence, to ensure clean optical surfaces, and to maximize throughput and versatility of operation.

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Caption: Pluto and its moon Charon are shown in this sequence of four K-band images obtained on different nights during June 1999 at Gemini North, utilizing the University of Hawaii's infrared camera QUIRC and adaptive optics (AO) system, Hokupa'a. The maximum separation between the two objects is 0.9", and the measured FWHM of unresolved images in these frames is 0.08".

Gemini is one of a new breed of telescope; it has active optical surfaces. The 1-m secondary is controlled through a five-axis mechanism that also allows chopping. The primary figure is controlled with 180 actuators. This control is effected through a number of servo loops that are operating at a variety of timescales, incorporating lookup tables, occasional pointings at bright stars and high-bandwidth (200 Hz) sampling of stars with low-order peripheral wave-front-sensors. As one might anticipate, the initial debugging of this hardware and software was not trivial. Progress was impeded by connectors that showed intermittent failures, processors that ran too slow, and many nights of clouds and high winds. These have all been overcome.

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Caption: The Gemini North Telescope.

The images that accompany this article show the truly dramatic potential of this telescope. Using the Hokupa'a adaptive optics system and the QUIRC 1024 1024 IR imager, both kindly made available by the University of Hawaii's Institute for Astronomy, the Gemini team has held its own in a game in which the rules have been set by the impressive first-light and commissioning images from the VLT and Subaru telescopes.

Gemini is a partnership. It is a partnership among funding agencies, and it is a partnership among national observatories. Despite the fact that there is a separate organization that has been established to build and operate the telescopes, this organization depends on a national project office in each partner country to act as the "gateway to Gemini." In the US, that is the US Gemini Program, a division of NOAO. In the operations phase of Gemini, the USGP will focus on its role of providing and supporting access to Gemini for the US community. That includes time allocation, assistance in technical areas, and data reduction. Thus, for most interactions, astronomers in the US will contact the USGP rather than the Gemini observatory. The exception will be when you actually go to the telescope for an observing run. Gemini will handle support of its observers when they are on-site.

Although the timing of this article is due to the dedication, it is also the right time for US astronomers to begin thinking about proposals, so here is some idea of what to expect over the next nine months. The first "semester" will run from 15 June 2000 through 31 January 2001. Thereafter, semesters will coincide with the usual NOAO semesters, and proposals for Gemini will be completely integrated with those for NOAO-operated facilities. It is expected that 60-80 nights will be available to US proposers in the first semester. The US share of Gemini North is 41.6% of the available time; a substantial amount of time during this first semester will be used for engineering and instrument commissioning.

One facility instrument and three "loaned" instruments will likely be available during the first semester:

1. NIRI, now being assembled and tested by Klaus Hodapp of the Institute for Astronomy, is a versatile 1-5m imager with three focal plane scales, a variety of filters, and grisms for low-dispersion spectroscopy. It uses a 1024 1024 InSb array as detector.

2. Hokupa'a is a 36-element natural-guide-star Adaptive Optics system on loan from the AO group at the University of Hawaii. It feeds either a 12.5 m imager with a 1024 1024 HgCdTe array or another instrument called CIRPASS.

3. CIRPASS is an uncooled 1-1.5 m spectrograph whose entrance aperture is an integral field unit. Its loan to Gemini by the University of Cambridge is currently being negotiated.

4. Gemini is also negotiating the loan of OSCIR, a mid-IR imager and spectrograph built by Charles Telesco (University of Florida). It provides 10 m low-dispersion spectroscopy and 10 m and 20 m imaging through various filters.

More information on all of these instruments and their expected performance on Gemini will be available on the Gemini and USGP web sites listed at the end of this article by the middle of December. Although the Gemini telescopes carry multiple instruments that can be switched in and out rapidly, all the instruments may not be available through all of the semester.

Proposals for Gemini time in this first semester will be due by midnight PST on 31 January 2000. Proposals must be submitted using the NOAO proposal form and associated tools. Complete instructions for using this form are available on the NOAO web site at http://www.noao.edu/noaoprop/noaoprop.html.

The Gemini telescopes will be queue scheduled approximately half of the time in order to optimally match the observations to the current conditions. While this might not seem so important in the early days of the observatory, the staff is eager to develop the processes and mechanisms that will allow them to support this observational mode. Proposers will have access to predicted frequency of occurrence of different atmospheric conditions, allowing them to understand whether their requirements are better suited for queue or classical observing. Classical observing can be carried out either from the summit or from the Hilo base-level facility.

As the proposal deadline nears, the USGP will widely publicize this new opportunity for the US community. More information will be circulated through the NOAO Newsletter, email announcements, and a forum at the January 2000 AAS meeting.

You can find out more about the Gemini Project and the telescope and facility status from the Gemini web site (mirrored for the US community at http://www.us-gemini.noao.edu/) and about access for US astronomers at the USGP web site (http://www.noao.edu/usgp/).

Todd Boroson


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