Gemini Focus
Gemini Focus is the Observatories newly revamped newsletter which is distributed twice a year (July and January). The current issue has articles on recent Gemini science results as well reports on Altair upgrades, the arrival of NIFS and a detailed look at the observing efficiency at Gemini, including queue completion rates. If you wish to be added to the Canadian distribution list (for future issues) please send e-mail to Dennis.Crabtree@nrc-cnrc.gc.ca. Electronic versions of Gemini Focus are available on the Gemini website.
Changes in Gemini Management
Applications to replace Matt Mountain as Gemini Director closed at the end of September. The Gemini Board has produced a short list and further interviews will be held.
Phil Puxley will leave Gemini at the end of February 2006 to take a new position at the National Science Foundation, Washington, D. C. in March.
Phil went to the Gemini Observatory in January 1996 and immediately demonstrated strong leadership while helping define the operations model that is used each night at Gemini. Phil played a crucial role in designing and implementing the systems that have allowed the current and unique multi-instrument queue observing now in place at Gemini North and South.
Phil's departure will be a big loss for Gemini, but he is moving to new and challenging responsibilities in the management of large astronomical projects at NSF.
Canadian Demand for Semester 2006A
There was strong demand for Canadian Gemini time in Semester 2006A. Subscription rates were 3.1 for Gemini North and 2.1 for Gemini South resulting in an overall subscription rate of 2.65. A post-CTAC time exchange with Argentina (Canada received 10 hours of Gemini North time in exchange for the same amount of Gemini South time) helped to address the differing subscription rates. As usual, the most requested instruments are the two GMOS spectrographs followed NIRI/Altair, GNIRS and straight NIRI. There was very little demand for Gemini’s mid-IR instrumentation.
Instrumentation Notes
Altair was designed under the assumption that the main turbulence layer was 6.5 km above Mauna Kea. This has turned out not to the case and the result is that the Altair corrected field is much smaller than expected. The solution settled on was to insert a field lens that re-conjugates Altair’s deformable mirror to ground-level (where most of the turbulence arises.). All of the tests thus far have resulted in Altair producing better off-axis corrected images (see Figure 1 for an example).
The Near-Infrared Integral Field Spectrograph was delivered earlier this year and saw first light in mid October. The on-sky commissioning progressed very well and is now completed. Gemini issued a call for Science Verification proposals in late November and the general user community should expect NIFS to be available in 2006B.
TEXES at Gemini (based on an article that originally appeared in the NOAO Newsletter)
One strong recommendation coming out of Gemini’s 2003 “Aspen” future instrumentation process was for Gemini to develop a capability for high-resolution, mid-infrared (IR) spectroscopy. Gemini North will offer a new and unique capability, beginning in 2006B, in response to the recommendation: R=100,000 spectroscopy at 5–25 microns. The University of Texas group has modified TEXES, the Texas Echelon Cross-Echelle Spectrograph (Lacy et al., 2002, PASP, 114, 153) for use at Gemini in order to make this capability available. TEXES has been in regular use at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea since fall 2000, and will be shared between the IRTF and Gemini. The high background at mid-infrared wavelengths means that ground-based spectrometers are still limited by background noise, even with very large resolving powers. Greater resolving power is then an advantage when lines are narrow, where the line-to-continuum ratio is low, or where the line shapes contain astrophysically useful information. The Aspen Report lists some of the many areas where high-resolution spectroscopy in the mid-IR can help solve important astronomical problems. The following examples of science results from TEXES at the IRTF illustrate areas where the community can reap substantial scientific benefit from the superior spatial and spectral resolution of Gemini/TEXES, as well as the better sensitivity that Gemini will provide.
Protostellar Disks:
The pure rotational lines of H2 , of which the S(1), S(2), and S(4) lines at
17.0, 12.3, and 8.0 microns are re
gularly accessible from Mauna
Kea, should be good probes of the anthropically interesting region of
protoplanetary disks at a radius of 1-10 Astronomical Units (AU). These transitions
should be thermalized, optically thin, and adequately excited at temperatures
found at these disk radii. Measurements of the intensities and Doppler profiles
of the three lines can provide information about the temperature and
distribution of the emitting gas. The superior sensitivity available at Gemini
will make several hundred Young Stellar Objects (YSOs) available for study,
including not only the optically thick sources like T Tau studied at the IRTF
(Figure 2), but also optically thin Class II and even Class III YSOs. Lines of
other molecules may provide information about disk chemistry as well.
Ultra Compact HII Regions: Radio continuum and recombination line observations of ultra compact HII regions have not been able to resolve the puzzle of why, despite their small sizes and high internal pressures, these regions last as long as they appear to. Using TEXES to observe the 12.8 micron [NeII] line (Jaffe et al. 2003, Zhu et al. 2005), it has been possible to map the kinematics of several UCHII regions and to conclude that their gas motions are dominated by surface flows rather than expansion, at least alleviating the “lifetime problem.”
Observing Opportunities: Gemini is still forming plans for the integration of TEXES into the observing schedule. We expect an engineering run to occur in February 2006, TEXES Arrives at Gemini in 2006 continued followed by a science verification run in summer 2006, and a longer science run in fall 2006. The opportunity to propose for both 2006 science runs will be announced in the Gemini 2006B Call for Proposals and/or via a special Demonstration Science or other call (that would be advertised on the Gemini and NGSC Web pages).Observations with TEXES will be made in collaboration with one or more instrument team members. The TEXES team will provide complete support for users, including assistance in proposal preparation, operation of the instrument, pipeline data reduction, and collaboration in data interpretation. For further information about proposing or observing with TEXES, contact John Lacy (lacy@astro.as.utexas.edu).