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AT THE KPNO 2.1-m and 4-m

Proposals for 2013B due on March 28, 2013

Phoenix was tested at the KPNO 2.1-m late in 2012A and used for science observations in 2012B at both the 2.1-m and 4-m telescopes. The 4-m integration time calculator reflects expected performance.

Phoenix at the KPNO 2.1-m and 4-m Telescopes

Phoenix is being offered at both the 2.1 m and 4 m KPNO telescopes. There are a few noteworthy differences (other than aperture!) between these telescopes:

  • PA -- The slit is fixed E-W at the 2.1 m. Full adjustment of the PA is possible at the 4 m.
  • Declination limit -- The maximum northern declination limit is 70 degrees at the 2.1 m while the pole can be observed at the 4 m. Raising the lower shutter to observe far south is possible at the 2.1 m. However when raised the lower shutter prevents observing near zenith. Operational rules exclude moving the lower shutter during the night.
  • DIQ -- Delivered image quality is at best ~1 arcsecond at the 2.1 m.
  • Plate scale -- The slit width and length in arcseconds goes as inverse of the telescope aperture. At the 2.1 m the 4 pixel slit is 1.4 arcseconds wide. At the 4 m it is 0.7 arcseconds wide. The slit length is 1 arcminute and 30 arcseconds at the 2.1 m and 4 m respectively.
  • Staffing -- There is no telescope operator at the 2.1 m. For observing at the 2.1 m it is recommended that two observers be present.

    Potential users are reminded that spectra must be taken in pairs nodded along the slit with a standard observation consisting of an ABBA set. Thus if a 1 hour exposure is desired enter 3600 seconds for the integration time and 900 seconds for the maximum time per single exposure. In the thermal infrared (red of 2.5 microns) the maximum exposure time is limited by background radiation from the telluric lines. At 4.6 microns the maximum exposure is 60 seconds. Thermal IR observations are also notoriously condition sensitive.

    The overhead to move the telescope and align a point source in the slit will be on the order of 10-15 minutes per target. Acquisitions in the thermal IR near limiting magnitudes will be difficult and more time should be scheduled in this case.

    The integration time calculators have been calibrated based on a combination of KPNO and Gemini experience. Further refinements will take place as additional Kitt Peak data are collected. Remember that results at the telescope depend on observing conditions. The ITCs are for clear weather.

    ITC for the KPNO 2.1 m

    ITC for the KPNO Mayall 4 m

    Phoenix Basics

    Phoenix is a cryogenic, long slit, high resolution infrared spectrograph designed for used at the f/15 focus of the KPNO 2.1-m, the Mayall, Blanco, and SOAR 4-m, and the Gemini 8-m telescopes. Phoenix was designed and built at NOAO-Tucson to extend high-resolution spectroscopy into the 1-5 micron region of the infrared. The driving design goal was for spectroscopy in the 1.5-2.5 micron region at resolution of 50,000 or higher to a limiting magnitude K~10 with a 2-meter telescope.

    Phoenix uses an Aladdin II 1024x1024 InSb array as the detector and is operable throughout the range of sensitivity of InSb, 1-5 microns. The grating is a 63.4 degree echelle with 32 lines per millimeter. The spectrograph is NOT cross dispersed with the spectral coverage limited by the 1024 pixels in the dispersion direction. This corresponds to ~1500 km s-1. Echelle orders are selected using order sorting filters. A variety of filters are available but filters are not available for all possible orders covering the 1-5 micron range. Slits of width 2, 3, and 4 pixels are available for resolution in the range 50000-70000. Most users select the 4 pixel wide slit which maximizes throughput. The (4 pixel) slit width and length is 0.7 by 28 arcseconds on the 4 m telescope, 1.4 x 56 arcseconds on the 2.1 m. Flat field and hollow cathode lamps are provided as part of the instrument package.

    The Phoenix vacuum vessel is about 0.7-m in diameter and 1.3-m high and weighs about 680 kg. It contains seven externally controlled moving parts and 32 optical elements. Development of Phoenix took place at Kitt Peak in the late 1990s with fully functional instrument shipped to Gemini in 2001. In late 2011 Phoenix was shipped back to Kitt Peak. Operation at Kitt Peak is similar to that at Gemini. The most important changes (other than the decreased telescope aperture!) are (1) tracking and pointing on the KPNO telescopes are not nearly as precise as at Gemini, (2) DIQ at these telescopes is about a factor of two worse than at Gemini, (3) the PA of the slit is fixed E-W on the 2.1 m, and (4) the declination is limited to less than 70 degrees on the 2.1 m. The plate scale is of course changed due to the change of aperture.

    This Web site contains a quick reference page, a draft user manual, integration time calculators (above), various reports on the instrument, and other associated documents supporting the use of the spectrograph.

    Please contact Ken Hinkle ( for additional information.

    Historical performance of Phoenix on Gemini

    Phoenix Documentation

    Papers Describing Phoenix

    Phoenix NOAO Newsletter Articles

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    Updated 30Jan2013