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                                            Phoenix Again at Gemini South

Phoenix has returned to Gemini South and will be offered as a visitor instrument.  Programs will be block scheduled and observations carried out by in a mini-queue mode.  For further information contact


Phoenix Basics

Phoenix is a cryogenic, long slit, high resolution (R~50000), near infrared (1 - 5 micron) spectrograph designed for used at the f/15 focus of 2 to 8-m class telescopes.   

At Gemini the limiting magnitude at K is about 12 depending on conditions.  The limiting magnitude is brighter in the thermal IR, about 7 at M.  Phoenix IS NOT cross-dispersed with a single integration spectral coverage of 0.5 percent (= 1550 km s-1 = 115 A at 23000 A = 22 cm-1 at 4300 cm-1) observed in one integration.  Phoenix IS long slit with a slit length of 15 arcseconds on Gemini.  

Phoenix was designed and built at NOAO-Tucson and is maintained and operated by NOAO staff. 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 a fully functional instrument shipped to Gemini in 2001. In 2011 Phoenix was shipped back to Kitt Peak in order to make space on the Gemini South ISS for F2. With the closure of the open access Kitt Peak facilities Phoenix was shipped back to Gemini South in early 2016 for use as a visitor instrument. 

The Phoenix detector is an Aladdin II 1024x1024 InSb array.  This detector has the advantage that it has good QE over the entire 1-5 microns.  However, the detector is considerably noisier than HgCdTe detectors with more limited wavelength range.  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 ~1550 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 to maximize throughput. The (4 pixel) slit width and length is 0.35 by 15 arcseconds on the Gemini 8 meter. A hollow cathode lamp is provided as part of the instrument package and the Gemini GCAL unit provides flat field lamps.

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 in the ITC 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.  


Observation Planning






Papers Describing Phoenix

  • Hinkle, K.H., Cuberly, R., Gaughan, N., Heynssens, J., Joyce, R.R. Ridgway, S.T., Schmitt, P., and Simmons, J.E., "Phoenix: A Cryogenic High-Resolution 1-5 micron Infrared Spectrograph," 1998, Proc. SPIE 3354, 810 (PDF)
  • Hinkle, K.H., Joyce, R.R., Sharp, N., and Valenti, J.A., "Phoenix: Operation and Performance of a Cryogenic High-Resolution 1-5 micron Infrared Spectrograph," 2000, Proc. SPIE 4008, 720 (PDF)
  • Hinkle, K. H., Blum, R., Joyce, R.R., Ridgway, S.T., Rodgers, B., Sharp, N., Smith, V., Valenti, J., and van der Bliek, N., "The Phoenix Spectrograph at Gemini South," 2003, Proc. SPIE 4834, 353 (PDF)


National Optical Astronomy Observatories, 950 N. Cherry Avenue, P.O. Bo x 26732, Tucson, AZ 85726, Phone: (520) 318-8000, Fax: (520) 318-8360

Updated 2015 Aug 19

Last updated or reviewed April 26, 2017.