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SMA: The Submillimeter Array

Link to SMA Web site

I. General project/facility description

  1. Overview of the facility/project
    The Submillimeter Array (SMA) consists of eight six meter diameter antennas located near the summit of Mauna Kea in "millimeter valley", about 150 meters west of the JCMT at an elevation of 4080 m. The Array is currently equipped with SIS mixer receivers to cover the bands 180-250 GHz, 240-350 GHz, and 620-690 GHz. The IF bandwidth is 2 GHz, and processing of both upper and lower sideband signals is implemented. The correlation spectrometer is very flexible in configuration, and  the full bandwidth mode allows for 1 MHz resolution over 2 GHz in two receiver bands simultaneously. In Hilo, at sea level, there is an 18,000 square foot facility to support the summit operation. SAO owns two bedrooms at the mid-level general support facility.

  2. Managing institution and organization
    The SMA is a joint project of the Smithsonian Astrophysical Observatory (SAO) (85 percent), a bureau of the Smithsonian Institution and the Institute of Astronomy and Astrophysics of the Academia Sinica (ASIAA) of Taiwan (15 percent). As described by the Operating agreement between SAO and the University of Hawaii, the Institute of Astronomy (IfA/UH) receives 15 percent of the observing time. The Director of the SMA is an employee of the SAO. The distribution of observing time is thus: SAO, 72 percent, UH, 15 percent, and ASIAA, 13 percent. The operating staff in Hawaii is 26 people, supported by a staff of 31 in Cambridge. There is an external Advisory Committee which meets once per year, and three separate telescope allocation committees.

  3. Funding source(s)
    The operating budget is split 85/15 percent between SAO and ASIAA, which are funded through their parent organizations, the Smithsonian Institution and the Academia Sinica. The SAO support is in the form of direct Federal appropriation by Congress to the Smithsonian Institution. The SI budget is considered with the the Department of the Interior and related agencies.

  4. Construction history and cost
    The total cost of construction from inception in 1990 to dedication in November 2003 was $103M (actual dollars - approximately equal to 1997 dollars) (of which ASIAA contributed about $15M in kind). This included the design, construction, partial operation of the array before 2004, and support of a science group during the construction period. The construction included $6.2M for the Hilo support facility.

  5. Operational history and cost
    Full operation of the SMA began in FY 2004. SAO contributes about $8M/year, which is in the form of support for 34 staff positions, $2.2M for direct operations, $2.0M for instrumentation, and $0.5M for renovation. ASIAA contributes about $1.4M/year. This budget also supports all the scientific staff associated with the project. 

II. Technical details

  1. Specifics of telescope/instrument
      Current capability2007 goal
    Antennas8 x 6 meter diameter + CSO & JCMT 
    Surface accuracy 12-24 12
    Pointing accuracy3" 1"
    slew rate 4 /sec  
    baselines 8 - 508 m 8 - 1000 m
    IF bandwidth 2 GHz  
    Highest spectral res 0.2 MHz  
    Fastest sampling2 sec 1 sec
    Data format MIR (OVRO)  
    Data processing MIRIAD, AIPS  
    1.3 mm band Current capability2007 goal
    Frequency coverage 175 - 255 GHz  
    Field of view 55"  
    max res0.4" 0.2"
    receiver (DSB) 70-90 K 70 K
    Sensitivity in 6 hrs (cont) 0.8 mJy 0.4 mJy
    Sensitivity in 6 hrs (1 km/s, 1" res)  2.0 1.0
    0.9 mm band Current capability2007 goal
    Frequency coverage 250 - 355 GHz  
    Field of view 36"  
    max res0.3" 0.15
    receiver (DSB) 80-150 K 80 K
    Sensitivity in 6 hours (cont) 2.0 mJy 1.0 mJy
    Sensitivity in 6 hrs (1 km/s, 1" res)  3.0 1.5
    0.45 mm GHz band Current capability2007 goal
    Frequency coverage 600-720 GHz  
    Field of view 18"  
    max res0.15" 0.07
    receiver (DSB) 300-600 K 300 K
    Sensitivity in 6 hours (cont) 20 mJy 10 mJy
    Sensitivity in 6 hrs (1 km/s, 1" res)  2.0 1.0

  2. New capabilities anticipated/planned in next 5-10 years

III. User profile

  1. % of "open skies" time
    About 10% of the SAO time is currently available to non-partner institutions. Fraction expected to increase as instrument becomes more user friendly.
  2. Institutional affiliations of users
    SAO/CfA, ASIAA, U Hawaii are partners.

  3. Student access, involvement, usage
    Graduate students have been involved in the testing, operating, and science programs of the SMA. Some technical development projects have been carried out by students.

IV. Science Overview

  1. Current forefront scientific programs

  2. Major discoveries (through 1999)
    New facility.

  3. Science highlights of last 5 years
    New facility.

  4. Main future science questions to be addressed
  1. Synergies with other major forefront facilities

  2. Unique contributions

V. Education/Outreach activities

  1. Visitor facility

  2. Student programs
    Smithsonian Predoctoral Fellowship. Available to students from any university who have completed pre-thesis requirements and wish to do their thesis work on the SMA with an SAO advisor. There are currently six students in this program, who are based in Hilo or Cambridge.

  3. Other (as apply)

VI. Documentation/website URLs

  1. URL of facility website"
  2. URL of EPO website
  3. URL(s) of any brief overviews of project/facility
  4. URL(s) of miscellaneous documentation" (SMA Observer Center - information for users)

This page created and maintained for the RMSPG by Martha Haynes
Last modified: Mon Feb 14 16:06:30 EST 2005 EST 2005 after review by Jim Moran.