Abstract
The 10% amplitude calibration accuracy achievable with the current standard calibration techniques may be sufficient to produce images with dynamic range of less than or equal to 10³, but achieving a dynamic range of 10⁴or higher with the MMA requires better than 1 percent accuracy in amplitude calibration. A self-calibration technique may be applied to improve images, but it may not be possible in all cases. Therefore, an emphasis is given to achieving accurate initial calibration. Multi-transition spectroscopic studies and multi-array synthesis also require high accuracy in absolute sense as well.

The conventional ``chopper wheel" and a two temperature load method for amplitude and flux calibrations are examined. The two temperature load calibration offers a potential to achieve the 1% accuracy in amplitude and flux calibration, but it is technically challenging. In comparison, the chopper wheel gain calibration and astronomical flux calibration cannot provide better than 5% accuracy. Whether the more complex two temperature load system is justifiable for the MMA may ultimately dependent on how well the radiometric phase correction will work. Several other relevant issues including establishment of astronomical flux standards are discussed, and engineering goals are identified.

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