Introduction

In Miriad a model of gains to the visibility data can be described as

$$g(t)g(\nu){\rm exp}\left[i2\pi\tau(t)(\nu-\nu_0)\right]$$

where $g(t)$ is a time variable complex number (or called antenna gain), $g(\nu)$ is the bandpass function, $\nu$ is frequency and $\tau$ is a time-varying delay term.

There are different approaches in solving for gains depending on the requirements by individual programs. In this Chapter, a general approach in the gain calibrations is given. In addition, strategies in calibrations for different science projects are being considered and are (will be) supported by the SMA software group.