smamfcal %inp Task: smamfcal vis = gc_rx1.lsb.tsys select = source(nra*) % select nrao530 flux = 2 % flux density assumed refant = 3 % reference antenna interval = 1 % solution interval weight = 1 % weight by 1/sigma**2 options = nopassol % not solve for bandpassThe solutions of antenna gains can be inspected with smagpplt. A setup for smagpplt is shown below. There may be a few bad points in the gain solutions. One may need to go back to smablflag to do further data flagging. Or, one can use gplist and gpedit to reset bad point to (amp,phase)=(1,0). Alternatively, smagpplt provides a nice feature for smoothing or polynomial fitting to the antenna gains. An intermediate order of polynomial function may be useful to fit the gain solutions in order to reduce the noise in the gains. Figs. 3.3 and 3.4 show the plots of antenna-based gain solutions (red points) in real and imaginary fit with the 5th order polynomial curves (blue). One can replace the original gain solutions with the polynomial fit by adding opolyfit to options or options = gains,opolyfit. Note that in this observation, antenna 2 showed odd values of the gain solutions in comparison with other antennas. The problematic antenna may contaminate the data. The antenna 2 has been flagged out. One may get rid of the data related to problematic antennas prior to further data processing. In most cases, the data from low S/N antennas will mar the quality of images. If the baseline coverage is not a concern, it would be wise to remove the bad quality data immediately.
smagpplt% inp Task: smagpplt vis = gc_rx1.lsb.tsys device = /xs yaxis = real,imag options = gains,opolyfit polyfit = 5 nxy = 2,4