5 Conclusions

The algorithms described in this paper have proved very successful at producing high quality images for the Canadian Galactic Plane Survey. The MODCAL method has been especially useful in removing the effects of strong sources such as Cyg A from many fields. Further, the results presented in Sect. 4.4 and in Sect. 4.5 showed that it is effective at removing many artifacts of unknown origin from ST images. It is not, however, a panacea for all system problems. In both Fig. 8 and Fig. 13 faint residual spokes remain centred on the position of Cyg A. Although there is a suspicion that these spokes are due to antenna pointing errors, efforts to find an effective procedure to remove them have been unsuccessful to date.

Continued improvement in the dynamic range of the telescope should be possible by further incorporation of measured instrumental characteristics, such as the bandpass shapes mentioned in Sect. 4.2, into the procedures for computing model visibilities and correction factors.

Acknowledgements

I thank Lloyd Higgs for suggesting the adoption of the MODCAL algorithm for use with seven-antenna ST data. S. Dougherty functioned as chief tester of many of the routines described here while he reduced CGPS data. The referee, J. Hamaker, proposed numerous improvements to the presentation of the paper. The DRAO Synthesis Telescope is operated as a national facility by the National Research Council of Canada.