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The Tianlai cylinder array is a pathfinder for developing and testing 21cmintensity mapping techniques. In this paper, we use numerical simulation toassess how its measurement is affected by thermal noise and the errors incalibration and map-making process, and the error in the sky map reconstructedfrom a drift scan survey. Here we consider only the single frequency,unpolarized case. The beam is modelled by fitting to the electromagneticsimulation of the antenna, and the variations of the complex gains of the arrayelements are modelled by Gaussian processes. Mock visibility data is generatedand run through our data processing pipeline. We find that the accuracy of thecurrent calibration is limited primarily by the absolute calibration, where theerror comes mainly from the approximation of a single dominating point source.We then studied the $m$-mode map-making with the help of Moore-Penrose inverse.We find that discarding modes with singular values smaller than a thresholdcould generate visible artifacts in the map. The impacts of the residuevariation of the complex gain and thermal noise are also investigated. Thethermal noise in the map varies with latitude, being minimum at the latitudepassing through the zenith of the telescope. The angular power spectrum of thereconstructed map show that the current Tianlai cylinder pathfinder, which hasa shorter maximum baseline length in the North-South direction, can measuremodes up to $l \lesssim 2\pi b_{\rm NS}/\lambda \sim 200$ very well, but wouldlose a significant fraction of higher angular modes when noise is present.These results help us to identify the main limiting factors in our currentarray configuration and data analysis procedure, and suggest that theperformance can be improved by reconfiguration of the array feed positions.

A simulation of calibration and map-making errors of the Tianlai cylinder pathfinder array