Wen-Tse Chien (ASIAA); Geoffrey Bower (ASIAA); Kai-Yang Lin (ASIAA)
Yuan-Tseh Lee Array (YTLA) observes the 3D power spectrum of molecular gas (CO) by the intensity mapping. Although the requirement of the spectral resolution is about 50MHz, the instrument has a higher resolution at 2MHz. YTLA is good at continuum level observation; however, it lacked the experience in molecular line observation. Molecular lines are important tracers for interstellar medium and star formation. To test and improve the line observation, we observed N2H+ J=1-0 in four high-mass star-forming regions in the Milky Way. To decrease the thermal noise of the deep integration, we maintained a fixed u-v pattern during observations. Nevertheless, the strategy caused a larger pointing offset (1.67 arcmins in average). We considered the primary beam attenuation and did the correction. The improvement of our correction for the flux loss is up to 27.1%. On the other hand, YTLA's deformation by gravity causes the phase error in baselines. The estimation of the loss by the phase error is 15.3%. Besides, YTLA's line observation error is two times larger than the thermal noise. There are other unknown system uncertainties in line observation. The uncertainties caused an extra 22.7% error. For YTLA's line observation, we need more verification and change the observing strategy in the future.