Performance of FAST with an Ultra-Wide Bandwidth Receiver at 500-3300 MHz

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has been running for several years. A new ultra-wide bandwidth (UWB) receiver, simultaneously covering 500-3300 MHz, has been mounted in the FAST feed cabin and has passed a series of observational tests. The whole UWB band is separated into four independent bands. Each band has 1,048,576 channels in total, resulting in a spectral resolution of 1 kHz. At 500-3300 MHz, the antenna gain is around 14.3-7.7 K Jy(-1), the aperture efficiency is around 0.56-0.30, the system temperature is around 88-130 K, and the half-power beamwidth is around 7.6 '-1.6 '. The measured standard deviation of pointing accuracy is better than similar to 7.9 '' when zenith angle is within 26.4 degrees. The sensitivity and stability of the UWB receiver are confirmed to satisfy expectations through spectral observations, e.g., H i and OH. The FAST UWB receiver has already demonstrated good performance in capturing sensitive observations for various scientific goals.