The fundamental performance of FAST with 19-beam receiver at L band

Abstract

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) has passed national acceptance and finished one pilot cycle of ‘Shared-Risk’ observations. It will start formal operation soon. In this context, this paper describes testing results of key fundamental parameters for FAST, aiming to provide basic support for observation and data reduction of FAST for scientific researchers. The 19-beam receiver covering 1.05–1.45 GHz was utilized for most of these observations. The fluctuation in electronic gain of the system is better than 1% over 3.5 hours, enabling enough stability for observations. Pointing accuracy, aperture efficiency and system temperature are three key parameters for FAST. The measured standard deviation of pointing accuracy is 7.9″, which satisfies the initial design of FAST. When zenith angle is less than 26.4°, the aperture efficiency and system temperature around 1.4 GHz are ∼0.63 and less than 24 K for central beam, respectively. The sensitivity and stability of the 19-beam backend are confirmed to satisfy expectation by spectral Hi observations toward NGC 672 and polarization observations toward 3C 286. The performance allows FAST to take sensitive observations for various scientific goals, from studies of pulsars to galaxy evolution.

The atomic gas of star-forming galaxies atz∼ 0.05 as revealed by the Five-hundred-meter Aperture Spherical Radio Telescope

“…This work made use of the data from FAST (Five-hundred-meter Aperture Spherical radio Telescope). A noise diode is used for FAST signal calibration (Jiang et al 2020). When it is 'on', it injects a noise of known temperature to the receiver.…”

“…Our observations were carried out in the tracking mode, using only the central beam (M01). Details for the FAST technical performance can be found in Jiang et al (2020).…”

“…We use the flux from the OFF pointing to estimate the background, and thus the ON-OFF spectra is the flux from our target. We calibrate the flux by the noise diode with known antenna temperature that injected into the receiver during the observation (Jiang et al 2020). Details of the data reduction and calibration processes are briefly described in Appendix A.…”

Diverse polarization angle swings from a repeating fast radio burst source

“…All the 19 beams have an average full half-power beam width (HPBW) of 3 , and the beams were spaced by 5.74 in a cellular structure 27 . Because burst 5−the strongest one that we detected, with S/N = 155−was not detected in the six beams surrounding the central beam above the S/N threshold of 8, the angular distance of FRB 180301 from the centre of Beam 1 cannot be larger than ∼ 2.6 .…”

Multi-Scale Coherent Magnetic Field from Atomic Medium to L1544 Molecular Core

“…The already magnetically supercritical envelope can in principle go on to form dense cores without having to reduce its magnetic flux relative to mass further, as indicated by the comparable values of λ (∼ 3) for both the molecular envelope and core of L1544 (see Table 1). receiver 31 . The central beam has an average system temperature of 24 K, a main beam efficiency of 0.63, and a main beam diameter at the half-power point of 2.9' with a pointing accuracy of The data reduction including gain and phase calibrations of the two polarization paths, bandpass calibrations of the four correlated spectra, and polarization calibrations to generate Stokes I, Q, U, and V spectra was made with the IDL RHSTK package written by C. Heiles and T. Robishaw that is widely used for Arecibo and GBT polarization data.…”