The BINGO Project II: Instrument Description
  The measurement of diffuse 21-cm radiation from the hyperfine transition of
neutral hydrogen (HI signal) in different redshifts is an important tool for
modern cosmology. However, detecting this faint signal with non-cryogenic
receivers in single-dish telescopes is a challenging task. The BINGO (Baryon
Acoustic Oscillations from Integrated Neutral Gas Observations) radio telescope
is an instrument designed to detect baryonic acoustic oscillations (BAOs) in
the cosmological HI signal, in the redshift interval $0.127 \le z \le 0.449$.
This paper describes the BINGO radio telescope, including the current status of
the optics, receiver, observational strategy, calibration, and the site. BINGO
has been carefully designed to minimize systematics, being a transit instrument
with no moving dishes and 28 horns operating in the frequency range $980 \le
\nu \le 1260$ MHz. Comprehensive laboratory tests were conducted for many of
the BINGO subsystems and the prototypes of the receiver chain, horn, polarizer,
magic tees, and transitions have been successfully tested between 2018 - 2020.
The survey was designed to cover $\sim 13\%$ of the sky, with the primary
mirror pointing at declination $\delta=-15^{\circ}$. The telescope will see an
instantaneous declination strip of $14.75^{\circ}$. The results of the
prototype tests closely meet those obtained during the modeling process,
suggesting BINGO will perform according to our expectations. After one year of
observations with a $60\%$ duty cycle and 28 horns, BINGO should achieve an
expected sensitivity of 102 $\mu K$ per 9.33 MHz frequency channel, one
polarization, and be able to measure the HI power spectrum in a competitive
time frame.
