3 research outputs found
The Brazilian Tunable Filter Imager for the SOAR telescope
This paper presents a new Tunable Filter Instrument for the SOAR telescope.
The Brazilian Tunable Filter Imager (BTFI) is a versatile, new technology,
tunable optical imager to be used in seeing-limited mode and at higher spatial
fidelity using the SAM Ground-Layer Adaptive Optics facility at the SOAR
telescope. The instrument opens important new science capabilities for the SOAR
community, from studies of the centers of nearby galaxies and the insterstellar
medium to statistical cosmological investigations. The BTFI takes advantage of
three new technologies. The imaging Bragg Tunable Filter concept utilizes
Volume Phase Holographic Gratings in a double-pass configuration, as a tunable
filter, while a new Fabry-Perot (FP) concept involves technologies which allow
a single FP etalon to act over a large range of interference orders and
spectral resolutions. Both technologies will be in the same instrument.
Spectral resolutions spanning the range between 25 and 30,000 can be achieved
through the use of iBTF at low resolution and scanning FPs beyond R ~2,000. The
third new technologies in BTFI is the use of EMCCDs for rapid and cyclically
wavelength scanning thus mitigating the damaging effect of atmospheric
variability through data acquisition. An additional important feature of the
instrument is that it has two optical channels which allow for the simultaneous
recording of the narrow-band, filtered image with the remaining (complementary)
broad-band light. This avoids the uncertainties inherent in tunable filter
imaging using a single detector. The system was designed to supply tunable
filter imaging with a field-of-view of 3 arcmin on a side, sampled at 0.12" for
direct Nasmyth seeing-limited area spectroscopy and for SAM's visitor
instrument port for GLAO-fed area spectroscopy. The instrument has seen first
light, as a SOAR visitor instrument. It is now in comissioning phase.Comment: accepted in PAS
The BINGO project - II. Instrument description
International audienceContext. The measurement of diffuse 21-cm radiation from the hyperfine transition of neutral hydrogen (H I 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 H I signal, in the redshift interval 0.127 ≤ z ≤ 0.449.Aims. This paper describes the BINGO radio telescope, including the current status of the optics, receiver, observational strategy, calibration, and the site.Methods. 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 ≤ ν ≤ 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 ∼13% of the sky, with the primary mirror pointing at declination δ = −15°. The telescope will see an instantaneous declination strip of 14.75°.Results. 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 μK per 9.33 MHz frequency channel, one polarization, and be able to measure the H I power spectrum in a competitive time frame.Key words: instrumentation: detectors / methods: observationa