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Register a new userThe Brazilian Tunable Filter Imager for the SOAR telescope
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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 SAMs 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.
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We described the design and operation principles of a new tunable-filter photometer developed for the 1-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences and the 2.5-m telescope of the Sternberg Astronomical Institute of the Moscow State University. The instrument is mounted on the scanning Fabry-Perot interferometer operating in the tunable-filter mode in the spectral range of 460-800 nm with a typical spectral resolution of about 1.3 nm. It allows one to create images of galactic and extragalactic nebulae in the emission lines having different excitation conditions and to carry out diagnostics of the gas ionization state. The main steps of observations, data calibration, and reduction are illustrated by examples of different emission-line objects: galactic HII regions, planetary nebulae, active galaxies with extended filaments, starburst galaxies, and Perseus galaxy cluster.
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