A scientific and engineering team led by the Department of Astronomy of the IAG, at the
University of São Paulo, is engaged in the development of a highly versatile, new
technology, optical imaging interferometer to be used both in seeing-limited mode and at
high spatial resolution using the SOAR Adaptive Optics Module (SAM: the GLAO
facility for the SOAR telescope). Such an instrument opens up important new science
capabilities for the SOAR astronomical community: from studies of nearby galaxies and
the ISM to statistical cosmological investigations.
The Brazilian Tunable Filter Imager (BTFI) concept takes advantage of two new
technologies that have been successfully demonstrated in the laboratory environment but
have yet to be deployed in any astronomical instrument. The iBTF (imaging Bragg
Tunable Filter) concept utilizes a Volume Phase Holographic Grating in double-pass
configuration (Blais-Ouellette et al. 20061) while the new Fabry-Perot concept involves
the use of commercially available technology allowing a single etalon to act over a very
large range of interference orders. Both technologies will be used in the same instrument.
The combination allows for highly versatile capabilities. Spectral resolutions spanning
the full range between 5 and 35,000 can be achieved in the same instrument through the
use of iBTF at low resolution and scanning Fabry-Perots beyond R ~2,000 with some
overlap in the mid-range.
The instrument is being developed in collaboration with several other Brazilian
Institutions (Poli/USP, INPE, LNA and Unipampa) and international collaborations with the Laboratoire d'Astrophysique de Marseille and the University of Montreal. The reader
is directed to the URL http://www.astro.iag.usp.br/~btfi/index.php for a full
representation of the project and its current status. The instrument should see first light,
mounted on the SOAR telescope, as a visiting instrument, on semester 2010B.