TFOSC is a direct imaging and a low-medium resolution spectrometer. Its optical design is similar to the FOSC series ( see http://www.astro.ku.dk/~per/ ) but it has been modified and optimised by TUG for the 1.5-m telescope. It will also have a calibration unit (CALU). (See the attached drawing for the positioning at the cassegrain focus, but, however, the relative placement has been changed slightly since this drawing was made). TFOSC's mechanical design is almost complete. The calibration unit is being designed.
TFOSC specifications (preliminary):
- Wavelength range: 330-1000 nm ( Grism No.s: 7, 8, 9, 10, 12, 14, 15, 17) (http://www.astro.ku.dk/~per/ for the transmission curves)
- Focal reduction: 0.58
- Field of view: 13'.6 x 13'.6
- Angular resolution : 0".8 ( sampling of 0".41/(15 micrometers) at F/7.7
- Resolution: R ~ 200-4000 (using a set of normal and echelle grisms).
- The aperture wheel, the filter wheel and the grism wheel will have 8 positions. The filter wheel will house filters with a diameter up to 60mm.
- A set of 12 filter holders, up to 11 grism holders, and 7 long and 4 short (echelle) slits.
- The following remotely controlled functions are supported:
- positioning of the aperture wheel;
- positioning of the filter wheel;
- positioning of the grism wheel;
- shutter control
- instrumental focus
CALU specifications (preliminary)::
Preliminary data of the CCD detector:
- CALU is a filter and calibration unit to be mounted between the telescope and the TFOSC
- The unit consists of 2 filter wheels with 5 positions each, housing filters with a diameter up to 90mm diameter,
- 4 spectral lamps: one hollow cathode (Fe/Ar or Cu/Ar), two Osram spectral lamps (He and Ne) and one halogen lamp; all lamps with associated power supplies.
- A set of 10 filter holders
- The following remotely controlled functions are supported :
- positioning of the two filter wheels;
- positioning of the relay optics;
- control of the power supplies for the 4 spectral lamps.
CCD - Fairchild CCD447 # of pixels ( 2048 x 2048 ) 4194304 pixel Pixel size 15 microns 0.39 arcsec/pixel FOV 13.3 arcmin