Fiber-fed echelle spectrometer of the 2.34 meter Vainu Bappu Telescope

Abstract

The optical design and performance of high resolution fiber-fed echelle spectrometer for the 2.34 meter Vainu Bappu Telescope (VBT) is described. An optical fiber of core 100 J-Lm and length 45 meter is used to link the spectrometer with the telescope. The instrument provides a resolving power of 72,000 (4 Km/s) with a 60 J-Lm slit and provides continuous coverage with gaps for ). < 1 J-Lm. The spectrum is recorded on a thinned back-illuminated Marconi 2048 x 4096, 15 J-Lm square pixel, charge coupled device (CCD) detector. The wavelength coverage in a single order varies from roughly 35Aat ,\ = 4050A(range 4030A- 4065A) to 70A(range 8465A- 8535A).The present overall efficiency of the spectrometer at 6000Ais about 10%. The operation of the spectrometer and object acquisition and guiding at the telescope end is described. Some of the observed spectra from VBT are also illustrated.