3.2 Spectroscopy

Spectroscopy is one of the main tools of modern astrophysics. Almost all we know about the physical properties of astrophysical objects comes from the analysis of their spectra. Studying starspots requires high-resolution spectrographs ( $Dc/c > 50 000$ ) with high-sensitivity detectors which have become available for the past two decades at mid and large aperture telescopes. Among $8 -10 m$ telescopes it is worth tomention UVES at VLT, HIRES at KECK, HRS at the Hobby-Eberly Telescope (HET), and HDS at Subaru. In addition, there are about $10$ high-resolution spectrographs on $4 m$ class telescopes and even more on $2 m$ class telescopes. Most of them are echelle cross-dispersed spectrographs allowing for a wide wavelength range in the optics. A recent overview of the currently available high-resolution spectrographs and future projects was given by Pallavicini (2002 ).

A study of starspots involves routine monitoring and data collection for a relatively large sample of stars. A great help comes from using robotic telescopes. The first dedicated robotic telescope T-13 was developed at the Tennessee State University and has started its operation in 2003 at the Fairborn observatory, Arizona (http://schwab.tsuniv.edu/t13/description.html). It is a $2 m$ telescope with a spectrograph working at two resolutions, 34 000 and 90 000, and full wavelength coverage in the optical. The second spectroscopic robotic telescope STELLA I of $1.2 m$ is being built by AIP and IAC. It is expected to start operation in 2006 on Tenerife and will be equipped with echelle spectrograph of maximum 50 000 resolution (http://www.aip.de/stella/). The two telescopes are planned to be complementary in studying starspots, as they are separated by about $o 95$ in longitude and, thus, will allow prolonging an observing night by $6 h$ .