Line-of-sight velocity fields in an irregular sunspot (NOAA 8990) have been determined from Stokes-I spectra of the line Fe I 630.15 nm, obtained with the La Palma Stokes Polarimeter at the Swedish Vacuum Solar Telescope on May 13, 2000. We show and discuss the resulting velocity maps, the dependence of velocities on the continuum intensities, and

Time series of two-dimensional spectra were taken with the Göttingen 2D spectrometer at the VTT on Tenerife in 1996. They were investigated for Doppler velocities and velocity oscillations in small spots and pores of rapidly evolving sunspot groups. For the present measurements the magnetically insensitive lines Fe i 557.6 nm and Fe i 709.0 nm were

The transit of Venus in 2004 offered the rare possibility to remotely sense a well-known planetary atmosphere using ground-based absorption spectroscopy. Transmission spectra of Venus' atmosphere were obtained in the near infrared using the Vacuum Tower Telescope (VTT) in Tenerife. Since the instrument was designed to measure the very bright

We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample

We present the statistical results of the monitoring of the optical turbulence profiles at the Roque de los Muchachos (ORM) and Teide observatories (OT), Spain. The data has been obtained using the Generalized-SCIDAR technique at the 1m Jacobous Kaptein telescope at the ORM and 1.5m Carlos Sánchez telescope at the OT. Statistical profiles are based

M87 is the only known nonblazar radio galaxy to emit very high energy (VHE) gamma rays. During a monitoring program of M87, a rapid flare in VHE gamma-rays was detected by the MAGIC telescope in early 2008. The flux was found to be variable above 350 GeV on a timescale as short as 1 day at a significance level of 5.6 σ. The highest measured flux