The mission of the ATST visible spectro-polarimeter (ViSP) is to provide precision measurements of the full state of polarization (Stokes parameters) simultaneously at diverse wavelengths in the visible spectrum and fully resolve (or nearly so) the profiles of spectrum lines originating in the solar atmosphere. We present the instrument science

The SW Sextantis stars are nova-like cataclysmic variables (CVs) which exhibit intricate behaviour which is still a matter of debate. For years the common belief has been that these systems were the "outlaws" of the CVs, mainly because of the lack of an overall understanding. We are now realizing that a large percentage (˜ 30%) of all nova-likes in

The telescope structure including control system and the complete retractable dome of the new 1.5 m solar telescope GREGOR were assembled during 2004 at Izana on Tenerife, Spain. The GREGOR telescope is build by a consortium of the Kiepenheuer Institut fuer Sonnenphysik, the Astrophysikalische Institut Potsdam, the Institut fuer Astrophysik

In the framework of the Local Group Census (LGC), a survey of the Local Group (LG) galaxies above Dec =-30° aimed at surveying the populations that have strong emission lines, we have searched for planetary nebulae (PNe) in the low-metallicity dwarf irregular galaxies IC 1613, WLM, GR 8. Two new candidate PNe have been found in IC 1613, one in WLM

Comparison of recent spectra by V. Motta et al. (V. Motta et al.: Astrophys. J. 574, 719 725) of two images of a distant gravitationally lensed quasar (z = 1.38) leads to an extinction curve of the lens galaxy (z = 0.83) showing clear evidence of a 2175A absorption feature. We compare these data with measured extinction curves from the Galaxy, LMC

We explore the imprint of the cosmological hydrogen recombination lines on the power spectrum of the cosmic microwave background (CMB). In particular, we focus on the three strongest lines for the Balmer, Paschen and Brackett series of hydrogen. We expect changes in the angular power spectrum due to these lines of about 0.3 μK for the Hα line