Radial velocity measurements were taken of a group of Ap stars using an improved FP-ISOS. Observations were made using the 1.5m TCS on Tenerife in May 1987 and December 1987. The already known rapidly oscillating Ap stars 33 Lib and HR1217 were observed in order to search for radial velocity variations corresponding to the photometric periods found

The Global Oscillation Network Group (GONG) project is planning to place six observing stations around the world to observe the solar oscillations as continuously as possible. This paper describes the procedures that are being used to select the six sites. The latest results of measurements of cloud cover obtained by networks of 6 (out of 10)

The abundance gradient in M 33 is studied on the basis of IPCS and CCD data on emission lines in selected H II regions, using O II, O III, S II, and S III in the wavelength range 3700-9600 A to refine the oxygen abundances in the inner parts as well as to study the behavior of S/O. Spatially resolved observations in each H II region permit the

Frequency differences between high-order p-modes of two stellar models, both with the mass and luminosity of the sun, are compared with results of asymptotic theory. The computed relative differences are closely approximated by averages of the relative sound-speed differences, weighted by the local sound travel-time, over the regions where the

Since 1984 the measurements of a quadruple photometer sited at the Observatorio del Teide (Izana, Tenerife) made it possible to identify the p-mode luminosity spectrum with simultaneous velocity observations. Comparing this data, the adiabatic behavior of solar atmosphere and theoretical expectations from solar models were tested. In order to

Low degree l=0-2 solar p-modes were detected with the SLOT instruments at Izana and Baja California. The main source of noise for these ground based observations is in the terrestrial atmosphere. However, the data acquisition system still has to have very low intrinsic noise. It is shown how this is achieved in the SLOT instruments. Design and