Observational Constraints on the Nature of the First Stars: From Nucleosynthesis to Reionization

Observational Constraints on the Number, Albedos, Sizes, and Impact Hazards of the Near-Earth Asteroids

Observational Constraints on Theories of Planet Migration and Dynamical Evolution

Observational Constraints on Theories of Planet Migration and Dynamical Evolution

Observational differences between Swift GRB classes

Observational evidence for the scattering properties of interplanetary and cometary dust clouds: an update.

Observational evidence of sudden stratospheric warming effects on the equatorial ionospheric electric fields

Observational facts in revealing a close relation between acoustic-gravity waves and midlatitude spread F

Observational limitations of the Doppler theory of quasars

Observational Model of the Ionized Gas in Seyfert and Radio-Galaxy Nuclei

Observational problems in determining the ages of open clusters

Observational signs of planet infall and Roche lobe overflow outward migration

Observational speckle interferometry

Observational studies of Cepheids. IV - The Feinheit functions

Observational studies of Cepheids. V - Radial velocities of bright Cepheids

Observational studies of Cepheids. VI - Period-radius relations

Observational Studies of Galaxies

Observational studies of the solar general circulation

Observational tests for stellar evolution and pulsation theory. I - The globular clusters M 4 and M 15

Observations and analysis of CF TUC