O some instruments invented by him
O sopro do magnetar
O star giant bubbles in M33
O Stars and OB Associations Observed from EINSTEIN.
O stars and supergiants south of declination -53.0 .
O stars and the interstellar medium
O Stars as a Probe of Gas Densities in the Low-Density Interstellar Medium
O Stars as Probes of the Interstellar Medium
O stars effective temperature and HII regions ionization parameter gradients in the Galaxy
O stars He II and H lines in the 1 micron region
O Stars in Transition. I. Optical Spectroscopy of Ofpe/WN9 and Related Stars
O Stars in Transition. II. Fundamental Properties and Evolutionary Status of Ofpe/WN9 Stars from Hubble Space Telescope Ultraviolet Observations
O stars with weak winds: the Galactic case
O Stars, WR Stars, and Emission-Line Central Stars of Planetary Nebulae.
O telescópio remoto do Observatório Abrahão de Moraes - Obelix
O terrestrial refractions
O the adoption of a standard of optical power
O the appearance of stars on the moon's disc
O the application of a camera lucida to a telescope
O the approaching return of Halley's comet