The atmospheres of planets orbiting other stars may be studied by the technique of transit spectroscopy. This technique needs a very high SNR, so large space telescopes are needed, and bright target stars must be found. This paper uses planetary atmosphere models to discuss the SNR performance required to achieve specific science goals for both

The location of the Advanced Technology Solar Telescope (ATST) is a critical factor in the overall performance of the telescope. We have developed a set of instrumentation to measure daytime seeing, sky brightness, cloud cover, water vapor, dust levels, and weather. The instruments have been located at six sites for periods of one to two years

We present an INTEGRAL data analysis of the X-ray transient SAX J2103.5+4545 during December 2002. The source showed two type-I outbursts in this period. The INTEGRAL location agrees with the position of the recently proposed optical counterpart. A power-law model was fitted to the 10 100 keV spectrum and a photon index of 2.5±0.1 was derived. The

We present observational evidence, from Hαin face-on galaxies, which strongly favours the hypothesis that escaping photons from H II regions are the basic cause of the ionization of the diffuse ionized gas in galaxy discs, and by implication are the chief cause of the Reynolds layer in the Milky Way, and refer the reader to models based on these

The enhancement factor to the thermonuclear reaction rate in the center of the Sun is calculated using the Feynman-Kac path integral of the grand-canonical partition function. Using the generalized virial expansion for a multicomponent quantum plasma, we have calculated the truncated pair distribution function for solar conditions up to the order

We introduce a new scheme to study the nature of the central engine in a lensed QSO. The compact emission regions could have different sizes in different optical wavelengths, and our framework permits us to obtain the source size ratios when a microlensing special high-magnification event (e.g., a caustic crossing event, a two-dimensional maximum