We present a CCD-based photometric survey covering 870 arcmin^2 in a young stellar cluster around the young multiple star sigma Orionis. Our survey-limiting R, I, and Z magnitudes are 23.2, 21.8, and 21.0, respectively, the completeness being about 2.2 mag brighter. From our color-magnitude diagrams, we have selected 49 faint objects (I=15-21 mag)

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We propose and experimentally realize an algorithmic benchmark that demonstrates coherent control with a sequence of quantum operations that first generates and then decodes the cat state (|000...>+|111...>)/sqrt(2) to the standard initial state |000...>. This is the first high fidelity experimental quantum algorithm on the currently largest

We have observed the high excitation planetary nebulae NGC 7027, NGC 6543 and the low excitation planetaries Hu 2-1 and Cn 3-1 in the optical & near IR with the aim to contribute accurate measurements of their gaseous iron abundances. Use was made of multi-level atomic models of iron ions to interpret the observed forbidden lines of various iron

We propose spectroscopic observations of two new gravitational lens candidates, 0502+675 and 1440+122, discovered in our HST R-band snapshot survey of ~100 BL Lac objects. Each contains a double point source with separation of only 0.3 arcsec. In each case, a candidate for the lensing galaxy is also found. For 0502+675, a subsequent NICMOS H-band

En esta Tesis se analiza la estructura de una mancha solar tipica, redonda, aislada y situada cerca del centro del disco solar, para 25 capas en profundidad óptica. Los datos fueron obtenidos con el "Advanced Stokes Polarimeter", uno de los mejores instrumentos disponibles, y la estratificación de los diferentes parámetros a lo largo de la