We report the results from recent observations of Sgr A* at short-/submillimeter wavelengths made with the partially finished Sub-Millimeter Array (SMA) on Mauna Kea. A total of 25 epochs of observations were carried out over the past 15 months in 2001 March to 2002 May. Noticeable variations in flux density at 1.3 mm were observed showing three “flares”. The SMA observations suggest that Sgr A...

Models for spatial autocorrelation and cross-correlation depend on the distance and direction separating two locations, and are constrained so that for all possible sets of locations, the covariance matrices implied from the models remain nonnegative-definite. Based on spatial correlation, optimal linear predictors can be constructed that yield complete maps of spatial fields from incomplete an...

It is known that the dependence of the emission-line luminosity of a typical cloud in the AGN broad-line regions upon the incident flux of ionizing continuum can be nonlinear. We study how this nonlinearity should be taken into account in estimating the size of the BLR by means of the “reverberation” methods. We show that the BLR size estimates obtained by cross-correlation of emission-line and...

We report the results from recent observations of Sgr A* at short-/submillimeter wavelengths made with the partially finished Sub-Millimeter Array (SMA) on Mauna Kea. A total of 25 epochs of observations were carried out over the past 15 months in 2001 March to 2002 May. Noticeable variations in flux density at 1.3 mm were observed showing three “flares”. The SMA observations suggest that Sgr A...

We present the results of optical and infrared photometry of the quiescent X-ray transient V404 Cyg during the period 1992–2003. The ellipsoidal modulations extracted from the most complete databases (years 1992, 1998 and 2001) show unequal maxima and minima with relative strength varying from year to year although their peak to peak amplitudes remain roughly constant at 0.24±0.01 magnitudes. F...

We propose observations of the molecular gas distribution during the era of reionization. At z ∼ 6 to 8, 12CO(J = 1 − 0) line intensity results in a mean brightness temperature of about 0.5 μK with rms fluctuations of 0.1 μK at 1 to 10 Mpc spatial scales, corresponding to 30 arcminute angular scales. This intensity fluctuations can be mapped with an interferometer, similar to existing and plann...