We model the correlated X-ray – UV observations of NGC 7469, for which well sampled data in both these bands have been obtained recently in a multiwavelength monitoring campaign. To this end we derive the transfer function in wavelength λ and time lag τ , for reprocessing hard (X-ray) photons from a point source to softer ones (UV-optical) by an infinite plane (representing a cool, thin accreti...

We present an analysis of high quality spectra of members of the young cluster M35. By using a multi-fiber spectrograph, we are able to collect high signal–to–noise, high resolution spectra of a sample of photometric candidate members. Accurate radial velocities are used to establish the membership status and rotational velocities are measured using cross-correlation. We also derive the metal c...

The search for expanding supershells in nearby galaxies has been the focus of substantial observational effort since the discovery of huge HI bubbles in the Magellanic clouds. Until recently, studies of this nature were limited: initially due to the lack of detailed models describing the predicted appearance of supershells, subsequently because it is challenging to quantify the similarity of mo...

Emission-line regions in active galactic nuclei (AGNs) and other photoionized nebulae should become larger in size when the ionizing luminosity increases. This ‘breathing’ effect is observed for the Hβ emission in NGC 5548 by using Hβ and optical continuum light curves from the 13-yr (1989–2001) AGN Watch monitoring campaign. To model the breathing, we use two methods to fit the observed light ...

Aims. We seek to provide 2MASS and OGLE identifications and coordinates for all stars in the finding chart published by Arp (1965, ApJ, 141, 43). This chart covers the low extinction area around NGC 6522, also known as Baade’s window, at coordinates (l, b) = (1.02,−3.92). Methods. A cross correlation, using numerical techniques, was performed between a scan of the original finding chart from Ar...

We present the results of an intensive ground-based spectrophotometric monitoring campaign of the Seyfert galaxy NGC 4151 for a period of over two months, with a typical temporal resolution of one day. Light curves for four optical continuum bands and the Hα and Hβ emission lines are given. During the monitoring period, the continuum at 6925 Å varied by ∼17% while the continuum at 4600 Å varied...

A new type of a linear decorrelating receiver, named Pseudo-Decorrelator, for asynchronous code division multiple access systems over a Rayleigh fading multipath channel is presented in this paper. Starting with the analyis of the multiple access components of the decision statistics, the outputs of a bank of matched filters, the (K × 3K) cross-correlation matrix for each bit is obtained. The n...

We analyse 15 XMM–Newton observations of the Seyfert galaxy NGC 4051 obtained over 45 d to determine the ultraviolet (UV) light curve variability characteristics and search for correlated UV/X-ray emission. The UV light curve shows variability on all time-scales, however with lower fractional rms than the 0.2–10 keV X-rays. On days–weeks time-scales the fractional variability of the UV is Fvar ...

We present velocity dispersion measurements of 14 globular clusters in NGC 5128 (Centarus A) obtained with the MIKE echelle spectrograph on the 6.5m Magellan Clay telescope. These clusters are among the most luminous globular clusters in NGC 5128 and have velocity dispersions comparable to the most massive clusters known in the Local Group, ranging from 10 – 30 km s−1. We describe in detail our...

We present velocity dispersion measurements of 14 globular clusters in NGC 5128 (Centarus A) obtained with the MIKE echelle spectrograph on the 6.5m Magellan Clay telescope. These clusters are among the most luminous globular clusters in NGC 5128 and have velocity dispersions comparable to the most massive clusters known in the Local Group, ranging from 10 – 30 km s−1. We describe in detail our...