Andrew Ranson: Seventeenth Century Pirate?

The later half of the seventeenth century saw the swashbuckling heyday of piracy in the West Indies. Here, English, French, and Dutch buccaneers, and audacious seafarers claiming no nation, roamed the seas almost at will, delighting particularly in preying on galleons flying the Spanish flag and in sacking and ransoming cities along the Spanish Main. It is true that the policy of European nations was changing from encouraging or winking at buccaneer activities to supporting legitimate trade with Spanish America, and some serious efforts were made to curb these seagoing marauders. Nevertheless, this was of little consolation to the inhabitants of Panama, which was ravished by the Englishman Henry Morgan in 1671, or to those of Maracaibo, which was destroyed by the Dutchman l’Olonnais in 1667, or to those of Vera Cruz, which was surprised by the Frenchman the Sieur de Grammont in 1683. In this same period similar fates befell many other cities, and their hapless residents endured unspeakable indignities

Lord Dunmore\u27s Loyalist Asylum in the Floridas

To the astonishment of many, Lord John Murray, fourth Earl of Dunmore, member of the House of Lords, formerly controversial colonial governor of New York and Virginia, became governor of the Bahama Islands in 1787. Immediately eyebrows were lifted and questions raised as to why the Earl had accepted the apparently insignificant governorship of islands whose total population, black and white, was not appreciably greater than that of Williamsburg when the colonial assembly had been in session. Dunmore had returned to America late in 1781 and had expected to resume his role as the Virginia governor in the wake of Cornwallis’ victories; but the defeat at Yorktown was responsible for his arriving at British-occupied Charleston rather than the governor’s palace at Williamsburg. Examining Dunmore’s post-1781 career helps explain what eventually drew him to the Bahamas and also clarifies British policy toward the Floridas, Louisiana, and the entire Mississippi Valley in the 1782-1783 Paris peace negotiations

1.4 GHz polarimetric observations of the two fields imaged by the DASI experiment

We present results of polarization observations at 1.4 GHz of the two fields imaged by the DASI experiment ($\alpha = 23^{\rm h} 30^{\rm m}$, $\delta = -55^{\circ}$ and $\alpha = 00^{\rm h} 30^{\rm m}$, $\delta = -55^{\circ}$, respectively). Data were taken with the Australia Telescope Compact Array with 3.4 arcmin resolution and $\sim 0.18$ mJy beam$^{-1}$ sensitivity. The emission is dominated by point sources and we do not find evidence for diffuse synchrotron radiation even after source subtraction. This allows to estimate an upper limit of the diffuse polarized emission. The extrapolation to 30 GHz suggests that the synchrotron radiation is lower than the polarized signal measured by the DASI experiment by at least 2 orders of magnitude. This further supports the conclusions drawn by the DASI team itself about the negligible Galactic foreground contamination in their data set, improving by a factor $\sim 5$ the upper limit estimated by Leitch et al. (2005). The dominant point source emission allows us to estimate the contamination of the CMB by extragalactic foregrounds. We computed the power spectrum of their contribution and its extrapolation to 30 GHz provides a framework where the CMB signal should dominate. However, our results do not match the conclusions of the DASI team about the negligibility of point source contamination, suggesting to take into account a source subtraction from the DASI data.Comment: 7 pages, six figures, submitted to MNRA

Atmospheric phase correction using CARMA-PACS: high angular resolution observations of the FU Orionis star PP 13S*

We present 0".15 resolution observations of the 227 GHz continuum emission from the circumstellar disk around the FU Orionis star PP 13S*. The data were obtained with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) Paired Antenna Calibration System (C-PACS), which measures and corrects the atmospheric delay fluctuations on the longest baselines of the array in order to improve the sensitivity and angular resolution of the observations. A description of the C-PACS technique and the data reduction procedures are presented. C-PACS was applied to CARMA observations of PP 13S*, which led to a factor of 1.6 increase in the observed peak flux of the source, a 36% reduction in the noise of the image, and a 52% decrease in the measured size of the source major axis. The calibrated complex visibilities were fitted with a theoretical disk model to constrain the disk surface density. The total disk mass from the best-fit model corresponds to 0.06 M_⊙, which is larger than the median mass of a disk around a classical T Tauri star. The disk is optically thick at a wavelength of 1.3 mm for orbital radii less than 48 AU. At larger radii, the inferred surface density of the PP 13S* disk is an order of magnitude lower than that needed to develop a gravitational instability

Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Angular Power Spectra

We present the temperature and polarization angular power spectra of the cosmic microwave background (CMB) derived from the first 5 years of WMAP data. The 5-year temperature (TT) spectrum is cosmic variance limited up to multipole l=530, and individual l-modes have S/N>1 for l<920. The best fitting six-parameter LambdaCDM model has a reduced chi^2 for l=33-1000 of chi^2/nu=1.06, with a probability to exceed of 9.3%. There is now significantly improved data near the third peak which leads to improved cosmological constraints. The temperature-polarization correlation (TE) is seen with high significance. After accounting for foreground emission, the low-l reionization feature in the EE power spectrum is preferred by \Delta\chi^2=19.6 for optical depth tau=0.089 by the EE data alone, and is now largely cosmic variance limited for l=2-6. There is no evidence for cosmic signal in the BB, TB, or EB spectra after accounting for foreground emission. We find that, when averaged over l=2-6, l(l+1)C^{BB}_l/2\pi < 0.15 uK^2 (95% CL).Comment: 29 pages, 13 figures, accepted by ApJ

Instrumental and Analytic Methods for Bolometric Polarimetry

We discuss instrumental and analytic methods that have been developed for the first generation of bolometric cosmic microwave background (CMB) polarimeters. The design, characterization, and analysis of data obtained using Polarization Sensitive Bolometers (PSBs) are described in detail. This is followed by a brief study of the effect of various polarization modulation techniques on the recovery of sky polarization from scanning polarimeter data. Having been successfully implemented on the sub-orbital Boomerang experiment, PSBs are currently operational in two terrestrial CMB polarization experiments (QUaD and the Robinson Telescope). We investigate two approaches to the analysis of data from these experiments, using realistic simulations of time ordered data to illustrate the impact of instrumental effects on the fidelity of the recovered polarization signal. We find that the analysis of difference time streams takes full advantage of the high degree of common mode rejection afforded by the PSB design. In addition to the observational efforts currently underway, this discussion is directly applicable to the PSBs that constitute the polarized capability of the Planck HFI instrument.Comment: 23 pages, 11 figures. for submission to A&

Status of CMB Polarization Measurements from DASI and Other Experiments

We review the current status and future plans for polarization measurements of the cosmic microwave background radiation, as well as the cosmology these measurements will address. After a long period of increasingly sensitive upper limits, the DASI experiment has detected the E-mode polarization and both the DASI and WMAP experiments have detected the TE correlation. These detections provide confirmation of the standard model of adiabatic primordial density fluctuations consistent with inflationary models. The WMAP TE correlation on large angular scales provides direct evidence of significant reionization at higher redshifts than had previously been supposed. These detections mark the beginning of a new era in CMB measurements and the rich cosmology that can be gleaned from them.Comment: 22 pages, 9 figures; To be published in the proceedings of "The Cosmic Microwave Background and its Polarization", New Astronomy Reviews, (eds. S. Hanany and K.A. Olive

Benchmark Parameters for CMB Polarization Experiments

The recently detected polarization of the cosmic microwave background (CMB) holds the potential for revealing the physics of inflation and gravitationally mapping the large-scale structure of the universe, if so called B-mode signals below 10^{-7}, or tenths of a uK, can be reliably detected. We provide a language for describing systematic effects which distort the observed CMB temperature and polarization fields and so contaminate the B-modes. We identify 7 types of effects, described by 11 distortion fields, and show their association with known instrumental systematics such as common mode and differential gain fluctuations, line cross-coupling, pointing errors, and differential polarized beam effects. Because of aliasing from the small-scale structure in the CMB, even uncorrelated fluctuations in these effects can affect the large-scale B modes relevant to gravitational waves. Many of these problems are greatly reduced by having an instrumental beam that resolves the primary anisotropies (FWHM << 10'). To reach the ultimate goal of an inflationary energy scale of 3 \times 10^{15} GeV, polarization distortion fluctuations must be controlled at the 10^{-2}-10^{-3} level and temperature leakage to the 10^{-4}-10^{-3} level depending on effect. For example pointing errors must be controlled to 1.5'' rms for arcminute scale beams or a percent of the Gaussian beam width for larger beams; low spatial frequency differential gain fluctuations or line cross-coupling must be eliminated at the level of 10^{-4} rms.Comment: 11 pages, 5 figures, submitted to PR