Status of the ROTSE‐III telescope network

ROTSE‐III is a homogeneous worldwide array of 4 robotic telescopes. They were designed to provide optical observations of γ ‐ray burst (GRB) afterglows as close as possible to the start of γ ‐ray emission. ROTSE‐III is fulfilling its potential for GRB science, and provides optical observations for a variety of astrophysical sources in the interim between GRB events. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Dense cores in the L1630 molecular cloud: discovering new protostars with SCUBA

Maps of the 450- and 850-μm dust continuum emission from three star-forming condensations within the Lynds 1630 molecular cloud, made with the SCUBA bolometer array, reveal the presence of four new submillimetre sources, each of a few solar masses (two of which are probably class I and two of which are class 0), as well as several sources the existence of which was previously known. The sources are located in filaments and appear elongated when observed at 450 μm. They probably have dust temperatures in the range 10 to 20 K, in good agreement with previous ammonia temperature estimates. Attempts to fit their structures with power-law and Gaussian density distributions suggest that the central distribution is flatter than expected for a simple singular isothermal sphere.
Although the statistics are poor, our results suggest that the ratio of 'protostellar core' mass to total virial mass may be similar for both large and small condensations.     

New Molecular Species in Comet C/1995 O1 (Hale-Bopp) Observed with the Caltech Ssubmillimeter Observatory

We present millimeter-wave observations of HNCO, HC₃N, SO, NH₂CHO, H¹³CN, and H₃O⁺ in comet C/1995 O1 (Hale-Bopp)obtained in February–April, 1997 with the Caltech Submillimeter Observatory (CSO). HNCO, first detected at the CSO in comet C/1996B2 (Hyakutake), is securely confirmed in comet Hale-Bopp via observations of three rotational transitions. The derived abundance with respect to H₂O is (4-13) × 10^-4. HC₃N, SO, and NH₂CHO are detected for the first time in a comet. The fractional abundance of HC₃N based on observations of three rotational lines is (1.9 ± 0.2) × 10^-4. Four transitions of SO are detected and the derived fractional abundance, (2-8) ×10^-3, is higher than the upper limits derived from UV observations of previous comets. Observations of NH₂CHO imply a fractional abundance of (1-8) × 10^-4. H₃O is detected for the first time from the ground. The H¹³CN (3-2)transition is also detected and the derived HCN/H¹³CN abundance ratio is 90 ± 15, consistent with the terrestrial¹²C/¹³C ratio. In addition, a number of other molecular species are detected, including HNC, OCS, HCO⁺, CO⁺, and CN(the last two are first detections in a comet at radio wavelengths). This revised version was published online in July 2006 with corrections to the Cover Date.     

Comparative soil CO2 flux measurements and geostatistical estimation methods on Masaya volcano, Nicaragua

We present a comparative study of soil CO₂ flux () measured by five groups (Groups 1–5) at the IAVCEI-CCVG Eighth Workshop on Volcanic Gases on Masaya volcano, Nicaragua. Groups 1–5 measured using the accumulation chamber method at 5-m spacing within a 900 m² grid during a morning (AM) period. These measurements were repeated by Groups 1–3 during an afternoon (PM) period. Measured ranged from 218 to 14,719 g m⁻² day⁻¹. The variability of the five measurements made at each grid point ranged from ±5 to 167%. However, the arithmetic means of fluxes measured over the entire grid and associated total CO₂ emission rate estimates varied between groups by only ±22%. All three groups that made PM measurements reported an 8–19% increase in total emissions over the AM results. Based on a comparison of measurements made during AM and PM times, we argue that this change is due in large part to natural temporal variability of gas flow, rather than to measurement error. In order to estimate the mean and associated CO₂ emission rate of one data set and to map the spatial distribution, we compared six geostatistical methods: arithmetic and minimum variance unbiased estimator means of uninterpolated data, and arithmetic means of data interpolated by the multiquadric radial basis function, ordinary kriging, multi-Gaussian kriging, and sequential Gaussian simulation methods. While the total CO₂ emission rates estimated using the different techniques only varied by ±4.4%, the maps showed important differences. We suggest that the sequential Gaussian simulation method yields the most realistic representation of the spatial distribution of , but a variety of geostatistical methods are appropriate to estimate the total CO₂ emission rate from a study area, which is a primary goal in volcano monitoring research.Editorial responsibility: H Shinohara     

Resik: A Bent Crystal X-ray Spectrometer for Studies of Solar Coronal Plasma Composition

We describe the RESIK (REntgenovsky Spektrometr s Izognutymi Kristalami) instrument, consisting of two double-channel X-ray spectrometers, designed to observe solar active region and flare plasmas. RESIK is one of the instruments making up the scientific payload of the Russian CORONAS-F solar mission. The uncollimated spectrometer uses two silicon and two quartz bent crystals observing flare, active region and coronal spectra in four wavelength bands with a resolving power (/ ) of 1000. The wavelength coverage, 3.3–6.1 Å, includes emission lines of Si, S, Cl, Ar, and K and in the third diffraction order, the wavelength range includes He-like Fe lines (1.85 Å) and Ni lines (1.55 Å) with dielectronic satellites, emitted during intense, hot flares. The instrument is believed to be the best calibrated space-borne crystal spectrometer flown to date. The spectrometer dynamically adjusts the data gathering intervals from 1 s to 5 minutes, depending on the level of solar X-ray emission at the time of observation. The principal aims of RESIK are the measurements of relative and absolute element abundances in the emitting plasma and the temperature distribution of plasma (differential emission measure) over the temperature interval 3 and 50 MK. This paper summarizes the scientific objectives of RESIK and describes the design, characteristics, and performance of the instrument.     

Magnitude of harvest of Atlantic horseshoe crabs,<Emphasis Type="Italic">Limulus polyphemus</Emphasis>, in Pleasant Bay,Massachusetts

Atlantic horseshoe crabs,Limulus polyphemus, are currently harvested for biomedical, scientific, and bait purposes. In recent years, changes in population abundance and magnitude of harvesting have raised concerns about the status of this resource. We found horseshoe crab harvest in Pleasant Bay, Massachusetts, was selective by sex and size. Biomedical harvest preferred larger individuals and females, the scientific harvest preferred smaller individuals and males, and the bait harvest preferred females. Total 2001 harvest for all purposes accounted for the mortality of ∼1–2% the adult population. Biomedical harvest accounted for the greatest loss of horseshoe crabs from Pleasant Bay, ∼1–1.6% of the total population. Although biomedical harvest had the lowest associated mortality rate (∼10–15%), many more crabs were harvested from Pleasant Bay for biomedical purposes than for other uses. The scientific harvest accounted for the mortality of ∼0.4% of the population, and bait harvest accounted for the smallest mortality at ∼0.06% of the population. Harvest mortality rate was estimated to be lower in Pleasant Bay than in other Cape Cod areas and may be lower than natural mortality in the population. This study is the first qualitative investigation of commercial harvest on horseshoe crab populations and emphasizes that harvest pressures on different populations need to be individually evaluated.     

Temperature structure of active regions deduced from the helium-like sulphur lines

Solar active-region temperatures have been determined from the full-Sun spectra of helium-like sulphur (Sxv) observed by the Bragg Crystal Spectrometer on board theYohkoh satellite. The average temperature deduced from Sxv is demonstrated to vary with the solar activity level: A temperature of 2.5 × 10⁶ K is derived from the spectra taken during low solar activity, similar to the general corona, while 4 × 10⁶ K is obtained during a higher activity phase. For the latter, the high-temperature tail of the differential emission measure of active regions is found most likely due to the superposition of numerous flare-like events (micro/nano-flares).