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The Molonglo Observatory Synthesis Telescope (MOST) is an 18000 m2 radio telescope located 40 km from Canberra, Australia. Its operating band (820–851 MHz) is partly allocated to telecommunications, making radio astronomy challenging. We describe how the deployment of new digital receivers, Field Programmable Gate Array-based filterbanks, and server-class computers equipped with 43 Graphics Processing Units, has transformed the telescope into a versatile new instrument (UTMOST) for studying the radio sky on millisecond timescales. UTMOST has 10 times the bandwidth and double the field of view compared to the MOST, and voltage record and playback capability has facilitated rapid implementaton of many new observing modes, most of which operate commensally. UTMOST can simultaneously excise interference, make maps, coherently dedisperse pulsars, and perform real-time searches of coherent fan-beams for dispersed single pulses. UTMOST operates as a robotic facility, deciding how to efficiently target pulsars and how long to stay on source via real-time pulsar folding, while searching for single pulse events. Regular timing of over 300 pulsars has yielded seven pulsar glitches and three Fast Radio Bursts during commissioning. UTMOST demonstrates that if sufficient signal processing is applied to voltage streams, innovative science remains possible even in hostile radio frequency environments.
The class of radio transients called Fast Radio Bursts (FRBs) encompasses enigmatic single pulses, each unique in its own way, hindering a consensus for their origin. The key to demystifying FRBs lies in discovering many of them in order to identity commonalities – and in real time, in order to find potential counterparts at other wavelengths. The recently upgraded UTMOST in Australia, is undergoing a backend transformation to rise as a fast transient detection machine. The first interferometric detections of FRBs with UTMOST, place their origin beyond the near-field region of the telescope thus ruling out local sources of interference as a possible origin. We have localised these bursts to much better than the ones discovered at the Parkes radio telescope and have plans to upgrade UTMOST to be capable of much better localisation still.
Dissipational formation theories (e.g. Larson 1974) predict a metallicity change with distance from the center in elliptical galaxies. Several authors have reported small color gradients in visual colors like B–V and B–R. The interpretation of these data is not easy, due to uncertainties caused by the short wavelength–baseline, and by the presence of a hot stellar population suggested by IUE–data (e.g. Burstein et al. 1986). Simultaneous measurements of visual and visual-infrared colors provide the means to determine both the average temperature of the giant branch and the turnoff–temperature of the main sequence. This allows to model fractional contributions of different populations, including age– and metallicity–effects. The required continuity of solutions at different radii provides a strong constraint in selecting a more unique overall population model, and relieves the ambiguous interpretation of single measurements.
We have carried out lunar occultation observations at λ = 2.2μm at the WHT and Calar Alto telescopes of young stellar objects both in the Taurus and the Ophiuchus star forming regions. We report the discovery of 4 new binary systems: IW Tau and HK Tau/G2 in Taurus as well as GSS 35 and VSSG 14 in Ophiuchus; the projected separations are about 70 milliarcseconds (mas) for each of the Taurus objects, while for the Ophiuchus sources they are about 20 and 100 mas, respectively (20 mas correspond to 3 AU).
We present new infrared photometry of Pleiades and Praesepe sources, and define the cluster sequences in colour magnitude and 2-colour diagrams. We identify non-members and unresolved binaries, and discuss the clusters binary fractions.
The subject of brown dwarfs has grown enormously since the announcement of the first brown dwarfs in 1995. Thus this conference is the largest conference ever devoted solely to brown dwarfs, with 150 delegates, 82 talks and 52 posters. This summary will struggle, therefore, to give a complete picture and, of course, it is only the impression of one individual.
Preliminary results from a deep R, I and Z band survey of ~ 6 square degrees of the Taurus Dark Cloud region are presented. 186 potential brown dwarfs have been unearthed, with seven having follow-up spectroscopic data. The spectra reveal three mid/late-type M dwarfs, of which two show weak Hα emission. If these objects are members of the TDC region, theoretical models suggest masses in the range 10 – 20 MJ.
Infrared photometry enables radii, and hence absolute magnitudes, to be derived more accurately than is possible using purely optical photometry. In this paper we present BVJHK observations of the galactic cepheids T Vul, U Vul and T Mon. Using this data we find reasonable agreement with current versions of the Period-Luminosity relations, in both the optical and infrared.
From these relations and existing optical and infrared data for LMC Cepheids we find for the LMC (i) Av = 0.35 and (ii) a distance modulus of 18.50. In addition we show that the P-L-C relation has the form
Mean temperatures for RR Lyrae stars in 7 globular clusters (M3, M4, M5, M15, M107, ω Cen and NGC 5466) have been determined using the optical-infrared colour <V>-<K> as a temperature indicator. Where <K> has been relatively well determined, from means of 3 or more observations, the scatter in relationships such as Log P’ vs log (temperature) and log (temperature) vs (blue amplitude) is significantly reduced when IR-derived temperatures are used instead of those derived from (B-V). Within the observational errors, the gradient in the log P’ vs log (temperature) diagram is the same for each cluster. Temperatures derived from <V>-<K> should also be less sensitive to metallicity differences than their optically derived counterparts. The Sandage Period-Shift Effect has therefore been re-examined using 6 of the 7 clusters (NGC 5466 was excluded because of too few data). A strong correlation between period-shift and metallicity is found; a smaller shift (but in the same sense) is also found for the temperature – amplitude relationship.
The log (Period) – infrared (2.2 micron) magnitude relationship has been measured for 7 clusters (M3, M4, M5, M15, M107, ω Cen and NGC 5466). For the clusters where there are several observations for each of the variables, enabling a good mean magnitude to be derived, there is no evidence for scatter in the relation outside observational error. This conclusion applies also to ω Cen, even though the variables observed covered a range of metallicity. It is argued that very accurate relative distances can be obtained which are insensitive to reddening errors and the effects of metallicity. Any mass difference between variables in different clusters may still introduce uncertainties in the relative distances. Recent Baade-Wesselink results by Fernley et al. have been used as an absolute calibration, including a small residual correction for metallicity effects. On this scale, the mean distance modulus for 6 of the clusters (excluding NGC5466) is essentially the same as that derived by Buonanno, Corsi and Fusi-Pecci (preprint) using a combination of horizontal branch magnitudes and main sequence fitting. However, individual distance moduli differ by typically 0.09 magnitudes. There is no clear correlation of this residual with metallicity.
We surveyed all stars in Taurus (3h 45m < α < 4h 15m, 15° < δ < 35°) for multiplicity which are contained in the Herbig-Bell catalogue of young stars and have a 2 micron brightness of K ≤ 9.5 mag. This sample consists of 106 stellar systems (single or multiple), of which 43 are double or multiple according to the criteria of our survey, i.e. with separations of ≈0″.2 ≤ d ≤ 10″. Of these, 23 binaries are new detections found in this survey. The resulting degree of multiplicity, 43/106 = 41±6%, is higher than found for main-sequence stars. Provided that the period distribution is the same for young stars as on the main sequence, our result implies that the vast majority of stars are born in binary or multiple systems.
A ‘pulsar timing array’ (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of ‘global’ phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 ms pulsars is being observed at three radio-frequency bands, 50 cm (~700 MHz), 20 cm (~1400 MHz), and 10 cm (~3100 MHz), with observations at intervals of two to three weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters, and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For 10 of the 20 pulsars, rms timing residuals are less than 1 μs for the best band after fitting for pulse frequency and its first time derivative. Significant ‘red’ timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array and a PTA based on the Square Kilometre Array. We also present an ‘extended PPTA’ data set that combines PPTA data with earlier Parkes timing data for these pulsars.
The Parkes pulsar data archive currently provides access to 144044 data files obtained from observations carried out at the Parkes observatory since the year 1991. Around 105 files are from surveys of the sky, the remainder are observations of 775 individual pulsars and their corresponding calibration signals. Survey observations are included from the Parkes 70 cm and the Swinburne Intermediate Latitude surveys. Individual pulsar observations are included from young pulsar timing projects, the Parkes Pulsar Timing Array and from the PULSE@Parkes outreach program. The data files and access methods are compatible with Virtual Observatory protocols. This paper describes the data currently stored in the archive and presents ways in which these data can be searched and downloaded.
Herbicides applied to container plants in nurseries are transported in runoff water to on- and off-site ponds and retention basins. This study was conducted to determine biotic and abiotic effects on isoxaben dissipation in model flow-through retention basins to maximize aqueous isoxaben degradation. Field studies were conducted in 1999 and 2000 to evaluate the effects of gravel and pine bark amendments and water retention times on isoxaben persistence in holding basins. In 1999, total isoxaben discharge into flow-through gravel-filled basins was greater than isoxaben losses from gravel and nongravel basins in which water was retained. Photodegradation appeared to be greater in basins without gravel, indicating that gravel protected isoxaben from photolysis. Further studies determined the effect of water retention time and the presence of aged pine bark amendment on isoxaben discharge from basins. Isoxaben discharge level was reduced when water retention time was increased from 3 to 5 d. In the 3-d retention time treatment, added pine bark reduced peak isoxaben discharge by 45% and total isoxaben by 53% at 14 d after treatment. In treatments containing pine bark within the retention basins, isoxaben was released over a longer period of time. No differences were observed in 5-d water retention time treatments with and without pine bark. Analysis of gravel from isoxaben-treated retention basins indicated the presence of several genera of bacteria including Pseudomonas, Arthrobacter, and Cellulomonas. Some isolates of Pseudomonas, Rahnella, Methobacterium, and Paenibacillus from the basins grew on M9 medium with isoxaben as the sole carbon and energy source, indicating their ability to metabolize isoxaben. Results indicate that retention basins are helpful in reducing isoxaben levels before release or reuse of runoff water from a container nursery, and that retention time of runoff water in basins is the most important factor in reducing isoxaben discharge.
Searches in Clusters, Stellar Associations and the Field
R. F. Jameson, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK,
S. T. Hodgkin, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1, 7RH, UK,
D. Pinfield, Department of Pure and Applied Physics, The Queen's University of Belfast, Belfast, BT7 1NN, Northern Ireland,
M. R. Cossburn, Department of Physics and Astronomy, University of Leicester, University Road, Leicester, LE1 7RH, UK
We combine the results from two CCD surveys covering a large area of the custer at I and Z wavebands. We have obtained follow-up K photometry for many of the numerous brown dwarf candidates discovered in these surveys which we employ as a test for cluster membership. From these data we derive the mass function of the whole Pleiades cluster down to 0.04 M⊙. We emphasise the importance of a careful consideration of the spatial distribution within the cluster and find the core radius for brown dwarfs to be 2±1 parsecs. The contribution of brown dwarfs to the total mass of the cluster is about 1%.
The Pleiades has long been recognised as one of the best places to search for brown dwarfs, e.g. Jameson & Skillen (1989), Stauffer et al. (1989, 1994), Simons & Becklin (1992), Rebolo et al. (1995), Cossburn et al. (1997), Zapatero Osorio et al. (1997), Bouvier et al. (1998), Festin (1998).
The cluster is both reasonably close (but not so close as to cover too large an area of the sky) and young, so that brown dwarfs are not too faint. Controversy still rages over the precise distance to the Pleiades, which Hipparcos places significantly closer (at 118 parsecs) than ground based measurements (at typically 133 parsecs). The Hipparcos results have been published by Van Leeuwen & Hansen Ruiz (1997) and Mermilliod et al. (1997) and critically discussed by Pinnsoneault et al. (1998).
The problem considered is the
determination of “lower bounds” of matrix operators on the spaces\ell_p(w)
or d(w,p). Under fairly general conditions, the
solution is the same for both spaces and is given by the infimum of a certain sequence. Specific cases
are considered, with the weighting sequence defined by w_n = 1/n^\alpha . The exact
solution is found for the Hilbert operator. For the averaging operator, two different upper bounds are
given, and for certain values of p and \alpha it is shown that
the smaller of these two bounds is the exact solution.
Irrigation of the bladder after transurethral resection of the prostate is often distressing because of pain arising from detrusor muscle spasm. The effect of post-operative oral diazepam was compared with sacral epidural (caudal) block at the time of surgery, both treatments together and a control group, assessed by three-point rank scoring. Either treatment significantly reduced the incidence of pain reported by patients, P < 0.001. No patient experienced pain after both treatments.
The results show that liquid fertilizers generally gave lower yields of dry matter than conventional solid fertilizers in four experiments on grassland. In seven trials, on autumn wheat, spring wheat, sugar beet and kale, the efficiencies of the two forms of fertilizer were similar.
Liquid fertilizers containing ammonia must be injected into the soil and this needs special equipment, more complicated, particularly where anhydrous ammonia is to be used, than the distributors used for solid fertilizers. Running the injector over established grassland sometimes resulted in considerable damage to the sward. When used to top-dress winter wheat across the line of drilling some plants were killed.
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