Neutron Rich Hypernuclei in Chiral Soliton Model

The binding energies of neutron rich strangeness $S=-1$ hypernuclei are estimated in the chiral soliton approach using the bound state rigid oscillator version of the SU(3) quantization model. Additional binding of strange hypernuclei in comparison with nonstrange neutron rich nuclei takes place at not large values of atomic (baryon) numbers, $A=B\leq\sim 10$. This effect becomes stronger with increasing isospin of nuclides, and for "nuclear variant" of the model with rescaled Skyrme constant $e$. Total binding energies of (Lambda)He-8 and recently discovered (Lambda)H-6 satisfactorily agree with experimental data. Hypernuclei (Lambda)H-7, (Lambda)He-9 are predicted to be bound stronger in comparison with their nonstrange analogues H-7, He-9; hypernuclei (Lambda)Li-10, (Lambda)Li-11, (Lambda)Be-12, (Lambda)Be-13, etc. are bound stronger in the nuclear variant of the model.Comment: 8 pages, 4 tables; amendments made, data on binding energy of (Lambda)He-8 and references added; prepared for the conferences Quarks-2012 and HYP201

Radio Astronomy in LSST Era

A community meeting on the topic of "Radio Astronomy in the LSST Era" was hosted by the National Radio Astronomy Observatory in Charlottesville, VA (2013 May 6--8). The focus of the workshop was on time domain radio astronomy and sky surveys. For the time domain, the extent to which radio and visible wavelength observations are required to understand several classes of transients was stressed, but there are also classes of radio transients for which no visible wavelength counterpart is yet known, providing an opportunity for discovery. From the LSST perspective, the LSST is expected to generate as many as 1 million alerts nightly, which will require even more selective specification and identification of the classes and characteristics of transients that can warrant follow up, at radio or any wavelength. The LSST will also conduct a deep survey of the sky, producing a catalog expected to contain over 38 billion objects in it. Deep radio wavelength sky surveys will also be conducted on a comparable time scale, and radio and visible wavelength observations are part of the multi-wavelength approach needed to classify and understand these objects. Radio wavelengths are valuable because they are unaffected by dust obscuration and, for galaxies, contain contributions both from star formation and from active galactic nuclei. The workshop touched on several other topics, on which there was consensus including the placement of other LSST "Deep Drilling Fields," inter-operability of software tools, and the challenge of filtering and exploiting the LSST data stream. There were also topics for which there was insufficient time for full discussion or for which no consensus was reached, which included the procedures for following up on LSST observations and the nature for future support of researchers desiring to use LSST data products.Comment: Conference summary, 29 pages, 1 figure; to be published in the Publ. Astron. Soc. Pacific; full science program and presentations available at http://science.nrao.edu/science/event/RALSST201

The Distribution of Quasars and Galaxies in Radio Color-Color and Morphology Diagrams

We positionally match the 6 cm GB6, 20 cm FIRST and NVSS, and 92 cm WENSS radio catalogs and find 16,500 matches in ~3,000 deg2 of sky. Using this unified radio database, we construct radio "color-magnitude-morphology" diagrams and find that they display a clear structure, rather than a random scatter. We propose a simple, yet powerful, method for morphological classification of radio sources based on FIRST and NVSS measurements. For a subset of matched sources, we find optical identifications using the SDSS Data Release 1 catalogs, and separate them into quasars and galaxies. Compact radio sources with flat radio spectra are dominated by quasars, while compact sources with steep spectra, and resolved radio sources, contain substantial numbers of both quasars and galaxies.Comment: 4 pages, 2 figures, to be published in the Proceedings of "Multiwavelength AGN Surveys", Cozumel, Dec 8 - 12, 200

Nuclei, Superheavy Nuclei and Hypermatter in a chiral SU(3)-Modell

A model based on chiral SU(3)-symmetry in nonlinear realisation is used for the investigation of nuclei, superheavy nuclei, hypernuclei and multistrange nuclear objects (so called MEMOs). The model works very well in the case of nuclei and hypernuclei with one Lambda-particle and rules out MEMOs. Basic observables which are known for nuclei and hypernuclei are reproduced satisfactorily. The model predicts Z=120 and N=172, 184 and 198 as the next shell closures in the region of superheavy nuclei. The calculations have been performed in self-consistent relativistic mean field approximation assuming spherical symmetry. The parameters were adapted to known nuclei.Comment: 19 pages, 11 figure

A Comparison of SDSS Standard Star Catalog for Stripe 82 with Stetson's Photometric Standards

We compare Stetson's photometric standards with measurements listed in a standard star catalog constructed using repeated SDSS imaging observations. The SDSS catalog includes over 700,000 candidate standard stars from the equatorial stripe 82 (|Dec|<1.266 deg) in the RA range 20h 34' to 4h 00', and with the $r$ band magnitudes in the range 14--21. The distributions of measurements for individual sources demonstrate that the SDSS photometric pipeline correctly estimates random photometric errors, which are below 0.01 mag for stars brighter than (19.5, 20.5, 20.5, 20, 18.5) in ugriz, respectively (about twice as good as for individual SDSS runs). We derive mean photometric transformations between the SDSS gri and the BVRI system using 1165 Stetson stars found in the equatorial stripe 82, and then study the spatial variation of the difference in zeropoints between the two catalogs. Using third order polynomials to describe the color terms, we find that photometric measurements for main-sequence stars can be transformed between the two systems with systematic errors smaller than a few millimagnitudes. The spatial variation of photometric zeropoints in the two catalogs typically does not exceed 0.01 magnitude. Consequently, the SDSS Standard Star Catalog for Stripe 82 can be used to calibrate new data in both the SDSS ugriz and the BVRI systems with a similar accuracy.Comment: 10 pages, color figures, presented at the meeting "The Future of Photometric, Spectrophotometric, and Polarimetric Standardization", Blankenberge, May 8-11, 200