Artículos de revistas sobre el tema "Astro Observatory (U.S.)"

AbstractA new speckle interferometer began operation with the 66-cm refractor in Oct. 1990. The interferometer is an improved version of the one operated by CHARA at Georgia State University. We describe the instrument, its calibration, and first observational results.

Abstract During the 40-year photographic period of astronomical observations, the Baldone Astrophysical Observatory has accumulated more than 22,000 direct and 2,500 spectral images. In 2018, the digitization of direct astrophoto images with a resolution of 1200 dpi was completed. A processing methodology for obtaining the equatorial coordinates and photometric characteristics of the objects recorded in digitized astronegatives using the LINUX/MIDAS/ROMAFOT environment has been developed at the Main Astronomical Observatory of the National Academy of Sciences of Ukraine. Program package with success already works in seven observatories. A description of the operation of this program complex in stages and analysis of the obtained results is given. The steps describe the astrometric and photometric reduction process of digital records, as well as the reduction of the obtained instrumental magnitudes to the Johnson UBVR photometric system. The methodology of characteristic curve construction in the case of one exposure is described in detail. From all digitized astrophotoplates to date Approximately 2200 V film negatives, 300 U plates and several R, B plates were processed. As a result, catalogs of the positions and magnitudes of Pluto, 1848 asteroids and comets were obtained. 31 new positions were recorded in the VizieR Pluto catalog VI/155. It was found that the root-mean-square errors of the reduction of the measured coordinates to the equatorial coordinate system of the Tycho-2 catalog have values σ RA , DEC = 0.1-0.2”, and the root-mean-square errors of the reduction of instrumental photometric quantities m to the Johnson system of stellar UBVR-values are also in within σ UBVR = 0.1 − 0.2 m .

Abstract We introduce the application of the clustering algorithm to the preliminary compiled list of probable wide pairs of co-moving stars. The main aim of such development is a possibility of unsupervised blind search of coeval loose stellar structures over significant regions in space. Using Gaia EDR3 data, we investigated the application of the method to nearby region hosting recently discovered loose structures – tidal tails of Coma Ber star cluster and a nearby stellar group named Group X. We compare the results of straightforward clustering of stellar data with results of using our method with varying parameters. We then compare the results of our method to the recent results of the two groups of authors who independently discovered the discussed structures. We find parameters allowing the method to find the full scope of distributed stellar groups without preliminary knowledge of their characteristics. It decreases the risk of false positive clustering and improves the ability to discover loose stellar groups, in comparison with the application of clustering algorithm to the individual stars. Further we obtain a refined dataset of probable members of both stellar groups and independently obtain their ages (700 ± 70 Myr and 450 ± 100 Myr) and space velocities ((U,V,W) = (8.63 ± 0.13, 6.63 ± 0.20, 6.65 ± 0.95) km/s for Coma Ber star cluster, and (U,V,W) = (7.70 ± 0.12, 3.27 ± 0.45, 5.69 ± 0.80) km/s for Group X). Our results are in very good agreement with those of previous investigators.

AbstractHitomi (ASTRO-H) is an X-ray observatory developed by an international collaboration led by JAXA. An X-ray microcalorimeter onboard this satellite has opened a new window of high-resolution spectroscopy with an unprecedented energy resolution of 5 eV (FWHM) at 6 keV. The spacecraft was launched on February 17, 2016 from Tanegashima Island, Japan, and we completed initial operations including deployment of the hard X-ray imagers on the extensible optical bench. All scientific instruments had successfully worked until the sudden loss of the mission on March 26. We have obtained a spectrum showing fully resolved emission lines through the first-light observation of the Perseus Cluster. The line-of-sight velocity dispersion of 164 ± 10 km s−1 reveals the quiescent environment of intracluster medium at the cluster core, implying that measured cluster mass requires little correction for the turbulent pressure. We also discuss observations to the Galactic Center which could be performed with Hitomi.

AbstractObservations with the Hopkins Ultraviolet Telescope on the Astro-1 and Astro-2 space shuttle missions have provided the first set of moderate (3 Å) resolution far ultraviolet (FUV) spectra of dwarf novae to include the wavelength range between Lyα and the Lyman limit. Important lines which are detected in the HUT spectra of dwarf novae in this wavelength range include S VI λλ933,945, C III λ977, O VI λλ1032,1038, P V λλ1118,1128 and C III λ1176, as well as the higher order Lyman lines. The observations confirm earlier IUE observations that two dwarf novae – U Gem and VW Hyi – have quiescent FUV spectra dominated by the white dwarf, but suggest that the quiescent FUV emission from three other dwarf novae – SS Cyg, WX Hyi and YZ Cnc – are dominated by emission from a hot portion of the disk or a disk corona. The spectra obtained of the dwarf novae Z Cam and EM Cyg in outburst and also of the nova-like variable IX Vel can be modeled reasonably successfully in terms of steady state disks constructed by adding appropriately-weighted stellar model spectra.

Data from the U. S. Naval Observatory annual astronomical almanacs (1970–1992) in “correlation” with the Maya Calendar Round (CR) sequence indicate that the Dresden Codex lunar table (51a-58b) very probably counted simultaneous sequences of both lunar and solar eclipses on the same set of day names. The contemporary sequence of day names in the CR and the astronomy consistent with it parallels Classic-period Maya observational experience between 9.16.0.0.0 and 9.17.0.0.0.

Abstract The Stellar Abundances and Galactic Evolution Survey (SAGES) of the northern sky is a specifically designed multiband photometric survey aiming to provide reliable stellar parameters with accuracy comparable to those from low-resolution optical spectra. It was carried out with the 2.3 m Bok telescope of Steward Observatory and three other telescopes. The observations in the u s and v s passband produced over 36,092 frames of images in total, covering a sky area of ∼9960 deg2. The median survey completenesses of all observing fields for the two bands are u s = 20.4 mag and v s = 20.3 mag, respectively, while the limiting magnitudes with signal-to-noise ratio of 100 are u s ∼ 17 mag and v s ∼ 18 mag, correspondingly. We combined our catalog with the data release 1 (DR1) of the first Panoramic Survey Telescope And Rapid Response System (Pan-STARRS, PS1) catalog, and obtained a total of 48,553,987 sources that have at least one photometric measurement in each of the SAGES u s and v s and PS1 grizy passbands. This is the DR1 of SAGES, released in this paper. We compared our gri point-source photometry with those of PS1 and found an rms scatter of ∼2% difference between PS1 and SAGES for the same band. We estimated an internal photometric precision of SAGES to be of the order of ∼1%. Astrometric precision is better than 0.″2 based on comparison with DR1 of the Gaia mission. In this paper, we also describe the final end-user database, and provide some science applications.

The USNO-A1.0 catalog was generated from the U. S. Naval Observatory's digitization of the Palomar Observatory Sky Survey IOandEsurvey plates for fields with central declination δ ≥ −30°, and from the European Southern ObservatoryRand Science Research CouncilJsurvey plates for fields with central δ ≤–35° using the Precision Measuring Machine (PMM) located at the Flagstaff Station. It lists positions (α and δ in J2000) and brightnesses (red and blue magnitudes on the parent plate system) for all objects. A flag indicates if the entry also exists in GSC1.1.

Observations of flare stars with high time resolution permit to register spiky type flares and also to study in detail bright curves of flares. In Byurakan observatory observations of EV Lac have been made with 0.1 s time resolution simultaneouslyin two filters “U” and “B” [1-3]. These observations permited to detect flares of a burst type (Fig.1) and also to reveil multipeak structure of long duration flares. It is necessary to stress that simultaneous observations in two colours increas appresiably the thrustworthiness of the registered spiky flares.

A high density reference star catalog is being compiled at the U. S. Naval Observatory for the purpose of making new reductions of the Astrographic Catalog. The catalog will be a replacement to the SAO catalog and will be derived from the large photographic catalogs and the modern meridian circle catalogs. It is expected that the final catalog will contain 346, 000 stars, with proper motion mean errors generally or less, on a uniform system, the data having been reduced first to FK4 and then to FK5 using the International Reference Stars (IRS).

We present a study of spin vector orientation of 14,118 SDSS (Sloan Digital Sky Survey) galaxies having redshift in the range 0.19 to 0.20 (radial velocity 57,000 km/s to 60,000 km/s) with respect to galactic coordinate system using 7th data release (2008, October). These galaxies were observed through SDSS telescope of Apache Point Observatory located at New Mexico, USA. The photometric database is made available through our collaboration with institute of Astro-particle physics, Innsbruck University, Austria. We used the `Godlowskian' method to convert two dimensional data to three dimensional galaxy rotation axes. Our intension is to find out non-random effects in the spatial orientation of galaxies and to check redshift dependence. The expected isotropy distribution curves are obtained by removing the selection effects and performing a random simulation method. The observed and expected polar and azimuthal angle distributions are compared by using three statistical tests- chi-square, auto-correlation and the Fourier. It is found that the spatial orientation of galaxies tend to be oriented randomly with respect to the galactic coordinate system, supporting hierarchy model of galaxy evolution. In few cases we noticed a preference, probably due to the gravitational shearing or tidal effects in the large scale structure. In general, redshift is found to be independent of orientation. Hence, a very good correlation between the Hubble flow (redshift) and the random alignments of spin vectors of SDSS galaxies is noticed.DOI: http://dx.doi.org/10.3126/bibechana.v12i0.11787BIBECHANA 12 (2015) 114-127

ABSTRACT PDS 70 is a ∼5-Myr-old star with a gas and dust disc in which several protoplanets have been discovered. We present the first ultraviolet (UV) detection of the system along with X-ray observations taken with the Neil Gehrels Swift Observatory satellite. PDS 70 has an X-ray flux of 3.4 × 10−13 erg cm−2 s−1 in the 0.3–10.0 keV range, and UV flux (U band) of 3.5 × 10−13 erg cm−2 s−1 . At the distance of 113.4 pc determined from Gaia Data Release 2, this gives luminosities of 5.2 × 1029 and 5.4 × 1029 erg s−1, respectively. The X-ray luminosity is consistent with coronal emission from a rapidly rotating star close to the log $\frac{L_{\mathrm{X}}}{L_{\mathrm{bol}}} \sim -3$ saturation limit. We find the UV luminosity is much lower than would be expected if the star were still accreting disc material and suggest that the observed UV emission is coronal in origin.

Currently the computation of mean positions and proper motions for the International Reference Stars (IRS) is hampered by large variations in the observational histories of the stars and lack of overlap between the magnitudes of the IRS and of the FK4. The poorest IRS observational histories are +60° to +80° in the north and −40° to −80° in the south. The much-needed extension of the fundamental system to the ninth magnitude will be made in the FK5. The Faint Fundamental Extension is currently being selected at the U. S. Naval Observatory. A proposed list of 1030 Faint Fundamental stars has been prepared for the Northern Hemisphere, and work has begun on the selection in the Southern Hemisphere.

Abstract Wind and turbulence profiles were analyzed during breezy, near-neutral conditions at the Boulder Atmospheric Observatory tower to quantify the effects of an abrupt 20- to 30-m increase in terrain located 3–5 km west of the tower. Results indicate that regional roughness length z0 is greatest and local z0 is smallest in sectors downwind of a long, shallow bluff, suggesting that distant, more complex, upwind terrain enhances horizontal turbulence but has little effect on local wind speed profiles. Turbulence parameter profiles are nearly constant up to 200 m above ground level (AGL), and friction velocity u∗ is nearly constant up to 150–200 m for simple fetch with z0 equal to 4 cm and near-surface wind speed approximately equal to 7 m s−1 at 10 m AGL. Horizontal turbulence parameters, however, increase by 50% to nearly 100% at all tower levels downwind of the distant terrain bluff when compared with those with simple fetch. The effect of the bluff on vertical turbulence increases with height. Although the effect on the 10-m standard deviation of vertical wind speed σw is negligible, the 200-m σw increases by about 0.5 m s−1, or about twice the 10-m value. The u∗ also increases by 16% to nearly 100% between the 10- and 200-m heights downwind of the bluff. Primarily because of the enhanced σw downwind of the bluff, atmospheric dispersion could be underestimated by factors of about 2.5, 2.0, and 1.3 at the 200-, 100-, and 50-m levels, respectively, if the vertical and transverse standard deviations of the wind angle fluctuations are estimated from 10-m values.

We present IRAM-30 m Telescope 12CO and 13CO observations of a sample of 55 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in the local universe. This sample is a subset of the Great Observatory All-Sky LIRG Survey (GOALS), for which we use ancillary multi-wavelength data to better understand their interstellar medium and star formation properties. Fifty-three (96%) of the galaxies are detected in 12CO, and 29 (52%) are also detected in 13CO above a 3σ level. The median full width at zero intensity (FWZI) velocity of the CO line emission is 661 km s−1, and ∼54% of the galaxies show a multi-peak CO profile. Herschel photometric data is used to construct the far-IR spectral energy distribution of each galaxy, which are fit with a modified blackbody model that allows us to derive dust temperatures and masses, and infrared luminosities. We make the assumption that the gas-to-dust mass ratio of (U)LIRGs is comparable to local spiral galaxies with a similar stellar mass (i.e., gas/dust of mergers is comparable to their progenitors) to derive a CO-to-H2 conversion factor of ⟨α⟩ = 1.8−0.8+1.3 M⊙ (K km s−1 pc2)−1; such a value is comparable to that derived for (U)LIRGs based on dynamical mass arguments. We derive gas depletion times of 400 − 600 Myr for the (U)LIRGs, compared to the 1.3 Gyr for local spiral galaxies. Finally, we re-examine the relationship between the 12CO/13CO ratio and dust temperature, confirming a transition to elevated ratios in warmer systems.

Abstract Supernova remnants (SNRs) are significant contributors of matter and energy to the interstellar medium. Understanding the impact and the mechanism of this contribution requires knowledge of the physical size, energy, and expansion rate of individual SNRs, which can only come if reliable distances can be obtained. We aim to determine the distance to the SNR DA 530 (G93.3+6.9), an object of low surface brightness. To achieve this, we used the Dominion Radio Astrophysical Observatory Synthesis Telescope and the National Radio Astronomy Observatory Very Large Array to observe the absorption by intervening H i of the polarized emission from DA 530. Significant absorption was detected at velocities −28 and −67 km s−1 (relative to the local standard of rest), corresponding to distances of 4.4 and 8.3 kpc, respectively. Based on the radio and X-ray characteristics of DA 530, we conclude that the minimum distance is 4.4 − 0.2 + 0.4 kpc. At this minimum distance, the diameter of the SNR is 34 − 1 + 4 pc, and the elevation above the Galactic plane is 537 − 32 + 40 pc. The −67 km s−1 absorption likely occurs in gas whose velocity is not determined by Galactic rotation. We present a new data processing method for combining Stokes Q and U observations of the emission from an SNR into a single H i absorption spectrum, which avoids the difficulties of the noise-bias subtraction required for the calculation of polarized intensity. The polarized absorption technique can be applied to determine the distances to many more SNRs.

AbstractCARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a next-generation instrument under construction for the 3.5 m telescope at the Calar Alto Observatory by a consortium of eleven Spanish and German institutions. The scientific goal of the project is a five-year exoplanet survey targeting 300 M stars with the completed instrument. The CARMENES hardware consists of two separate échelle spectrographs covering the wavelength range from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. Both spectrographs are housed in a temperature-stabilized environment in vacuum tanks, to enable a long-term radial velocity precision of 1 m s−1 employing a simultaneous calibration with Th-Ne and U-Ne emission line lamps.

The star AY Vulpeculae was recognized as variable and labeled as an Algol-type system by Hoffmeister, (A.N. 242, 133, 1931). Koch et al. (I.B.V.S. 1709 1979), included it in their list of eclipsing binaries for which photoelectric work was needed. The system is faint, but because its primary minimum is very deep it is of astrophysical interest. The observations of the present investigation represent the first definitive photometric study made of AY VUL and is one of several systems with periods greater than two days being observed with the 1.0 meter Ritchey-Chretian reflector at the Flagstaff Station . A total of 1242 observations of AY Vul (406 in V, 417 in B, and 419 in U) were obtained on 12 nights in 1986.Orbital elements for AY VUL were obtained by using the Wood model, and the calculations were performed on the VAX 11/750 computer at the Flagstaff Station of the U. S. Naval Observatory. AY Vulpeculae can be regarded as a classical Algoltype semidetached system in which the secondary component fills its Roche lobe, while the primary lies well inside its own lobe. Both eclipses are partial. The orbital elements are listed below.

The Mark IIIA correlator system is currently operating at the U. S. Naval Observatory in Washington, D.C. in support of VLBI geodetic measurements being made by NASA, NGS, NRL, and USNO. This correlator system, developed at Haystack Observatory, is a second-generation version of the original Mark III correlator, and adds significant new capabilities such as double-speed operation, longer integration periods, and improved internal modelling.The Mark IIIA correlator can simultaneously process up to 10 baselines of data from 5 stations. Experiments including more than 5 stations may be processed with multiple passes through the correlator. The architecture of the correlator allows a future expansion to a maximum of 16 stations. Due to a simple modular design and the low cost of required computer-support equipment, expansion is straightforward and relatively economical.Although current geodetic VLBI observations are made using data from distant natural continuum radio sources, the Mark IIIA correlator was designed to also support processing of data collected from pulsars, artificial earth satellites, and from earth-orbiting antennas receiving signals from natural sources. These capabilities may be important in the future as efforts continue, for example, to tie satellite-related reference frames to current VLBI reference frames.The design approach of the Mark IIIA correlator will be discussed, including its performance with respect to systematic and random errors which may affect geodetic VLBI data.

At the Quonochontaug Observatory of the University of Rhode Island, we specialize in the development of simple seeing limited optical telescopes. Our main instrument is a heavy Serrier trussed f/10.7, .4-m astrometric reflector which provided the last-minute astrometry in the successful prediction of the occultation of SAO 120774 by Herculina in 1978. It is similar in design to the U. S. Naval Observatory 1.5-m reflector. Its scale of 47.1“/mm makes it potentially more powerful than the Lick .5-m, f/7 astrograph. However, its field of view of 1.3° × 1.7° is insufficient to capture enough AGK3R reference stars which are needed to consistently provide tenth-of-a-second-of-arc accuracy. To solve this problem, a .24-.32-m, f/6.3 lensless Schmidt was developed to provide a 3.8° field at 135”/mm and is mounted on the .4-m telescope. It can be used by itself and/or to provide a secondary reference frame for the main instrument. The measures from the plates and film are reduced by a suite of interactive computer programs which allows one to choose the proper reduction model based on the Eichhorn criterion. Over 100 positions of stars, asteroids, comets and supernovae have been provided with these instruments, and a regular observing program including participation in the IHW is underway.

Abstract The POLISH2 optical polarimeter has been in operation at the Lick Observatory 3 m Shane telescope since 2011, and it was commissioned at the Gemini North 8 m in 2016. This instrument primarily targets exoplanets, asteroids, and the Crab Pulsar, but it has also been used for a wide variety of planetary, galactic, and supernova science. POLISH2's photoelastic modulators, employed instead of rotating wave plates or ferroelectric liquid crystal modulators, offer the unprecedented ability to achieve sensitivity and accuracy of order 1 ppm (0.0001%), which are difficult to obtain with conventional polarimeters. Additionally, POLISH2 simultaneously measures the intensity (Stokes I), linear polarization (Stokes Q and U), and circular polarization (Stokes V), which fully describe the polarization state of incident light. We document our laboratory and on-sky calibration methodology and our archival on-sky database, and we demonstrate the conclusive detection of circular polarization of certain objects.

Surface layer turbulence has an important influence on land-air interactions and pollutant dispersion, and studying the characteristics of surface layer turbulence in complex terrain can contribute to understanding land-air interactions, improving model surface layer parameterization, and enhancing pollution prediction capabilities. The surface layer turbulence observations from the Semi-Arid Climate and Environment Observatory (SACOL) of Lanzhou University in 2008 were processed in this study. High-quality turbulence parameters were calculated, the statistical and transfer characteristics of turbulence were analyzed, and the formation of turbulence was assessed in terms of dynamics and thermodynamics. The atmospheric stability in the semiarid region of the Loess Plateau is basically dominated by neutral/near-neutral and weakly unstable/weakly stable conditions; this pattern is significantly different from the preponderance of unstable and stable layers at other sites. The turbulence intensity differs significantly in both the horizontal and vertical directions and basically shows the relationship I u ≈ I v > I w . The mean values of I u and I v are 0.42 and 0.40, respectively, and the mean value of I w is 0.14, which is different from the general pattern of I u > I v > I w , indicating that the turbulence intensity at SACOL is characterized by a large lateral wind contribution. The dimensionless standard deviations of the nonneutral wind velocity components satisfy the “1/3rd law,” and the dimensionless standard deviations of u, v , and w components are 3.35, 2.98, and 1.26, respectively, in the semiarid Loess Plateau. These values are larger than those over flat terrain. The contribution of the shear term to the formation of turbulence is greater than that of the buoyancy term, and the mean annual values of the shear term and the buoyancy in the kinetic energy budget equation in SACOL are 47.94 × 10−4 m2·s−3 and 11.32 × 10−4 m2·s−3, respectively. The annual mean values of the momentum transfer coefficient C D and the heat transfer coefficient C H under near-neutral conditions are 8.54 × 10−3 and 2.52 × 10−3, respectively.

AbstractCARMENES (Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical Echelle Spectrographs) is a new instrument currently undergoing commissioning at the 3.5 m telescope of the Calar Alto Observatory. It has been constructed by a consortium of eleven Spanish and German institutions. The scientific goal of the project is a 600-night radial-velocity survey targeting 300 M dwarfs with sufficient precision to detect terrestrial planets in their habitable zones. The CARMENES instrument consists of two separate échelle spectrographs covering the wavelength range from 0.55 to 1.7 μm at a spectral resolution of R = 82,000, fed by fibers from the Cassegrain focus of the telescope. Both spectrographs are housed in a temperature-stabilized environment in vacuum tanks, to enable a long-term radial velocity precision of 1 m s−1. The wavelength calibration will be done with Th-Ne and U-Ne emission line lamps, and with Fabry-Pérot etalons.

AbstractKaz 163 is a close double galaxy. Its southern component S is compact, with a very blue nucleus, in which heated active processes take place. From time to time gas formations are ejected from it, which behave themselves like emission components around the main emission lines Hα and Hβ, around both from their long-wave and short-wave sides. This paper presents the spectral data of new observations, which were carried out with the 2.6m telescope at the Byurakan Astrophysical Observatory in September 2011. During the former observation in October 1981, lines [NII] λλ 6584,6548 were not visible in the spectrum of the component S. In 2001 they were already visible on the spectrum, and on the spectrum obtained in 2011 they already surpassed the intensity of Hα. The magnitude of the component S is also changing: its nucleus is very blue and its U-B = −0m.63. In the soft X-ray spectral range (0.1–2 keV) the flux of the radiation changed by 45% during 55,000 sec, and in the hard one (2–10keV) it changed up to 3.4 times. Photoindices Γ for the soft and hard ranges in the spectrum of galaxy S, unlike other objects, do not so much differ from each other. The mean value for the first interval is approximately 2.5 and is equal −2.0 for the second one. On the histogram of redshifts Kaz 163 corresponds to the first big peak of the distribution. It is concluded that the component S of the galaxy Kaz 163 is a NLS1 galaxy, with the development of their evolution, is in the preliminary stage. Component N is a normal elliptical galaxy with no activity.

Abstract We present the Local Volume Complete Cluster Survey (LoVoCCS; we pronounce it as “low-vox” or “law-vox,” with stress on the second syllable), an NSF’s National Optical-Infrared Astronomy Research Laboratory survey program that uses the Dark Energy Camera to map the dark matter distribution and galaxy population in 107 nearby (0.03 < z < 0.12) X-ray luminous ([0.1–2.4 keV] L X500 > 1044 erg s−1) galaxy clusters that are not obscured by the Milky Way. The survey will reach Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) Year 1–2 depth (for galaxies r = 24.5, i = 24.0, signal-to-noise ratio (S/N) > 20; u = 24.7, g = 25.3, z = 23.8, S/N > 10) and conclude in ∼2023 (coincident with the beginning of LSST science operations), and will serve as a zeroth-year template for LSST transient studies. We process the data using the LSST Science Pipelines that include state-of-the-art algorithms and analyze the results using our own pipelines, and therefore the catalogs and analysis tools will be compatible with the LSST. We demonstrate the use and performance of our pipeline using three X-ray luminous and observation-time complete LoVoCCS clusters: A3911, A3921, and A85. A3911 and A3921 have not been well studied previously by weak lensing, and we obtain similar lensing analysis results for A85 to previous studies. (We mainly use A3911 to show our pipeline and give more examples in the Appendix.)

The ROSAT Wide Field Camera all-sky EUV survey of 1990-91 identified over 200 active late-type stars (Pounds et al. 1993). Most of these were not known to be active prior to the survey and follow-up optical spectroscopy has been successful in selecting the most active dMe stars. These stars are characterized by their Balmer line emission which is direct evidence for an active chromosphere. We present photometric monitoring data for 4 new dMe stars, including the discovery of flaring activity on all 4 stars.The observations were made at the South African Astronomical Observatory at Sutherland near Capetown in October 1994, using the 0.5m and 1.9m telescopes for photometry and spectrometry, respectively. The 0.5m telescope is equipped with an automated, pulse-counting photometer. Flare monitoring of all the stars was done in the U-band with either 5 or 10 s integration times. All the stars monitored were between magnitude V = 11 and 13. A total of 15 flares were detected, including at least one on each star (Table 1). Comparison stars were measured in standard UBVRI photometric bands for each star.

Abstract A new interstellar molecule, FeC (X 3Δ i ), has been identified in the circumstellar envelope of the carbon-rich asymptotic giant branch star IRC+10216. FeC is the second iron-bearing species conclusively observed in the interstellar medium, in addition to FeCN, also found in IRC+10216. The J = 4 → 3, 5 → 4, and 6 → 5 rotational transitions of this free radical near 160, 201, and 241 GHz, respectively, were detected in the lowest spin–orbit ladder, Ω = 3, using the Submillimeter Telescope of the Arizona Radio Observatory (ARO) for the 1 mm lines and the ARO 12 m at 2 mm. Because the ground state of FeC is inverted, these transitions are the lowest energy lines. The detected features exhibit slight U shapes with LSR velocities near V LSR ≈ −26 km s−1 and linewidths of ΔV 1/2 ≈ 30 km s−1, line parameters characteristic of IRC+10216. Radiative transfer modeling of FeC suggests that the molecule has a shell distribution with peak radius near 300 R * (∼6″) extending out to ∼500 R * (∼10″) and a fractional abundance, relative to H2, of f ∼ 6 × 10−11. The previous FeCN spectra were also modeled, yielding an abundance of f ∼ 8 × 10−11 in a larger shell situated near 800 R *. These distributions suggest that FeC may be the precursor species for FeCN. Unlike cyanides and carbon-chain molecules, diatomic carbides with a metallic element are rare in IRC+10216, with FeC being the first such detection.

ABSTRACT We studied the polarized spectrum of the post-AGB binary system 89 Herculis on the basis of data collected with the high-resolution Catania Astrophysical Observatory Spectropolarimeter, HArps-North POlarimeter and Echelle SpectroPolarimetric Device for the Observation of Stars. We find the existence of linear polarization in the strongest metal lines in absorption and with low excitation potentials. Signals are characterized by complex Q and U morphologies varying with the orbital period. We rule out magnetic fields, continuum depolarization due to pulsations and hot spots as the possible origin of this ‘Second Solar Spectrum’-like behaviour. The linear polarization we detected in the Caii 8662-Å line is clear evidence of optical pumping polarization and rules out scattering polarization from free electrons of the circumbinary environment. In the framework of optical pumping due to the secondary star, the observed periodic properties of the spectral line polarization can be justified by two jets, with a flow velocity of a few tens of km s−1, at the basis of that hourglass structure characterizing 89 Herculis. We also discovered linear polarization across the emission profile of metal lines. Numerical simulations show that these polarized profiles could be formed in an undisrupted circumbinary disc rotating at ≤10 km s−1 and with an orientation in the sky in agreement with optical and radio interferometric results. We conclude that the study of aspherical envelopes, the origin of which is not yet completely understood, of PNe and already present in post-AGBs can benefit from high-resolution spectropolarimetry and that this technique can shape envelopes still too far away for interferometry.

A total of 53,259 observations(26,793 in declination and 26,466 in right ascension) of the Sun, Mercury and Venus made with the Washington, six-inch and nine-inch transit circles from 1911 to 1971 and the Cape of Good Hope reversible transit circle from 1907 to 1959 are used to obtain equator and equinox solutions.

Abstract We present UV and/or optical observations and models of SN 2023ixf, a type II supernova (SN) located in Messier 101 at 6.9 Mpc. Early time (flash) spectroscopy of SN 2023ixf, obtained primarily at Lick Observatory, reveals emission lines of H i, He i/ii, C iv, and N iii/iv/v with a narrow core and broad, symmetric wings arising from the photoionization of dense, close-in circumstellar material (CSM) located around the progenitor star prior to shock breakout. These electron-scattering broadened line profiles persist for ∼8 days with respect to first light, at which time Doppler broadened the features from the fastest SN ejecta form, suggesting a reduction in CSM density at r ≳ 1015 cm. The early time light curve of SN 2023ixf shows peak absolute magnitudes (e.g., M u = −18.6 mag, M g = −18.4 mag) that are ≳2 mag brighter than typical type II SNe, this photometric boost also being consistent with the shock power supplied from CSM interaction. Comparison of SN 2023ixf to a grid of light-curve and multiepoch spectral models from the non-LTE radiative transfer code CMFGEN and the radiation-hydrodynamics code HERACLES suggests dense, solar-metallicity CSM confined to r = (0.5–1) × 1015 cm, and a progenitor mass-loss rate of M ̇ = 10 − 2 M ⊙ yr−1. For the assumed progenitor wind velocity of v w = 50 km s−1, this corresponds to enhanced mass loss (i.e., superwind phase) during the last ∼3–6 yr before explosion.

AbstractA project devoted to astrometric and photometric observations of asteroids at the Molėtai Observatory is described. One of its most important results is the discovery of the asteroid 2010 BT3 belonging to the Amor group of the near-Earth objects. The results of astrometric and photometric observations of the asteroid are presented. The brightness variations of the asteroid are found to be about 0.2 mag in R. The orbit of the asteroid was computed from 96 observations. This orbit, combined with the apparent brightness, gives the absolute magnitude 21.34 mag and the diameter between 160 m and 360 m, taking albedos of S-type and C-type asteroids, respectively.

Within the framework of cooperation between Byurakan Astrophysical Observatory and Special Astrophysical Observatory during 2013–2015 y the 1-m Schmidt telescope of the Byurakan Astrophysical was upgraded. We completely redesigned the control system of the telescope: we replaced the actuating mechanisms, developed telescope control software, and made the guiding system. In the Special Astrophysical Observatory the 4k×4k Apogee (USA) liquid-cooled CCD was reworked and prepared. Detector was mounted in the focus of the telescope and provides 1 degree field of view with pixel-size of 0.868, and RON∼11e−. The detector is equipped with a turret with 5 holes for filters. The 20 intermediate-band filters (FWHM= 250A) uniformly covering the 4000–9000 AA wavelength range, five broadband filters (u, g, r, i, z SDSS), and three narrow-band filters. During the first year of test operation of the 1-m telescope we performed pilot observations within the framework of three programs: search for young stellar objects, AGN evolution, and stellar composition of galaxy disks. We confirmed the possibility of efficiently selecting of young objects using observations performed in narrow-band Hα and [S II]filters and the intermediate-band 7500̊Afilter.Three-hours long exposures with SDSS g, r, and i band filters allow us to reach the surface brightness level of 28m from square arcsecond when investigating the stellar content of galaxy disks for a sample of nine galaxies. We used observations performed with the 1-m telescope in five broadband (SDSS u, g, r, i, and z) and 15 intermediate-band filters (4000–7500A) to construct a sample of quasar candidates with 0.5<z<5(330 objects) in about one-sq. degree SA 68 field complete down to RAB=23m. Spectroscopic observations of 29 objects (19.m5<R<22m) carried out at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences confirmed the quasar nature of 28 objects.

We present here the information on the design and performance of the recently commissioned 2.5-meter telescope at the PRL Mount Abu Observatory, located at Gurushikhar, Mount Abu, India. The telescope has been successfully installed at the site, and the Site Acceptance Test (SAT) was completed in October 2022. It is a highly advanced telescope in India, featuring the Ritchey-Chrétien optical configuration with primary mirror active optics, tip-tilt on sideport, and wave front correction sensors. Along with the telescope, its two first light instruments namely Faint Object Camera (FOC) and PARAS-2 were also integrated and attached with it in the June 2022. FOC is a camera that uses a 4096 X 4112 pixels detector SDSS type filters with enhanced transmission and known as u’, g’, r’, i’, z’. It has a limiting magnitude of 21 mag for 10 minutes exposure in the r’-band. The other first light instrument, PARAS-2, is a state-of-the-art high-resolution fiber-fed spectrograph operating in the 380-690 nm wave-band, aimed to unveil the super-Earth like worlds. The spectrograph works at a resolution of ∼107,000, making it the highest-resolution spectrograph in Asia to date, It is employed in an ultra-stable temperature and pressure environment, at 22.5 ± 0.001 ◦C and 0.005 ± 0.0005 mbar, respectively. Initial calibration tests of the spectrograph using a Uranium Argon Hollow Cathode Lamp (UAr HCL) have yielded intrinsic instrumental RV stability down to 30 cm s−1.

Landing in the Midwest after a lifetime in Los Angeles, I was shocked to learn how “famous” that great city really is. It used to seem perfectly reasonable that the freeways on CHiPs looked just like the ones I rode to school. When I was five, I remember being secretly bummed that my mom never took us to the disco-classical mural from Xanadu, which I was convinced had to be hidden somewhere in Venice Beach. In high school, it never seemed strange that the Peach Pit on Beverly Hills 90210 was the same as the Rose City Diner. From the L.A. River to the Griffith Park Observatory, from the Hollywood Sign to Venice Beach, the places I had been in, through, and around were inscribed with meanings in ways that I could never fully grasp. Even marginalized localities like Inglewood, Compton, and East L.A., which especially during the 1980s and early 1990s were being ravaged by urban warfare, got to be the stars of movies, songs, and many music videos. And on April 29, 1992, the corner of Florence and Normandie “blew up” into a full blown riot, sparked by the acquittal of the four white officers who beat black motorist, Rodney King. I could watch the city burn on T.V. or from the hill behind my house. All my life, I lived with a foot in each L.A., the one that’s outside my living room and the one that’s inside my living room, oblivious to the fact that I lived in a famous city. It was only after I moved away from L.A. that I realized my homesickness could often be softened by a click of the remote. I could look for a familiar stretch of road, a bit of the skyline, or a clean but otherwise familiar segment of sidewalk, and it didn’t even matter who, what, where, or why was taking place in the story on screen. It was as though fragments of my life had been archived for me in media space. Some memories were real and some just recollections of other representations – like seeing the observatory in Bowfinger and wondering if I was remembering Rebel Without a Cause or a second grade field trip. But when I arrived here, the question that greeted me most often at parties was, “Why are you in Bowling Green!?!” And the second was, “Did you meet any famous people?” And so I tell them about how I went to driver’s education class with Mayim Byalik, the star of Blossom. Or that I met Annette Funicello one New Year’s Eve at my Uncle Phil’s house. Aside from the occasional queer chuckle about my brush with Blossom, this record is unimpressive. People are hoping for something a little bit more like, “I spent the night in jail with Poison,” “I was an extra on Baywatch,” or “I was at the Viper Room the night River Phoenix passed away.” In spite of my lackluster record of interactions with the rich and the famous, I would still get introduced as being “from California.” I had become the recipient of a second-rate, secondhand fame, noted for being from a place where, if I were more ambitious, I could have really rubbed shoulders with famous people. To young people, many of whom were itching to travel to a place like LA or New York, I was a special kind of failure. But if you aren’t famous, if you are a loser like me, life in L.A. isn’t about the a-list at all. It is about living in a city that captures the imagination, even as you walk down the street. So earning notoriety in a city that speaks in spectacle is an exercise in creativity. It seems like everybody, even the most down-to-earth people, are invested in developing a character, an image, a persona that can bubble up and be noticed in spite of the overwhelming glow of Hollywood. Even at my suburban high school, during the late 1980s and early 1990s, I knew upper-middleclass boys who got nose jobs and manicures. I knew girls who would go trolling for rich men to buy them pretty things that their parents couldn’t afford. There were kids whose parents helped them cheat their way into college. There were wannabe junkies who drove their moms’ minivans into the ghetto to score. I saw people panic, pout, and scream over cars and allowances and shoes. I know that consumer culture is growing stronger just about everywhere, but back home it happened a lot sooner and a lot stronger. Because of our proximity to Hollywood, the crest of the cultural tidal wave looks much higher and its force is much stronger. And I guess I was just too fat to be in California, so I left. However, every once in a while, somebody does manage to make a scene in L.A. A little loser, or whatever you want to call one of the peasants who tend to the vast fiefdoms of L.A.’s elites, rises from banality to achieve celebrity, even if it is a minor celebrity, in the City of Angels. One such figure is the notorious Daniel Ramos, who in 1991 became a central figure in the city’s struggle over its own image. Daniel Ramos was not a star, a politician, or a leader of industry – but before he even appeared in the news, he had trafficked illegally in making a name for himself. A teenager from the projects, Ramos was more widely known as “Chaka,” a graffiti writer credited with over 10,000 tags from San Diego to San Francisco. I had seen Chaka’s tags just about everywhere, and had determined that he might be superhuman. His name, taken after a hairy little missing link from the popular fantasy show, The Land of the Lost, made me smirk as it conjured up images of a sub-humanoid with broken dialect creeping out from the darkness with cans of paint, marking the walls with his sign, calling out to the rest of us half-humans stranded in the land of the lost. Meanwhile, L.A.’s rich and famous whizzed by, casting resentful glances at Chaka’s do-it-yourself media blitz. I knew that Chaka was “bad,” but my imagination loved him. And when he allegedly left his mark in the courthouse elevator on the day of his release from a five-month stretch in prison (Costello), I couldn’t help but feel glad to know that Chaka was still alive, that legends don’t die (his name even made it, through the hand of Dave Grohl, into Nirvana’s “Smells Like Teen Spirit Video” in 1991). For me, and I imagine for many others, it was the beginning of a political awakening. I wondered what was so bad about graffiti, even though I had been taught all my life that it was wrong. More than ten years later, as I sit by the railroad tracks in my small, Midwestern town, eagerly waiting for messages from California painted on the sides of boxcars, I find myself asking a related question – what is good about advertising? I’m not the first to make the welcomed association between graffiti and advertising. In an interview with the vastly capable scholar, Joe Austin, New York graffiti legend IZ THE WIZ explained it thusly: OK, now you’re on a poorer economic level and what do you have? Years ago, and even today, a boxer makes a name for himself in the boxing ring. So when this art form starts developing, why would it be any different? It’s all in the name. When you’re poor, that’s all you got. (40) Austin elaborates on this insight, explaining: The proliferation of posters, advertisements, and signs bearing the images and names of products and proprietors in twentieth-century cities is one obvious place to begin. These are the directly visible extensions of individual/corporate identities into the new shared urban public spaces of the streets, a quantitatively and qualitatively new site in human history where hundreds of thousands of often spectacularly displayed names abound, each catching the eyes of potential consumers and imprinting itself on their memories. (39) So, on one level, the story of Chaka is the story of a poor man who went toe to toe with big media, in a town run by big media, and held his own. It is the story of someone who has managed to say in no insignificant way, “I am here.” Or has Ramos himself yelled as he was being shackled by police, “I am the famous ‘Chaka’” (Walker A4). In spite of everything else, Ramos had a name that was widely recognized, respected by some, reviled by others. Nancy Macdonald, in her important study the culture of writing, shifts the focus away from the more solidly class-based argument employed by Austin in his study of the origins of New York graffiti art to one which lends itself more readily to understanding the culture of writing in the 1990s, after hip hop had become more accessible to middleclass enthusiasts. Macdonald explains, “Writers use the respect and recognition of their peers to validate their masculine identities” (124). While I am reluctant to downplay the class struggle that certainly seems to have implicitly informed Chaka’s quest for recognition, his outlaw appeal lends itself such an interpretation. In a city like Los Angeles, where middle class agency and upward mobility for the service class are not simply functions of wealth, but also of scrupulously maintained images, feelings of powerlessness associated with the lack of a compelling image are to be expected. It is the engine that drives the exuberant extravagance of consumer culture, lifestyle choices, and ultimately biopolitics. In a society where culture and capital are the dual poles which determine one’s social standing, the pursuit of notoriety is not simply a measure of masculinity – hijacking images is a way to assert one’s agency in spite of the diminished value of unskilled labor and the collective fear of underclass masculinities. In her book Wallbangin’: Graffiti and Gangs in L.A., Susan A. Philips provides discussion of Chaka’s contribution to L.A. graffiti. Notably, Chaka was seen by those in the graffiti community as an everyman, who was responsible for two significant cultural achievements: he “open[ed] up the style of the New York-based tags and creat[ed] the phenomenon of the individual tagger” (Phillips 320). He also, as Phillips notes, “wrote tags that you could read…in blockish gang-type lettering” (320). Unlike his New York graffiti-writing peers, which are best known for their beautiful “wildstyle,” Chaka did not typically traffic in multicolor murals and displays of painterly virtuosity. His chief accomplishment was his cunning pervasiveness and daring criminality. As such, his body of work should be seen as incompatible with High Art attempts to bring collectible graffiti into gallery spaces through the 1980s and ‘90s. Chaka’s medium, in a sense, has less to do with paint, than it has to do with the city and its rules. For the majority of the public, Chaka was seen as an individual face for the graffiti pandemic that was strategically linked in the public mind with specter of gang violence. However, to those familiar with the writing scene in L.A., Chaka is more than a lone individual: THE OG’Z OF THE LEGION OF DOOM WERE THE ONE RESPONSIBLE FOR BRINGING THE EARLY LOS ANGELES GRAFFITI SCENE TO IT’S KNEES! AND GAVE US MOST OF THE LEGENDS WE KNOW TODAY! I REMEMBER I TIME WHEN EVERY LOS ANGELES INTERSTATE HEAVEN ROCKED BY EITHER LEST-CAB-STANS-SUB OR THE CHAKA!!! (god i miss those days!) remember the CAB undercover story on the news where he did those loks on dope throwies on the 110 pasadena? I think it was chuck henry channel 7 ??? does anyone still have that on vhs? i had it on vhs along with the CHAKA PUBLIC SERVICE ANOUNCEMENT (that was great!). (Poncho1DEcrew) Instead of being an individual tagger, Chaka is recognized as a member of a crew (LOD), who managed to get up in legendary ways. In reclaiming freeway overpasses (the “Heavens”), walls, trains, road signs, and just about everything else for his crew, vicariously for the many other people who respect his name, and also for himself, Chaka is more than simply selfish, as is often suggested by his detractors. In the heavens is the right place to begin. High up in the sky, over the freeways, for all to see, the writing in the heavens is visible, mysterious, and ultimately risky. The problem of climbing along the girders underneath the bridges, escaping detection, but leaving something bold points to what distinguishes writing from an ad-campaign. Sure, some of what the tagger does is about simply being a recognized image all over the place. But the other part is about finding the place, working within environmental constraints, battling against time, stretching one’s limits, and doing it with style. While the image may be everywhere, the act of writing itself is a singularity, shrouded by secrecy, and defined by the moment of its doing. The aftereffect is a puzzle. And in the case of Chaka, the question is, “How the hell did this guy get up over 10,000 times?” While I can’t see how he did it and I don’t know where, exactly, he got all that paint, I do know one thing: Chaka went everywhere. He mapped the city out as a series of landmarks, he put his name to the space, and he claimed Los Angeles for people other than the ones who claim to own the rights to beam their generalized and monolithic messages into our living rooms. Instead of archiving the city in the banalities of mass media, he has created an archive of an alternative L.A., filled with singularities, and famous in the way that only one’s hometown can be. Instead of being a celebrity, renowned by virtue of a moderately unique character, his ability to generate money, and an elite image, Chaka represents an alternative fame. As a modern day “everyman” and folk hero, he brings a message that the city belongs to all people. Far from the naïve and mean-spirited equations between graffiti writing and canine scent-marking as a primitive drive to mark territorial boundaries with undesirable substances (writers:paint::dogs:piss), Chaka’s all-city message is not so much a practice of creating exclusionary spaces as it is an assertion of one’s identity in a particular space. A postmodern pilgrim, Chaka has marked his progress through the city leaving a perceptible record of his everyday experience, and opening up that possibility for others. This is not to say that it is necessary for all people to paint in order to break loose from the semiotic order of the city, it is only to say that is hopeful to realize that this order is not fixed and that is not even necessarily our own. Reflecting back on my own experience as one who has grown up very much in love in the produced spaces of the scripted and archived fame of Los Angeles, the realization that such an overwhelming place is open even to my own inscriptions is an important one. This realization, which has been many years in the making, was set into place by the curious fame of Chaka. For a writer and scholar disturbed by the “death of the author,” it comes as a relief to see writing resurrected in the anti-authoritarian practice of a teenage boy from the projects. References Austin, Joe. Taking the Train: How Graffiti Art Became an Urban Crisis in New York City. New York: Columbia UP, 2001. Costello, D. “Writing Was on the Wall.” Courier-Mail 9 May 1991. Macdonald, Nancy. The Graffiti Subculture: Youth, Masculinity and Identity in London and New York. Hampshire: Palgrave, 2001. Phillips, Susan A. Wallbangin’: Graffiti and Gangs in L.A. Chicago: U of Chicago P, 1999. Poncho1DEcrew. 50mm Los Angeles Forum. 18 June 2004. 11 July 2004 http://www.50mmlosangeles.com/>. Walker, Jill. “Letter from the Streets; Handwriting on the Wall: 10,000 Chakas.” Washington Post 4 May 1991: A4. Citation reference for this article MLA Style Heckman, Davin. "Being in the Shadow of Hollywood: Celebrity, Banality, and the Infamous Chaka." M/C Journal 7.5 (2004). echo date('d M. Y'); ?> <http://journal.media-culture.org.au/0411/12-heckman.php>. APA Style Heckman, D. (Nov. 2004) "Being in the Shadow of Hollywood: Celebrity, Banality, and the Infamous Chaka," M/C Journal, 7(5). Retrieved echo date('d M. Y'); ?> from <http://journal.media-culture.org.au/0411/12-heckman.php>.