bluuebunny/crossref_metadata_2025 huggingface dataset:
Ground-Based Observations of PKS2155-304 in November 1991
Authors: Blecha A. , Courvoisier T. J.-L , Aller H. D. , Aller M. F. , Bouchet P. , Bratschi P. , Carini M. T. , Donahue M. , Feigelson E. D. , Filippenko A. V. , Glass I. S. , Heidt J. , Hughes P. A. , Kollgaard R. I. , Matheson T. , Miller H. R. , Noble J. C. , Smith P. S. , Wagner S.
Published: July 2016

We present ground-based data of the BL Lac object PKS 2155-305 obtained during a large international campaign spanning the electro–magnetic spectrum from the radio waves to X-rays in November 1991. For the complete description of the observations and data analysis we refer to the paper by Courvoisier et al. 1993, and references therein. The ground-based data include radio, infrared JHKL and UBVRI fluxes as well as optical and near IR polarimetry.

The broad-band optical and near IR data from U to I exhibit the same behaviour in all bands: the flux nearly doubled over the well-covered period of 23 days. The cross-correlation function does not reveal any significant changes in the light-curves. Though significant variations in 24 hours have been recorded, the cumulated Fourier power spectrum drops to the noise level for periods shorter than 2.5 days. The spectral index remained constant.

The polarised flux varied by a larger factor than the total flux and did not follow the same pattern. The degree of polarisation and polarisation angle are nearly independent of the wavelength and are strongly correlated in all filters.

In the radio domain the spectral index increased from −0.1 on November 5 to +0.02 on 25-th.

The absence of the lag between the optical and infrared bands and the polarisation variations are consistent with a model in which the variability is caused by micro-lensing of the source (Stickel, Fried and Kühr 1988). One would, however, expect in this model that the variation in the polarisation and the total flux are tightly correlated contrary to what is observed.

The constant shape of the continuum spectral energy suggests that only the number of electrons whose emission is beamed towards the observer changes, rather than the arrival of fresh electrons that are being accelerated.

The variability of the polarisation may be explained by changes in the geometry of the magnetic field (dominant direction). This is consistent with the observed variations of the polarisation angle.
Observations of PKS 2155–304 with the Extreme Ultraviolet Explorer
Authors: Fruscione A. , Bowyer C.S. , Carone T.E. , Kahn S.M. , Königl A. , Marshall H.L.
Published: July 2016

We have studied the first extreme ultraviolet spectroscopic data and a high accuracy light curve for the BL Lac object PKS 2155–304 observed with the Extreme Ultraviolet Explorer (EUVE) on July 21–22, 1992. This target was observed with the Deep Survey Spectrometer telescope for approximateley 30,000 sec during the in-orbit-calibration phase of the mission, allowing to obtain simultaneous image and spectrum.
Simultaneous Long Term Millimetre and Sub-millimetre Monitoring of Blazars
Authors: Litchfield S.J. , Stevens J.A. , Robson E.I.
Published: July 2016

We have monitored a sample of 17 blazars at 375, 270, 230 and 150 GHz with the James Clerk Maxwell Telescope (JCMT). We also have 230, 150, 90 GHz data from IRAM and SEST, and 37, 22 GHz from Metsähovi Radio Research Station, Finland. The data shows a range of flaring time-scales, from months for e.g. 0851+202 to years in the case of e.g. 1641+399. Superimposed shorter time-scale variability (‘flickering’ behaviour) is seen in many sources from our sample. We make no conclusive statements on whether BL Lacs as a class are preferentially variable on shorter time-scales. All sources show variability on many time-scales regardless of classification.
Multifrequency Observations of the Jet of 3C 273
Authors: Röser H.-J. , Meisenheimer K. , Neumann M. , Conway R.G.
Published: July 2016

Previously we have studied the jet of the quasar 3C 273 at optical and radio frequencies. In our first set of X-ray data with 17.2 ksec integration time obtained with the ROSAT HRI, the jet is easily visible extending out from the bright quasar core. The total number of counts in the jet lies in the range 200 to 300, depending on the details of the background model. This corresponds to an X-ray flux fv(2.9 × 1017 Hz) = 65 … 140 nJy (lower limit, synchrotron radiation α = −0.8 … upper limit, bremsstrahlung α = 0, NHI = 1.8 × 1020 cm−2), in good agreement with the value derived from the EINSTEIN observations.
Auger Process Following 1s-Photoionization: Ne III and Ne IV Line Production
Authors: Petrini D. , De Araújo F.X.
Published: July 2016

Removal of a 1s electron from atomic neon by highly energetic photons, gives rise mainly to the 1s2s22p6 state of singly ionized neon. This state c decay mostly by ejection of an Auger electron to form various excited terms of Ne+2. This process dominates largely the radiative Kα decay (ωK = 0.018). The main route to Ne+2 is 1s22s22p41D (61%) and there is no Auger decay to the ground final term (Krause et al, 1971). Shake up processes, i.e excitations of outer shells accompagning the 1s–electron ejection, produce mainly 1s2s22p5 np 2S states (n=3,4), 5% relatively to all processes (Krause, 1971). These np states radiationless decay producing numerous Ne+2 states. Shake off processes, i.e. ionizations of outer shells by the photoelectron, are not negligible, nearly 14% relatively to all processes (Krause, 1971) for photons with energy greater than 1 keV. Shake off process leads by radiationless transitions to three or four times ionized neon. The 1s2s2p5 state is strongly favoured by shake off process and decay to the main configurations of Ne+3 1s22sm2pn (Krause, 1971). In an analagous way, the case of oxygen presents the same interesting features but there is actually a lack of experimental and theoretical data (Caldwell and Krause, 1993, Petrini and Araújo, 1993).
Supernova Fragments and the Origin of the Rapid X-ray Variability
Authors: Cid Fernandes R. , Terlevich R. , Tenorio-Tagle G. , Franco J. , Rozyczka M.
Published: July 2016

The Starburst model for Radio Quiet Active Galactic Nuclei proved able to explain the origin of the broad line region, the variability characteristics of line and continuum in Seyfert galaxies, X-ray spectra, the luminosity function of QSOs and etc. But can we understand the rapid X-ray variability observed in several AGN with supernovae?
Soft X-ray Emission of Quasars
Authors: Schartel N. , Walter R. , Fink H.H.
Published: July 2016

From a list of known quasars compiled from various catalogues we selected all sources detected by the PSPC (0.1 – 2.4 keV) aboard ROSAT with more than 80 counts during the all sky survey. A sample of 102 sources resulted. At higher redshifts most of the selected sources are radio-loud. At a redshift smaller than 0.50 we found 54 radio-quiet quasars and 30 radio-loud sources. For this reduced sample the mean spectral index of the radio-quiet sources (< Γ > = 2.53) and that of the radio-loud ones (< Γ > = 2.26) are clearly different with a significance of 3.3 σ.

About 2/3 of the bright quasars observed with Einstein also belong to our sample. The spectra observed with ROSAT are sytematically steeper than the ones observed with Einstein yielding a < ΓROSAT – ΓEinstein > of 0.66 ± 0.18 for radio quiet and of 0.68 ± 0.19 for radio-loud sources, respectively.

For radio loud quasars, the mean spectral slope decreases from 2.3 to 1.5 when the redshift increases beyond 0.5 (figure 1). The fact that high redshift sources show a photon index of about 1.5, which is similar to the mean index observed with Einstein for radio-loud sources, suggests that this decrease towards higher redshifts can be interpreted by the shift of the soft X-ray excess outside of the ROSAT spectral band when the redshift increases. The solid lines in figure 1 represent theoretical pathes of the photon index as a function of the redshift as derived from simulations assuming a power law plus black body model spectrum for the quasars X-ray emission. In curve No 1 the powerlaw index is fixed to 1.4. To be compatible with the observation the temperature of the blackbody component must range between 50 and 70 eV. Curve No 2 asssumes the same model with a powerlaw index fixed to 1.8 to account for radio quiet sources.
X-rays from Photoionized Accretion Discs
Authors: Matt G. , Fabian A.C. , Ross R.R.
Published: July 2016

The presence of iron lines and high energy excesses in the X-ray spectra of Seyfert galaxies has been firmly established by Ginga (e.g. Nandra & Pounds 1993 and references therein). These features are generally interpreted as signatures of the reprocessing of the primary X-rays by matter in the neighbourhood of the central black hole, probably distributed in an accretion disc (Lightman & White 1988, George & Fabian 1991, Matt, Perola & Piro 1991).
X-ray Observations of Blazars with Ginga and ASCA
Authors: Tashiro M. , Makishima K. , Kohmura Y. , Ohashi T. , Otani C. , Kii T. , Fujimoto R. , Makino F. ,   Ginga Team,   ASCA Team
Published: July 2016

Among 13 BL Lacs observed with Ginga, 1H 0323+022, Mkn 421 and PKS 2155-304 exhibited significant variablity during each (typically one day) observation. On the flux-hardness plane, the data points obtained from each source draw a sort of clockwise hysteresis motion. It means that the spectrum hardens before the source gets brighter, while the spectrum softens before the source becomes fainter. Such a soft-lag behavior, first pointed out for PKS2155-304 by Sembay et al. These properties were also confirmed with the discrete cross correlation function technique.
ROSAT Spectra and Lightcurves of Bright BL Lacertae Objects at Low Interstellar Absorption
Authors: Thomas H.-C. , Fink H. H.
Published: July 2016

A programme to obtain soft X-ray spectra of bright BL Lac's from pointed observations with ROSAT has been started. So far 13 objects have been observed and another 6 have been accepted for observation. Available data for the following sources were reduced: OQ 530, OJ 287, B2 0912+29, GB 1011+496, ON 231, B2 1215+30, B2 1308+32, and Mrk 421.

In this sample the most outstanding observation clearly is that of Mrk 421. This source was observed with the ROSAT PSPC for a total of 34 ksec between May 5 and May 7, 1992, at a mean countrate of 159 cts/s (see Fink et al., 1991, A&A246, L6 for ROSAT survey results). At the time of the observations Mrk 421 was also very luminous in the optical bands (see poster by S. Kikuchi, this conference). Within the ROSAT band the spectrum is flatter at the soft end (photon index for broken power law model between −2.2 and −2.0) than at the hard end (photon index between −2.6 and −2.4). The countrate increases during the first 5 orbits with a maximum e-folding time of 1.5 days, reaching a maximum luminosity of 4 × 1045erg/s in the energy range of 0.1 to 2.4 keV (for H0 = 75km/s/Mpc). It is followed by a slow decline until a second rise starts which is much stronger in harder X-rays than at low energies. Plotting the hardness ratio (defined as the difference in the countrates above and below 0.5 keV divided by the total countrate) versus the total countrate the second rise displays a much steeper gradient than the first one (see figure 1a).

For most of the other BL Lac's the countrates are too low to detect variability on these timescales of hours to days, except for B2 1215+30 and OQ 530, where the chance probability for the observed variations is 4 × 10−4 and 10−10, respectively. Also no clear correlation between hardness ratio and countrate could be found. Spectral fits of single power law models with absorption result in photon indizes ranging from −3.1 to −1.9 with no detectable absorption above the galactic value for 5 of these sources, and some additional absorption for GB 1011+496 and B2 1215+30 (see figure 1b).
Centiarcsecond Structure and Variability of AGN
Authors: Altschuler D.R. , Gurvits L.I. , Alef W. , Graham D. , Dennison B. , Carson J.E. , Trotter A.S.
Published: July 2016

One possible approach to distinguish between “intrinsic” and “external” mechanisms for variability implies a study of possible correlations between flux variability and the fine structure of sources. We present results of snapshot global VLBI observations at 327 MHz of a sample of 16 extragalactic radio sources (1 radio galaxy, 9 quasars, 4 BL Lacs, 2 unidentified) selected on the basis of the bi-monthly flux monitoring at five frequencies (1400, 880, 606, 430, and 318 MHz). The observed source sample is presented in the Table I.
Variable IR and Optical Sources in Blazars
Authors: Hagen-Thorn V.A.
Published: July 2016

As was shown by Choloniewski (1981), in the frame of two-component model (constant component + variable source) the confrontation of the fluxes observed in various spectral bands permits to find relative spectral energy distribution (if it is unchanged) of the variable source. In this case the observed points are settled on straight lines the slopes of which give the flux ratios in various bands for the variable source.
Line Profile Variations in AGN
Authors: Kollatschny W. , Dietrich M.
Published: July 2016

An international collaboration is monitoring the variable Seyfert galaxy NGC 5548 in the optical spectral range since 1988. In Fig. 1 (left) the Hα light curves of the blue wing (–6000 until – 1000 km s−1) and the red wing (+1000 until + 6000 km s−1) are shown for the first year of the monitoring campaign from Dec.1988 until Oct.1989. It can be seen that these line components of the Hα profile have different amplitudes in the light curves. The mean Hα and Hβ difference spectra with respect to the minimum state are plotted in Fig. 1 (right) for the same period. The relative strength of the blue component at vrel = −2000 km s−1 is different with respect to the core of the line profiles. Therefore, these components originate under different physical conditions or in regions with different dust content. This work has been supported by DFG grant Ko 857/13-1
Coordinated Multifrequency Observations of OJ 287 and MK 421 (March 1993)
Authors: Sillanpää A. , Takalo L.O. , Valtaoja E. , Teräsranta H. , Efimov Yu.S. , Shakhovskoy N. , Heidt J. , Bock H.
Published: July 2016

We present some very preliminary results of the multifrequency microvariability campaign of two BL Lac objects OJ 287 and Mk 421 carried out mainly during four days in March 1993. During these four days also IUE was observing these blazars. In this poster we present only a small part of the whole data: radio observations at Metsähovi, CCD observations on La Palma and Heidelberg and UBVRI photopolarimetric observations at Crimea. Because of the very bad global weather conditions and also because of the faintnes of OJ 287 our optical observations were very limited.
Long Term Monitoring of AGN with the Metsähovi and SEST Telescopes
Authors: Teräsranta H. , Tornikoski M. , Valtaoja E.
Published: July 2016

The monitoring of extragalactic sources with the Metsähovi radio telescope started in 1980. Since then we have made more than 21000 observations at 12, 22, 37, 77 and 87 GHz. Currently we have 84 sources in our sample which should be observed once a month at 22 and 37 GHz. The sample is limited to declinations above −10 degrees. In most cases our sampling is dense enough to cover all the outbursts at these two frequencies, because our earlier observations have shown the timescales of a typical outburst at 22 and 37 GHz to be from 0.3 to several years.
On the Age of GPS Radio Sources
Authors: Carvalho Joel C.
Published: July 2016

The GHz-Peaked-Spectrum (GPS) radio sources are galaxies and quasars with compact structures on scales of tens to hundreds of parsecs and spectrum peaking around 1 GHz. Phillips and Mutel (1982) suggested that the double GPS sources (also called compact doubles, CD) are an early stage of the evolution of the classical double sources of Fanaroff-Riley class II type. We have presented a model (Carvalho, 1985) in which we show that the properties of the CD sources are consistent with such a scenario. Their ages would be of the order of 104 yr.
Interpretation of Some Properties of Extragalactic Jets in the Context of a Two Component Model
Authors: Vicente Lourdes
Published: July 2016

We have studied a sample of extragalactic jets within the context of a two component model. This model supposes the existence of two flows in the extragalactic jets. An electron-positron fast beam coming from the internal regions of the accretion disk, responsible for the VLBI jet at the parsec scale and for the observed superluminal speeds. A second slow component, responsible for the jet observed at larger scales. The fast beam is destroyed when the parallel magnetic field is smaller than a critical value, BII < Bcrit = 3.2 × 10−3np1/2, where np is the density of the background thermal plasma of the slow component.
Emission Line Variations of BLRG
Authors: Dietrich M. , Kollatschny W.
Published: July 2016

In late 1989 we started a monitoring campaign of the line profile variations of more than 40 Broad-Line Radio Galaxies (BLRG) at Calar Alto Observatory/Spain. BLRG are the most extreme species of AGN regarding line width and structure of their optical emission line profiles showing FWZI up to 35000 km s−1, eg. 3C332 or Arp102B. Quite often the broad emission line profiles are characterized by a double hump structure. The analysis of the broad emission lines provides information about fundamental parameters of the inner part of the AGN like size, structure and kinematics of the line emitting region. In the following we present line profile variations of a BLRG we are studying.
Composite Models for Narrow Line Regions
Authors: Komossa Stefanie
Published: July 2016

The basic excitation mechanism for the emission lines of Seyfert galaxies is generally believed to be photoionization by radiation emerging from the central power source. In order to deduce the essential physical parameters appropriate to the narrow line region (NLR) on this basis and to overcome some systematic deficiencies of existing photoionization models, we drop the frequent assumption of a constant ionization parameter throughout the NLR and, in particular, allow for a range of densities at fixed radius. We predict all observed emission-lines (ranging from CIV λ1549 in the UV- to [SIII]λ9069 in the NIR spectral region) for the sample of Sy 2 galaxies using the code CLOUDY (Ferland 1993).
Size of the Broad Line Region in NGC 3227: Results from the LAG Campaign
Authors: Salamanca I. , Baribaud T. , Alloin D.
Published: July 2016

We present the results of a monitoring campaign of the AGN in NGC 3227, conducted at La Palma by the LAG european consortium. The data are long slit spectra, obtained with the 1.5m INT and 4.2m WHT, from January to June 1990. The slit width was 1.5 arcsec. The spectral resolution was about 3 A.
A Unified View of NGC 4151
Authors: Schulz Hartmut
Published: July 2016

Using crude constraints from recent HST images, we fit the emission-line spectra of the NLR and VNLR of NGC 4151 with photoionization models. There is no need for an intrinsic anisotropy of the distribution of the ionizing flux.
The Anisotropic Radiation Field in NGC 3516
Authors: Yankulova I. , Golev V. , Bonev T. , Jockers K.
Published: July 2016

We present new narrow-band images of the Extended Emission-Line Region (EELR) in NGC 3516 in light of [O III] λ 4959, Hα + [N II] λλ 6548, 84, [O I] λ 6364, He is/c λ 6678 and [Fe VII] + [Ca V] λ 6087. The observations were carried with the 2-m reflector of the Bulgarian National Astronomical Observatory and the Focal Reducer of the Max-Plank-Institut for Aeronomy. Our [O III] and Hα + [N II] images confirm previously reported EELR features. In contrast, the image in the high-excitation [Fe VII] + [Ca V] line shows a different structure. We identify a biconical morphology over a kiloparsec scale with peak intensities 5.9 × 10−16 ergs cm−2 s−1 arcsec−2 and 3.5 × 10−16 ergs cm−2 s−1 arcsec−2 to north and south of the nucleus, respectively. The total flux of the [Fe VII] + [Ca V] emission in 5″ and 24″ circular apertures centered at the nucleus is (9.97 ± 0.38) × 10−14 ergs cm−2 s−1 and (1.53 ± 0.15) × 10−13 ergs cm−2 s−1, respectively, which is in good agreement with measurements of Boksenberg & Netzer (1977) through the 5″ aperture. The cone axis lies at PA ∼ −10°. The continuum images (Veilleux et al., 1993, Miyaji et al., 1992) indicate a “bar” aligned along PA ∼ −10°. The velocity extrema regions revealed by Veilleux et al. (1993) are coincident with the peak intensities in our [Fe VII] + [Ca V]. We suppose that our image in [Fe VII] + [Ca V] outlines a Coronal-Line Region (CLR) of NGC 3516, which extends far beyond the classical NLR of the galaxy. Korista & Ferland (1989) have recently shown theoretically that the CLR in Seyferts may be a result of a low-density interstellar medium exposed to and photoionized by a “bare” active nucleus. A typical ISM with Ne ∼ 1–5 cm−3 may produce such an extended CLR as that observed by us.
The Intranight Variability of Optical Polarization in PKS 0109+224
Authors: Valtaoja L.
Published: July 2016

It is found that the statistics of the photopolarimetric intraday data of PKS 0109+224 do not favor the shocked jet scenario as an explanation for intranight variability in this source.
On the Accretion Disk Models by Stationary and Non-Stationary Shock Waves
Authors: Chakrabarti Sandip K.
Published: July 2016

An important point which emerged from this meeting is that disks in AGNs are not simply thin, Keplerian type; they show more complex behaviour. Chakrabarti (1990a and references therein) has shown that in an inviscid accretion disk with significant angular momentum, the centrifugal barrier is strong enough to produce axisymmetric standing shock wave. Subsequently, this work was extended to include the non-axisymmetric and viscous disks (Chakrabarti, 1990b). Particularly important are the solutions with viscosity, as they show that as the viscosity is increased, the stable becomes weaker and weaker till it disappears completely. This solution has a unifying character that inviscid pressure driven disks have almost constant angular momentum and can have shock discontinuities, but viscous driven disks dissipate angular momentum quick enough not to have centrifugal barrier and therefore no shock waves. Chakrabarti & Molteni (1993), using Smoothed Particle Hydrodynamics have shown that shocks are produced in inviscid disks, exactly where they are predicted.

Unlike a Keplerian disk, a disk with a shock has basically two temperature zones. The post shock solution is responsible for the Big Blue Bump and UV excess (Chakrabarti and Wiita, 1992). At the shock location, the disk is ‘bulged’ the hard radiation from this region is intercepted by the cooler pre-shock flow. The shock strength and location are sensitive to input specific energy of the flow. This configuration might be responsible for the ‘zero-lag’ correlated variability of, say, NGC 5548 (Chakrabarti, Haardt, Maraschi & Molendi, AA, submitted) discussed in this meeting. Spiral shocks which may be produced in disks in a binary system can also appear in disks around AGNs; the perturbation may be due to passage of massive objects (Chakrabarti & Wiita, 1993a). They also cause time variations in the double horned pattern from disk line emission (Chakrabarti & Wiita 1993b) as observed in, say ARP 102B. All these observations point that shocks are probably important ingredients in any accretion disk in AGNs
AGN Accretion Disks with Finite Turbulent Prandtl Number
Authors: Heinrich O. M.
Published: July 2016

The present paper reports results of a study of turbulent energy transport in AGN accretion disks. We follow the spirit of the papers by Shakura et al. and Rüdiger et. al in which the concept of an eddy heat conductivity was introduced and developed. For the viscosity we use a standard α− description with the main component of the stress tensor trø proportional to the gas pressure. The dimensionless Prandtl number Pr given as the ratio of turbulent kinematic viscosity and turbulent heat conductivity enters the model as a free parameter. The disk structure depends sensitively on material properties such as opacities and specific heats. In our calculations we have used an equation of state and mean opacities taking into account a list of the most important ionization processes as well as the radiation contributions to thermodynamic quantities.
Simultaneous Implosive Accretion and Jet Formation in Quasars: Correlation of Optical Outbursts by VLBI Jets
Authors: Romanova M.M. , Lovelace R.V.E.
Published: July 2016

A model and simulation code have been developed for time-dependent axisymmetric disk accretion onto a compact object including for the first time the influence of an ordered magnetic field and magnetically driven outflow of energy and angular momentum in (±z) directions (see also Lovelace et al., 1993). It was shown that the system behaviour crucially depends on the amplitude of the poloidal magnetic field fluctuation Bp, compared to the critical value Bcr ∼ (α2T1/2σ/R3/2)1/2, where T(r, t) is the temperature, σ(r, t) the surface density of the disk, R the radial distance, α the alpha coefficient of Shakura-Sunyaev disk model. If the fluctuation is small, Bp < Bcr, then it diffuses outwards with decreasing the amplitude and eventually disappears. In the opposite case Bp > Bcr, a soliton-like structure forms in the disk density, temperature, and magnetic field and propagates implosively inward. In this case the radial accretion speed u(r, t) is shown to be the sum of the usual viscous contribution and magneitic contribution ∼ R3/2B2p/σ. The essential part of angular momentum and energy is going to the jet from the region of fluctuation. Compression of matter in the propagating wave leads to enhancement of magnetic field and more effective angular momentum outflow. This leads in turn to accelerated accretion and subsequent enhancement of magnetic field. It gives the implosive nature of the process, which can be observed as: simultaneous burst in the radiation and outflow. The model is pertinent to the formation of discrete components observed in VLBI jets which appear to originate at times of optical outbursts at some quasars.
Hybrid Accretion-Disks in AGN and the AGN Contribution to the XRB
Authors: Wandel Amri
Published: July 2016

The hybrid accretion-disk (HAD) model links the two characteristic components of AGN spectra – the UV bump and the X-ray power-law – in the framework of one physical model. The radially stratified hybrid disk is a self consistent combination of a thin, cool accretion disk at large radii, with an inner hot two-temperature disk. Its spectrum consists of three components, corresponding to the three radial disk regions: a blackbody thermal spectrum from the outer cool disk, a Comptonized soft photon power-law spectrum from the intermediate region, and a thermal Comptonized bremsstrahlung spectrum from the inner region. The dependence of the hybrid disk spectrum on the accretion rate and on other parameters is discussed and applied to AGN spectral evolution, and in particular to explaining the cosmic X-ray background by AGN.
Spatial Distribution of Quasars in the LBQS Sample
Authors: Chu Yaoquan , Tao Jianhui
Published: July 2016

The information of spatial distribution of quasars would be very important in building the model of formation of AGN. Following the development of high efficiency detectors and related technique, quasar samples with less selection effect were and will gradually available. As we know that the power spectrum analysis gives a more robust determination of large scale distribution of objets. We develop a new methods to determine the power spectrum in a three dimension ball, which is more suited to the case of quasars survey. The details of our approach can be found in Tao and Chu (1993).
On the Way AGN's Turn Off
Authors: Friedli D.
Published: July 2016

Observations of nearby galaxies indicate non-negligible (dark) mass in their nuclei, interpreted either as very dense clusters or Massive Black Holes (MBH's). The latter hypothesis is supported by the widespread idea that MBH's can be the engine powering Active Galactic Nuclei (AGN's), and that interaction- or bar-induced central mass accretion can feed MBH's with large scale, plentiful fuel. However, there are fewer AGN's at the present time than at high redshifts, although many if not all bright galaxies must harbour relics of central active MBH's. How can we explain the fact that some AGN's are now turned off? Is it only due to the exhaustion or evaporation of the available fuel, and/or to the lower rate of interactions at the present epoch?
Radio to X-ray Energy Distribution of BL Lacertae Objects
Authors: Giommi P. , Ansari S. G. , Micol A.
Published: July 2016

We have constructed radio to X-ray energy distributions for a large number of BL Lacertae objects using archival data. We find that Radio to optical spectra of RBLs and XBLs are very similar. Large differences are seen at higher frequencies where RBLs very frequently show a cutoff near the optical band while XBLs usually do not show any turnover before UV/X-ray energies. Our data is consistent with a picture where RBL and XBL are from the same parent population, the XBL simply being those (rare) objects where the break in the energy distribution is located at high energy.
A ROSAT Survey of a Spatially and Magnitude Complete Quasar Sample
Authors: Molthagen K. , Wendker H.J. , Briel U.G.
Published: July 2016

The field studied is part of the Hamburg Quasar Survey (Engels et al. 1988, PASPC 2, 143). It contains a spatially and magnitude (down to ∼ 18.m5) complete AGN sample. Several follow-up observations were made: a deep radio continuum survey at 21 cm and 74 cm, a HI survey and a ROSAT survey consisting of 48 overlapping PSPC pointings with .
Buried Quasars in Radiogalaxies?
Authors: Simpson C.J. , Ward M.J. , Clements D.L. , Rawlings S. , Wilson A.S.
Published: July 2016

We report on the results of a near-infrared imaging survey of low-redshift radiogalaxies. We find that one of our 13 objects harbours an unresolved source at K, which we interpret as a quasar-like central engine seen through ∼ 40 magnitudes of visual extinction.
A Comparison of the Centimetre-to-Submillimetre Continuum Spectra of BL Lacertae Objects and Flat Spectrum Radio Quasars
Authors: Stevens J.A. , Litchfield S.J. , Robson E.I. , Gear W. K. , Hughes D.H.
Published: July 2016

A comparison of the centimetre to submillimetre continuum spectra of 22 BL Lacertae objects and 24 flat-spectrum radio quasars (FSRQ) has been conducted in order to search for systematic differences between the two classes. The same overall spectral shape is found for all sources and it is concluded that the same basic physical model applies to the continuum emission over this frequency range in both cases. There is clear evidence, however, for the BL Lacs to have flatter high frequency spectra and this difference is reconciled with an intrinsic difference in the underlying jets of the two classes.
Notes on the variation of latitude
Authors: Jeffreys Harold
Published: July 2016

If the methods of observation are changed it is most important that there should be some period of overlap so that possible systematic differences can be determined.
A Study of the Magnetic Field of the Moon
Authors: Dolginov S. S. , Eroshenko E. G. , Zhuzgov L. I. , Pushkov N. V.
Published: July 2016

The question as to whether the planets and their satellites possess magnetic fields unavoidably arose in connection with the question as to the origin of the Earth's mágnetic field and the nature of a number of geophysical effects.
The U.S. Naval Observatory Survey of the Marginal Zone of the Moon
Authors: Watts C. B.
Published: July 2016

In a survey of the marginal zone now approaching completion at the U.S. Naval Observatory about 700 photographs of the Moon, made on 503 nights, have been utilized. These photographs, made at the Naval Observatory, the Yale-Columbia Southern Station at Johannesburg, and the Lowell Observatory, were measured by an automatic photoelectric device. The measures were recorded graphically in the form of profiles, which are on a scale of 41 mm per degree in position angle and 16 mm per second of arc in radius.
Television Astronomical Observations at the Pulkovo Observatory
Authors: Kuprevich N. F.
Published: July 2016

In recent years we witnessed in science and technology a wide application of the methods of television in intensifying the brightness of faint images. The increase in brightness of the image makes it, in turn, possible to shorten considerably the time of exposure. In astronomical observations using photographic techniques this proves to be very important, since it enables us to lessen the adverse effects of the atmospheric disturbance and thereby to bring the resolving power of the telescope closer to its theoretical value. Besides, in the television system the image is converted into a series of electrical signals, one following the other with very high speed. This makes it possible to perform any kind of a manipulation with the video signals—for example, to add them, to subtract them, etc., and to examine the results in the form of an image on the screen of the kinescope. On it, it is possible to view at the same time several images of simultaneous phenomena occurring at different points in space. This characteristic of the television system distinguishes it from other methods and possibilities for electron amplification of the brightness of images used in practice.
Laboratory Simulation of Lunar Luminescence
Authors: Geake J. E. , Lipson H. , Lumb M. D.
Published: July 2016

Work has recently begun in the Physics Department of the Manchester College of Science and Technology on an attempt to simulate lunar luminescence in the laboratory. This programme is running parallel with that of our colleagues in the Manchester University Astronomy Department, who are making observations of the luminescent spectrum of the Moon itself. Our instruments are as yet only partly completed, but we will describe briefly what they are to consist of, in the hope that we may benefit from the comments of others in the same field, and arrange to co-ordinate our work with theirs.
Lunar Luminescence
Authors: Grainger J. F. , Ring J.
Published: July 2016

Photometry Of the penumbra of lunar eclipses over a considerable number of years has shown an excess of light over that which can be reasonably explained as an effect of the Earth's atmosphere. Link [1, 2] introduced the hypothesis of surface luminescence on the Moon and showed that it could account for the eclipse phenomenon. However, it is clear that eclipse observations cannot be used to investigate the detailed spectrum and distribution of the luminescent regions. A more powerful approach was suggested by Link [3] which has subsequently been called the “line depth” method.
First Results from Observations of the Moon by Means of a Polarimeter
Authors: Dzhapiashvili V. P. , Ksanfomaliti L. V.
Published: July 2016

Until recently, no instrument was available for a direct measurement of the degree of light polarization and of the angle determining the position of the polarization plane. The degree of polarization was calculated by formulafrom the measurements of the maximum Φmaxand minimum Φminlight fluxes through an analyzer. A laborious additional reduction of the observational data was necessary for obtaining the final characteristics of light polarization.
Eclipse Temperatures of the Lunar Crater Tycho
Authors: Sinton William M.
Published: July 2016

Shorthill, Borough, and Conley discovered during the total eclipse of the Moon on 13 March 1960 that the floor of the crater Tycho did not cool as much as the surrounding area, but remained some 40 to 60° warmer [1]. They found that other rayed craters, specifically Copernicus and Aristarchus, also remained warmer than their surroundings.
Radar Measurements of the Lunar Surface
Authors: Pettengill G. H. , Henry J. C.
Published: July 2016

In this paper some recent measurements of the radio echo power scattered by the lunar surface are reported. These measurements were made at a radio frequency of 440 Mcps using a parabolic reflector of 84 ft diameter and a peak transmitted power of approximately 2·5 MW. The received echo power was processed by a high-speed digital computer which is an integral part of the measuring system.
The Electromagnetic Parameters of Selected Terrestrial and Extraterrestrial Rocks and Glasses
Authors: Fensler W. E. , Knott E. F. , Olte A. , Siegel K. M.
Published: July 2016

Determination of the physical properties of the surface layers of celestial bodies is one of the areas of research in radar astronomy. Radar pulses reflected from such a body contain information about the reflecting surface. Information concerning the composition and density of the outer layer of the lunar surface derived from radar echoes is of practical importance in view of proposed lunar landing.
Laboratory data on atomic spectra for extreme ultra-violet solar spectroscopy
Authors: Edlén B.
Published: July 2016

Expected relative prominence of elements and ionization stages is estimated from existing recordings of the solar XUV spectrum. The following 3 groups of elements, apart from H and He, need be considered : (C, N, O), (Ne, Mg, Si, Fe), (Na, Al, S, Ar, Ca, Ni), the relative abundance descending by approximately an order of magnitude from one group to the next, and all other elements being at least another order of magnitude less abundant. Lines of low and medium stages of ionization are expected only from most abundant elements. The observed presence in the solar spectrum of lines from the neon-like Fe XVII suggests that very high stages of ionization must not be a priori excluded.

These considerations indicate that a discussion of laboratory data may be confined to atomic systems containing from 1 to 18 electrons. Observed data on these 18 isoelectronic sequences, and the possibilities of their extrapolation, are reviewed. It is concluded that required data for the first 10 sequences are well in hand, but considerable laboratory work remains to be done on the third-period sequences.

A comprehensive paper is being prepared for later publication.
Some preliminary results from the solar monitoring Satellite NRL 1964 1 D obtained at the Arcetri Station
Authors: Landini M. , Piattelli M. , Righini G. , Russo D. , Tagliaferri G. L.
Published: July 2016

This paper contains the following subjects; a) a description of the telemetry set operating in Arcetri (Florence, Italy) in order to record the measurements of solar X and UV radiation, via satellite:

b) the values of solar flux at 44–60 Å during the period March-April 1964, as deduced by telemetry of NRL 1964–01 D satellite:

c) a typical example of atmospheric absorption at optical and X-ray wavelengths during the sunrise on the satellite:

d) a particular feature of recording when the satellite passes through the sub-auroral belt.
Rayonnement visible et infrarouge : Soleil, Étoiles, planètes, comètes
Authors: Swings Par P.
Published: July 2016

1)

Visible region.

When carried on board of space vehicles, telescopes can be used with their maximum theoretical resolving power, by avoiding the effects of atmosphere turbulence. As the atmospheric scattering is suppressed, observations of very low contrast phenomena are made easier. Closer observations of the solar system objects are made possible.

2)

Infra red region.

Observations taken from 30 km high are freed of most of the atmospheric absorption. But some infra red observations require the use of satellites (for example scanning of the whole sky within spectral regions). Needed observations are reviewed.
Spacecraft observation of Venus Infra-red limb-darkening
Authors: Sagan Par Carl , Pollack James B.
Published: July 2016

The limb-darkening laws predicted for several models of the atmosphere and clouds of Venus are compared with limb-darkening observations in the 8–13μ interval made from the ground and from Mariner II. Model A attributes the limb-darkening to pure molecular absorption by the atmosphere above the Gytherean cloud layer; Model B, to multiple scattering by cloud particles of arbitrary albedo and altitude distribution. In each model, the temperature regime is considered specified, alternatively by convective and by radiative equilibrium. In Model A, limb-darkening arises from the increase of temperature with atmospheric depth. In Model B, both the T — τ relation and the dependence of emissivity on the angle of emergence contribute to the limb-darkening. Each model can be made to agree with observation, with an appropriate specification of atmospheric and cloud parameters. With the angular resolution available from the vicinity of the Earth, a discrimination among these models is difficult to achieve. But a Venus flyby or orbiter which performs only somewhat better than Mariner II can potentially determine uniquely the cause of the limb-darkening, and provide significant new information on the structure and composition of the atmosphere and clouds of Venus.
Spaceborne observations of radio noise from 0.7 to 7.0 MHz and their dependence on the terrestrial environment
Authors: Huguenin G. R. , Papagiannis M. D.
Published: July 2016

Observations of long-wavelength (λ > 30 m) radio radiation in space are reported and analyzed in the framework of the terrestrial environnement.

Measurements at low altitudes (~ 300 km) at the frequencies of 4.0 and 7.0 MHz have revealed the existence of very high radio noise levels during the night and on certain occasions during the day. These strong signals were at least 50 db higher than the expected cosmic background and are attributed to man-made and atmospheric radio noise.

Measurements at high altitudes (3000–11000 km) at the frequencies of 2.2 and 0.7 MHz have produced a flux value at 2.2 MHz in agreement with the expected cosmic radio background, but the flux value obtained at 0.7 MHz is approximately 15 db higher than the anticipated flux from cosmic sources. Harmonic gyroradiation from the artificial and the outer Van Allen belts might be the cause of the high radio flux observed at 0.7 MHz.
Solar noise observations from the Alouette satellite
Authors: Hartz T. R.
Published: July 2016

Solar radio noise in the frequency range 1.5 to 10 MHz appears sporadically in the Alouette sweep-frequency recordings above the galactic noise level. The type III bursts can be readily identified, but other spectral types are much more difficult to identify from only the satellite records. Using a plausible model for the coronal electron densities, the Type III frequency drift curves have been interpreted as corresponding to a source velocity in the range 0.1 to 0.15 times the velocity of light. Preliminary estimates have also been made of the coronal temperatures from some of the burst durations.

Other solar noise events of longer duration have not been classified other than as enhanced solar noise at this stage. These enhancements frequently show an intensity structure, extending down to the 1.5 MHz lower frequency limit of the equipment. These events are discussed briefly.
Mirrors
Authors: Pierce A. K.
Published: July 2016

PIERCE : The organizers of our conference prepared a very logical program. We first started with the optical arrangement for both the telescopes and the spectrographs. Second, we deal with the mirrors themselves, both with respect to their fabrication and testing, and third, during the next days, we will go into telescope design, the mountings, the dome, and so forth. In this intermediate program we start to bring together the engineers and the fabricators of the materials from which we make the telescopes. I'd like to emphasize that we're talking about telescopes in the $ 107to $ 108size range. Let's keep our thoughts directed towards this kind of a telescope in our session.
Telescope Driving
Authors: Rule B. H.
Published: July 2016

Rule: First off this afternoon we're going to be hearing something about telescope drives, about read out and data recording systems. We didn't in the previous session really complete all the drive details, so you'll be hearing more about this in problems presented by the speakers today.
Problems of Logistics
Authors: Whitford A. E.
Published: July 2016

I call then first for comments about site development for large telescopes. Byron Hill has been for a long time the superintendent of the Palomar Mountain Station of the Mt Wilson and Palomar Observatories, and I think he is peculiarly fitted to tell us about the construction of the initial mountain facilities, and transport, support shop, and so on.
Neutron Star Formation and Birth Properties
Authors: Janka Hans-Thomas
Published: July 2016

Our current knowledge of neutron star formation, progenitors, and natal masses, spins, magnetic fields, and space velocities is briefly reviewed from a theorist's perspective. More observational information is badly needed to constrain theoretical possibilities.
A Rocket Model of Neutrino Jet for Pulsar Kicks
Authors: Peng Q. H. , Zhang L. D. , Luo X. L. , Chou C. K.
Published: July 2016

On the basis of the neutrino emission from the isotropic 1S0 neutron superfluid vortices in neutron star interiors, we propose a rocket model of neutrino jet for the observed pulsar kick.
Magnetic Field Decay, or Just Period-Dependent Beaming?
Authors: van Leeuwen Joeri , Verbunt Frank
Published: July 2016

Several recent papers conclude that radio-pulsar magnetic fields decay on a time-scale of 10 Myr, apparently contradicting earlier results. We have implemented the methods of these papers in our code and show that this preference for rapid field decay is caused by the assumption that the beaming fraction does not depend on the period. When we do include this dependence, we find that the observed pulsar properties are reproduced best when the modeled field does not decay. When we assume that magnetic fields of new-born neutron stars are from a distribution sufficiently wide to explain magnetars, the magnetic field and period distributions we predict for radio are pulsars wider than observed. Finally we find that the observed velocities overestimate the intrinsic velocity distribution.
Orbital Trends of Binary Pulsars
Authors: Chatterjee Tapan
Published: July 2016

We try to understand the eccentricity of high-mass binary pulsars using some methods of statistical mechanics.
Radio Expansion Studies of Two Historical Supernova Remnants: SN 1006 and SN 1572
Authors: Moffett David , Caldwell Caitlin , Reynoso Estela , Hughes John
Published: July 2016

We present results that trace the dynamics of two historical remnants, SN 1006 and SN 1572 (Tycho), for the past two decades. 21-cm radio images of each remnant were recorded during two previous epochs: 1983–1984 and 1991–1994. We obtained third-epoch images of both remnants from 2001 to 2003. After a direct comparison of images from these three epochs, we found the mean radio expansion rate of Tycho now agrees with a previous X-ray expansion study, and for the first time, we have measured the azimuthal expansion rate over the entire rim of SN 1006.
The Association of PSR B1757–24 and the SNR G5.4–1.2
Authors: Gvaramadze V. V.
Published: July 2016

The association of PSR B1757–24 and the supernova remnant (SNR) G5.4–1.2 was recently questioned by Thorsett et al. (2002) on the basis of proper motion measurements of the pulsar and the “incorrect” orientation of the vector of pulsar transverse velocity (inferred from the orientation of the cometary-shaped pulsar wind nebula). We show, however, that the association could be real if both objects are the remnants of an off-centered cavity supernova explosion.
Thin Circular Disk Shells of OH Masers Toward SNRs
Authors: Zhi-yao Yu
Published: July 2016

We propose a new model of distinct thin circular disk shells to analyze Gaussian fits to spectral features of OH emission at 1720 MHz toward supernova remnants. We have inferred that the OH(1720 MHz) maser features toward G348.5+0.1 are radiated from three distinct thin circular disk shells, and have obtained the parameters of the shells.