Extension of Tycho catalog for low-extinction windows in the galactic bulge

We present in this work secondary catalogs up to $m_{Val} \sim 13$ based on the Tycho reference frame (ESA, 1997) for 12 selected low-extinction fields towards the galactic bulge. The observations have been performed with the Askania-Zeiss Meridian Circle equiped with a CCD camera, located at the Abrah\~ao de Moraes Observatory (Valinhos, Brazil) and operated by the Institute of Astronomy and Geophysics, S\~ao Paulo University. The presented catalog, though not complete, has been designed to help in intensive search programmes (e.g. microlensing and variable searches) and therefore the selected standards have a high astrometric and photometric ($V$ band, approximately) quality. The mean precisions obtained were $0.0018^{s}$ in $\alpha$, 0.013'' in $\delta$, 0.030 for the standard deviation in magnitude and 0.0042 for the magnitude when weighted with the error bars in each night (in the mean, 42 stars for the catalog of each window). Tables B.1 to B.12 are also available in eletronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.Comment: 16 pages, 6 figures, A&A Latex style. Published in A&A

Stellar variability in low-extinction regions towards the Galactic Bulge

Intensive monitoring of low-extinction windows towards the galactic bulge has provided in the last years valuable information for studies about the dynamics, kinematics and formation history of this part of the galaxy, mainly by characterizing the bulge stellar populations (Paczy\'nski, 1996). Since 1997, we have been conducting an intensive photometric-astrometric survey of the galactic bulge, with the monitoring of about 120000 stars in 12 windows uniformly distributed in galactic latitude and longitude (Blanco & Terndrup, 1989 e Blanco, 1988) never before submitted to this kind of survey. For this purpose, we have used the IAG/USP CCD Meridian Circle of the Abrah\~ao de Moraes Observatory. The main objective of this work is the identification and classification of variable objects. In this work we present the set up and development of the necessary tools for a project like this and the posterior analysis of our data. We briefly describe the construction of a program to organize and detect variables among the observed stars, including real time alerts (for variations greater than 0.3 magnitudes). The preliminary analysis after the processing of 76 nights of observation yielded 479 variable stars, from which 96.7 % of them are new. We discuss the preliminary classification of this variables, based on: a) the observed amplitude of variation; b) the shape of light curve; c) the expected variable classes among our data and d) the calculated periods, whenever possible. Finally, we discuss the future perspectives for the project and for the applications and analysis of the discovered variable stars.Comment: 10 pages, 14 figures. Accepted by A&A

M2000 : an astrometric catalog in the Bordeaux Carte du Ciel zone +11 degrees < {delta} < +18 degrees

During four years, systematic observations have been conducted in drift scan mode with the Bordeaux automated meridian circle in the declination band [+11 ; +18]. The resulting astrometric catalog includes about 2 300 000 stars down to the magnitude limit V_M=16.3. Nearly all stars (96%) have been observed at least 6 times, the catalog being complete down to V_M=15.4. The median internal standard error in position is about 35 mas in the V_M magnitude range [11 ; 15], which degrades to about 50 mas when the faintest stars are considered. M2000 provides also one band photometry with a median internal standard error of 0.04 mag. Comparisons with the Hipparcos and bright part of Tycho-2 catalogs have enabled to estimate external errors in position to be lower than 40 mas. In this zone and at epoch 1998, the faint part of Tycho-2 is found to have an accuracy of 116 mas in alpha instead of 82 mas deduced from the model-based standard errors given in the catalog.Comment: The catalogue can be fetched directly from: ftp://cdsarc.u-strasbg.fr/cats/I/272 or queried from: http://vizier.u-strasbg.fr/viz-bin/VizieR?-source=I/272 More information at : http://www.observ.u-bordeaux.fr/~soubiran/m2000.ht

Long-term optical variability of the blazars PKS 2005-489 and PKS 2155-304

We present optical light curves for the period 1996-2000, of two of the brightest known EGRET BL Lac objects: PKS 2005-489 and PKS 2155-304, the latter also one of the few known TeV sources. For both objects, quiescent epochs of low level of variability were followed by active periods, without any indication of periodicity. In PKS 2005-489, several variability events with duration of about 20 days were observed. In PKS 2155-304 fast drops and subsequent rises in luminosity occurred in time scales of days. We proposed an explanation in which a region moving along the relativistic jet is eclipsed by broad line region clouds or star clusters in the host galaxy. We compare our light curves with contemporaneous X-ray observations from All-Sky Monitor/RXTE. Correlations between optical and X-ray activity were not found in any of the sources at long time scales. However in PKS 2005-489 possible correlations were observed in 1997 and 1998 at short time scales, with optical variability preceding X-rays by 30 days in 1997 and succeeding them by about 10 days in 1998. The analysis of the SED, using the optical data presented here and BeppoSAX contemporaneous observations obtained from the literature, shows only small shifts in the synchrotron peak as the X-ray flux density changes.Comment: 23 pages,12 figures, accepted for publication in A

Measurement of the (π−\pi^-, Ar) total hadronic cross section at the LArIAT experiment

We present the first measurement of the negative pion total hadronic cross section on argon, which we performed at the Liquid Argon In A Testbeam (LArIAT) experiment. All hadronic reaction channels, as well as hadronic elastic interactions with scattering angle greater than 5~degrees are included. The pions have a kinetic energies in the range 100-700~MeV and are produced by a beam of charged particles impinging on a solid target at the Fermilab Test Beam Facility. LArIAT employs a 0.24~ton active mass Liquid Argon Time Projection Chamber (LArTPC) to measure the pion hadronic interactions. For this measurement, LArIAT has developed the ``thin slice method", a new technique to measure cross sections with LArTPCs. While generally higher than the prediction, our measurement of the ($\pi^-$,Ar) total hadronic cross section is in agreement with the prediction of the Geant4 model when considering a model uncertainty of $\sim$5.1\%.Comment: 15 pages, 15 figures, 3 tables, accepted by PR

The Liquid Argon In A Testbeam (LArIAT) Experiment

The LArIAT liquid argon time projection chamber, placed in a tertiary beam of charged particles at the Fermilab Test Beam Facility, has collected large samples of pions, muons, electrons, protons, and kaons in the momentum range 300-1400 MeV/c. This paper describes the main aspects of the detector and beamline, and also reports on calibrations performed for the detector and beamline components

Ansiedade dos estudantes diante da expectativa do exame vestibular

Este estudio investigó la ansiedad de los estudiantes en las escuelas privadas en un estado de Brasil en el examen de ingreso. La muestra fuese compuesta de 124 estudiantes de la escuela secundaria participantes del PISM (Proceso de Admisión Común), siendo 66 mujeres e 58 hombres, 69 alumnos del 1er año de escuela secundaria y 55 del 3er año. Los estudiantes respondieron a un cuestionario socio-demográfico y al Inventario de Ansiedad Rasgo-Estado (IDATE), en sus propias aulas. Hubo una diferencia significativa en relación con el género (p=0,036) que se encontró un mayor nivel de ansiedad estado en el 1er año de las mujeres en comparación con los hombres del 1er año (p = 0,004). El mismo resultado se encontró con respecto a la ansiedad-rasgo: las mujeres de 1er año son más ansiosas que los hombres del 1er año (p=0,000).O presente estudo investigou a ansiedade dos jovens estudantes de escolas particulares de um estado do Brasil em relação ao exame vestibular. A amostra foi composta por 124 estudantes do ensino médio participantes do vestibular seriado PISM (Processo de Ingresso Seletivo Misto), sendo 66 do gênero feminino e 58 do gênero masculino, 69 alunos do 1º ano do ensino médio e 55 do 3º ano. Os estudantes responderam a um questionário sócio-demográfico e ao Inventário de Ansiedade Traço-Estado (IDATE) na suas próprias salas de aula. Foi observada uma diferença significativa quanto ao gênero (p=0,036) sendo que foi encontrado um maior nível de ansiedade-estado nas mulheres do 1º ano comparativamente aos rapazes do 1ºano (p=0,004). O mesmo resultado foi encontrado com relação à ansiedade-traço: moças do 1º ano são mais ansiosas do que rapazes do 1º ano (p=0,000).This study investigated the anxiety of private schools students at the expectation of attending colleges' entrance examination in one Brazilian state. The sample consisted of 124 high school students participating in the PISM series of examination (Joint Selective Admission Process). They were 66 females and 58 males, 69 students from the 1st year and 55 from the 3rd year. Students answered a sociodemographic questionnaire and the State-Trait Anxiety Inventory in their respective classrooms. A significant difference regarding gender (p=0.036) was found, women from the 1st year presented higher levels of state-anxiety compared to men from the 1st year (p=0.004). The same result was found with respect to the trait-anxiety, women from the 1st year were more anxious than men from the 1st year (p=0.000)