264 research outputs found
First light of engineered diffusers at the Nordic Optical Telescope reveal time variability of the optical eclipse depth of WASP-12b
No full textWe present the characterization of two engineered diffusers mounted on the 2.5-meter Nordic Optical Telescope, located at Roque de Los Muchachos, Spain. To assess the reliability and the efficiency of the diffusers, we carried out several test observations of two photometric standard stars, along with observations of one primary transit observation of TrES-3b in the red (R band), one of CoRoT-1b in the blue (B band), and three secondary eclipses of WASP-12b (V band). The achieved photometric precision is in all cases within the submillimagnitude level for exposures between 25 and 180 s. Along with a detailed analysis of the functionality of the diffusers, we add a new transit depth measurement in the blue (B band) to the already observed transmission spectrum of CoRoT-1b, disfavoring a Rayleigh slope. We also report variability of the eclipse depth of WASP-12b in the V band. For the WASP-12b secondary eclipses, we observe a secondary depth deviation of about 5σ, and a difference of 6σ and 2.5σ when compared to the values reported by other authors in a similar wavelength range determined from Hubble Space Telescope data. We further speculate about the potential physical processes or causes responsible for this observed variability
Multifrequency Observations of the Gamma-Ray Blazar 3C 279 in Low-State during Integral AO-1
No full textAuthors: - W. Collmar, M. Böttcher, V. Burwitz, T. Courvoisier, S. Komossa, P. Kretschmar, E. Nieppola, K. Nilsson, T. Ojala, K.Pottschmidt, M. Pasanen, T. Pursimo, A. Sillanpää, L. Takalo, M. Tornikoski, H. Ungerechts, E. Valtaoja, R. Walter, R. Webster, M. Whiting, K. Wiik, I. WongWe report first results of a multifrequency campaign from radio to hard X-ray energies of the prominent gamma-ray blazar 3C 279 during the first year of the INTEGRAL mission. The variable blazar was found at a low activity level, but was detected by all participating instruments. Subsequently a multifrequency spectrum could be compiled. The individual measurements as well as the compiled multifrequency spectrum are presented. In addition, this 2003 broadband spectrum is compared to one measured in 1999 during a high activity period of 3C 279.https://arxiv.org/abs/astro-ph/041030
Troponiinien aptameerisitojat
No full textSydän- ja verisuonisairaudet ovat johtava kuolinsyy maailmanlaajuisesti, ja niissä sydäninfarkti toimii merkittävänä tekijänä edellyttäen tarvetta nopeaan ja tarkkaan diagnoosin. Perinteisiä vasta-aineita käyttäviä immunomäärityksiä käytetään yleisesti troponiinien havaitsemiseen, mutta aptameerit, joilla on korkea sitoutumisaffiniteetti ja selektiivisyys, ovat nousseet lupaavaksi vaihtoehdoksi. Tämä tutkielma on kirjallisuuskatsaus, joka keskittyy sydämen troponiini I (cTnI) -pitoisuuksien määrittämiseen verinäytteistä vertaamalla aptameerien käyttöä perinteisiin vasta-aineisiin perustuviin immunomäärityksiin sekä pohditaan aptameerien tulevaisuudennäkymiä sydäninfarktidiagnostiikassa. Troponiinit ovat sydänlihaksen säätelyproteiineja, joista etenkin troponiini I (cTnI) ja troponiini T (cTnT) voivat toimia sydäninfarktin biomarkkereina. Muihin biomarkkereihin verrattuna troponiinit pysyvät verenkierrossa usein kauemmin ja ovat hyvin sydänspesifisiä. Aptameerit ovat yksijuosteisia nukleiinihappoja tai peptidejä, jotka voivat sitoutua selektiivisesti spesifisiin kohdemolekyyleihin. Ne tarjoavat etuja vasta-aineisiin verrattuna, kuten helppo synteesi, alhainen immunogeenisyys ja kemiallinen stabiilisuus. Aptasensorit, jotka käyttävät aptameereja biologisina tunnistuselementteinä, osoittavat korkeaa herkkyyttä ja nopeita havaitsemisaikoja. Haasteita, kuten aptameerituotannon skaalautuvuus ja biostabiilisuuden parantaminen, on kuitenkin edelleen. Toisin sanoen aptameerit tarjoavat merkittäviä etuja vasta-aineisiin verrattuna troponiinien havaitsemisessa, erityisesti synteesin helppouden, stabiilisuuden ja spesifisyyden suhteen. Lisätutkimusta kuitenkin tarvitaan aptameerien tuotannon ja käytön optimoimiseksi diagnostiikassa, mutta niillä on lupaavaa potentiaalia
Multiwavelength observations of the BL Lac object Mkn 501 during the 1997 high state.
No full textDuring the observation period 1997, the nearby blazar Mkn 501 showed
extremely strong emission and high variability. The authors examine
multiwavelength aspects of this event using radio, optical, soft and
hard X-ray and TeV data. They concentrate on the medium-timescale
variability of the broadband spectra, averaged over weekly intervals.
They confirm the previously found correlation between soft and hard
X-ray emission and the emission at TeV energies, while the source shows
only minor variability at radio and optical wavelengths. The lightcurves
at different frequencies are shown
THE HIGH AV Quasar Survey: Reddened Quasi-Stellar Objects selected from optical/near-infrared photometry. II
No full textQuasi-stellar objects (QSOs) whose spectral energy distributions (SEDs) are reddened by dust either in their host galaxies or in intervening absorber galaxies are to a large degree missed by optical color selection criteria like the ones used by the Sloan Digital Sky Survey (SDSS). To overcome this bias against red QSOs, we employ a combined optical and near-infrared (near-IR) color selection. In this paper, we present a spectroscopic follow-up campaign of a sample of red candidate QSOs which were selected from the SDSS and the UKIRT Infrared Deep Sky Survey (UKIDSS). The spectroscopic data and SDSS/UKIDSS photometry are supplemented by mid-infrared photometry from the Wide-field Infrared Survey Explorer. In our sample of 159 candidates, 154 (97%) are confirmed to be QSOs. We use a statistical algorithm to identify sightlines with plausible intervening absorption systems and identify nine such cases assuming dust in the absorber similar to Large Magellanic Cloud sightlines. We find absorption systems toward 30 QSOs, 2 of which are consistent with the best-fit absorber redshift from the statistical modeling. Furthermore, we observe a broad range in SED properties of the QSOs as probed by the rest-frame 2 μm flux. We find QSOs with a strong excess as well as QSOs with a large deficit at rest-frame 2 μm relative to a QSO template. Potential solutions to these discrepancies are discussed. Overall, our study demonstrates the high efficiency of the optical/near-IR selection of red QSOs
Multiwavelength picture of the misaligned BL Lac object 3C 371: Table A.1 (online version)
No full textComplete version of Table A.1 from the publication "Multiwavelength picture of the misaligned BL Lac object 3C 371" accepeted in Astronomy & Astrophysics.
Authors: J. Otero-Santos, C. M. Raiteri, A. Tramacere, J. Escudero Pedrosa, J. A. Acosta-Pulido, M. I. Carnerero, M. Villata, I. Agudo, I. A. Rahimov, T. S. Andreeva, D. V. Ivanov, N. Marchili, S. Righini, M. Giroletti, M. A. Gurwell, S. S. Savchenko, D. Carosati, W. P. Chen, S. O. Kurtanidze, M. D. Joner, E. Semkov, T. Pursimo, E. Benítez, G. Damljanovic, G. Andreuzzi, G. Apolonio, G. A. Borman, V. Bozhilov, F. J. Galindo-Guil, T. S. Grishina, V. A. Hagen-Thorn, D. Hiriart, H. Y. Hsiao, S. Ibryamov, R. Z. Ivanidze, G. N. Kimeridze, E. N. Kopatskaya, O. M. Kurtanidze, V. M. Larionov, E. G. Larionova, L. V. Larionova, M. Minev, D. A. Morozova, M. G. Nikolashvili, E. Ovcharov, L. A. Sigua, M. Stojanovic, I. S. Troitskiy, Yu. V. Troitskaya, A. Tsai, A. Valcheva, A. A. Vasilyev, O. Vince, E. Zaharieva, and A. V. Zhovtan
Table A.1: Modelfit results derived from the VLBI data analysis for all epochs and each identified component. Columns correspond to the identified components, the corresponding epoch, the flux density and the position of the component in milli-arcseconds. Components without an associated name correspond to those used for the modelfitting but not included in our analysis due to high noise, making them not suitable for the kinematic evaluation and for tracing their evolution and continuity. More details on the modelfit results can be consulted in the documentation of difmap.With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2021-001131-S)Peer reviewe
INTEGRAL observations of the GeV blazar PKS 1502+106 and the hard X-ray bright Seyfert galaxy Mkn 841
No full textOptical behaviour of BL Lacertae during the great 1997 outburst.
No full textThe authors report here optical observations of BL Lac performed during
its large outburst in 1997. During this monitoring the source reached
the brightest magnitude observed in the last 25 years, showing a
variability pattern characterized by rapid flares lasting from few hours
to days
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