Anisotropic power spectrum and the observed low-l power in PLANCK CMB data

In this work,we study a direction dependent power spectrum in anisotropic Finsler spacetime. We use this direction dependent power spectrum to address the low-l power observed in WMAP and PLANCK data. The angular power spectrum of the temperature fluctuations has a lower amplitude in comparison to the ΛCDM model in the multipole range l = 2-40. Our theoretical model gives a correction to the isotropic angular power spectrum C_l~T~T ldue to the breaking of rotational invariance of the primordial power spectrum. We estimate best-fit model parameters along with the six ΛCDM cosmological parameters using the PLANCK likelihood code in Cosmo MC software. We find that this modified angular power spectrum fits the CMB temperature data in the multipole range l = 2-10 to a good extent but fails for the whole multipole range l = 2-40.     

On the extraction of extended structure from Herschel-SPIRE scanning observations in the presence of 1/f noise

We present results from a study of the impact of uncorrelated 1/ f noise on the extraction of spatial structure, on a range of scales, from sky mapping observations made using the Herschel-SPIRE (the spectral and photometric imaging receiver) photometer in the scan-map mode. These studies were carried out using a detailed instrument simulator, and the output reduced using the map-making algorithm to be implemented in the SPIRE data pipeline. The influence of source size scale, telescope-scanning rate and 1/ f noise knee frequency is investigated, and operational bounds to the expected losses are presented, using the case of zero 1/ f (white) noise as a benchmark. Both cross-linked and non-cross-linked observing options are studied. The results presented here represent the best current estimate of the sensitivity of the SPIRE photometer to emission on arbitrary scales. The data presented are general and scalable to any SPIRE observation made using the scanning mode.     

Evaluation of the effect of equal power spectrum filtering in image restoration

The effectiveness of equal power spectrum filtering in image restoration is analyzed via digital simulation. We start with a gray-scale map of concentric rings with different grey values. To obtain a dirty image, the original image is first transformed via a linear space-invariant system. Then, white noise is mixed into the image. The equal power spectrum filter is then used for the image restoration. The signal to noise ratio (SNR) and a defined steepness of the steps, together with the visual impression, are accepted to characterize the performance of the image restoration. It is concluded that a satisfactory restoration can be realized when the SNR > 15. When SNR < 5, the image is completely un-restorable. The effect of system's transfer function on image restoration is also discussed. The effectiveness of the presented model of equal power spectrum filter is confirmed by applying it to the restoration of an actual astronomical image. Finally, a typical application of the equal power spectrum filter is given.     

Achieving sub electron noise in CCD systems by means of digital filtering techniques that lower 1/f pixel correlated noise

Scientific CCDs designed in thick high resistivity silicon (Si) are excellent detectors for astronomy, high energy and nuclear physics, and instrumentation. Many applications can benefit from CCDs ultra low noise readout systems. The present work shows how sub electron noise CCD images can be achieved using digital signal processing techniques. These techniques allow 0.4 electrons of noise at readout bandwidths of up to 10?Kpixels per second while keeping the full CCD spatial resolution and signal dynamic range.     

UBV(RI) C photometry and spectroscopy of the young open cluster Haffner 18

UBV(RI) _C CCD photometry of a 2.1 × 3.3 arcmin² field centred on the young open cluster Haffner 18 is presented and discussed. Spectroscopic classification of seven stars is also provided. 44 cluster members are identified, the earliest type being O6. The distance to the cluster is found to be 6.3 kpc, corresponding to a galactocentric distance of 12.7 kpc (for a Sun galactocentric distance of 8.5 kpc). An excellent fit to the observed main sequence is achieved by a solar composition isochrone of 2 × 10⁶ yr reddened by E(B − V)  = 0.62 mag. Differential reddening of intracluster origin is present. Pre-main-sequence members are likely to be present over the 6 mag range explored by our observations (reaching down to earliest A spectral types). The presence of differential reddening and pre-main-sequence members agrees with the evidence for a bright parent nebulosity embedding the whole cluster. The radial velocity of the cluster is consistent with the Hron model of Galactic rotation.     

A preliminary measurement of the doppler and compton effect in the blue spectrum of 13 monocerontis

A preliminary radial velocity of 13 Mon and the redshift caused by the scattering of photons in its chromosphere are given. They have been obtained from the wavelengths of 39 spectral lines, measured in 2 spectra and the corresponding halfwidth measured in 4 spectra, taken in 1980 with a dispersion of about 9 Å/mm. (1 Å = 0.1 nm), in the range 3700 Å-5000 Å.     

H and K (Ca II) emissions as observed in coronal spectrum in the July 20, 1963 solar eclipse

From a detailed analysis of a coronal spectrum taken from a DC-8 jet airplane during the Eclipse of 20 July, 1963 a rough model of a coronal cold region (T 10⁵ K) has been obtained.The model explains the presence of the abnormal H and K (Ca II) emissions and the large amount of F corona present in the spectrum.     

Comparison of observed and theoretical absolute energy distributions in the spectrum of Vega

Principal Astronomical Observatory, USSR Academy of Sciences; Kazan State University. Translated from Astrofizika, Vol. 28, No. 3, pp. 573–585, May–June, 1988.     

Polarimetry and BVRI photometry of the potentially hazardous near-Earth Asteroid (23187) 2000 PN9

The results of V-band polarimetric observations of the potentially hazardous near-Earth Asteroid (23187) 2000 PN₉ at large phase angles are presented as well as its photometric observations in BVRI bands. Observations were made in March-April 2006 during its close approach to the Earth using the 1.82-m Asiago telescope (Italy) and the 0.7-m telescope at the Chuguevskaya Observational Station (Ukraine). We obtained polarimetric measurements at the phase angle of 115°, the largest phase angle ever observed in asteroid polarimetry. Our data show that the maximum value of the polarization phase curve reached 7.7% and occurred in the phase angle range of 90-115°. The measured values of linear polarization degree, BVRI colors and magnitude-phase dependence correspond to the S-type composition of this asteroid. Based on our observations the following characteristics of the Asteroid (23187) 2000 PN₉ were obtained: a rotation period of 2.5325±0.0004 h, a lightcurve amplitude of 0.13 mag, an albedo of 0.24±0.06 and a diameter of 1.6±0.3 km.     

X-ray variability of the Seyfert 1 Markarian 335: power spectrum and time lags

To investigate further the comparison between active galactic nuclei (AGN) and black hole X-ray binaries, we have studied the main X-ray variability properties of the Seyfert 1 galaxy Mrk 335. We put particular emphasis on the X-ray time lags, which is a potentially important diagnostic of physical models. From a 100 ks observation by XMM–Newton , we show that the power spectrum of this source is well fitted by a bending power-law model, and the bend time-scale T _b is precisely at the value predicted by the T _b versus Hβ linewidth relation of McHardy et al. Variations in different energy bands show time-scale-dependent time lags, where higher energy bands lag lower ones. The lag, τ, varies as a function of the Fourier frequency, f , of the variability component in the light curves as  τ∝ f ⁻¹  at low frequencies, but there is a sharp cut-off in the lags at a frequency close to the bend frequency in the power spectrum. Similar behaviour is seen in black hole X-ray binary systems. The length of the time lags increases continuously with energy separation, in an almost loglinear relation. We show that the lag spectra can be produced by fluctuations propagating through the accretion flow as long as the energy spectrum of the X-ray emitting region hardens towards the centre.     

Ultraviolet solar identifications based on extended absorption series observed in the laboratory spectrum of Sii

The absorption spectrum of Sii in the wavelength region 1500–1900 Å has been photographed at high resolution. The silicon vapour was produced in a 122 cm long King furnace at 1800–2300°C. Forty-two Rydberg series have been observed from the ground state terms 3p ^{2 3} P and¹ D to terms associated with the 3pns and 3pnd configurations. All of the series from these configurations withJ<4 have been extended with the 3pnd ³ D ₃ ^o levels reachingn=56. Numerous perturbations have been observed. This laboratory work has provided the basis for extending the identification of silicon lines in the solar spectrum. Nearly all lines found in the laboratory spectrum are also found in rocket spectrograms of the solar chromosphere. More than 300 lines have been attributed to Sii. The excellent correlation between laboratory and solar Sii lines will be illustrated.     

The effect of f(T) gravity on an interplanetary clock and its time transfer link

As an extension of the"teleparallel"equivalent of general relativity,f(T)gravity is proposed to explain some puzzling cosmological behaviors,such as accelerating expansion of the Universe.Given the fact that modified gravity also has impacts on the Solar System,we might test it during future interplanetary missions with ultrastable clocks.In this work,we investigate the effects of f(T)gravity on the dynamics of the clock and its time transfer link.Under these influences,theΛ-term and theα-term of f(T)gravity play important roles.Here,Λis the cosmological constant andαrepresents a model parameter in f(T)gravity that determines the divergence from teleparallel gravity at the first order approximation.We find that the signal of f(T)gravity in the time transfer is much more difficult to detect with the current state of development for clocks than those effects on dynamics of an interplanetary spacecraft with a bounded orbit with parameters 0.5 au≤a≤5.5 au and 0≤e≤0.1.