0000000000267788
AUTHOR
R. Chato
Long-term optical/IR variability of the Be/X-ray binary LS V +44 17/RX J0440.9+4431
We present the first long-term study of the optical counterpart to the X-ray pulsar LS V +44 17/RX J0440.9+4431. The results of our photometric and spectroscopic analysis show that LS V +44 17/RX J0440.9+4431 contains a moderately reddened, E(B-V)=0.65+-0.05, B0.2V star located at about 3.3 kpc. The Ha line consistently shows a double-peak profile varying from symmetric shape to completely distorted on one side (V/R phases). A correlation between the equivalent width of the Ha line and the infrared magnitudes is seen: as the EW(Ha) decreases the IR magnitudes become fainter. This long-term optical/IR variability is attributed to structural changes in the Be star's circumstellar disc. The ob…
A coded mask for γ-ray astronomy. Design and calibration
Abstract The high-resolution γ-ray spectrometer (SPI) is one of the two main instruments on board the ESA INTEGRAL satellite successfully launched in October 2002. SPI uses coded aperture mask technique in order to have imaging capabilities at the energy band (20 keV–8 MeV) it will study celestial sources. The SPI imaging performance depends critically on the quality of the coded mask response and also on the precise knowledge of such response function. In this paper we present a general description of the SPI Coded Mask design together with its main features. Scientific impact of INTEGRAL SPI Coded Mask design on the instrument capabilities is also discussed. Results obtained for Mask cali…
Determination of IBIS mask transmission matrix
The high-angular resolution imager IBIS is one of the two main instruments aboard the ESA INTEGRAL satellite launched in October 2002. IBIS uses coded aperture mask technique in order to provide the required imaging capabilities for energies between 15 and 10 MeV.The precise knowledge of the coded mask response function critically determine the IBIS imaging performances. In this paper, we present a general description of the IBIS coded mask design together with its main features. Transparency and homogeneity values of the IBIS mask flight model from our laboratory measurements are presented with indication of the instrumental set-up used and accuracy achieved. Mask transmission as a functio…
Discovery of the optical counterpart to the X-ray pulsar SAX J2103.5+4545
We report optical and infrared photometric and spectroscopic observations that identify the counterpart to the 358.6-s X-ray transient pulsar SAX J2103.5+4545 with a moderately reddened V=14.2 B0Ve star. This identification makes SAX J2103.5+4545 the Be/X-ray binary with the shortest orbital period known, Porb= 12.7 days. The amount of absorption to the system has been estimated to be Av=4.2+-0.3, which for such an early-type star implies a distance of about 6.5 kpc. The optical spectra reveal major and rapid changes in the strength and shape of the Halpha line. The Halpha line was initially observed as a double peak profile with the ratio of the intensities of the blue over the red peak gr…