Search Publications
In-flight calibrations of IBIS/PICsIT
Foschini, L.; Di Cocco, G.; Malaguti, G. +6 more
PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. It consists of 4096 independent detection units, ~ 0.7 cm2 in cross-section, operating in the energy range between 175 keV and 10 MeV. The intrinsically low signal to noise ratio in the gamma-ray astron…
A study of the two northern open clusters NGC 1582 and NGC 1663
Baume, G.; Villanova, S.; Carraro, G.
We present CCD UBV(I)C observations obtained in the field of the previously unstudied northern open clusters NGC 1582 and NGC 1663. For the former, we also provide high-resolution spectra of the brightest stars and complement our data with Two-Micron All-Sky-Survey (2MASS) near-infrared photometry and with astrometric data from the Tych…
Time resolved spectroscopy of GRB 030501 using INTEGRAL
Götz, D.; Mereghetti, S.; von Kienlin, A. +8 more
The gamma-ray instruments on-board INTEGRAL offer an unique opportunity to perform time resolved analysis on GRBs. The imager IBIS allows accurate positioning of GRBs and broad band spectral analysis, while SPI provides high resolution spectroscopy. GRB 030501 was discovered by the INTEGRAL Burst Alert System in the ISGRI field of view. Although t…
Far and mid infrared observations of two ultracompact H II regions and one compact CO clump
Ghosh, S. K.; Mookerjea, B.; Verma, R. P. +1 more
Two ultracompact H II regions (IRAS 19181+1349 and 20178+4046) and one compact molecular clump (20286+4105) have been observed at far infrared wavelengths using the TIFR 1 m balloon-borne telescope and at mid infrared wavelengths using ISO. Far infrared observations have been made simultaneously in two bands with effective wavelengths of ~ 150 and…
Structure and mass distribution of spiral galaxies at intermediate redshifts
Tamm, A.; Tenjes, P.
Using the HST archive WFPC2 observations and rotation curves measured by Vogt et al. (\cite{vogt1}), we constructed self-consistent light and mass distribution models for three disk galaxies at redshifts z=0.15, 0.90 and 0.99. The models consist of three components: the bulge, the disk and the dark matter. The light distribution of the galaxies in…
The stellar environment of SMC N81
Schaerer, D.; Heydari-Malayeri, M.; Charmandaris, V. +4 more
We present near infrared JHK imaging of the Small Magellanic Cloud compact H II region N81 using the ISAAC camera at the ESO Very Large Telescope (Antu). Our analysis of the stellar environment of this young massive star region reveals the presence of three new stellar populations in the surrounding field which are mainly composed of low mass star…
Extension of the ICRF for selected areas down to the 16th magnitude - II
Ducourant, C.; Le Campion, J. -F.; Teixeira, R. +3 more
In this paper we provide a major upgrade of the work presented in \citet{cam}, aiming at the extension of the ICRF at optical wavelengths in regions of special astronomical interest, using observations from the Bordeaux and Valinhos meridian circles. Along with the new fields, the main differences, when compared to the first release, are: a much l…
First results from the IBIS/ISGRI data obtained during the Galactic Plane Scan. II. The Vela region
Goldoni, P.; Rodriguez, J.; Foschini, L. +14 more
We report on INTEGRAL/IBIS observations of the Vela region during a Galactic Plane Scan (hereafter GPS) presenting the IBIS in-flight performances during these operations. Among all the known sources in the field of view we clearly detect 4U 0836-429, Vela X-1, Cen X-3, GX 301-2, 1E 1145.1-6141, and H0918-549 in the 20-40 keV energy range. Only Ve…
Relationship between decrease of net magnetic flux and solar major events
Liu, Y.; Tian, L. R.
Using the full disk magnetograms taken by SOHO/MDI, we studied the evolution of magnetic fluxes in the line-of-sight for twelve solar active regions in the 23rd cycle, which produced strong solar activities. It is measured that the fluxes of these regions were appreciably imbalanced when they moved past the central meridian, where reliable measure…
Anomalously bright UV lines of Fe II as a probe of gas condensations in the vicinity of hot stars
Johansson, S.; Letokhov, V. S.
Two UV lines of Fe II at 2507/2509 Å are extremely bright in spatially resolved HST/STIS spectra of dense gas condensations (the so called Weigelt blobs) close to the central star of η Carinae. The lines also appear unresolved in HST/FOS spectra of the star AE And. Under normal conditions the lines should hardly be observable. Based on recent stud…