منابع مشابه
Radio astrometry with chromatic AGN core positions
Aims. The effect of frequency-dependent AGN core positions (“core-shifts”) on radio Very Long Baseline Interferometry (VLBI) global astrometry measurements is investigated. Methods. The basic equations relating to VLBI astrometry are reviewed, including the effects of source structure. A power-law representation of core-shifts, based on both observations and theoretical considerations of jet co...
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We discuss the use of the block adjustment method for determining astrometric positions from a mosaic of CCD frames taken with a long focus reflector telescope. The observations cover an area of 25 × 25 around the open cluster Rup21. The source of reference positions was the Tycho-2 Catalogue. The internal error in the measured positions is analyzed, and the external error is estimated from com...
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Since the end of the 2005-2006 austral summer, the IceCube detector consists of an array of 9 strings, deployed between 1450 m and 2450 m of depth and containing 540 digital optical sensors and 16 IceTop surface stations with 64 sensors. With the integrated AMANDA-II experiment this is the world’s largest neutrino telescope in operation. The construction status of IceCube is presented along wit...
متن کاملRecent Radio Monitoring of Microquasars with Ratan-600 Radio Telescope
We report about the multi-frequency (1-30 GHz) daily monitoring of the radio flux variability of the three microquasars: SS433, GRS1915+105 and Cyg X-3 during the period from September 2005 to May 2006. 1. We detected clear correlation of the flaring radio fluxes and X-rays ’spikes’ at 2-12 keV emission detected in RXTE ASM from GRS1915+105 during eight relatively bright (200-600 mJy) radio fla...
متن کاملAstrometry with the Hubble Space Telescope: A Parallax of the Fundamental Distance Calibrator RR
We present absolute parallaxes and relative proper motions for the central stars of the planetary nebulae NGC6853 (The Dumbbell), NGC 7293 (The Helix), Abell 31, and DeHt 5. This paper details our reduction and analysis using DeHt 5 as an example. We obtain these planetary nebula nuclei (PNNi) parallaxes with astrometric data from Fine Guidance Sensors FGS 1R and FGS 3, white-light interferomet...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1973
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/164.3.223