... The HST uses an onboard model of its orbit to perform in real-time various control functions relating to spacecraft operations and observation support. ... New coefficients for the ephemeris are updated every other day, and are archived as FITS keywords for each HST observation data set. Using these coefficients,an observer can perform a variety of calibration and characterization calculations relating to the orbital position and velocity of the telescope. ...

... Some of these (e.g., 1 through 6) test specific components of the instruments while others characterize its performance within the HST environment (e.g., 7, 8, 17, and 22). Activities 12 and 13 align the NICMOS fore-optics; activities 9, 10, 11, and 21 enable the use of the coronograph in Camera 2; activities 15 and 20 characterize the detectors; and activities 18 and 19 establish the initial photometric calibration. ... Characterize the effect of severe overexposure of the NICMOS detectors. ...

... Archives . ... The PCA and ICA is used for separating mixed components with some assumptions. ... The need of source separation methods in astronomy has led various adaptations of decomposition methods available. ... I rarely come up with a paper which gathered and summarized component separation methods applicable to astronomical data. In that regards, the following paper seems useful to overview methods of reducing dimensionality for astronomers. [arxiv:0805.0269] . ... Chandra Blog . ...

Text of these problems is available also in other languages : . ... What can one see in the Moon's sky more often - the Sun or the Earth? ... There are about of 250 millions of stars in the elliptical galaxy M32 (a satellite of Andromeda galaxy). ... The masses of Capella's components. ... You are proposed to estimate the masses of Capella's components, using our observational data. ... A galaxy's mass. ... Estimate the mass of FGC 1908 and compare it to the mass of our galaxy. ...

Next: General CCF Components Up: Calibration Access and Data Previous: List of CAL Routines Contents . This section contains descriptions of the structure of CCF constituents. ... The calibration team of the SOC is also providing additional CCF components where required in conjunction with data that were generated with SciSim. ... These CCF components are generated on a need basis and are identical in structure to the real life components. ... Generation from Ground Calibration Data . ...

Peremennye Zvezdy", . ... Star Name: . GSC 3710-00312, USNO-A2.0 1425-04252279 . ... Variability type: . ... USNO-A2.0 1425-04252279 is located at the distance of 15?.7 from the X-ray source 1RXS J031707.9+572942, which is larger than the position error of the source (12?), but its hardness ratio HR1 = 0.03 0.29, typical of chromospherically active stars, and its character of variability allow us to assume that the star is related to the X-ray source. ... Eclipsing variability . Sine wave 1 . ...

... Among the objectives of Principal Components Analysis are the following. dimensionality reduction; љ . the determining of linear combinations of variables; љ . ... identification of groups of objects or of outliers. ... Finding a set of principal axes allows the objects to be adequately characterised on a smaller number of (artificial) variables. ... Reduction of dimensionality is practicable if the first new axes account for approximately 75 % or more of the variance. ...

Near-Earth Asteroids and the Arecibo Observatory Radar The Arecibo Observatory radar is the world's most powerful instrument for post-discovery characterization and orbital refinement of near-Earth asteroids. Arecibo radar observations are critical for identifying asteroids that might be on collision course with Earth and, if necessary, preventing a collision. ... A model of the primary component of asteroid 1999 KW4, derived from radar data. ...

... The Science Operation Department is composed of Astronomers, Telescope Instruments Operators(TIOs) and Data Handling Administrators(DHAs). ... Astronomers have proposed several methods to quantitatively measure the amount of turbulence above the telescope, which the most common ones is Differential Image Motion Monitor (DIMM). In optical testing, the Hartmann test is the common method to test the quality of optical components. ... Hartmann mask consists of 48 lenses. ...

The AstroGuide . ... AstroGuide | ... AstroGuide Listing . ... See many more Astronomy Listings by: Category or Alphabet . ... Listed Since July 15, 1998 . ... 775) 246-5281 . ... 775) 246-5211 . Web Site . ... Web . www.astronomy.net . About Astronomy Net | Advertise on Astronomy Net | ... Unless otherwise specified, web site content Copyright 1994-2016 John Huggins All Rights Reserved . dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . are trademarks of John Huggins ...

... A radio galaxy is a galaxy that emits an unusually big amount of energy at radio wavelengths. ... Inside of each galaxy with an active nucleus (radio galaxies are among them) there must be a system of a "central machine" responsible for the colossal amount of the emitted energy from radio to gamma ranges. ... Sometimes a radio source in an active galaxy may flare again if the needed conditions appear (a new portion of matter would fall into the furnace of the "central machine"). ...

The VLTI Calibrator Selector Tool is a tool intended to assist in the selection of suitable interferometric calibrators for VLTI observations wi