... If the measuring aperture varies, a varying amount of starlight will be excluded. Furthermore, the excluded fraction is wavelength-dependent; so the transformation from instrumental to standard system changes. ... Unfortunately, sometimes it is necessary to combine measurements made with different field stops. Observers should realize that this really means different instruments; the differences are usually several per cent. ... Usually, the actual aperture sizes are only approximately known. ...

... Bojan Nikolic web pages (r. 329) . ... Using high-resolution three-dimensional realisations of turbulent fields, we investigate the limits on achievable performance of atmospheric phase correction using water-vapour radiometers arising from following effects: the incoherent measurement of power from water by the radiometers (in contrast to coherent detection of the astronomical signal); the different tapers of the response patterns of the astronomical and radiometer receivers; and, the ...

... A three-cell test section roughly representative of the primary mirror was provided for this test by the Steward Mirror Lab. ... Additionally, the tests are intended to determine relative airflow vs. pressure drop characteristics for each of the air flow patterns so the results can be evaluated both as a function of flow rate and of pressure drop along the flow path. ... The bottom (top as installed) was cut out so it could close the chamber for heating and be removed for the cooling tests. ...

We critique the method of constructing extinction curves of lensing galaxies, using multiply imaged QSOs. If one of the two QSO images is lightly reddened, or if the dust along both sight lines has the same properties, then the method works well and produces an extinction curve for the lensing galaxy. ... Instead, it is a measurement of the difference between two extinction curves. ... The resulting lens difference curve is not an average of the dust along the two sight lines. ...

Next: Some theory Up: userhtml Previous: Calibration . By many measures, the ATCA 3-mm observing band is a completely different domain to the other ATCA bands. ... Not surprisingly many aspects of the data reduction are also different. This chapter reviews the theory behind some of the differences, and then considers a practical approach to calibration. ... Antenna gain considerations and flux calibration . Instrumental phase . Atmospheric phase and phase calibration considerations . ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2001 January 7 . Tycho Brahe Measures the Sky . ... Explanation: Tycho Brahe was the most meticulous astronomical observer of his time. ... To do this Brahe and his assistants created the first major astronomical observatory where they devised and used the most accurate pre-telescopic astronomical instruments . ... About APOD | ...

... Optical constants of amorpous SiO 2 and GeO 2 in the region of valence band. ... The optical constants were determined by 4 methods: (i) Measurements of reflectivity of polarized radiation incident at 3 different angles following by solution of the Fresnel equations; (ii) Measurements of trasmittance (for tablettes of ultra-fine powder); (iii) A combined method applied to both kind of the data following by solution of Fresnel equation for the normal incidence; (iv) Kramers-Kronig method. ...

Galileo showed convincingly that heavy objects fell no faster that light ones. ... If an iron ball was pulled down with a much greater force than a wooden one of the same size, why didn't it fall any faster? ... 1) It is harder to lift. ... It is the fact that the loaded wagon has a greater mass that gives it a larger inertia , a larger tendency to oppose any change in its state of rest or of constant motion in a straight line. ... One important quantity was the body mass of the astronauts. ...

... The difference is that inertia is an inherent property of matter, while weight also depends on gravity. ... They use gravity, balancing its force on the astronaut's body against a calibrated spring or against the force of gravity on some calibrated weights. ... Using scales and the local force of gravity, one can determine gravitational mass; or else, one might dispense with gravity, like the astronauts aboard Skylab, sand measure the "inertial mass," and in principle they may differ. ...

... Archives . ... If you do not mind the time predictor, it is hard to believe that this is a light curve, time dependent data. ... It?s hard to say this data set is designed for time series analysis apart from the complication in statistical inference due to measurement errors. How to design the statistical study with measurement errors, huge gaps in time, and unequal time intervals is complex and unexplored. ... The following is R output without measurement errors. ... Chandra Blog . ...

The ESA/ESO Astronomy Exercise Series 2 . The Distance to Messier 100 as Determined by Cepheid Variable Stars . ... The small variations in distance to the individual Cepheid variable stars in the Cloud are negligible compared with the much larger distance to the SMC. ... In this way Cepheid variable stars can be used as one of the 'standard candles' in the Universe that act either as distance indicators themselves or can be used to calibrate (or set the zero point for) other distance indicators. ...

The cal values for lband narrow were measured on 28jan02 in the early morning using the sky/absorber technique. ... Comparing phil's and karen's cal values. ... Fig 1 is the cal value in deg K versus frequency. ... fig top: The cal values in kelvins. black:karen, red:phil, green: old cal values (after correcting for 6%error). fig middle: ratio of "new" cal to old cal. black:karen's computations, red: phil's. fig bottom: Ratio of phil's cal values/ karen's cal values. ... Fig 1. ...

ON-LINE STATIC EIT RECONSTRUCTION SERVER . ... Static image reconstruction from the data measured in vivo is still intriguing problem in EIT. ... dipole (adjacent) current injection and voltage measurements on pairs of adjacent electrodes (like in Sheffield systems) . ... You can view examples of the text files for polar , dipole and trigonometric injection, use them for testing the server and find more details on HOW TO PREPARE INPUT FILE FOR THE ON-LINE EIT RECONSTRUCTION SERVER page. ...

This lesson introduces you to the different types of uncertainty, and how you can estimate them from the scatter in your measurements, or from knowledge of your experimental set-up. It also outlines how to quote uncertainties. Back Main Uncertainties Page .

XMM­Newton CCF Release Note XMM­CCF­REL­119 OM PSF Bing Chen June 13, 2002 1 CCF components Name of CCF VALDATE List of Blocks changed CAL VERSION XSCS flag OM PSF1DRB 0006 2000­01­01T00:00:00 PSF­U No PSF­B No PSF­V No PSF­UVW1 No PSF­UVM2 No PSF­UVW2 No 2 Changes This CCF file provides new measurement of OM PSF. ... 1 XMM­Newton CCF Release XMM­CCF­REL­119 Page: 2 Figure 1: Growth curves as a function of radius for V and UVW1 filters. ... Therefore, this new PSF is field position independent. ...

Next: The Scenario Machine: Operational Up: Evolution of Magnetic Rotators Previous: Ejector-propeller hysteresis . ... The length of this segment is determined by the eccentricity. ... In this case no hysteresis occurs and transitions E -- P and the reverse take place in symmetrical points of the orbit. ... Here EP means a mixed state of the rotator at which it is in the ejector state during one part of the orbit, and in the propeller state during the rest of the orbital cycle. ...

... The black line shows the spectrum from the Jungfrau atlas, while the redline shows the average spectral profile measured from a single spectral scan. ... Right: The residual line center positions averaged over all twenty spectral scans, showing the horizontal stripes due to spectral variations in the fringe pattern that are uncorrected due to the lack of flat fielding. ... The line center positions determined for each spectral line also show random fluctuations of approimately the same magnitude. ...

... Colours of stars and galaxies hold information on intrinsic and extrinsic parameters, such as stellar temperatures and galaxy populations, selective absorption and colour changes due different dust contents and inclination angles of galaxies, as well as galaxy redshifts and evolution. ... The colour magnitude diagram of 65000 galaxies to which all above-mentioned quantities and others contribute can only be explained by comparison with simulations. ... Colours are also of technical help. ...

On Systematic Differences in Individual Solutions and IERS Products Zinovy Malkin Institute of Applied Astronomy RAS, St. Petersburg, Russia 1 Present status Proper determination, modelling, and accounting for systematic differences between contributed series is of the great importance in compilation of the IERS products. ... Possible sources of systematic differences are: · Different reference systems (e.g. TRF, CRF, geopotential, time scale). ... 87 IERS Technical Note No. ...

... On-line calibration consists of calibration operations performed to maintain the ALMA observing system properly tuned to successfully execute the planned observations. ... Among processing operations are the calibration of the atmospheric absorption, of phase radiometric correction, of pointing scans, of phase and amplitude reference measurements, .. ... In the mean time tests of the calibration software will proceed using both simulated data and data from the antenna prototypes...?re 1 . ...