Next: Deep Depletion Up: CCD Scientific Performance Previous: Energy resolution . Conventional CCDs are illuminated through a front-surface electrode structure which may be m thick. This severely limits the sub-keV detection efficiency. They also have a detection volume defined by the depletion layer depth of m. This should be compared with, for example, the 1/e attenuation length for 6keV photons which is m; hence CCD sensitivity falls rapidly with increasing energy. ... Deep Depletion . ...

The problem of quantum efficiency hysteresis (QEH) due to back-side charge accumulation has been reviewed in detail by Griffiths, et al. (1989), and Janesick and Elliot (1991). QEH is not present in the Loral CCDs, because they are front-side illuminated and incorporate MPP operation. ... The absence of QEH means that the devices do not need to be UV-flooded and so decontamination procedures are planned without the constraint of maintaining the UV-flood. ... Voice: (410) 338-1082 . ...

Next: Filtering ROSAT HRI data Up: ROSAT HRI Recipes Previous: Correlating Spectral Data with . Although the spatial variation of the quantum efficiency across the HRI is nominally within 10% for most of the detector, occasionally it may be desirable to flat-field a map with preflight calibration measurements. ... Store the new gain map image using ``blink" in SaoImage. ... The quantum efficiency correction (QEC) is the inverse of the intensity determined from the QE map at the source position. ...

... The PlutoCCD CCD is a video rate, low noise, 2048 x 1024 element, 9-micron or 12-micron pixel back-illuminated CCD. ... PlutoCCD 2048 x 1024 Element Split-Frame Transfer CCD . ... A picture of a Split Frame Transfer version of the PlutoCCD CCD is shown in Figure 2-1. ... As can be seen in Table 2-2, which documents the performance measured for the design, the 12-micron PlutoCCD CCD achieves less than 5 electrons rms. noise, full well exceeding 240,000 electrons, and linearity better than one percent...

... Beamwidth defines the field of view 2. ... Large diameter = high sensitivity = small beamwidth 3 To calculate the radiation pattern : Compute field in focal plane from surface currents excited by the incoming wavefront. ... Feed Legs (quadrupod on the AT antennas) plane wave shadows (radiation which does not reach the main reflector) spherical wave shadows (radiation blocked between the main and the sub-reflector) 6 Surface Errors н Ruze formula Let be the rms surface error. ...

... Polarizer efficiency is defined as , where and are the respective measured signals for a polarizer oriented parallel and perpendicular to the axis of a fully polarized beam... angle 12.2 . Polarizer position angle as measured from the NICMOS Aperture Offset Angle of , about the aperture center toward the +U3 axis.. IDL 14.1 . IDL (Interactive Data Language) is an interactive analysis and visualization program written by Research Systems, Inc.... resolution. ...

Next: Comments on Individual Sources Up: Sample Identification Previous: Sample Identification . In Figure 2, we show the spectra of the optical counterparts to 85 of 97 observed X-ray/radio sources. ... Positional information for all 85 sources for which we announce identifications herein are given in Table 3, including information from WGACAT, the PMN and Green Bank surveys, the NVSS and our ATCA survey. ... Of the 85 newly identified sources, 59 are FSRQs, and 22 are BL Lacs. ...

... The behaviour of the polarization efficiency (see Eq. ( 14 )) for non-absorbing and absorbing spheroids is shown in Fig. 11 for the case when a maximum polarization is expected (PF alignment, ). ... Figure 11: Polarization efficiency against for prolate and oblate spheroids with and , picket fence orientation, . The size/shape effects are illustrated. ... Figure: Polarization efficiency as a function of particle equivolume radius for prolate core-mantle spheroids with and , PF orientation, . ...

Alexander S. Dmitriev . Institute of Radioengineering and Electronics of the Russian Academy of Sciences . Mokhovaya st., 11, Moscow, 103907, Russia. ... Moscow Institute for Physics and Technology . ... The relationship between the problem of cleaning chaotic signals off noise and the information properties of the signals is shown. Some methods for chaotic signal cleaning are considered. The efficiency of these methods is evaluated by computer simulation. ...

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... Next: The PROS Big Up: Software Systems Previous: Data Reduction Software . ... The srcinten task provides PROS users with a tool to compute count rates for point sources in the ROSAT High Resolution Imager (HRI). ... Corrected upper limits are cited at locations where the count rate falls below the source detection threshold. ... Srcinten is a new PROS task that computes and applies the above correction factors to the net counts in a user-specified aperture. ...

... Frequency: 100 GHz Bandwidth: 84 GHz ­ 116 GHz Cross-polar level: <-30 dB Return loss: >30 dB Notes: · Horn length improved (25% less than previous) · Waist closer to the aperture Horn profile and phase centre location (PCL): 20dB taper weighted phase centre: Return loss (-S11[dB]) and cross-polar level: Beam waist (w0): Feed pattern (FP) Vs best fit gaussian beam (BFGB)(45°): Gaussian beam efficiency: Best-fit gaussian beam efficiency: ...

Next: Front End Construction Up: Minutes of the 1st Previous: Minutes of the 1st . ... Calculated system temperature: 25-26K at 1525 MHz, 29-30K at 1375 MHz and 34-25K at 1225 MHz. ... Calculated G/T - again, center pixel better . ... Multi Beam Sky Footprint: Separation 2 beam widths between individual beams . ... Calculated Beam Comatic Level about 8 dB . ... German . ... Slide 1.9 shows calculated T sys with 2 points for each frequency; one is for the center beam and other is for the outside. ...

... Although many elliptical galaxies are in clusters of galaxies, NGC 1132 appears as a large, isolated galaxy toward the constellation of the River (Eridanus). To probe the history of this intriguing trillion-star ball, astronomers imaged NGC 1132 in both visible light with the Hubble Space Telescope and X-ray light with the Chandra X-ray Observatory . ... The X-ray light also likely traces out the location of dark matter . ... Publications with keywords: Elliptical Galaxy - dark matter . ...

... LABOROSCOPES . ... MICROSCOPES . ... Home Products Microscopes Laboroscopes Oblique Illumination Package for Laboroscope (UP-BOM): . BRIGHTFIELD/ OBLIQUE ILLUMINATION UPGRADE PACKAGE FOR LABOROSCOPE (UP-BOM) . ... It includes two interchangeable top lens elements, a 1.3 N.A. lens for medium to high-power objectives and a 0.3 N.A. lens for low-power objectives, as well as an iris diaphragm. ... 1 – Optical Head 1.3 N.A. 2 – Optical Head 0.3 N.A. 3 – Iris Aperture Diaphragm Opening Ring . ...

Today's APOD | ... Editor's choices for the most educational Astronomy Pictures of the Day about elliptical galaxies: . ... Elliptical galaxies appear typically yellow-red, as opposed to spirals which have spiral arms that appear quite blue. ... APOD: 2004 June 16 - Elliptical Galaxy M87 . ... In general, elliptical galaxies contain similar numbers of stars as spiral galaxies , but are ellipsoidal in shape (spirals are mostly flat), have no spiral structure, and little gas and dust . ... Index | ...

... Our Galaxy . ... Stars . ... We all love bright and showy spiral galaxies! So much so, that we tend to overlook the elliptical galaxies which make up about 30% of the galaxies out there. Smaller than spiral galaxies, elliptical galaxies may be full of stellar living fossils, surviving virtually unchanged from an older cosmic era. ... Elliptical galaxies are smaller than spiral galaxies, roughly spherical and full of old stars. ... We know that galaxies interact and even collide. ...

The seminar is supported by the grant of Federal Programm "Integration" . ... ADVECTIVE ACCRETION DISKS WITH MAGNETIC FIELDS AROUND BLACK HOLE" . Advection-dominated, accretion flow onto a compact object, recently considered by a number of authors, assume that the dissipation of turbulent energy of the flow heats the ions and that the dissipated energy is advected inward. It leads to efficiency of conversion of accretion energy to radiation very much smaller than unity. ...

Precision Telescope Control System PTCS Project Note 51.1 A Preliminary Analysis of the Correlation Scales of Wavefront Errors of the GBT Using the Moon Bojan Nikolic, Dana S. Balser & Richard M. Prestage 27 June 2006 GBT Archive: PR063 File: PROJECTS Keys: PTCS, OOF Abstract Observations of the GBT error beam are performed using the Moon to explore the spatial scales in the aperture plane over which the dominant wavefront errors are correlated. ... The expected observed scan is shown in Figure 7. ...

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