... The task first computes a background image in order to identify pixels that may be part of a source. The task uses two different algorithms for detecting ``point'' and ``extended'' sources. ... If a likely source is found its position and shape parameters are computed by moments and the pixels assigned to the source are set equal to the source number. ... The source is again classified as either ``point'' or ``extended'' from a comparison of its with to that of the PSF width. ...

... In most astronomical observations the image intensity consists of contributions from both object and sky background. Depending on the complexity of the field and the type of object, different methods are used to estimate and subtract the background intensity. ... Non--linear filters are often used to remove stellar images and other sharp features (see Section ) while extended objects are very difficult to eliminate automatically. ...

... WFPC2 ETC for Extended Sources + Background - v4.0 . Home . ... Data . ... WFPC2 Home . ... Instrument Home . WFPC2 History . ... Calibration Home . ... LRF Data . ... Data Analysis Home . ... ETCs . ... Brightness: (mag. arcsec -2 ) . ... Line: Ly 1216 C IV 1550 He II 1640 C III 1907 Mg II 2800 0 II 3727 Ne III 3869 H 4340 0 III 4363 He II 4686 H 4861 0 III 4959 0 III 5007 N II 5755 He I 5876 0 I 6300 N II 6548 H 6563 N II 6583 S II 6716 S II 6731 S III 9531 Specify Z Vel. : (units) . ...

The antenna element Ravi ATNF, Narrabri 1. ... Miriad works out the radio Parabolic reflector: A parabolic reflector adds all the fields from a surface = aperture at a focal point. ... Feeds are `compact' and `corrugated' horns The inner profile is curved The inner surface has grooves Cross-section of a horn Sub-reflector 28 main-reflector Feed horn O `optical axis' The feed horn adds all the rays that come from the 28 deg. wide sub-reflector. The feed down-weights rays that come off-axis. ...

Next: *errcreate* - Use of Up: Background Corrections Previous: *imcalc* - Obtain a . Obtain a radial profile estimating the background level from a background map. input files: xdata$snr.qp; xdata$snr_bbk.imh . intermediate file: broad.imh . output file: broad_cnt.tab . ... Alternatively, the blocking and pi selection can be done as input to the task avoiding the creation of another data file. input files: xdata$snr.qp; xdata$snr_bbk.imh . ...

... 2005 January 11 . Machholz Meets the Pleiades . ... Explanation: Sweeping northward in planet Earth's sky, comet Machholz extended its long ion tail with the Pleiades star cluster in the background on January 7th. ... While the visible coma spans about 500,000 kilometers, the nucleus of the comet, likely only a few kilometers across, lies hidden within . Comet tails can extend many millions of kilometers from the nucleus, but appear substantially shortened because of perspective. ...

Next: Imaging Polarimetry with NICMOS Up: NICMOS Data Calibration and Previous: The Photometric Performance of . ... NICMOSlook and Calnic C . ... Extracting spectra from a large number of NICMOS grism images requires a convenient interactive tool which allows a user to manipulate direct/grism image pairs. ... NICMOSlook and Calnic-C are two programs that were designed to take advantage of the fact that the NICMOS grism mode typically consists of taking both a direct and a grism image. ...

Extended time series of Solar Activity Indices (ESAI) is database including observational, synthetic and simulated sets to study Solar magnetic field variations and their influence on the Earth. ESAI extend the ordinary lengths of some traditional indices of solar activity: sunspot areas, Wolf numbers (equatorial component of magnetic field of the Sun), polar faculae numbers (polar component), mean latitudes, N-S asymmetry of hemispheres (location of activity). Series . ...

Next: Generating Calibration Reference Files with an OPUS Pipeline . Up: Data Pipelines and Quality Control . ... Space Telescope Science Institute, Baltimore, MD 21218 . ... The OPUS pipeline data processing software, developed at the Space Telescope Science Institute (STScI), handles this demanding level of throughput by providing a distributed, concurrent pipeline processing environment for the set of applications that transform the raw telescope telemetry into archival products. ...

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OptInt PmWiki : Pm Wiki / Wiki Style Examples . Wiki styles | ... PmWiki uses WikiStyles for styling text with color and other attributes. PmWiki 2.0 introduced the ability to control the styling further and to even place styles on blocks. ... In addition, an author can define a style "shortcut" by using the define= property. For example, to define a style of %red% , one can use: . define=mystyle color=red% Here is some %mystyle% red text created using a style shortcut. ...

This page will present a review with brief descriptions (incl. refs) of different methods. differential equation methods: . ... extended boundary condition method (EBCM): . homogeneous and multilayered) spheres, finite cylinders, spheroids, Chebyshev particles and so on, incl. non-axisymmetric particles (refs) . ... Rayleigh one (conditions + refs) . Rayleigh-Gans one (conditions + refs) . Anomalous Diffraction one (conditions + refs) . Geometrical Optics one (conditions + refs) . ...

Next: The root filesystem Up: Overview of the Directory Previous: Overview of the Directory . This chapter is loosely based on the Linux filesystem standard, FSSTND, version 1.2 (see the bibliography, [ Qui95 ]), which attempts to set a standard for how the directory tree in a Linux system is organized. ... This chapter does not explain all files in detail. ... The major parts are the root, /usr љ , /var љ , and /home љ filesystems (see figure 2.1 ). ... Figure 2.1: Parts of a Unix directory tree. ...

... Get used to using the mouse and its buttons for such tasks. Figure out the function of each of the three mouse buttons. ... Fire up textedit application and practice editing text files. ... Figure out basic options like cut and paste of text around the file, saving and loading files, searching for strings in the text and replacing strings. ... Familiarise yourself with other UNIX functions by creating various files of text etc. and trying out the various functions listed in handouts. ...

... self-absorption - the absorption of light shining on an object by a process similar to that which produced the light originally; if a cloud emits less light than it absorbs from other clouds behind it, this net loss of light, termed self-absorption , causes the foreground cloud to appear darker than the background field (the term is from spectroscopy, where small absorption dips sometimes occur in larger emission lines, making the latter look as if it is absorbing part of itself) . ... HISA Main ...

... It allows observations of extended and starlike objects in different modes: CCD photometry, panoramic spectroscopy with the Fabry-Perot interferometer, spectroscopy and spectropolarimetry with a "long-slit", slit-free spectroscopy, multi-object spectroscopy. ... Digital servo drives that were installed have improved the reliability of the complex, extended the range severalfold, and reduced the telescope's speed control step. ... A software and hardware set for the BTA control system was implemented...

A FRAGMENT of BACKGROUND. Schoolchildren of Russia and France participated in the development, testing and delivery (in November 1998) to the Russian Orbital Station MIR of the communication satellite SPUTNIK-41. ... In his greeting to the participants in the youth Space Program, in connection with that satellite launch, the President of Russian Federation said: "I believe it is not only a fascinating but also a promising trend in youth education. ...

In calculating the NIFS sensitivity, we adopt a read noise of 5 e - , a dark current of 0.01 e - s -1 pix -1 , and a maximum exposure time of 3600 s. Grating . ... e/pix) . ... OH Cont. (e/pix) . ... NIFS should achieve signal-to-noise ratios of ~ 10 per spectral pixel in a 0.1" 0.1" aperture for single 1800 s exposures on uniform, extended, continuum sources with surface brightnesses of J = 15.4, J = 15.0, H = 14.8, and K = 13.5 mag arcsec -2 using the Z , J , H , and K gratings, respectively. ...

... The X-Ray Moon . ... It shows three distinct regions: a bright X-ray sky, a bright part of the Moon, and a relatively dark part of the Moon. ... Pictured above is a three person Russian Soyuz capsule with wing-like solar panels extended, joined to the Mir space station. In Russian soyuz means "union" and indeed one of the milestones achieved by a Soyuz spacecraft was an orbital union with a US Apollo command module during the first international space mission (Apollo-Soyuz) in 1975. ...

... Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2000 February 28 . The Sombrero Galaxy from VLT . ... FORS1 , VLT ANTU , ESO . ... Reasons include the Sombrero 's unusually large and extended central bulge of stars, and dark prominent dust lanes that appear in a disk that we see nearly edge-on. Billions of old stars cause the diffuse glow of the extended central bulge. ... About APOD | ...