... The GIMP currently (version 0.54) supports images with only 8 bits per channel. A channel can be thought of as one of the base colors of Red, Green and Blue (thats an over simplification, but we'll go with that for now) in RGB images or the range of intensities that White will range through in grayscale images. ... With 8 bits to work with, every pixel in a GIMP image occupies at least one byte (or more precisely, one octet) of memory. ... Values in the range of 0 to 255 are possible using 8 bits. ...

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• Lighting plug-in
• APOD: 2005 April 5 - Light from a Distant Planet
• Hands On; Lighting Effects1

... ESO is building what will be the World's largest optical telescope array, The Very Large Telescope (VLT). The VLT Project organisation is responsible for the design and construction of the Unit Telescopes, including enclosures, optics, adapter-rotators and coating unit. ... Unit Telescopes Overview - This page is outdated, an update is in process. ... Secondary mirror (M2 Unit) - This page is outdated, an update is in process. ... Coating Unit - This page is outdated, an update is in process. ...

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Next: *timsort* Up: Timing Analysis Previous: Summary of tasks in . ... Events will be time ordered in the output file. xt> timsort xdata$snr psr ``c 503 513 24'' none A light curve is then generated and plotted so we can inspect the gross properties of the sample (the sequence of good-data intervals and gaps) and any source variability. xt> ltcurv psr none psr 500 xt> ltcplot psr_ltc Finding this sample satisfactory, we search for periodicity with a fast Fourier transform. ...

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• Multi-Rsh parallelized rsh program
• *fold* - Make a folded light curve
• *ltcurv* - Generation of the light curve

Editing Files . The SEARCH command finds text strings in files and displays any lines it finds that match the text string. Two arguments are used: the filenames to be searched and the text strings to be found; wildcards and lists of files can be used to search multiple files, and several text strings can be simultaneously matched--each string is separated by a comma. ... For example: . ... Figure 4.10 shows an example of how the DIFFERENCE command can be used to compare two text files. ...

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• compare_table.pro
• Observing Faint Targets Near Bright Objects
• Surface Brightness of Background Light

In this gallery are many images of Low Surface Brightness Galaxies which have recently been discovered and analyzed. ... The central surface brightness of this galaxy is 24.28 . Malin 2 This galaxy is another huge disk galaxy with a scale length of 15 kpc and a redshift of 15000 km/a. The high surface brightness knot in one of its spiral arms actually has the same color, luminosity and H-alpha equivalent width as the entire Large Magellanic Cloud . ... Truly it is a Low Surface Brightness Galaxy. ...

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• The Galaxy Gallery Page 6: Comparative Morphology
• Galaxy Gallery Page II
• CCD Astronomy Magazine Article Page 4

... Bad Astronomy . Misconceptions . ... Bad Astronomy : "We're light years more advanced than our competition!" ... Even the closest astronomical object, the Moon, is 400,000 kilometers away! ... A beam of light will travel 9,500,000,000,000 kilometers in one year. This distance is defined as a light year ; the distance light travels in a year. ... This is another example of Bad Astronomy; like a light year, a parsec is a unit of distance, not time (to be specific, it equals 3.26 light years) . ...

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• Phil Plait's Bad Astronomy: Bad News
• Phil Plait's Bad Astronomy: Bad TV
• Phil Plait's Bad Astronomy: Q and BA

... The basic Input/Output class in Karma is the ``channel''. ... A channel is a (possibly) full duplex buffered stream of data. ... The remaining lines contain the array data . # include stdio.h # include errno.h # include karma.h # include karma_ch.h # include karma_m.h int main (int argc, char **argv) { Channel channel ; int xlen, ylen, x, y; float * array ; extern char *sys_errlist[]; static char usage_string[] = readfile infile ; if (argc != 2) { fprintf (stderr, Usage ...

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• Common Output Area and Log File
• difx:plotpcal [ATNF VLBI Wiki]
• Luminosity of Stars

... New Stars In 30 Doradus . ... Compare these matched Hubble Space Telescope views (visible-light on top; infrared on bottom) of a region in the star-forming 30 Doradus Nebula. Find the numbered arrows in the infrared image which identify newborn massive stars. ... Gas and dust clouds in 30 Doradus, also known as the Tarantula Nebula, have been sculpted into elongated shapes by powerful winds and ultraviolet radiation from these hot cluster stars. ... Our Galaxy in Stars, Gas, and Dust . ...

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Once students get the hang of it, they can find and measure the brightness of Delta Cephei in a few minutes. ... of Delta Cephei . ... Oct. ... The following table lists the measurements of Delta Cephei made by one amateur astronomer in autumn 1990. ... 4.0 . ... This activity is a simplified version of one that appeared in Hands-On Astrophysics, a series of activities prepared by the American Association of Variable Star Observers with support from the National Science Foundation. << previous page | ...

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• ASP: Light Pollution
• ASP: Accidental Astrophysics: The Devil's In the Magnitudes, Part II
• ASP: An Ancient Universe - The Age of Light from the Most Distant Galaxies

... This thread contains a step-by-step recipe to extract EPIC (pn will be used as an example) light-curves of a point-like source, starting from a calibrated, concatenated event list (either produced with epproc or available as PPS product; it will bear the name: PN.fits in this thread). The content of this thread is the same as Extraction of a X-ray light curve for a point-like source (command-line version). ... in the lccorr GUI window (see Fig.7) define at least the following widgets: . ...

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• Usage Examples
• Light Curve Extraction

November 2006 Astronotes 1 Candles in the Dark Image Credit: Wikipedia.org By Colin Johnston, Science Communicator Since the mid-ninteenth century astronomers have used the principle of parallax to measure the distance to other stars. ... How then can we tell, for example, that M31, the galaxy in Andromeda, is 2.2 million light years away? It would be straight-forward to tell how far away a star was if it was exactly the same brightness as our own Sun. ...

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• NGC4666: Secrets of a Starburst Galaxy | Astronotes

You Can Make Stellar Images Brighter . Articles | ... A few months ago I wrote an article titled "You Can’t Make Them Brighter". So why am I now writing that you can make them brighter. ... The image of a focused star is actually a small disk called the Airy disk, named after the 19 th century scientist Sir George Airy. ... For a given aperture, a smaller Airy disk means that the light is focused to a smaller disk and is therefore brighter. ... www.astronomy.net . About Astronomy Net | ...

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• You Can't Make Stellar Images Brighter - an Astronomy Net Article
• Astronomy Terms - To Help You Study The Universe - an Astronomy Net Article
• Your First Telescope - an Astronomy Net Article

... The nominal output of a CCD--element to a quantum of light can be given as . ... In the following we ignore the pre-flash and skim term, and hence only take the bias and dark frames into account. The objective in reducing CCD frames is to determine the relative intensity of a science data frame. ... flat frames to determine the term . ... This is achieved by averaging Dark, Flat and Science frames. is further reduced if S=F , then Equation ( ) simplifies to . ...

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• Interpreting the output
• Back-Illuminated CCD Imaging Low Light Levels - PixelVision
• Electron bombarded sensors-intro

... Telescopes ћ Binoculars ћ Microscopes . Meade Ultra-High Transmission coatings (UHTC ) Group . ... Meade Standard Coatings: The optical surfaces of all Meade telescopes include high-grade optical coatings fully consistent in quality with the precision of the optical surfaces themselves. ... These specialized, and extremely advantageous, coatings are offered here as the Meade Ultra-High Transmission Coatings (UHTC) group, a coatings group available optionally on many Meade telescope models. ...

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• Meade Sports Optics - How to Select the Right Binocular
• Meade #607 DC Power Cord w/Cigarette Lighter Adapter
• Meade #607 DC Power Cord w/Cigarette Lighter Adapter - Power Supplies and

... It was shown in the early 1980's that spectral lines formed around 1-2.5 x 10 5 K were enhanced in radiance by factors up to 15-25 over the normal quiet Sun. From the dynamical viewpoint, this would suggest a pressure imbalance between the sunspot and the surrounding region. ... Here, the electron density was evaluated over a bright sunspot plume region using lines within the O V 760? multiplet. ... The derived densities in all four regions are indicated. ...

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• Armagh Observatory
• Objects in the Sky
• Abstract

... We describe the software tool bspec which models the dispersion and diffraction of light in the HST Faint Object Spectrograph. ... The HST Faint Object Spectrograph (FOS) uses blazed, ruled gratings and detectors that are sensitive over wide wavelength ranges. ... The program bspec has been developed to model the dispersion and diffraction of light in the FOS with an accuracy sufficient for the estimation of scattered light contamination in observed FOS data. ... We run bspec as follows: . ...

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• A Spectroscopy Exposure Time Calculator for IRAF
• Variable-Pixel Linear Combination

To compare two versions of the same SCCS file: /usr/sccs/sccsdiff -r1.3 -r1.5 s.foo.c SCCS/s.foo.c: 1.3 vs. 1.5 21c21 < static char exname[] = "Template Xternals"; --- > static char exname[] = "Template XTernals"; . This displays a line by line difference between versions 1.3 and 1.5 of the SCCS file s.foo.c which is in the current directory. ... To compare two versions of two or more SCCS files: /usr/sccs/sccsdiff -r1.2 -r1.3 s.part[1-3].c . ...

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• Example of comparing directories with the diff command
• Examples of using pipelines to connect commands
• Examples of changing environment variables: Bourne shell

A computer controlled low light photometer for nightglow observations. Hardware units of portable photometer for low light measurements, especially night glow emission is described. ... Interface card contain three channels of 24 bit counter, 4 channels of 12 bit ADC and the buffer bus for the controlled motors of the altazimuthal fork mounting and filters wheel, the position encoders. ... Where N( ) is output signal photometer generated input light flux F( l ) . ... PMT # . 599 . ...

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• Laboratory static Fourier-spectrometer

grdhisteq - Histogram equalization for grd files grdhisteq in _ grdfile [ -G out _ grdfile ] [ -C n _ cells ] [ -D ] [ -N [ norm ] ] [ -Q ] [ -V ] grdhisteq allows the user to find the data values which divide a given grdfile into patches of equal area. ... One could use grdhisteq to write to stdout an ASCII list of those data values which divide the range of the data into n _ cells segments, each of which has an equal area in the image. ... C Sets how many cells (or divisions) of data range to make. ...

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• UBV light curves (Duerbeck and Walter, 1976)
• UBV light curves (van den Bergh, 1976)
• Nomenclature

... How much brighter is the Sun as viewed from the planet Mercury as compared to Earth ? ... Actually, all of these questions can be answered through a very simple mathematical relationship known as the inverse square law. ... As the distance from the Sun increases the surface area of the sphere grows by the square of the distance. ... Common sense tells us that the Sun will be brighter and the inverse square law tells us how much brighter. ... gr = 0.912 G or 91.2% gravity felt at Earth's surface. ...

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• mod_ext_filter - Apache HTTP Server
• Observing capabilities
• mod_dumpio - Apache HTTP Server