are denoted by the following symbols and may be taken to have the values below Elementary charge Speed of light in vacuum Planck constant Permeability of vacuum Permittivity of vacuum Unified atomic mass constant Rest mass of proton Rest mass of electron Boltzmann constant Avogadro constant Gravitational ... Write down the expression for the gravitational field, g, at distance r from a point mass of mass m, carefully defining all the terms in your expression. ...

... In this talk, I will discuss a study of the effect of ionization on the low end of HI mass function. The existence of a large population of low mass galaxies follows from CDM theory. ... HIDEEP found no low HI column density galaxies. One possible explanation is that the disks are "frozen". ... We assume that galaxies are exposed to an ionizing background radiation, from a uniform quasar distribution. ... We find a gap in the average column densities around N H which drops to 10 17 cm -2 . ...

Next: Young Energetic pulsars Up: A Tutorial on Radio Previous: The population of millisecond . Assuming a thin-screen model, calculate the apparent angular diameter of the Crab pulsar at 600 MHz. Assume that the apparent angular diameter = 100mas at 100 MHz. Calculate the apparent angular diameter at 600 MHz if the screen is located at 1% of the distance from the pulsar to the Earth. ... Calculate the parallax's for pulsars with distances of 100, 500, 1000, 5000, 10000 parsecs. ...

A spherical meteorite of radius 3m enters the Earth's atmosphere at an altitude of 100km and a speed (relative to the Earth) of 30 km/s. The atmosphere slows it down, so when it hits the Earth's surface it is travelling at only 1 km/s. If half of the heat generated as it passes through the atmosphere is absorbed by the meteorite, how hot will it be when it is about to land? ... However, the number I calculated (500,000 K) is correct, as is the discussion that follows it. ...

... We can not observe the Universe when it is 1000 years old because a) there was no matter \b there were not photons \c the universe was opaque to radiation \d the speed of light was still changing at that time \e it had not begun its expansion \m Which of the following is a prediction ... heliocentric model for the Sola r System? \m \a stellar parallax \b retrograde motion \c Venus would never be observed at midnight \d different constellations would be seen at ...

WFC3 Instrument Handbook for Cycle 24 . ... Wide Field Camera 3 Instrument Handbook for Cycle 24 > Appendix A: WFC3 Filter Throughputs > A.2 Throughputs and S/N Ratio Data . ... Note that the plots show the S/N as a function of source magnitude for exposure times as short as 0.1 s, although the minimum exposure time for the UVIS channel is actually 0.5 s. Wide Field Camera 3 Instrument Handbook for Cycle 24 > Appendix A: WFC3 Filter Throughputs > A.2 Throughputs and S/N Ratio Data . ...

Q: Are the magnitudes in the ETCs AB or Vega magnitudes? ... Q: How is the signal to noise defined? A: In optical and infrared imaging, the applications display a signal to noise over the PSF area, which is computed in a circle of radius seeing/plate_scale. ... In optical imaging only, a second signal to noise is computed which is the signal to noise at the central pixel. ... A: The template spectra stored in the database are measured or simulated spectra covering different wavelength range. ...

... By using the tools of sections (20) and (21), the mathematics of approximate solutions developed in (M-5), and assuming all orbits are circles, it is a relatively straightforward job to calculate the distance to the Lagrangian L1 point (or to L2). ... Let the gravitational constant be denoted by G , the mass of the Sun by M , that of Earth by m , the Earth's distance from the Sun by r and its velocity in its orbit by v . ... GMm / r 2 = mv 2 / r . and multiplying both sides by r / m . ...

SAS home . ... List of SAS threads . Let us assume we are working in /home/user/my_work and have our XMM observation data files in /home/user/sasdata/ <my_obs>, where <my_obs> identifies a specific XMM observation. ... 2) Where are stored all the Calibration files? ... That is done by creating a Calibration Index File ( CIF ) which will tell our reduction processes which CCF s we need to use out of all available in SAS_CCFPATH , for the specific date of our observation data. ...

... It is reasonable to expect a priori that the evolution of events is strongly time dependent, so the star formation history in a galaxy is another important parameter. Therefore, by calculating the evolution of events after a -function like star formation burst,   one gets a Green function for any arbitrary star formation history. ... The source evolution in a galaxy with given star formation rate is thus calculated as . ...

Blackholes Forum Message . ... Good Question. ... We really don’t know what causes gravity ( mass properties ) only how it works in the present universe state. ... It may be that you have just proven your assumption is wrong and gravity/mass properties do depend on the present universe state to exist. ... www.astronomy.net . About Astronomy Net | ... Forum posts are Copyright their authors as specified in the heading above the post. "dbHTML," "AstroGuide," "ASTRONOMY.NET" & "VA.NET" . ...

... Great oppositions. ... Proxima Centauri. ... Scientists proved that the problem of preserving the Earth's climate and the annual change of seasons can be solved by a small star, negligible mass, but similar to a main-sequence star, moving in a circular orbit around the Sun. ... Sombrero Galaxy. The Sombrero Galaxy, M104, is known as a holder of one of supermassive black holes. ... Roughly estimate the approximate mass of the supermassive black hole in the center of M104 (answer in solar masses m). ...

... spectrum . ... SPECTRUM will compute synthetic spectra, line profiles equivalent widths, specific intensities, assuming LTE, from model atmospheres of early-type stars. ... sterne models . file containing model atmosphere in 2006 Sterne format . ... T=25000, log g=4.0, vt=0, 1400-1415A. a) NLTE model atmosphere, spectrum computed with SYNSPECv25 (black). b) LTE model atmosphere, same linelist in converted format, spectrum computed with SPECTRUM (red) using this input file and this linelist . ...

... To rephrase [the question]: if you have a ?7.5 sigma? feature, with a day-long [imaging Markov Chain Monte Carlo] run you can only show that it is ?>3sigma?, but is it possible, even with that day-long run, to tell that the feature is really at 7.5sigma ? ... Category: CHASC , Cross-Cultural , Data Processing , Imaging , MC , Quotes , Stat | ... Category: Data Processing , Frequentist , Imaging , Methods , Misc , Quotes , Stat , Timing | ... Category: Data Processing , Imaging , Quotes , Spectral | ...

Main . ... About meteorites . ... What to do if you found a meteorite! ... About the laboratory . ... You may have a question: what to do if you found a stone which looks like meteorite. ... According to the Meteorite Nomenclature Committee, in order for a meteorite to be officially registered in the International Meteorite Catalog, 20% by weight of the main mass of the identification sample must be contributed to a qualified scientific organization. ... The Staff of the Laboratory of Meteoritics. ...

... The Big Dipper . ... This common question frequently precedes the rediscovery of one of the most commonly recognized configurations of stars on the northern sky: the Big Dipper. ... But near local midnight on April 11, this mosaic of 3 minute long exposures revealed a green, unusually intense, atmospheric airglow stretching over thin clouds. ... This skyscape finds an esthetic balance of interstellar dust and gas residing in the suburbs of the nebula rich constellation of Orion. ... April . ...

... We present a computer program for modelling energy flux distribution and light curves of eclipsing binaries from far ultraviolet to infrared regions. The Roche model is assumed. Proximity effects of components (reflection of radiation and surface gravity darkening) are taken into account. ... Figure 1: The surface temperature distribution for Algol A-B system before (upper plot) and after (lower plot) correction for temperature due to the irradiation effect. ...

... Hi, As I read in that introduction a network device driver has to alloc a sk_buff in it's ISR and this has to happen atomically, isn't it? ... So my idea was I alloc a few sk_buff's (with GFP_KERNEL flag) in the device drivers open function. The device driver would organize these sk_buff's as ring. Else the device driver must forbid the higher layer to free the sk_buff's. Is this possible just by setting the lock flag inside sk_buff? ... Re: Question on alloc_skb() by Erik Petersen . ...

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