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" . ...