The science dealing with objects and phenomena located beyond Earth. In particular, this applies to observations and data. At its core, astronomy is the physically informed cataloging and classifying of the contents of the universe in order to better understand what is out there.

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How did Kepler arrive at his laws?

How did Kepler arrive at his laws? If one already knows the distances to the planets (and the eccentricity of the orbits etc.) it is understandable how one might proceed to establish the second and ...
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39 views

Classification of small extra-solar system bodies

A Small Solar System Body (SSSB) is an object in the Solar System that is neither a planet, nor a dwarf planet, nor a satellite. This encompasses all comets and all minor planets, as well as all ...
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470 views

Ephemeris calculations: Light time correction of the moon

I am currently trying to calculate apparent positions from raw JPL data. I've got it pretty much figured out, but there is one thing that's bugging me: Has the light time correction of the moon to be ...
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47 views

Import of Celestial Effects on Satellite Radio Interference

Some internet (among other) infrastructure comprises satellites, which beam communications in radio frequencies. These satellites, to ground observers, appear as very small solid angles in the sky. ...
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188 views

Analyse astronomical data

Recently I was told of a job offer to analyse astronomical data. The job offer states that they want somebody with knowledge of astronomical data analysis software and it will be a plus somebody who ...
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39 views

Binary Mass Function Plot

Suppose that we have a circular eclipsing binary system with orbital period of $P = 2 \text{days}$, and with one star with a radial velocity of $v_{1r} = 100 km/s$. The other star is to dim for its ...
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312 views

Why is my approach to the equation of time off by a constant?

I'm trying to better understand the causes for the equation of time by deriving an approximation from first principles. My naive approach, $EOT_{NAIVE}$, is to take the difference between the right ...
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181 views

Suntan: UV absorption vs daytime

I guess that these questions were being asked by many people on the Northern Hemisphere during this summer (and other summers) and someone may give a nice, coherent answer. The general question is how ...
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255 views

Mirrors and light beam divergence technology limits

There are many applications for orbital space mirrors in astronomy (better telescopes) and space propulsion (solar power for deep space probes), but this is limited by the minimum beam divergence ...
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59 views

How do we decode the image formed by a gravitational lens?

Using our own sun as a gravitational lens, we can scrutinise planetary surfaces in distant solar systems with a good deal of accuracy: ...
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76 views

Calculus used by Gauss to find Ceres' position?

With very little data, the great mathematician Gauss was able to predict the exact location of where to find the asteroid Ceres. If possible I would like a reconstruction of his work, from the data ...
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44 views

Why can't Wetterich's “Universe without expansion” be tested compared to standard cosmological redshift?

I have read on several sites that this is a theory that cannot be tested. Why is this a theory that can not be tested? It seems to me that if the mass of particles is continually increasing, then the ...
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41 views

Alma correlator for visible light and for space based telescopes?

I was shocked to see that one can simulate interferometry on a computer like the ALMA Correlator described by this video (posted on Wikipedia's article on ALMA) Is is possible to do the same in ...
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119 views

Maximum-Entropy Method deconvolution implementation?

I am looking for an implementation of the Maximum Entropy Method for image deconvolution, ideally in MATLAB or Mathematica. I'm trying to reconstruct an image from fringe visibilities, as is often ...
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69 views

How to predict Iridium Flare?

I want to find out how to predict Iridium flares, but I don't know where to start. If I know Solar position, Iridium satelites' TLE and it's shape, I need a magnitude(time) function for some place on ...
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133 views

Parallax Cloud Displacement - Angular Distance from Geostationary Satellite

When observing clouds from a geostationary satellite, they appear displaced because of the parallax effect. The satellite looks at the clouds "at an angle" and it projects them on a point of the earth ...
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28 views

What's the evidence, if any, for some local concentration(s) of dark matter in some region(s) smaller than a galaxy?

What's the evidence, if any, for some local concentration(s) of dark matter in some region(s) smaller than a galaxy? Galactic-sized--or larger--gravitating halos seem to get all the attention. I'm ...
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31 views

Milky way rotation data

Can anyone tell me where I can download sample rotation curve data for the Milky Way in csv format?
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38 views

Precession period matching solar year

Consider the case of a tidally locked planet: its axis of rotation must be perpendicular to the plane of its revolution around the parent star. Therefore, no precession. It is possible for a planets ...
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55 views

Gamma ray bursts luminosity measurement

physicists use millisecond fluxes i.e.,fluxes calculated within a very short timescale to measure the actual 1 second flux for these grbs.But to do that they have to multiply the millisecond fluxes ...
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53 views

Where can I get latest full updated list of supernovae candidates from the SDSS-II Supernova Survey?

I am doing a project where I need the list of supernovae candidates from the Sloan Digital Sky Survey II (SDSS-II) supernova survey. One list is available as part of the data-release-7 (DR7) website. ...
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68 views

Elimination of the node

Recently I have been reading a lot of astronomy papers on reductions in models of the solar system. A reoccurring concept is the elimination of the node. However, they never explain what the node is ...
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123 views

Calculating distance to an asteroid on a given day

I'd like to calculate the distance between the Earth and an asteroid at a given date. Is this possible using the data from JPL's small-body database? Is there a better way?
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14 views

Why does the Zodiacal light vary between dawn and dusk?

According to several pages, in the Fall the Zodiacal light is better seen at dawn than at dusk: In the mid-latitudes, the zodiacal light is best observed in the western sky in the spring after the ...
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37 views

Sharpness of starlight

I am interested in argument that the observed lack of blurriness in starlight refutes the "tired light" theories. I have not been able to find this argument expanded in detail. There are two ways ...
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33 views

Sun reaching zenith at a particular latitude

I need to find when the sun reaches the Zenith at a given latitude. What I've done so far: $L=23.5 \cdot \sin(\frac{2\pi}{365.25}\cdot D) $ Here L is the latitude (<23.5) and D is number of days ...
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62 views

Sedna, VP113 and the likelihood of the PX/Tyche/Thelistos hypotheses

The recent discoveries in exoplanetary science (specially those findings of planets orbiting far far away from its parent star/stars) raise questions about how much we know about the (true, AIU ...
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56 views

How to prove the Hubble law is the unique expansion law compatible with homogeneity and isotropy?

In the book physical foundations of cosmology, it saids that Hubble law is unique and a problem seems to be a hint of proving that. In order for a general expansion law,v=f(r,t), to be the same ...
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33 views

How is the formula derived for finding the field of view given drift time and declination of a star?

How is the formula for field of view derived given the drift time of a star and its declination? $FOV = (drift\ time \cdot \cos(declination)\cdot360 ) / 86164$
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19 views

Velocity dispersion of galaxies

I couldn't find on web how can I get the velocity dispersion and velocity maps of galaxies from the 3D data cube I get from integral field spectrograph.
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47 views

When viewed from a telescope, does an object get more magnified if its angular diameter is increased?

and if yes, how can the diameter be increased? Lets say I want to view saturn from a small telescope. Increasing the angular diameter will give a better magnification if the answer to the above ...
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43 views

Estimating the Hubble constant of Virgo Cluster questions?

Im estimating the $H_0$ (Hubble constant) using the calculated distance to galaxy (M100) in the Virgo cluster, but given that the cluster is about 1-2 megaparcecs in diameter, what issues can I expect ...
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60 views

Present experimental status of Moffat's Modified theory of Gravity

Modified theories of Gravity have been discussed before in this 2-year old question, Are modified theories of gravity credible? I was going through Moffat's modified gravity, given in ...
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53 views

How do you calculate the radiant for Kreutz Sungrazer comets? where in the sky do I look?

According to wikipedia: All known members of the [Kreutz Sungrazer] group up until 1965 had almost identical orbital inclinations at about 144°, as well as very similar values for the ...
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77 views

Why is infrared imagery of Mars' surface sharper / richer in contrast than that from the visible spectrum?

Looking at the terrain of Mars through Google Mars, it seems to me that the infrared imagery is much crisper, the images from the visible spectrum seem to be somewhat hazy. I'm wondering if that is ...
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518 views

Map of the gravitational strength of the solar system

I am looking for a map or plot of the gravitational strength in the solar system. In an ideal world there should be something like google earth to move around in the solar system, zoom in and out and ...
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162 views

How do I obtain the Point Spread Function (PSF) of a ground telescope?

I have some galaxy kinematic maps (velocity maps) extracted from Integral Field Spectroscopy (IFS) datacubes. Like any observation data coming from a ground telescope, these velocity maps include (ie: ...
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40 views

Information-theoretic limits in observational astronomy

It seems to me that with ever larger and better telescopes and powerful statistical methods, humans are gleaning surprising amounts of information from observations of distant stars. I am especially ...
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132 views

What is the angular distance between Ptolemaic perigees of Mercury?

In his excellent treatment of the history of the science of astronomical distances and sizes, Albert van Helden says (p.29) that The complicated [Ptolemaic] model of Mercury has the curious ...
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222 views

Is the conclusion that the cosmic burst observed in the Draco constellation from gamma rays that are streaming towards a massive black hole correct?

Referencing this news article: http://www.smh.com.au/technology/sci-tech/cosmic-burst-in-far-away-galaxy-puzzles-nasa-20110408-1d6kz.html It also references an event id: (GRB) 110328A The article ...
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31 views

Algorithm for calculating lunar crescent visibility

Is there a simple algorithm for predicting lunar crescent visibility. Simple enough to do with a calculator at least. Those offered in Meeus' Astronomical Algorithms are a bit too involving to do by ...
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21 views

Simplified calculation to find Lagrange point L1

I'm trying to find the position of Lagrange point L1 in the earth-moon system. To make the whole thing easier (I thought) I don't care about the sun's influence or any other forces than the ...
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15 views

Synthesising types of galaxies using various stellar spectra

I have been given the task of synthesising an elliptical galaxy, a starburst galaxy and a spiral galaxy (considering the arms and the bulge separately and adding them) using stellar spectra which I ...
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19 views

Calculating distance to a binary as well as star pair in cluster, based on reference star data of related spectral class

The problem at hand consists of calculating the absolute magnitude $M_V$ for a B0V type star, then the distance to a binary system with one star A1V and one B0V type star, and finally a star pair ...
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24 views

Recommendations regarding high-energy astrophysical objects (AGNs, jets, etc.)

I know basic astronomy and I know a few good textbooks for general astrophysics (eg. "Introduction to Astrophysics" by Carroll and Ostlie). I also have a strong background in theoretical physics and ...
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47 views

Why are other universes in the picture of Dark Flow?

It seems to me that the popular suggestive explanation of dark flow is another universe interacting with ours. Isn't there other alternative explanations?
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98 views

How fast do large asteroids usually travel?

I have just watched this video made by discovery channel, and you can hear the narrator at 0:51 saying that : "even though it is moving at 720 THOUSANDS kilometers per hour..." I stopped once I heard ...
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69 views

How to measure distances to stars by means of spectroscopic parallaxes?

How to measure distances to stars by means of spectroscopic parallaxes on practice? What is the accuracy of measuring distances using this method compared with distances based on HIPPARCOS ...
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163 views

Reference request: Hollow concave Earth hypothesis

Reference request concerning the Hollow concave Earth hypothesis. I am searching for this paper: A Geocosmos: Mapping Outer Space Into a Hollow Earth authored by M. Abdelkader and published in ...
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105 views

Mass loss rate of planetary nebulae

The “interacting wind” model of planetary nebulae is based on the idea that the white dwarf phase of stellar evolution is preceded by a red giant phase. A fast wind from the hot white dwarf overtakes ...