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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29 views

How to practically find the RA-DEC coordinates of a star?

How are RA-DEC (Right Ascension & Declination) coordinates of a star measured i.e. if scientist spot a new star in the sky how do they accurately measure it's coordinates?
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123 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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351 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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37 views

Our universe the surface of a 4-dimensional sphere?

The cosmic microwave background that we observe uniformly around us is usually explained by assuming that our universe is the surface of a four dimensional sphere. That way the uniformity makes sense ...
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266 views

Calculate the latitude / longitude coordinates of the location where the Sun is at the zenith

There are plenty of resources showing how to calculate zenith and azimuth of the Sun when the time and the location are given. However, I need to calculate the location where the sun is at the ...
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48 views

Sun's Right Ascension appears to be wrong in my Stellarium

The Stellarium version 0.12.4 I have shows the RA of the sun at 22.5 Hour while Google says it is 19h 4m 31s. I am confused. Please help.
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288 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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119 views

Does it make sense to continue searching for dark matter on Earth?

The Large Underground Xenon Detector (LUX) recently released results1 that they have found no signs of dark matter2 after a ~3 month search this spring and summer. The LUX group plans to spend all of ...
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130 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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237 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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194 views

Future space-based telescope array

Radio-telescopes (e.g. the Very Large Array (VLA)) can simulate one gigantic dish by using separate smaller dishes. Q: Could such an array of optical telescopes potentially see an exoplanet at say 20 ...
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37 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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39 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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32 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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84 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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56 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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119 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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30 views

How to measure the effects of the rotation around the Sun?

It is well know that we can measure the spinning of the Earth with a Foucault pendulum. But, is there a similar experiment for the rotation of the Earth around the Sun? I would like to know if we ...
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25 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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27 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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34 views

What is the origin and nature of the “hydrogen envelope” located on the sun side of a comet coma?

It is tempting to assume the origin of the hydrogen is water vapor from the comet, in which case, what process "breaks up" the water molecule (or perhaps ammonia molecule?)? Is the hydrogen actually ...
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66 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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59 views

Could a Class A Stellar Engine Use A Brown Dwarf

Could a class A stellar engine (or maybe a class C one) be built using a brown dwarf (for argument's sake, a T-dwarf like Gliese 229B)? Would it be capable of enough thrust to move itself any ...
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104 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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40 views

Radial and tangential velocities of a star

(source) Early in this piece it states that the radial and tangential velocities are: $$V_r = V_c \cos(\alpha) -V_{c,0} \sin (l)$$ $$V_t = V_c \sin(\alpha) -V_{c,0} \cos (l)$$ but I am struggling ...
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26 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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13 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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37 views

Calculus used by Gaus to find Ceres' position?

With very little data, the great mathematician Gauss was able to predict the exact location of where the asteroid Ceres, having only few data. If possible I would like-a-reconstruction of his work, ...
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44 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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37 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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44 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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30 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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44 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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62 views

equatorial-supergalactic conversion

What are the conversion formulas from equatorial to supergalactic coordinate system. Thanks for any help.
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71 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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336 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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128 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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34 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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129 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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219 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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21 views

Is there a simple formula for calculating semimajor axis bounds of “habitable zone”?

I understand that an accurate determination of the bounds of the "habitable zone" for a given stellar system depends on a large number of factors, including many beyond characteristics of the parent ...
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77 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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55 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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37 views

Equation for a galaxy's overall gravitational pull?

Can the Newton's formula be used to express $g$ between two Galaxies in proximity. Gravity on Earth uses two concepts, one is the radius (R) of earth and the other is the distance (h) from the ...
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140 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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54 views

How to calculate max/min Right Ascension and Declination in telescope field of view

I have a telescope with focal length 1200mm. My camera has 5184x3456 pixels with size 4.3um. This combination should give me a resolution of 0.74"/pixel and thus a field of view of 1.06° x 0.71°. ...
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35 views

Are there any programs or codes widely used for computing spherical multipole expansion, especially for CMB?

I have data of coordinates and values of a part of sky, and I'm supposed to calculate multipole expansion, change some components between some $\ell$s, and finally calculate back to values. The ...
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21 views

How I can measure the statistical errors of my catalog in Astronomy

I have a catalog including information about position, magnitude, and redshift of galaxies in one patch of sky. I need to be sure about the complementary of my catalog about detecting objects. How I ...
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95 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 ...