Questions involving basic astronomical concepts or information.

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4answers
87 views

Image sets for testing stacking algorithms?

I am looking for sets of astronomical images for testing different kinds of stacking algorithms. The idea is simple: if one has $N$ images of the same object, the signal-to-noise ratio of the ...
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1answer
55 views

How to calculate position of an unknown star knowing positions of some other stars from an image?

Suppose I know the coordinates (right ascension and declination) of the stars marked with red. How should I calculate the coordinates of an unknown star, marked with yellow? Searching over the web, ...
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1answer
11 views

Circumstances that would make it impossible to predict a large metorite strike?

Under what circumstances would it be impossible to observe a large meteorite on collision course with Earth, and thus to do anything to prevent or mitigate the consequences of the impact?
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0answers
27 views

Coordinates of the Moon

How does one compute the right ascension and declination of the Moon at a given time (or for that matter, the altitude and azimuth)?
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0answers
21 views

How are errors on X-ray photon index propagated to X-ray spectral index?

I have seen that in X-ray astronomy, astronomers often talk in terms of photon index $\Gamma$, which is related to spectral index $\alpha$ by relation $\Gamma$ = $\alpha$ + 1. Are the errors on ...
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0answers
26 views

What significance does coincidence or luck have in astronomy?

Astronomy is basically about looking around, and what happens to be there is very important for what we are able to discover. To what degree is astronomy shaped by coincidences in our neighborhood? ...