Questions involving basic astronomical concepts or information.

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4answers
101 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
43 views

Calculate time when star is above altitude 30°

To find the best observation time for an object, I'd like to calculate the time when it is 30° or more above the horizon. Local Sideral Time would be sufficient. To include that in my program, I need ...
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0answers
30 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
22 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
30 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? ...