Questions involving basic astronomical concepts or information.

learn more… | top users | synonyms (1)

1
vote
3answers
146 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 ...
1
vote
2answers
103 views

What is the effect of the axial precession on the orientation of the planet's orbits?

I am working on an online application to visualize the positions of the planets and to calculate their ephemerides (you find it here, but it is not complete yet). I do not have much knowledge in ...
1
vote
1answer
55 views

Equation of the Center constant factor

This questions concerns the longitudinal aspect of the Equation of Time, also called the Equation of the Center. In some sources the equation looks like the following: $\nu - M = 2\varepsilon \sin M$ ...
1
vote
1answer
61 views

K-Pg asteroid impact

Is it possible to determine what daytime the Chicxulub impactor striked the Earth 66 mya? Was it day or night, what was the current phase of the Moon etc.? Can sediments, rhytmites or something else ...
3
votes
0answers
41 views

What is meant by ionization states?

I am going through the theory of saha equation but I am not able to understand the concept of ionisation state? What are ionization states actually?
1
vote
0answers
52 views

Planetary reference systems and time

I am researching into how coordinate systems of solar systems objects are created by reading some of the reports written by the Working Group on Cartographic Coordinates and Rotational Elements (e.g. ...
1
vote
0answers
41 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)?
0
votes
0answers
14 views

Where can I find the DR12 SDSS dataset in their website

I have to cross-match the SDSS DR12 dataset with that of GALEX but apparently I cannot find the fits document which has the same field as that in GALEX. I have explored the website but I couldn't find ...
0
votes
0answers
8 views

IDL (particularly GBTIDL) velocity axis explanation?

I have been working with GBTIDL (the Green Bank Telescope version of IDL I suppose) to look at some spectra, and in addition to having the x-axis be frequency or wavelength, you can also have it in ...
0
votes
0answers
42 views

Converting ecliptical to equatorial coordinates

When looking for a formula to convert polar ecliptic geocentric coordinates of an object to equatorial coordinates I find various sources that give these formulae (like Wikipedia): Declination $δ = \...